Immediate repair of intestinal injury during laparoscopically assisted vaginal hysterectomy

With the increasing popularity of laparoscopic surgery in gynecologic diseases, complications with this procedure are noted more frequently. The majority of complications occur during operation, and most of the cases are immediately identified. The recovery and outcome are relatively good due to urgent repair and management. Herein, we report a complication--a trocar, inducing small intestinal damage, which was detected during laparoscopically assisted vaginal hysterectomy. The damage was repaired promptly extraperitoneally with an uneventful recovery. Through a review of the literature and our experience, possible preventive methods of this complication are discussed. In addition, by this case review, we hoped that such a complication could be avoided in the future.

Impact of assisted reproductive technology on modern medicine

A surge in knowledge and interest in reproductive biology has occurred since the advent of assisted reproductive technology (ART) in the 1960s. These innovative medical advances soon challenged societies and invited criticism. Nevertheless, ART has superseded older therapies and serves as a back-up when all else fails. There are currently 61 ART clinics in Taiwan. Thanks to a group of young physicians and scientists who have devoted great effort in catching up with the modern advances in assisted reproduction, most of the important advances in ART have been introduced to Taiwan promptly and resulted in good success rates. The complications of multifetal pregnancies as well as controversies regarding gestational surrogacy and new technologies such as intracytoplasmic sperm injection, preimplantation genetic diagnosis, and cloning have challenged conventional wisdom, ethics, laws, and religions. Society now faces a dilemma in striking a balance among science, ethics, and human rights. It is, thus, advisable that we stand back once in a while and carefully consider where we should go next.

Nitric oxide synthase inhibitor ameliorates oral total parenteral nutrition-induced barrier dysfunction

The expression of inducible nitric oxide synthase (iNOS) is increased in the intestine and results in mucosal damage after endotoxin challenge. Although the oral administration of total parenteral nutrition (TPN) solution promotes bacterial translocation (BT) and increases the intestinal permeability, the role of NO in the nutrition-induced loss of mucosal barrier function remains unclear. The distribution of fluorescein isothiocyanate-dextran (FITC-dextran, 4400) across the lumen of small intestine in rat was examined to investigate the role of NOS activity on the intestinal permeability under oral TPN feeding. Fifty-one rats were randomly divided into 4 groups. Group I (control group) was fed with rat chow, group II received TPN solution orally. Groups III and IV received TPN solution supplemented with NOS inhibitors. On day 9, FITC-dextran was injected into the intestinal lumen. After 30 min, blood samples were taken from portal vein and analyzed for plasma FITC-dextran level by fluorescence spectrophotometry. Samples of small intestine were frozen and sectioned in a cryostat for morphological and NOS histochemical studies. Homogenates of small intestine were used for NOS activity measurement. The plasma level of FITC-dextran showed a significant increase (P < 0.05) in rats fed with oral TPN compared with the control ones. Supplement with NOS inhibitors significantly decreased the intestinal permeability in groups III and IV compared with group II. Similarly, the total NOS activities showed a significant 2-fold increase (P< 0.05) in group II, and NOS inhibitors decreased the elevated NOS activity. These data suggest that oral TPN feeding for 9 days leads to an increase in permeability to dextran and the total NOS activity of small intestine, and both induction of the intestinal permeability and NOS activity were inhibited by treatment with NOS inhibitors. Addition of S-methylisothiourea (SMT), an iNOS selective inhibitor, profoundly inhibited 66% of the induced iNOS activity (P < 0.05) and reduced 74% of the diet-induced increase in intestinal permeability (P < 0.05) in group II. The induced permeability change in rats receiving oral TPN is mainly due to the activity of intestinal mucosal iNOS. The induction of iNOS is an important mediator for intestinal barrier dysfunction. Administration of SMT, which specifically decreases iNOS activity, is useful in the prevention of diet-induced barrier failure.

