The granaticin biosynthetic gene cluster of Streptomyces violaceoruber Tü22: sequence analysis and expression in a heterologous host

BACKGROUND: The granaticins are members of the benzoisochromanequinone class of aromatic polyketides, the best known member of which is actinorhodin made by Streptomyces coelicolor A3(2). Genetic analysis of this class of compounds has played a major role in the development of hypotheses about the way in which aromatic polyketide synthases (PKSs) control product structure. Although the granaticin nascent polyketide is identical to that of actinorhodin, post-PKS steps involve different pyran-ring stereochemistry and glycosylation. Comparison of the complete gene clusters for the two metabolites is therefore of great interest. RESULTS: The entire granaticin gene cluster (the gra cluster) from Streptomyces violaceoruber T-22 was cloned on either of two overlapping cosmids and expressed in the heterologous host, Streptomyces coelicolor A3(2), strain CH999. Chemical analysis of the recombinant strains demonstrated production of granaticin, granaticin B, dihydrogranaticin and dihydrogranaticin B, which are the four known metabolites of S. violaceoruber. Analysis of the complete 39,250 base pair sequence of the insert of one of the cosmids, pOJ466-22-24, revealed 37 complete open reading frames (ORFs), 15 of which resemble ORFs from the act (actinorhodin) gene cluster of S. coelicolor A3(2). Among the rest, nine resemble ORFs potentially involved in deoxysugar metabolism from Streptomyces spp. and other bacteria, and six resemble regulatory ORFs. CONCLUSIONS: On the basis of these resemblances, putative functional assignments of the products of most of the newly discovered ORFs were made, including those of genes involved in the PKS and tailoring steps in the biosynthesis of the granaticin aglycone, steps in the deoxy sugar pathway, and putative regulatory and export functions.     

Interruption of a transforming growth factor alpha autocrine loop in Caco-2 cells by antisense oligodeoxynucleotides

BACKGROUND & AIMS: We have previously shown that Caco-2 cell proliferation is driven by basolateral membrane epidermal growth factor receptors. The aim of this study was to investigate whether autocrine production of transforming growth factor alpha (TGF-alpha) activates these receptors and stimulates proliferation using antisense oligodeoxynucleotides. METHODS: Caco-2 cells grown on microporous membranes or Jurkat cells were exposed to conventional or 5' cholesterol-modified oligodeoxynucleotides synthesized with random, antisense, or missense base sequences. Indices of proliferation were measured, including [3H]thymidine or [3H]uridine uptake for studies of short-term stimulation and the methylthiotetrazole assay as an index of cell number increase over longer periods. Secretion of TGF-alpha by cells was detected using a soft agar bioassay. RESULTS: Incubation with antisense oligodeoxynucleotides inhibited TGF-alpha secretion compared with controls. Random and missense oligodeoxynucleotides had no effect on proliferation. The TGF-alpha antisense oligodeoxynucleotides markedly inhibited proliferation, an effect that was abolished by adding TGF-alpha to the medium. Oligonucleotides had no effect on Jurkat cells, a lymphocytic cell line lacking epidermal growth factor receptors. Cholesterol-modified oligodeoxynucleotides were more effective and specific than unmodified oligodeoxynucleotides. CONCLUSIONS: Caco-2 cell proliferation is driven by autocrine stimulation of epidermal growth factor receptors by TGF-alpha. This mechanism may be effectively inhibited by antisense oligodeoxynucleotides, particularly those modified by the 5' attachment of cholesterol.     

Long-term follow-up of an EORTC randomized prospective trial comparing intravesical bacille Calmette-Guérin-RIVM and mitomycin C in superficial bladder cancer. EORTC GU Group and the Dutch South East Cooperative Urological Group. European Organisation for Research and Treatment of Cancer Genito-Urinary Tract Cancer Collaborative Group

Posterior laryngeal clefts (PLCs) are described in the literature as rare laryngeal abnormalities. The authors believe type I clefts are much more common than previously reported. In two busy pediatric tertiary care centers, such clefts are the second most common congenital laryngeal finding at rigid endoscopy, second only to laryngomalacia. PLCs frequently present with symptomatology that can be attributed to other common disease processes and are often undiagnosed unless the surgeon maintains a high index of suspicion and specifically examines the posterior glottis by palpation during microlaryngoscopy. This report presents a series of 41 patients with type I PLCs, reviews their subtle and often confusing presenting signs and symptoms, and describes a simple yet reliable method of diagnosis.     

