Arterial tissue of arsenic, selenium and iron in Blackfoot disease patients

In order to identify arsenic as one of the major factors that cause Blackfoot disease on the southwest coast of Taiwan, an atomic absorption spectrophotometric method was used to determine arsenic, selenium and iron concentrations in the tissue of plantar digital arteries. Samples from 31 patients with Blackfoot disease and 30 controls with road traffic accident or occupational injuries were studied. The results indicate that the arterial tissue from Blackfoot disease patients had higher arsenic concentration (3.06+/-1.42 microg/g) than that from healthy controls (0.59+/-0.28 microg/g). The variability was very large 418% at p<0.001. It was also noted that the concentrations of selenium (1.23+/-0.41 microg/g and 1.05+/-0.13 microg/g in patients and controls respectively; with variability 17.1%) and iron (72.7+/-34.9 microg/g and 35.2+/-16.5 microg/g in patients and controls respectively; with variability 106.5%) were both higher than those of controls. However, only the iron concentration was significantly different (p<0.05).

Isotopic analogues as internal standards for quantitative analyses of drugs and metabolites by GC-MS--nonlinear calibration approaches

In order to achieve accurate quantitation of drugs and metabolites (analytes) in complex matrices, 2H- (and less commonly 13C-) labeled analogues of the analytes are now routinely adapted as the internal standards (IS) using linear calibration models to fit data generated by selected ion monitoring gas chromatography-mass spectrometry (GC-MS) protocols. In this study, the effects of cross-contribution (contribution of the IS to the intensity of the ion designated for the analyte and vice versa) on the linearity of the calibration data are examined. Nonlinear approaches that may address this problem are also studied. Two ion pairs (one with least and one with significant cross-contribution) from each of the following analyte/IS pairs are used as the exemplar systems for this study: butalbital/13C4-butalbital, butalbital/2H5-butalbital, secobarbital/13C4-secobarbital, and secobarbital/2H5-secobarbital. Analyte/IS ion intensity ratios of a series of standard solutions are correlated with the analyte/IS concentration ratios using one-point, multiple-point (unweighted and weighted) linear, and hyperbolic functions. The one-point calibration approach produces excellent calibration results in treating data derived from ion pairs with no significant cross contribution. In cases where significant cross-contribution exists, results derived from the one-point approach show, as expected, significant deviations at both ends of the concentration range. With the cross-contribution phenomenon accounted for, the hyperbolic calibration model is clearly more effective in fitting calibration data at both the lower and higher analyte concentration ends, thus significantly lowering the detection limit and extending the calibration range to a higher level. However, the calibration range cannot be extended indefinitely. At the low concentration end, noise-to-signal ratio and the cross-contribution of the IS to the intensity of the ion designated for the analyte, however insignificant, will incrementally reduce the quality of the observed ion intensity and intensity ratio data. At the high concentration end, detection saturation and the cross-contribution of the analyte to the intensity of the ion designated for the IS, however insignificant, will incrementally decrease the "slope" of the calibration curve. Thus, acceptable sensitivity (increase in analyte/IS ion-pair intensity ratio per unit increase in analyte concentration) of the calibration curve will become the limiting factor.

Adverse health effects among household waste collectors in Taiwan

Household waste collectors (HWCs) are potentially exposed to a variety of bioaerosols and toxic materials. Collection of household waste is also a job which requires repeated heavy physical activity such as lifting, carrying, pulling, and pushing. The object of this study was to assess whether there is an excess of adverse health outcomes among HWCs. The subjects were all current employees of the Household Waste Collection Department in the County of Kaohsiung, Taiwan. The survey questionnaire was completed by 533 HWCs and 320 office workers. Our data indicate that household waste collection presents a risk for the development of chronic respiratory symptoms (cough, phlegm, wheezing, and chronic bronchitis), musculoskeletal symptoms (low back pain and elbow/wrist pain), and injuries caused by sharp objects.

