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PubMed2003

A simple method for DNA extraction from marine bacteria that produce extracellular materials.

We present a simple method for extracting DNA from the marine bacteria Hahella chejuensis, a Streptomyces sp., and a Cytophaga sp. Previously, DNA purification from these strains was hindered by the presence of extracellular materials. In our extraction method, the marine bacteria are lysed by freezing and grinding in liquid nitrogen, and treated with SDS. The extracted DNA is purified using a phenol/chloroform mixture, and precipitated in isopropanol. The extracted DNA is of high quality and suitable for molecular analyses, such as PCR, restriction enzyme digestion, genomic DNA blot hybridization, and genomic DNA library construction. We used this method to extract genomic DNA from several other marine bacteria. Our method is a reproducible, simple, and rapid technique for routine DNA extractions from marine bacteria. Furthermore, the low cost of this method makes it attractive for large-scale studies.

Bacteria↗

PubMed1996

Correction of mass spectral drift using artificial neural networks.

For pyrolysis mass spectrometry (PyMS) to be used for the routine identification of microorganisms, for quantifying determinands in biological and biotechnological systems, and in the production of useful mass spectral libraries, it is paramount that newly acquired spectra be compared to those previously collected. Neural network and other multivariate calibration models have been used to relate mass spectra to the biological features of interest. As commonly observed, however, mass spectral fingerprints showed a lack of long-term reproducibility, due to instrumental drift in the mass spectrometer; when identical materials were analyzed by PyMS at dates from 4 to 20 months apart, neural network models produced at earlier times could not be used to give accurate estimates of determinand concentrations or bacterial identities. Neural networks, however, can be used to correct for pyrolysis mass spectrometer instrumental drift itself, so that neural network or other multivariate calibration models created using previously collected data can be used to give accurate estimates of determinand concentration or the nature of bacteria (or, indeed, other materials) from newly acquired pyrolysis mass spectra. This approach is not limited solely to pyrolysis mass spectrometry but is generally applicable to any analytical tool which is prone to instrumental drift, such as IR, ESR, NMR and other spectroscopies, and gas and liquid chromatography, as well as other types of mass spectrometry.

Ampicillin↗

PubMed2005

Molecular analysis of the anaerobic rumen fungus Orpinomyces - insights into an AT-rich genome.

The anaerobic gut fungi occupy a unique niche in the intestinal tract of large herbivorous animals and are thought to act as primary colonizers of plant material during digestion. They are the only known obligately anaerobic fungi but molecular analysis of this group has been hampered by difficulties in their culture and manipulation, and by their extremely high A+T nucleotide content. This study begins to answer some of the fundamental questions about the structure and organization of the anaerobic gut fungal genome. Directed plasmid libraries using genomic DNA digested with highly or moderately rich AT-specific restriction enzymes (VspI and EcoRI) were prepared from a polycentric Orpinomyces isolate. Clones were sequenced from these libraries and the breadth of genomic inserts, both genic and intergenic, was characterized. Genes encoding numerous functions not previously characterized for these fungi were identified, including cytoskeletal, secretory pathway and transporter genes. A peptidase gene with no introns and having sequence similarity to a gene encoding a bacterial peptidase was also identified, extending the range of metabolic enzymes resulting from apparent trans-kingdom transfer from bacteria to fungi, as previously characterized largely for genes encoding plant-degrading enzymes. This paper presents the first thorough analysis of the genic, intergenic and rDNA regions of a variety of genomic segments from an anaerobic gut fungus and provides observations on rules governing intron boundaries, the codon biases observed with different types of genes, and the sequence of only the second anaerobic gut fungal promoter reported. Large numbers of retrotransposon sequences of different types were found and the authors speculate on the possible consequences of any such transposon activity in the genome. The coding sequences identified included several orphan gene sequences, including one with regions strongly suggestive of structural proteins such as collagens and lampirin. This gene was present as a single copy in Orpinomyces, was expressed during vegetative growth and was also detected in genomes from another gut fungal genus, Neocallimastix.

AT Rich Sequence↗

PubMed2007

Expression of phosphoproteins and amelotin in teeth.

The organic material of our teeth consists of collagens and a number of calcium-binding phosphoproteins. Six of these phosphoproteins have recently been grouped in the family of the SIBLINGs (small integrin-binding ligand, N-linked glycoproteins), namely osteopontin, bone sialoprotein, dentin matrix protein (DMP1), dentin sialophosphoprotein (DSPP), matrix extracellular phosphoglycoprotein (MEPE) and enamelin. We prepared a cDNA library from rat incisors in order to identify the genes involved in tooth formation. The library was screened by subtractive hybridization with two probes; one specific for teeth, the other for bone. We found that the vast majority of the clones from our library were expressed at similar levels in bone and teeth, demonstrating the close relationship of the two tissues. Only 7% of all the clones were expressed in a tooth-specific fashion. These included clones for the enamel proteins; amelotin, amelogenin, ameloblastin and enamelin; for the dentin proteins DSPP and DMP1; and for the intermediate filament protein cytokeratin 13. Several typical bone proteins, including collagen I, osteocalcin, alkaline phosphatase and FATSO, were also expressed at significantly higher levels in teeth than in bone, probably due to the extreme growth rate of rat incisors. The amino acid sequence of rat amelotin showed 62% identity with the sequence from humans. It was expressed considerably later than the other enamel proteins, suggesting that amelotin may serve a function different from those of amelogenin, ameloblastin and enamelin.