[Ribozyme which specifically cleave 12-lipoxygenase mRNA: in vitro activity and its dynamics]

The ribozyme gene which specifically cleaved 12-lipoxygenase mRNA was designed, synthesized and cloned according to hammer-head ribozyme model. A 25-bp-long segment of 12-lipoxygenase mRNA was chemically synthesized as substrate, which was incubated with transcribed ribozyme RNA to detect its cleavage activity in vitro. The results showed that the ribozyme had a relatively high cleavage activity against 12-lipoxygenase mRNA segment at 37 degrees C. It's kcat value and Km value was 0.083/min and 1300 nmol/L respectively. The ribozyme had a very high activity at 50 degrees C and its kcat value was 0.31/min.

Lighting direction affects recognition of untextured faces in photographic positive and negative

Face recognition in photographic positive and negative was examined in a same/different matching task in five lighting direction conditions using untextured 3-D laser-scanned faces. The lighting directions were +60, +30, 0, -30 and -60 degrees, where negative values represent bottom lighting and positive values represent top lighting. Recognition performance was better for faces in positive than in negative when lighting directions were at +60 degrees. In one experiment, the same effect was also found at +30 degrees. However, faces in negative were recognized better than positive when the direction was -60 degrees. There was no difference in recognition performance when the lighting direction was 0 and -30 degrees. These results confirm that the effect of lighting direction can be a determinant of the photographic negative effect. Positive faces, which normally appear to be top-lit, may be difficult to recognize in negative partly because of the accompanying change in apparent lighting direction to bottom-lit.

Enterovesical fistula: experiences with 41 cases in 12 years

BACKGROUND

A retrospective analysis of enterovesical fistula treated at Chang Gung Memorial Hospital was conducted to determine the optimal diagnosis and management of this disease.

METHODS

The records of 41 patients who presented from 1984 to 1996 and had a final diagnosis of enterovesical fistula were retrospectively reviewed. The etiology, symptoms on presentation, diagnostic tools, and modality of treatment were analyzed.

RESULTS

The majority of these cases were associated with malignancy (38, 92.7%), and the others with diverticulitis (2, 4.9%) and iatrogenic causes (1, 2.4%). In those with malignancy, 15 patients (39.5%) were found to have tumor recurrence. The most frequent symptom in enterovesical fistula was fecaluria (58.5%), followed by abdominal pain (22%) and dysuria (14.6%). Diagnostic tools included the barium enema, cystography, and cystoscopy; these methods could identify the fistula in 63.2%, 60%, and 53.8% of the patients, respectively. Methods of management included diversion only (39%), one-stage fistula repair (36.6%), and watchful surveillance (24.4%).

CONCLUSION

Enterovesical fistula should be considered if fecaluria, pneumaturia, or persistent non-specific urinary tract infection present as the initial complaint. A thorough surgery for a possible underlying malignancy is mandatory when confronted with enterovesical fistula, since the incidence of inflammatory bowel disease is low in this area. An abdominal computer tomography (CT) scan, barium enema, and cystogram can be useful diagnostic tools. Treatment of this entity should be individualized according to each patients clinical status.

Vascular endothelial cell adherens junction assembly and morphogenesis induced by sphingosine-1-phosphate

Vascular endothelial cells undergo morphogenesis into capillary networks in response to angiogenic factors. We show here that sphingosine-1-phosphate (SPP), a platelet-derived bioactive lipid, activates the EDG-1 and -3 subtypes of G protein-coupled receptors on endothelial cells to regulate angiogenesis. SPP induces the Gi/mitogen-activated protein kinase/cell survival pathway and the small GTPase Rho- and Raccoupled adherens junction assembly. Both EDG-1-and EDG-3-regulated signaling pathways are required for endothelial cell morphogenesis into capillary-like networks. Indeed, SPP synergized with polypeptide angiogenic growth factors in the formation of mature neovessels in vivo. These data define SPP as a novel regulator of angiogenesis.

Sphingosine-1-phosphate: extracellular mediator or intracellular second messenger?