Triptolide and chemotherapy cooperate in tumor cell apoptosis. A role for the p53 pathway

Triptolide (PG490), a diterpene triepoxide, is a potent immunosuppressive agent extracted from the Chinese herb Tripterygium wilfordii. We have previously shown that triptolide blocks NF-kappaB activation and sensitizes tumor necrosis factor (TNF-alpha)-resistant tumor cell lines to TNF-alpha-induced apoptosis. We show here that triptolide enhances chemotherapy-induced apoptosis. In triptolide-treated cells, the expression of p53 increased but the transcriptional function of p53 was inhibited, and we observed a down-regulation of p21(waf1/cip1), a p53-responsive gene. The increase in levels of the p53 protein was mediated by enhanced translation of the p53 protein. Additionally, triptolide induced accumulation of cells in S phase and blocked doxorubicin-mediated accumulation of cells in G(2)/M and doxorubicin-mediated induction of p21. Our data suggest that triptolide, by blocking p21-mediated growth arrest, enhances apoptosis in tumor cells.

Aortic stenting on a type B aortic dissection with visceral and limb ischemia

Aortic dissection complicated with limb and visceral ischemia is a clinical dilemma since surgical intervention carries high risk of morbidity and mortality. The management is further complicated when renal perfusion is impaired and thus associated with severe renovascular hypertension. As catheterization techniques advanced over the past decade, percutaneous endovascular intervention provides a less invasive alternative for management of such cases. We report a case of chronic Stanford type B aortic dissection complicated with visceral and limb ischemia presenting with marked renovascular hypertension, which was successfully treated with percutaneous endovascular aortic stenting.

Control of idiopathic ventricular fibrillation by implantable cardioverter-defibrillator in a child who survived sudden death

Idiopathic ventricular fibrillation (VF) is extremely rare in children who have not previously undergone cardiac surgery. Patients resuscitated from idiopathic VF remain at risk for recurrence. The use of an implantable cardioverter-defibrillator (ICD) effectively prevents such recurrences. We report the case of a 12-year-old girl who had a history of recurrent syncope and had survived an episode of VF. Serial studies after prolonged but successful resuscitation, including echocardiography, an electrocardiogram (ECG), and coronary angiography failed to reveal abnormal cardiac structures responsible for VF. No abnormal conduction pathways or abnormal early or late after depolarization were found on electrophysiologic study. The ST segments of the 12-lead ECG remained normal after procainamide challenge. The patient underwent ICD implantation 2 weeks after admission and syncope did not recur during a follow-up of 14 months. This report emphasizes that idiopathic VF may be responsible for syncope in children. ICD therapy prevents the recurrence of idiopathic VF and the associated risk of sudden death.

Point mutation associated with X-linked dominant Charcot-Marie-Tooth disease impairs the P2 promoter activity of human connexin-32 gene

Many lines of evidence suggest that connexin-32 gap junction is involved in the exchange of information and metabolites in the peripheral nervous system. It has been shown that connexin-32 protein and mRNA are expressed in Schwann cells that function as myelinating cells of the peripheral nervous system. The physiological importance of connexin-32 gap junctions in regulating the normal function of myelinating Schwann cell is indicated by recent findings that X-linked dominant Charcot-Marie-Tooth disease, a hereditary peripheral neuropathy, is associated with the mutations of connexin-32 gene. Recently, we encountered a Taiwanese family affected with X-linked dominant Charcot-Marie-Tooth neuropathy. Therefore, we investigated the possible mutation in the coding and noncoding regions of the connexin-32 gene of affected members of this family. Our results suggest that a G-to-A transition at the position -215 (in relation to the transcription initiation site) of the nerve-specific P2 promoter region is associated with the pathogenesis of X-linked dominant Charcot-Marie-Tooth disease. Further experiments using the promoter assay indicate that G-to-A mutation at the position -215 greatly impairs the transcriptional activity of connexin-32 P2 promoter. These findings propose that a reduced expression of connexin-32 mRNA and protein in the myelin sheath could be responsible for the development of X-linked dominant Charcot-Marie-Tooth neuropathy.

