Endoscopic Decompression of Recurrent Sigmoid Volvulus in Pregnancy

Sigmoid volvulus is a rare condition seen during pregnancy with high maternal and fetal morbidity and mortality. We report a case of a young 26-year-old woman, primipara, in her third trimester who presented with recurrent sigmoid volvulus at both 30 and 32 weeks of gestation. She underwent successful repetitive endoscopic decompression on both admissions with uneventful recovery. Endoscopic evaluation is safe in pregnancy and uncomplicated volvulus. It allows for diagnostic confirmation and assessment of complications; and it has successful outcomes in the presence of a multidisciplinary team.

Collagenous Gastritis: An Unusual Presentation With Tubular Shaped Stomach

Collagenous gastritis is a rare histopathologic entity that causes marked subepithelial collagen deposition in the gastric mucosa. Clinical presentation is diverse, considering only less than 100 cases have been reported. However, we report a unique case of isolated collagenous gastritis in a 71-year-old female who presented with a 6-month history of dyspepsia and 27 kg weight loss. Her endoscopic findings revealed a tubular shaped stomach with diffuse gastric mucosal atrophy, findings that differ with previous case reports of a cobblestone pattern. Treatment remains unclear.

Diagnosis and Treatment of Metastatic Disease to the Pancreas

Introduction: Metastatic disease to the pancreas is a rare entity from all malignant pancreatic masses. Its diagnosis is very challenging, but with the introduction of endoscopic ultrasound (EUS)-fine needle aspiration (FNA), now there is a feasible way to make an accurate histopathological and definitive diagnosis. Materials and Methods: This is a retrospective review of 11 patients with metastasis to the pancreas diagnosed with EUS-FNA in a tertiary referral center over a period of 3 years. We describe our institutional experience in diagnosing metastatic disease to the pancreas through EUS-FNA. Results: Between January 2015 and June 2018, 115 patients were diagnosed with pancreatic malignancy by EUS-FNA and only 11 (10%) with metastatic disease to the pancreas. Most common primary malignancy was renal cell carcinoma, followed by colon carcinoma, squamous/small cell carcinoma of the lung, and urothelial carcinoma. Five of 11 patients presented as a solitary pancreatic mass on initial imaging without any evidence of primary or metastatic disease elsewhere. Conclusions: In our experience, metastatic disease to the pancreas can represent up to 10% of solid pancreatic masses, which is lower compared to the reported incidence in previous literature. Our findings reveal that early identification and diagnosis help patient management and limit surgical morbidity and mortality.

Primary astrocytes retrovirally transduced with a tyrosine hydroxylase transgene driven by a glial-specific promoter elicit behavioral recovery in experimental parkinsonism

We used a retroviral-mediated gene transfer system to transduce primary rat astrocytes with a transgene in which the activity of a tyrosine hydroxylase (TH) cDNA is under the transcriptional control of a human promoter of the glial fibrillary acidic protein (GFAP). The engineered cells were tested for their therapeutic efficacy in a rodent model of Parkinson's disease (PD). The method is based both on the properties of astrocytes, as well as on those of the promoter. Astrocytes are an integral part of the neural tissue, have a long life span, are more resistant to oxidative stress than neurons, and possess an efficient secretory system. The GFAP promoter is active throughout postnatal life, and its activity is up-regulated by many insults to the brain, including PD. Transduced astrocytes were implanted into the striata of rats lesioned with 6-hydroxydopamine (6-OHDA), and the efficacy of grafted cells tested. Implanted astrocytes induced a significant reduction in the turning behavior that occurs in response to apomorphine for at least 4 weeks after grafting, and transgenic mRNA and protein could be detected in implanted brains. These results indicate that the gFa2-TH construct can be readily adapted to be used with a retroviral gene transfer system to obtain nontumorigenic cells that sustain a sufficient level of transgene activity to enable therapeutic effectiveness for prolonged periods. These results further endorse the use of astrocytes for gene therapy in the central nervous system.