Sphingosine-1-phosphate (SPP), a polar sphingolipid metabolite, has received much attention recently as an extracellular mediator and an intracellular second messenger. It regulates a wide range of biological responses such as cell growth, death, differentiation, and migration. Recent identification of plasma membrane receptors and the cloning of SPP metabolizing enzymes have increased our understanding of the biology of SPP synthesis and action. However, controversy exists regarding the mode of action of this molecule. EDG-1 and related G-protein-coupled receptors were identified recently as plasma membrane receptors for SPP. In light of this recent discovery, many of the functions of SPP previously thought to be due to intracellular second messenger action should be reevaluated. In addition, signaling properties and functions of the three known receptors for SPP need to be fully delineated. The structures and the evolutionary conservation of SPP metabolizing enzymes from yeast to mammals support the hypothesis that SPP also plays a role as an intracellular second messenger. However, definitive assignment of the intracellular role of SPP awaits purification/molecular cloning of elusive intracellular receptors. Better knowledge of the molecular basis of SPP action is needed to assess the physiological and pathophysiological significance of this bioactive lipid mediator.

Development of spatial and temporal vision during childhood

Using the method of limits, we measured the development of spatial and temporal vision beginning at 4 years of age. Participants were adults, and children aged 4, 5, 6, and 7 years (n = 24 per age). Spatial vision was assessed with vertical sine-wave gratings, and temporal vision was assessed with an unpatterned luminance field sinusoidally modulated over time. Under these testing conditions, spatial contrast sensitivity at every frequency increased by at least 0.5 log units between 4 and 7 years of age, at which point it was adult-like. Grating acuity reached adult values at 6 years of age. Temporal vision was more mature: at 4 years of age temporal contrast sensitivity at higher temporal frequencies (20 and 30 Hz) and critical flicker fusion frequency were already adult-like. Sensitivity at lower temporal frequencies (5 and 10 Hz) increased by 0.25 log units after the age of 4 to reach adult levels at age 7. The results suggest that temporal vision matures more rapidly than spatial vision during childhood. Thus, spatial and temporal vision are likely mediated by different underlying neural mechanisms that mature at different rates.

Are there qualitative differences between face processing in photographic positive and negative?

The question whether face recognition in photographic negative relies more on external features and pictorial cues than in photographic positive was studied in five experiments. Recognition of whole faces as well as both external and internal features of the faces was compared in experiments 1 and 2. The conditions in which views of faces between learning and test were either identical (hence providing maximum pictorial cues) or different (hence reducing such cues) were compared in experiments 3, 4, and 5. The results showed that recognition of internal features in two-tone and multi-tone images suffered more from use of photographic negatives than recognition of external features. Testing with both multi-tone and two-tone images revealed that the deficit caused by view changes between learning and test was no more severe with negatives than with positives. Finally, removing external features made recognition of different views equally more difficult for positives and negatives. Overall, these results point to a qualitative rather than quantitative difference between processing face images in photographic positive and negative.

Cyclooxygenase-1 and -2 isoenzymes

The cyclooxygenase isoenzymes (COX-1 and -2) catalyze the rate-limiting steps in prostanoid biosynthesis. COX-1 and -2 genes encode two isoenzymes with overlapping yet distinct expression patterns and functions. Physiologically, various extracellular stimuli such as growth factors, cytokines and tumor promoters regulate the expression of COX-1 and -2 genes at both transcriptional and post-transcriptional levels. COX-2 is overexpressed in rheumatoid arthritis, colorectal and breast cancer. Prostanoids produced by the COX pathway signal via plasma membrane-localized, G-protein-coupled receptors as well as via nuclear receptors. Currently, several COX-2-selective inhibitors are developed to control the anti-inflammatory and anti-neoplastic activities of the COX-2 isoenzyme. Inhibition of the COX isoenzyme activity and/or expression may be the basis of future generation of anti-inflammatory and anti-neoplastic drugs.