Chemical derivatization and the selection of deuterated internal standard for quantitative determination--methamphetamine example

Use of an isotopic analogue of the analyte as the internal standard in a quantitative gas chromatography-mass spectrometry targeted-compound-analysis protocol is often hindered by the availability of an adequate number (typically three for the drug/metabolite and two for the isotopic analogue) of sufficiently high mass ions that can be attributed to each member of the pair and are sufficiently free of interference by the contribution from the other component of the pair, a phenomenon termed "cross-contribution". Methamphetamine (MA) is selected as the exemplar compound to examine the effectiveness in using different chemical derivatization routes to produce derivatized analyte-isotopic analogue pairs that can generate more favorable mass spectrometric data to meet this analytical requirement. Trimethylsilyl-, trichloroacetyl-, and pentafluoropropionyl-derivatization and MA-d5, MA-d8, and MA-d9 are studied. Data resulting from this study indicate that the number of ion pairs suitable for quantitation and the degree of cross-contribution of these ions vary significantly. These data empirically demonstrate that derivatization methods play a significant role in deciding which deuterated analogue of the analyte provides the most suitable ion pairs that cause the least cross-contribution. The most suitable internal standard varies with the derivatization route adapted for an analytical protocol.

Persistent myocardial ischemia after termination of dipyridamole-induced ventricular tachycardia by intravenous aminophylline: scintigraphic demonstration

Ventricular tachycardia is a rare complication of dipyridamole stress testing. We present a case in which dipyridamole induced symptomatic ventricular tachycardia. The patient, a 41-year-old man with a history of chest discomfort on exertion for 1 year, underwent dipyridamole thallium imaging. Sustained ventricular tachycardia occurred 1 minute and 40 seconds after completion of the dipyridamole infusion. Intravenous aminophylline (125 mg) was given immediately and the tachycardia was terminated. Two minutes later, thallium-201 was injected and subsequent myocardial imaging showed reversible perfusion defects in the inferior wall, septum, and apex. Coronary angiography revealed three-vessel disease. This case discloses that reversible perfusion defects can still be demonstrated on thallium scan in spite of injection of aminophylline, an antagonist of dipyridamole, before thallium administration.

Isolation of spermidine synthase gene (spsA) of Dictyostelium discoideum

The gene encoding spermidine synthase (spsA) was isolated from Dictyostelium discoideum using the technique of insertional mutagenesis. Northern blot analysis showed that the spsA mRNA is expressed maximally during the vegetative stage and decreases gradually during the 24 h of development. Sequencing of the genomic DNA and a full-length cDNA clone indicated the presence of one intron in a gene coding for a predicted protein (SpsA) with 284 amino acids. The sequence is highly conserved, with amino acid identities compared to spermidine synthases of humans, 59.5%, to mouse, 61.3%, and to yeast, 58.1%. A null mutant of the spsA gene is unable to grow in the absence of exogenous spermidine. Development of spsA null cells grown in the absence of spermidine produced fruiting bodies that have abnormally short stalks.

A novel adenylyl cyclase detected in rapidly developing mutants of Dictyostelium

Disruption of either the RDEA or REGA genes leads to rapid development in Dictyostelium. The RDEA gene product displays homology to certain H2-type phosphotransferases, while REGA encodes a cAMP phosphodiesterase with an associated response regulator. It has been proposed that RDEA activates REGA in a multistep phosphorelay. To test this proposal, we examined cAMP accumulation in rdeA and regA null mutants and found that these mutants show a pronounced accumulation of cAMP at the vegetative stage that is not observed in wild-type cells. This accumulation was due to a novel adenylyl cyclase and not to the known Dictyostelium adenylyl cyclases, aggregation stage adenylyl cyclase (ACA) or germination stage adenylyl cyclase (ACG), since it occurred in an acaA/rdeA double mutant and, unlike ACG, was inhibited by high osmolarity. The novel adenylyl cyclase was not regulated by G-proteins and was relatively insensitive to stimulation by Mn2+ ions. Addition of the cAMP phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX) permitted detection of the novel adenylyl cyclase activity in lysates of an acaA/acgA double mutant. The fact that disruption of the RDEA gene as well as inhibition of the REGA-phosphodiesterase by IBMX permitted detection of the novel AC activity supports the hypothesis that RDEA activates REGA.