Recombinant adeno-associated virus-mediated expression of O6-alkylguanine-DNA-alkyltransferase protects human epithelial and hematopoietic cells against chloroethylating agent toxicity

Recombinant adeno-associated virus (rAAV) encoding the human O6-alkylguanine-DNA-alkyltransferase (hAT) protein and a selectable marker (Neo(r)) was used to transduce human cervical carcinoma (HeLa) cells and erythroleukemic (K562) cells and clones were selected using G418 (0.4 mg/ml). Thirteen HeLa clones were isolated, 9 of which survived for 2-3 months before cell death ensued, presumably owing to the loss of G418 resistance. Northern blot analysis of the remaining four clones, using a neo probe, showed high levels of RNA equivalent in size to the bicistronic RNA expected to be produced from this construct. Analysis of hAT activity showed that 2000-5000 fmol/mg protein was expressed relative to untransduced cells (800-900 fmol/mg protein). Cell survival analysis following exposure to the chloroethylating agent mitozolomide revealed that expression of hAT at levels two- to fourfold higher than background conferred significant resistance (p < 0.001) to the toxic effects of this drug. Two days following infection of K562 cells with the rAAV vector, immunoblot analysis showed that hAT protein was being produced. Three K562 clones, isolated using G418 selection, were studied in detail and were shown to express hAT activities of 1500, 1010, and 890 fmol/mg protein, respectively, at 40 days posttransduction (mock-transduced K562 cells contain <2 fmol of hAT/mg protein). As with HeLa cells, Northern blot analysis showed the production of an appropriately sized transcript and immunoblot analysis indicated that hAT protein was being produced. These clones were assayed for cell survival following exposure to mitozolomide. Expression of hAT at levels 800- to 1500-fold higher than background conferred significant resistance (p < 0.001) to the toxic effects of mitozolomide. We have therefore successfully conferred a protective advantage against mitozolomide toxicity to cells by rAAV-mediated hAT expression.

Molecular cloning and expression analysis of the Rhodobacter capsulatus sodB gene, encoding an iron superoxide dismutase

Genetic complementation of a sodA sodB Escherichia coli mutant strain was used to clone Rhodobacter capsulatus genes involved in detoxification of superoxide radicals. After sequence analysis, 1 of the 16 identical clones obtained by this selection procedure was shown to contain an open reading frame with sequence similarity to that coding for Fe-containing superoxide dismutases (SodB). The R. capsulatus sodB gene was expressed in E. coli, and the nature of the metal ligand was confirmed by inhibitor sensitivity assays with lysates from both bacterial species. Activity staining of cleared Rhodobacter lysates resolved by polyacrylamide gel electrophoresis indicated that SodB was the only superoxide dismutase present in this phototrophic organism. The sodB gene was expressed at low levels in R. capsulatus cells grown under anaerobic or semiaerobic conditions, but expression was strongly induced upon exposure of the bacteria to air or to methyl viologen. Attempts to construct a sodB mutant in this organism by allelic exchange of the chromosomal copy of the gene with a suicide plasmid containing a mutated sodB gene were unsuccessful, strongly suggesting that the encoded superoxide dismutase is essential for viability of R. capsulatus in aerobic cultures.

Association of LHIα(B870) Polypeptide with Phospholipids During Insertion in the Photosynthetic Membrane of an LHII − Mutant of Rhodobacter capsulatus