Efficiency of supercritical fluid extraction for determining 4-nonylphenol in municipal sewage sludge

When the sewage sludge containing the persistent, lipophilic, metabolite 4-nonylphenol (4-NP) has been disposed of in the environment it's toxic nature can lead to serious health risks to human beings and can also affect plants and aquatic organisms. Supercritical fluid extraction (SFE) is a new and powerful technique for extracting the organic contaminants from the solid phase. The present study was conducted to investigate optimal conditions for the quantitative extraction of 4-NP by SFE and to determine the concentration of 4-NP in municipal sewage sludge. The effect of several parameters such as temperature, pressure, static extraction time, dynamic extraction time, CO2 flow-rate, sample mass and modifier on the extraction were investigated. The optimal conditions for the extraction of the spiked sample were fluid pressure 97 bar, temperature 40 degrees C, flow-rate 3.0 ml/min, static extraction time 2 min, dynamic extraction time 5 min and modifier methanol (0.5 ml). Extracts were analyzed by gas chromatography-mass spectrometry. Concentration of 4-NP in the anaerobically degraded sludge of the De-Haw Sewage Treatment Plant in Taiwan was found to be 243.9 mg/kg. The extraction efficiency of the SFE method was compared with the conventional Soxhlet extraction method. The overall recovery of the SFE method was found to be greater and the results indicate that SFE is an efficient method for extracting 4-NP from sewage sludge.

Ligand-induced trafficking of the sphingosine-1-phosphate receptor EDG-1

The endothelial-derived G-protein-coupled receptor EDG-1 is a high-affinity receptor for the bioactive lipid mediator sphingosine-1-phosphate (SPP). In the present study, we constructed the EDG-1-green fluorescent protein (GFP) chimera to examine the dynamics and subcellular localization of SPP-EDG-1 interaction. SPP binds to EDG-1-GFP and transduces intracellular signals in a manner indistinguishable from that seen with the wild-type receptor. Human embryonic kidney 293 cells stably transfected with the EDG-1-GFP cDNA expressed the receptor primarily on the plasma membrane. Exogenous SPP treatment, in a dose-dependent manner, induced receptor translocation to perinuclear vesicles with a tau1/2 of approximately 15 min. The EDG-1-GFP-containing vesicles are distinct from mitochondria but colocalize in part with endocytic vesicles and lysosomes. Neither the low-affinity agonist lysophosphatidic acid nor other sphingolipids, ceramide, ceramide-1-phosphate, or sphingosylphosphorylcholine, influenced receptor trafficking. Receptor internalization was completely inhibited by truncation of the C terminus. After SPP washout, EDG-1-GFP recycles back to the plasma membrane with a tau1/2 of approximately 30 min. We conclude that the high-affinity ligand SPP specifically induces the reversible trafficking of EDG-1 via the endosomal pathway and that the C-terminal intracellular domain of the receptor is critical for this process.

Molecular characterization of germline mutations in the BRCA1 and BRCA2 genes from breast cancer families in Taiwan

A total of 18 families with multiple cases of breast cancer were identified from southern Taiwan, and 5 of these families were found to carry cancer-associated germline mutations in the BRCA1 and BRCA2 genes. One novel cryptic splicing mutation of the BRCA1 gene, found in two unrelated families, was shown to be a deletion of 10 bp near the branch site in intron 7. This mutation causes an insertion of 59 nucleotides derived from intron 7 and results in a frameshift, leading to premature translational termination of BRCA1 mRNA in exon 8. Deletions of 2670delC, 3073delT and 6696-7delTC in the BRCA2 gene were found in three other breast cancer families. All three deletions are predicted to generate frameshifts and to result in the premature termination of BRCA2 protein translation. Several genetic polymorphisms in both BRCA1 and BRCA2 genes were also detected in this investigation.

High-performance liquid chromatographic method for determination of tramadol in human plasma

A modified high-performance chromatographic method using UV detection was developed for determination of tramadol concentration in human plasma. Plasma samples were extracted with ethyl acetate in a one-step liquid-liquid extraction (recovery 88.5+/-2.1%). Analysis of the extract was performed on a reversed-phase LiChrospher 60 RP-select B column with a particle size of 5 microm. The mobile phase consisted of 0.05 M KH2PO4 aqueous solution (pH 3.5) and acetonitrile in a ratio of 90:10 (v/v). Metoprolol was used as the internal standard and UV detection at 225 nm was employed. Accuracy of the assay in the concentration range examined was from 1.3 to 11.9% for the intra-day run and from 1.4 to 8.1% for the inter-day run. The precision of this method varied from 1.2 to 8.7%. The reproducibility of the method was determined to be from 0.8 to 7.2% over the six-day period. A limit of detection was 9 ng/ml at a signal-to-noise ratio of 3. This validated method was then applied to the determination of tramadol concentrations in healthy volunteers after oral administration of 100 mg of tramadol in capsules of Painlax and Tramal.