Production and activity of spore differentiation factors (SDFs) in Dictyostelium

SDF-1 and SDF-2 are peptides that promote terminal spore differentiation under submerged conditions. The present study shows that they accumulate differentially and are released during the development of wild-type cells and can promote spore formation in cells disaggregated from wild-type culminants. SDF-1 accumulates during the slug stage and is released in a single burst at the onset of culmination while SDF-2 accumulates during early culmination and is released in a single burst from mid-culminants. The effects of SDF-1 and SDF-2 on stalk cell formation in cell monolayers were investigated. SDF-1 by itself induces stalk cell formation in some strains and also synergizes with the stalk-cell-inducing factor, DIF-1. cAMP has an inhibitory effect on stalk cell formation when either DIF-1 or SDF-1 are present on their own but is almost not inhibitory when both are present. SDF-2 alone does not induce stalk cell formation and appears to inhibit the response to DIF-1. At the same time, it increases the extent of vacuolization of the stalk cells that are produced. We propose that the release of SDF-1 and then of SDF-2 may mark irreversible steps in the developmental programme associated, respectively, with culmination and spore maturation.

Mutational analysis of Caenorhabditis elegans CED-4

Much of our knowledge concerning the genetics that regulate cell death has come from the studies of cell death during the development of the nematode Caenorhabditis elegans. Of the 14 genes identified as components of nematode cell death pathways, two genes, ced-3 and ced-4, are required to promote cell death and a third, ced-9, blocks cell death. Recent studies show CED-4 to be an activator of CED-3 and CED-9 to be an inhibitor of CED-4. Two published sequence alignments suggest that CED-4 contains a death effector domain (DED), a protein sequence motif present in other death signaling proteins like Fadd and Flice; one study suggests a DED sequence similarity near the N-terminus while the other found sequence similarity near the C-terminus of CED-4. Using mutational analysis we have tested the functional significance of the conserved residues found within the putative DEDs of CED-4. Mutations in two conserved residues within the putative N-terminal DED of CED-4 affected its function, while mutations in the conserved residues within the putative C-terminal DED had no effect on CED-4 function. Our results do not support the presence of a DED in the C-terminus of CED-4 and suggest a potential role for the N-terminus in CED-4 function, possibly as a DED or as a CARD (caspase recruitment domain). We also found that CED-9 associated with all the CED-4 mutants and inhibited the activity of all the active-CED-4 mutants.

Evidence that the RdeA protein is a component of a multistep phosphorelay modulating rate of development in Dictyostelium

We have isolated an insertional mutant of Dictyostelium discoideum that aggregated rapidly and formed spores and stalk cells within 14 h of development instead of the normal 24 h. We have shown by parasexual genetics that the insertion is in the rdeA locus and have cloned the gene. It encodes a predicted 28 kDa protein (RdeA) that is enriched in charged residues and is very hydrophilic. Constructs with the DNA for the c-Myc epitope or for the green fluorescent protein indicate that RdeA is not compartmentalized. RdeA displays homology around a histidine residue at amino acid 65 with members of the H2 module family of phosphotransferases that participate in multistep phosphoryl relays. Replacement of this histidine rendered the protein inactive. The mutant is complemented by transformation with the Ypd1 gene of Saccharomyces cerevisiae, itself an H2 module protein. We propose that RdeA is part of a multistep phosphorelay system that modulates the rate of development.

An intersection of the cAMP/PKA and two-component signal transduction systems in Dictyostelium