Membranes from in vivo labeled cells of Rhodobacter capsulatus U43[pTX35] grown photosynthetically carried 60% of the [32P]-Pi in the "heavy" fraction (HM) after sucrose gradient sedimentation. Metal-chelating chromatography of either"heavy" or "light" (LM) membrane fractions rendered similar Bchl-protein complex profiles after octyl-glucoside treatment,including most of the radioactivity in the same corresponding elution fraction (F II). Similar labeling distribution of pigment-protein complexes was obtained for membranes of dark-grown cells induced by lowering oxygen tension. Fractions derived from HM showed highly labeled LHIalpha, whereas the same complex from LM was essentially [32P]-Pi-free, as revealed by SDS-PAGE followed by autoradiography. Phospholipid analysis showed a similar pattern for membranes isolated from cells photosynthetically or semiaerobically grown, being the most abundant: phosphatidylglycerol,phosphatidylethanolamine, cardiolipin, and phosphatidylcholine. Part of the phospholipids from HM comigrated with LHIalpha during SDS-PAGE and dissociated from the complexes only after solvent extraction and hydrophobic chromatography. However, a small amount remained always attached to LHIalpha,indicating an unusual strong interaction. These results suggest the existence of two operationally defined membrane regions carrying LHIalpha complexes differing in phosphorylation status and protein-phospholipid interaction.

Possible role of the highly conserved amino acids Trp-8 and Pro-13 in the N-terminal segment of the pigment-binding polypeptide LHI alpha of Rhodobacter capsulatus

Trp-8 and Pro-13 of the Rhodobacter capsulatus light-harvesting (LH) I alpha polypeptide are highly conserved among LHI and LHII alpha proteins of several species of the Rhodospirillaceae. Exchange of Trp-8 and Pro-13 to other amino acyl residues similar in structure and/or hydrophobicity indicates that Trp-8 is involved in the insertion of the LHI alpha polypeptide into the intracytoplasmic membrane (ICM). Pro-13, however, seems not to participate in the integration process of the LHI alpha protein but seems to be important for stable insertion of the LHI beta partner protein in the ICM.

A negatively charged N terminus in the alpha polypeptide inhibits formation of light-harvesting complex I in Rhodobacter capsulatus

Light-harvesting complex I (LHI) of Rhodobacter capsulatus contains bacteriochlorophyll and carotenoids which are noncovalently bound to two different apoproteins (alpha and beta polypeptides) carrying oppositely charged N-terminal ends. The contribution of these charged segments to the assembly of LHI was studied with mutants having oppositely charged amino acids in the alpha or beta polypeptide. The influence of these mutations on the insertion and assembly process of the LHI complex was investigated by means of spectroscopic analysis of isolated intracytoplasmic membranes and pulse-chase experiments. Exchange of four positively charged amino acids to negatively charged amino acids on the N-terminal domain of the alpha subunit inhibited completely the assembly of the LHI complex. Although this mutant has no antenna, the reaction center is active and the cells were able to grow anaerobically in the light. Conversely, mutation of the four negatively charged amino acids of the N-terminal segment of the beta polypeptide did not prevent the assembly of the LHI complex, although the stability of the complex and the size of the photosynthetic unit were affected. The presence of the mutated beta polypeptide was confirmed by protein sequencing.

Stromal serine protein kinase activity in spinach chloroplasts

At least twelve 32P-labeled stromal proteins were detected by electrophoresis under denaturing conditions when intact chloroplasts were incubated with 32Pi, in the light but only three were detected in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) or in the dark. Incubation of isolated stroma with [gamma-32P]ATP resulted in the preferential phosphorylation of one of them, a 70-kDa polypeptide, in serine residues. Thylakoid membranes in the dark promoted the phosphorylation of two additional stromal polypeptides of 55 and 40 kDa. Illumination during the phosphorylation of stroma in the presence of thylakoids stimulated severalfold the labeling of the 40-kDa polypeptide but not when DCMU was added. The protein kinase activity present in isolated stroma phosphorylated exogenous substrates like histone III, phosvitin, histone II, and casein with specific activities of 3, 1.8, 0.7, and 0.2 pmol X mg-1 X min-1. Histone III polypeptides were phosphorylated differently by stroma and by thylakoids in the dark. Moreover, histone III phosphorylated by thylakoids in the dark yielded a pattern of phosphopeptides after V8 protease treatment that was different from the pattern obtained when histone III was phosphorylated by stroma.