Studies on the determination of diacetyl guanfubase A concentration in rabbit plasma and pharmacokinetics

A gas chromatographic method for monitoring diacetyl guanfubase A in plasma is described. The procedure involved a single solvent extraction of drug from rabbit plasma into ethyl acetate with guanfubase A as an internal standard. The extract was analyzed subsequently on a gas chromatograph equipped with a hydrogen flame ionization detector. The recovery was 86.43% +/- 6.90% (+/- SD); the RSD of within-day and between-day was 2.81%-5.26% and 5.22%-8.24%, respectively; the regression line was linear over the concentration range of 25-200 micrograms/mL, the limit of detection was 10 micrograms/mL. No endogeneous interference was found in chromatograms of the biological samples. This method was applied to the pharmacokinetic study of diacetyl guanfubase A in rabbits.

Surgical and pathologic observations of epididymal tubules during microscopic epididymal sperm aspiration for intracytoplasmic sperm injection

Microscopic epididymal sperm aspiration (MESA) for sperm retrieval and intracytoplasmic sperm injection (ICSI) is currently our routine treatment for selected male patients with obstructive azoospermia. In order to refine the surgical technique and obtain better quality sperm for our assisted reproductive technology program, we observed the epididymal tubules in 40 sessions of surgical exploration of the epididymis for sperm aspiration. Epididymal tubules with long-term obstruction could be divided into three groups on the basis of clinical observations and pathology findings: markedly dilated, mildly dilated, and nondilated. All of the markedly dilated epididymal tubules (grade III, n = 10) were azoospermic and ICSI could not be done. Epididymal sperm obtained from the mildly dilated tubules (grade II, n = 9) resulted in poorer fertilization (49%) and pregnancy (33%) rates than sperm obtained from nondilated epididymal tubules (grade I, n = 21, fertilization rate 72%, pregnancy rate 57%). These findings demonstrate that nondilated epididymal tubules are best for sperm retrieval and successful ICSI. We believe this observation will be a good surgical parameter for urologic surgeons performing MESA.

The actin cytoskeleton and integrin expression in the recovery of cell adhesion after oxidant stress to a proximal tubule cell line (JTC-12)

This study examines the role of the actin cytoskeleton and integrin expression in the recovery of cell adhesion in the proximal tubule cell line JTC-12 after peroxide injury. The cells were exposed to 10, 20, or 50 mM hydrogen peroxide for 10 min and then allowed to recover. Viability measurements by trypan blue exclusion confirmed that the injury was largely nonlethal with 85% viability at 1 h even at 50 mM peroxide. ATP levels fell immediately after the peroxide incubation in all groups to approximately 10% of normal, but already showed some recovery by 1 h and full recovery in the 10 and 20 mM groups by 24 h. Cell adhesion to extracellular matrix immediately after injury was depressed at 20 and 50 mM peroxide, but by 12 h was abnormal only at 50 mM peroxide and at 24 h was essentially normal at all peroxide concentrations. Immediately after exposure to 10 mM peroxide, there were subtle abnormalities in the actin cytoskeleton (thickening of fibrils) as assessed by phalloidin staining, with more pronounced effects at 20 and 50 mM. At 1 h, many cells showed collapse of the actin cytoskeleton to the periphery. There was some recovery at 4 h; by 12 h, the actin cytoskeleton showed further recovery, although was still abnormal (coarsened microfilaments), especially at 20 and 50 mM peroxide. By 24 h, the actin cytoskeleton showed only subtle coarsening. Integrin surface expression was assessed by flow cytometry. The alpha6 subunit on cells exposed to 20 mM peroxide was unchanged at 1 h and 4 h, but by 12 h had increased to 118.5+/-4.5% and by 24 h to 146+/-13.4% of control levels. The expression of the beta1 and alphaVbeta3 integrins remained unchanged. Thus, despite coarsening of the actin cytoskeleton and depressed ATP levels, cell adhesion recovered from oxidant stress. Abnormal cell adhesion after injury was not a consequence of a decrease in integrin expression, and recovery of cell adhesion was not a consequence of the modest and selective increase in integrin expression.