Terminal differentiation of both stalk and spore cells in Dictyostelium can be triggered by activation of cAMP-dependent protein kinase (PKA). A screen for mutants where stalk and spore cells mature in isolation produced three genes which may act as negative regulators of PKA: rdeC (encoding the PKA regulatory subunit), regA and rdeA. The biochemical properties of RegA were studied in detail. One domain is a cAMP phosphodiesterase (Km approximately 5 microM); the other is homologous to response regulators (RRs) of two-component signal transduction systems. It can accept phosphate from acetyl phosphate in a reaction typical of RRs, with transfer dependent on Asp212, the predicted phosphoacceptor. RegA phosphodiesterase activity is stimulated up to 8-fold by the phosphodonor phosphoramidate, with stimulation again dependent on Asp212. This indicates that phosphorylation of the RR domain activates the phosphodiesterase domain. Overexpression of the RR domain in wild-type cells phenocopies a regA null. We interpret this dominant-negative effect as due to a diversion of the normal flow of phosphates from RegA, thus preventing its activation. Mutation of rdeA is known to produce elevated cAMP levels. We propose that cAMP breakdown is controlled by a phosphorelay system which activates RegA, and may include RdeA. Cell maturation should be triggered when this system is inhibited.

Three-dimensional PET emission scan registration and transmission scan synthesis

The duration of a positron emission tomography (PET) imaging scan can be reduced if the transmission scan of one patient which is used for emission correction can be synthesized by using the reference transmission scan of another patient. In this paper, we propose a new intersubjects PET emission scan registration method and PET transmission synthesis method by using the boundary information of the body or brain scan of the PET emission scans. The PET emission scans have poor image quality and different intensity statistics so that we preprocess the emission scans to have similar histogram and then apply the point distribution model (PDM) [15] to extract the contours of the emission scan. The extracted boundary contour of every slice is used to reconstruct the three-dimensional (3-D) surface of the reference set and the target set. Our registration is 3-D surface-based which uses the normal flow method [17] to find the correspondence vector field between two 3-D reconstructed surfaces. Since it is difficult to analyze internal organ using the PET emission scan imaging without correction, we assume that the deformation of internal organ is homogeneous. With the corresponding vector field between the two emission scans and the transmission scan of the reference set, we can synthesize the transmission scan of the target set.

Production of chitinase from shellfish waste by Pseudomonas aeruginosa K-187

The production of chitinolytic enzyme by Pseudomonas aeruginosa K-187, using shrimp and crab shell powder (SCSP) as the carbon source, was studied. It was observed that chemically treated SCSP induced a significant increase of enzyme production, as compared with untreated SCSP. Spent HCl and NaOH from the chitin production industry was used to process SCSP. Various strategies of SCSP processing are examined and compared in terms of chitinolytic enzyme production. A three-and-one-half-fold increase of enzyme production (0.68 U/ml to 2.4 U/ml) was attained using HCl/NaOH treated SCSP. The microorganism (K-187) was isolated from soil in Taiwan and has been characterized and reported in a previous paper.

Purification and characterization of two bifunctional chitinases/lysozymes extracellularly produced by Pseudomonas aeruginosa K-187 in a shrimp and crab shell powder medium

Two extracellular chitinases (FI and FII) were purified from the culture supernatant of Pseudomonas aeruginosa K-187. The molecular weights of FI and FII were 30,000 and 32,000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 60,000 and 30,000, respectively, by gel filtration. The pIs for FI and FII were 5.2 and 4.8, respectively. The optimum pH, optimum temperature, pH stability, and thermal stability of FI were pH 8, 50 degrees C, pH 6 to 9, and 50 degrees C; those of FII were pH 7, 40 degrees C, pH 5 to 10, and 60 degrees C. The activities of both enzymes were activated by Cu2+; strongly inhibited by Mn2+, Mg2+, and Zn2+; and completely inhibited by glutathione, dithiothreitol, and 2-mercaptoethanol. Both chitinases showed lysozyme activity. The purified enzymes had antibacterial and cell lysis activities with many kinds of bacteria. This is the first report of a bifunctional chitinase/lysozyme from a prokaryote.

Identification of the cell fate gene stalky in Dictyostelium

Using insertional mutagenesis, we have isolated a "stalky" mutant in which cells destined to become spores end up as stalk cells. Similar mutants were previously observed after chemical mutagenesis, but the affected gene could not be isolated. Our mutant, like the previous ones, is in stkA. Its defect is cell-autonomous and not overcome by overexpressing cAMP-dependent protein kinase. stkA is strongly expressed in the prespore region of aggregates but not in the anterior prestalk zone. The mutant expresses normal levels of prespore-cell transcripts but fails to produce the spore transcript spiA. stkA encodes a predicted 99 kDa protein (STKA) with two putative C4 zinc fingers, one of which is a GATA-type finger, indicating that it may be a transcription factor. This conclusion is supported by localization of STKA in the nucleus.