Functional treatment of patellar dislocation in an athletic population

OBJECTIVE: To determine the clinical applicability of ultrasound-guided detrusor biopsy from the anterior bladder wall and to assess whether it is as representative and as sufficient for determining detrusor ultrastructure as the traditional transurethral biopsy from the lateral bladder wall. MATERIALS AND METHODS: The detrusor structure in 22 biopsies. 11 obtained transabdominally and 11 transurethrally from 11 patients, was evaluated without knowledge of the biopsy method by light and electron microscopy, including morphometric analysis. In addition, several specimens from each of three bladders were evaluated, also 'blindly', for ultrastructural diagnosis of the detrusor in an independent current study of voiding dysfunction in geriatric patients. RESULTS: There were no differences in intercellular distances and cell: nucleus ratios between transabdominal and transurethral biopsies in eight of the 11 patients. Furthermore, ultrasound-guided transabdominal biopsies were as representative of the detrusor as were transurethral biopsies. CONCLUSION: The transabdominal approach is recommended as an easy, relatively inexpensive and efficient method of obtaining biopsies of the detrusor for study of its structure in voiding dysfunction. On the other hand, the observations and diagnoses made by 'blind' qualitative study of several specimens from the same bladder were identical. This, together with the similarity of detrusor structure in the transabdominal and transurethral biopsies, strongly supports the idea that such structure is relatively uniform throughout the entire bladder wall.     

Persistent gastroesophageal reflux disease after antireflux surgery in children: I. immediate postoperative evaluation using extended esophageal pH monitoring

PURPOSE: There is a paucity of quantitative and reproducible follow-up data on childhood operations for gastroesophageal reflux disease (GERD). With the development of minimally invasive techniques for antireflux operations in children, there is a need to quantitatively determine immediate outcomes for such operations performed by laparotomy for comparison. METHODS: A retrospective review of 385 children (age range, 1 week to 15 years) who had a primary antireflux operation in a Children's or University Hospital performed by laparotomy between 1983 and 1997, and who also had an extended esophageal pH study performed within the first 12 postoperative weeks, was conducted. The operations performed included Nissen fundoplication (n = 135), Thal fundoplication (n = 195), and Boerema gastropexy (n = 55). An immediate postoperative failure of the operation to control GERD was defined as an abnormal esophageal pH score persisting up to the twelfth postoperative week. RESULTS: Eleven patients (2.9%) were classified as having an immediate postoperative failure of their operation to control GERD. An additional three patients had an abnormal esophageal pH score 2 weeks postoperatively, which subsequently reverted to a normal esophageal pH score by 12 weeks. The immediate postoperative failure rate was 1.5% (2 of 135) for the Nissen fundoplication, 1.5% (3 of 195) for the Thal fundoplication, and 10.9% (6 of 55) for the Boerema gastropexy. A higher failure rate (five patients, 36%) was seen for the first 14 patients who underwent a Boerema gastropexy during the learning curve period for this operation before 1985, and by excluding these patients the failure rate was 2.4% (1 of 41) after 1985. There was no significantly increased probability of immediate postoperative failure in patients with central nervous system disorders, prematurity, repaired esophageal atresia, or gastric emptying abnormalities. Only 5 (36%) of the 14 children with persisting symptoms suggestive of GERD had immediate postoperative failure of their operation. CONCLUSIONS: Extended esophageal pH monitoring during the first 12 postoperative weeks is a helpful tool to assess the immediate outcome of antireflux operations in children because clinical symptoms alone may be unreliable. The immediate failure rate for an antireflux operation performed in children by laparotomy is very low and seems to be unaffected by comorbid factors.     

CTA-based angle selection for diagnostic and interventional angiography of saccular intracranial aneurysms

Coil embolization is a safe treatment for cerebral aneurysms only if the width of the neck in relation to the fundus of the aneurysm is small. Therefore, accurate visualization of the aneurysmal neck is required both in the diagnostic process and during the intervention. Conventional digital subtraction angiography (DSA) is still the preferred modality for the examination of cerebrovascular abnormalities like aneurysms, but it often does not provide the required morphological characteristics due to the suboptimal selection of projection angles and resulting overprojections of surrounding vasculature. This paper presents a method for performing a computer-assisted calculation of the optimal projection angles for DSA by post-processing computed tomographic angiography (CTA) volume data using ray-casting techniques and a combination of image processing algorithms. By means of phantom studies, retrospective simulations of angiograms, and in vivo applications of calculated optimal viewing angles, it is demonstrated that the proposed method results in better angiographic projections of the neck of saccular aneurysms with small neck-fundus ratio than those acquired at standard angles prescribed by clinical protocols.     

In vivo 1H MR spectroscopic imaging and diffusion weighted MRI in experimental hydrocephalus

The severity and progression of ventricular enlargement, the occurrence of cerebral edema, and the localization of ischemic metabolic changes were investigated in a rat model of hydrocephalus, using in vivo 1H MR spectroscopic imaging (SI) and diffusion weighted MRI (DW MRI). Hydrocephalic rats were studied 1, 2, 4, and 8 weeks after injection of kaolin into the cisterna magna. Parametric images of the apparent diffusion coefficient (ADC) revealed a varying degree of ventriculomegaly in all rats, with different time courses of ventricular expansion. Extracellular white matter edema was observed during the early stages of hydrocephalus, most extensively in cases of progressive ventriculomegaly. In gray matter regions, ADC values were not changed, compared with controls. In case of fatal hydrocephalus, high lactate levels were observed throughout the whole brain. In all other rats, at all time points after kaolin injection, lactate was detected only in voxels containing cerebrospinal fluid. This suggests accumulation of lactate in the ventricles, and/or an ongoing periventricular production of lactate as a consequence of cerebral ischemia in experimental hydrocephalus.