Lysophosphatidic acid stimulates the G-protein-coupled receptor EDG-1 as a low affinity agonist

EDG-1, an inducible G-protein-coupled receptor from vascular endothelial cells, is a high affinity receptor for sphingosine 1-phosphate (SPP) (Lee, M-J., van Brocklyn, J. R., Thangada, S., Liu, C. H., Hand, A. R., Menzeleev, R., Spiegel, S., and Hla, T. (1998) Science 279, 1552-1555). In this study, we show that lysophosphatidic acid (LPA), a platelet-derived bioactive lipid structurally related to SPP, is an agonist for EDG-1. LPA binds to EDG-1 receptor with an apparent Kd of 2.3 microM. In addition, LPA binding to EDG-1 induces receptor phosphorylation, mitogen-activated protein kinase activation, as well as Rho-dependent morphogenesis and P-cadherin expression. These data suggest that LPA is a low-affinity agonist for EDG-1. Activation of the endothelial receptor EDG-1 by platelet-derived lipids LPA and SPP may be important in thrombosis and angiogenesis, conditions in which critical platelet-endothelial interactions occur.

Dual actions of sphingosine-1-phosphate: extracellular through the Gi-coupled receptor Edg-1 and intracellular to regulate proliferation and survival

Sphingosine-1-phosphate (SPP), a bioactive lipid, acts both intracellularly and extracellularly to cause pleiotropic biological responses. Recently, we identified SPP as a ligand for the G protein-coupled receptor Edg-1 (Lee, M.-J., J.R. Van Brocklyn, S. Thangada, C.H. Liu, A.R. Hand, R. Menzeleev, S. Spiegel, and T. Hla. 1998. Science. 279:1552-1555). Edg-1 binds SPP with remarkable specificity as only sphinganine-1-phosphate displaced radiolabeled SPP, while other sphingolipids did not. Binding of SPP to Edg-1 resulted in inhibition of forskolin-stimulated cAMP accumulation, in a pertussis toxin-sensitive manner. In contrast, two well-characterized biological responses of SPP, mitogenesis and prevention of apoptosis, were clearly unrelated to binding to Edg-1 and correlated with intracellular uptake. SPP also stimulated signal transduction pathways, including calcium mobilization, activation of phospholipase D, and tyrosine phosphorylation of p125(FAK), independently of edg-1 expression. Moreover, DNA synthesis in Swiss 3T3 fibroblasts was significantly and specifically increased by microinjection of SPP. Finally, SPP suppresses apoptosis of HL-60 and pheochromocytoma PC12 cells, which do not have specific SPP binding or expression of Edg-1 mRNA. Conversely, sphinganine-1-phosphate, which binds to and signals via Edg-1, does not have any significant cytoprotective effect. Thus, SPP is a prototype for a novel class of lipid mediators that act both extracellularly as ligands for cell surface receptors and intracellularly as second messengers.

Wiskott-Aldrich syndrome protein-deficient mice reveal a role for WASP in T but not B cell activation

The Wiskott-Aldrich syndrome (WAS) is a human X-linked immunodeficiency resulting from mutations in a gene (WASP) encoding a cytoplasmic protein implicated in regulating the actin cytoskeleton. To elucidate WASP function, we disrupted the WASP gene in mice by gene-targeted mutation. WASP-deficient mice showed apparently normal lymphocyte development, normal serum immunoglobulin levels, and the capacity to respond to both T-dependent and T-independent type II antigens. However, these mice did have decreased peripheral blood lymphocyte and platelet numbers and developed chronic colitis. Moreover, purified WASP-deficient T cells showed markedly impaired proliferation and antigen receptor cap formation in response to anti-CD3epsilon stimulation. Yet, purified WASP-deficient B cells showed normal responses to anti-Ig stimulation. We discuss the implications of our findings regarding WASP function in receptor signaling and cytoskeletal reorganization in T and B cells and compare the effects of WASP deficiency in mice and humans.