Detection of k-ras point mutations in codons 12 and 13 in non-small cell lung cancers

Point mutations of the K-ras gene have been reported in a wide variety of human tumors. By using polymerase chain reaction followed by direct DNA sequencing, we screened for point mutations at codons 12 and 13 of the K-ras gene in specimens obtained from fresh frozen tumors in 38 patients with non-small cell lung cancers. Point mutations were detected in two of 38 (5.3%) resected non-small cell lung cancers. Both of them were G to T transversions. One patient was found to have a K-ras codon 13 point mutation (GGC to TGC, gly to cys), while the other had a codon 12 point mutation (GGT to GTT, gly to val). Based on the limited numbers in this study, we found that the frequency of K-ras point mutations in codons 12 and 13 among Asian patients with lung adenocarcinomas was lower than that detected among Caucasian patients.

Evidence for transcriptional modulation but not acid phosphatase expression during programmed cell death in the colonial tunicate Botryllus schlosseri

Botryllus schlosseri is a clonally modular ascidian in which asexually derived adults (zooids) exhibit developmental synchrony. At the conclusion of the blastogenic (asexual) cycle every 5 days at 21 degrees C, all zooids within a colony die simultaneously in 24 hours and are replaced by a new asexual generation of zooids. This cyclical process, called takeover, involves the selective destruction of the zooid's visceral tissues which include the pharynx, esophagus, stomach, intestine, endostyle, neural complex and heart, whereas bud tissues and mesenchymal components (muscle and blood cells) remain unaffected. Ultrastructural analysis indicates that the most prevalent form of cell death occurs by apoptosis, although necrotic changes are also observed in several tissues (i.e., stomach and intestine). Blood-derived macrophages and neighboring cells subsequently engulf visceral tissues, reducing the zooid to the size of a small vesicle. Here, we have tested the possibility that acid phosphatase, a hydrolase whose presence is associated with cell death in several invertebrate systems, could account for some of the regressive changes observed during takeover. Our observations indicate that acid phosphatase (AP) activity was selectively localized in the gut of parent zooids during the growth phase of the cycle, with the stomach exhibiting the most intense histochemical staining on tissue sections. As zooid regression progressed during takeover, stomach AP staining gradually disappeared. Other visceral tissues never became AP-positive. Therefore, this hydrolase appears to play a minimal role in zooid death. In order to characterize genes whose expression pattern was selectively altered during takeover, we have carried out differential mRNA display analysis. We report on two genes, 790.3 and 790.4, that are down- and upregulated, respectively, during this process. Collectively, these findings indicate that the takeover phase of blastogenesis in Botryllus involves modulated gene expression.

Surgical management of the buried penis

BACKGROUND

Buried penis is a congenital abnormality in which the phallus is concealed within the surface of prepubic skin. It is probably more common than is generally recognized. The objective was to describe the pathophysiology, and search for the best management of this disease.

METHODS

Over a period of 6 years, a total of 31 cases receiving surgery for buried penis at this hospital were analyzed. According to their major pathophysiology, patients were divided into three groups: in the first, the major mechanism was poor skin suspension; in the second, prominent suprapubic fat pad was the major cause. In the third group, the dartos fascia was abnormally thickened and attached to the penile shaft. Different surgical techniques were applied in the different groups.

RESULTS

All 15 children in the first group had satisfactory results after penile skin fixation. In the second group, nine children underwent adjunctive lipectomy but only five had satisfactory results. Seven patients in the third group needed degloving of the penis and the three cases who underwent preputial unfurling had severe lymphedema of the inner preputial layer. One of them received revision. The end results were good in the other six patients after long-term follow up.

CONCLUSIONS

The buried penis occurs in a spectrum. Although, there are three major pathophysiology mechanisms, most of the patients had a combination. Surgical management should be individualized, and results are usually satisfactory. For the obese patient, weight loss is important. Preputial unfurling and using inner preputial layer to cover the defect should be avoided because of severe postoperative lymphedema.