Face recognition with multi-tone and two-tone photographic negatives

The effects of photographic negatives on face recognition are often studied in two different ways--faces are learned and tested in photographic negatives (NN) or the contrast is reversed between learning and testing, i.e. they are learned in positives and tested in negatives (PN) or vice versa (NP). We have examined recognition performance for faces under these three conditions along with a control condition where faces were learned and tested in positives (PP). Using multi-tone face images, we found that the effect of photographic negatives was more pronounced in PN and NP than in NN. No differences were found between PN and NP or between NN and PP. When two-tone face images were used, recognition performance was worse in all conditions, except PP, when compared to the multi-tone counterparts. Our results show that contrast incongruency between learning and testing is the predominant factor affecting performance and that deficits in sensory coding or retention of negative face images are unlikely to be major factors. The advantage of multi-tone over two-tone negatives can be attributed to preserved facial information carried by the high-spatial-frequency components of the image.

Evidence against the Bm1P1 protein as a positive transcription factor for barbiturate-mediated induction of cytochrome P450BM-1 in bacillus megaterium

The Bm1P1 protein was previously proposed to act as a positive transcription factor involved in barbiturate-mediated induction of cytochrome P450BM-1 in Bacillus megaterium. We now report that the bm1P1 gene encodes a protein of 217 amino acids, rather than the 98 amino acids as reported previously. In vitro gel shift assays indicate that the Bm1P1 protein did not interact with probes comprising the regulatory regions of the P450BM-1 gene. Moreover, disruption of the bm1P1 gene did not markedly affect barbiturate induction of P450BM-1 expression. A multicopy plasmid harboring only the P450BM-1 promoter region could increase expression of the chromosome-encoded P450BM-1. The level of expression is comparable with that shown by a multicopy plasmid harboring the P450BM-1 promoter region along with the bm1P1 gene. These results strongly suggest that the Bm1P1 protein is unlikely to act as a positive regulator for barbiturate induction of P450BM-1 expression. Finally, deletion of the Barbie box did not markedly diminish the effect of pentobarbital on expression of a reporter gene transcriptionally fused to the P450BM-1 promoter. This suggests that the Barbie box is unlikely to be a key element in barbiturate-mediated induction of P450BM-1.

Airway mechanics, gas exchange, and blood flow in a nonlinear model of the normal human lung

A model integrating airway/lung mechanics, pulmonary blood flow, and gas exchange for a normal human subject executing the forced vital capacity (FVC) maneuver is presented. It requires as input the intrapleural pressure measured during the maneuver. Selected model-generated output variables are compared against measured data (flow at the mouth, change in lung volume, and expired O2 and CO2 concentrations at the mouth). A nonlinear parameter-estimation algorithm is employed to vary selected sensitive model parameters to obtain reasonable least squares fits to the data. This study indicates that 1) all three components of the respiratory model are necessary to characterize the FVC maneuver; 2) changes in pulmonary blood flow rate are associated with changes in alveolar and intrapleural pressures and affect gas exchange and the time course of expired gas concentrations; and 3) a collapsible midairway segment must be included to match airflow during a forced expiration. Model simulations suggest that the resistances to airflow offered by the collapsible segment and the small airways are significant throughout forced expiration; their combined effect is needed to adequately match the inspiratory and expiratory flow-volume loops. Despite the limitations of this lumped single-compartment model, a remarkable agreement with airflow and expired gas concentration measurements is obtained for normal subjects. Furthermore, the model provides insight into the important dynamic interactions between ventilation and perfusion during the FVC maneuver.