Antenatal diagnosis and early surgery for choledochal cyst: a report of two cases

Since the advent of routine antenatal sonography to detect fetal abnormalities, two cases of choledochal cyst have been found prenatally in our hospital. The first presented when a choledochal cyst was demonstrated at 31 weeks of gestation, and a firm diagnosis established within 2 days of birth. Technetium 99m disofenin (DISIDA) cholescintigram revealed delayed visualization of the small bowel. The second case was found by ultrasound examination at 21 weeks of gestation to have a choledochal cyst, and diagnosis was confirmed within 3 days of birth. DISIDA scintigram demonstrated complete obstruction of the extrahepatic biliary tree. Both infants received early excision of the cyst at the ages of three and four days respectively. The postoperative course was quite smooth, and there were no abnormal symptoms after follow up of four and two years, respectively. Neonates with distal common bile duct obstruction in association with presumed choledochal cyst should have prompt surgical exploration, and early excision of the cyst is a safe procedure in the newborn.

Trapping developmental promoters in Dictyostelium

Recently an insertional mutagenesis procedure has been developed to permit cloning of genes affected in developmental mutants of Dictyostelium discoideum (Kuspa and Loomis, Proc. Natl. Acad. Sci. USA 89, 8803-8807, 1992). In this procedure a plasmid bearing the URA (pyr5-6) gene is linearized with a restriction enzyme and electroporated into URA- amoebae (auxotrophic for uracil) together with the corresponding restriction enzyme. Transformants that can grow without uracil are screened for developmental defects resulting from insertion of the plasmid into a gene of developmental importance. We have modified this procedure to permit characterization of the promoters and structural sequences of genes that would be missed by the standard procedure because their disruption produces no obvious phenotype. Constructs carrying a promoter-less Escherichia coli lacZ gene were designed so that expression of lacZ requires insertion into an active host transcription unit. By screening restriction enzyme-generated transformants we have isolated several strains in which lacZ is under the control of a developmentally activated promoter and have cloned the 5' flanking DNA adjacent to the insertion site. Sequencing the junction between plasmid and host genome has confirmed in-frame fusion with the lacZ gene, and reintroduction of the cloned plasmids into parental cells has shown that the cloned sequences do actually contain the relevant promoters. This procedure should give ready access to a wide range of developmental promoters without the need for prior identification of the developmental genes involved.

Jejunoileal atresia in neonates

BACKGROUND

Jejunoileal atresia is the most common intestinal atresia and the most frequent cause of neonatal intestinal obstruction. The prognosis depends on several important factors. The patients reported were collected for evaluation of the factors contributing to their prognoses.

METHODS

In the ten-year period from October 1982 to October 1992, all jejunoileal atresia patients who received treatment in this hospital were entered in this study. Possible factors contributing to prognosis, such as prematurity, low birth weight, apple peel atresia, anastomotic leakage, sepsis, short bowel syndrome were evaluated using Mann-Whitney U-test.

RESULTS

Twenty-four patients of jejunoileal atresia had been managed in our hospital in 10 years period. Their ages ranged from one to thirteen days old (mean 3.9 days). The numbers and types of atresia were as follow: type I (n = 4), type II (n = 4), type IIIa (n = 10), type IIIb (n = 5), type IV (n = 1). All patients received surgical correction. Nine complications were found in eight patients, which included four anastomotic leakage, three wound infections and two intestinal obstructions. There were three mortalities from sepsis. Total parenteral nutrition was applied to 14 patients (58.3%). The mean hospital stay was 45.1 days, and the survival rate was 87.5%. Low birth weight and anastomotic leakage contributed to prolonged hospital stays (p < 0.05).

CONCLUSIONS

Jejunoileal atresia is a common neonatal surgical condition. The prognosis is generally good, except when a patient presented with factors, such as, low birth weight or anastomotic leakage, which prolonged hospital stays. Moreover, sepsis is the only important factor contributing to mortality.