Amino Acid Sequence↗

PubMed1996

"In vivo" pose estimation of artificial knee implants using computer vision.

This paper describes an algorithm to estimate the position and orientation (pose) of artificial knee implants from fluoroscopy images using computer vision. The resulting information is used to determine contact position from " in vivo" bone motion in implanted knees. This determination can be used to support the development of improved prosthetic knee implants. Current generation implants have a limited life span due to premature wear of the polyethylene material at the joint surface. To get "in vivo" motion, fluoroscopy videos were taken of implant patients performing deep knee bends. Our algorithm determines the full 6 degree of freedom translation and rotation of knee components. This is necessary for artificial knees which have shown significant rotation out of the sagittal plane, in particular internal/external rotations. By creating a library of images at known orientation and performing a matching technique, the 3-D pose of the femoral and tibial components are determined. By transforming the coordinate systems into one common system contact positions can be determined. The entire process, when used at certain knee angles, will give a representation of the positions in contact during normal knee motion.

Algorithms↗

PubMed1999

Cloning and characterization of a beta-galactoside-binding protein (galectin) from the gut of the gastrointestinal nematode parasite Haemonchus contortus.

A cDNA encoding a beta-galactoside-binding lectin (galectin) was identified by immunoscreening a Haemonchus contortus cDNA library with antisera from lambs vaccinated with a membrane protein complex (H-gal-GP) derived from the parasites' gut. The cDNA sequence, exhibiting a tandem repeat structure and designated Hco-gal-2, showed significant levels of similarity with galectins from several species of nematode as well as mammalian galectin type 4. Native galectin was preferentially extracted from the H-gal-GP complex and also from an insoluble membrane fraction prepared from adult worms using lactose-agarose affinity chromatography. The affinity-purified material had apparent molecular mass of around 35 kDa with 3 distinct bands visible on SDS-PAGE. All 3 bands were identified as galectins by reaction with antiserum raised to recombinant Hco-GAL-2 on Western blot. To determine whether H. contortus galectins have any protective capacity against infection lambs were vaccinated with affinity-purified galectin and subsequently given a single challenge infection. Vaccination did not confer any protection against infection with H. contortus as judged by faecal egg output or worm counts.

Amino Acid Sequence↗

PubMed1994

Characterisation of cDNA and genomic clones encoding homologues of the 65 kDa regulatory subunit of protein phosphatase 2A in Arabidopsis thaliana.

Two cDNA species encoding sequences homologous to the 65 kDa regulatory subunit (PR 65) of protein phosphatase 2A (PP2A) have been isolated from an Arabidopsis thaliana cDNA library. These were designated pDF1 and pDF2. pDF1 is 1795 bp long and by comparison with the human and porcine PP2A regulatory subunit sequences represents a full-length clone. It encodes a predicted polypeptide of 587 amino acid residues. pDF2 is truncated at the 5' end by 237 bp. The complete nucleotide sequences have been determined for both cDNA species. Comparison of the nucleotide and the deduced amino acid sequences showed that the two sequences were homologous but not identical and therefore must be derived from two different genes. Northern blot analysis was performed on total RNA and poly(A)+ RNA isolated from seed at various stages of development and from young leaf material of Brassica napus L. (oilseed rape). Both cDNA probes hybridised to a single major mRNA species of ca. 2.2 kb. The highest level of expression was observed in the total RNA from developing rape seed at about 33 days after flowering, and the transcript level in the poly(A)+ RNA of the seed was higher than in young leaf of oilseed rape. Southern blot analysis was performed on two varieties of A. thaliana and B. napus genomic DNA; this identified a small family of genes in A. thaliana consisting of at least 2 or 3 members and a larger multigene family in B. napus of at least 5 or 6 members. Two independent genomic clones were isolated from an A. thaliana genomic library. Sequencing of a fragment common to both revealed that the sequence was identical in both clones and, therefore, they were assumed to contain the same genomic sequence. The genomic sequence selected, designated regA, is 3639 bp long and the coding sequence contains eleven introns. The gene encodes a predicted polypeptide of 590 amino acid residues. The sequence comparison with both cDNA sequences showed that it is homologous but not identical to the two, confirming that at least three different genes exist in A. thaliana which encode PR65 of PP2A.

Amino Acid Sequence↗

PubMed2001

Surgical interventions for treating distal radial fractures in adults.

BACKGROUND: Fracture of the distal radius is a common clinical problem, particularly in older white women with osteoporosis. OBJECTIVES: To determine when, and if so what type of, surgical intervention is the most appropriate treatment for fractures of the distal radius in adults. SEARCH STRATEGY: We searched the Cochrane Musculoskeletal Injuries Group's specialised register, Cochrane Controlled Trials Register (The Cochrane Library Issue 4, 2000), MEDLINE, EMBASE, CINAHL, the National Research Register (Issues 2 to 4, 2000) and bibliographies of trial reports. The full search was concluded in December 2000. SELECTION CRITERIA: Randomised or quasi-randomised clinical trials involving skeletally mature patients with a fracture of the distal radius, which compared surgical treatment with conservative treatment, different types of surgical intervention or the duration of immobilisation after surgery. The main categories of surgical intervention were external fixation, percutaneous pinning, open reduction and internal fixation, and the insertion of bone scaffolding materials. DATA COLLECTION AND ANALYSIS: All trials, meeting the selection criteria, were independently assessed by both reviewers for methodological quality. Data were extracted for anatomical, functional and clinical outcomes (including complications). The trials were grouped into categories relating to the main comparisons and types of surgical intervention. Despite clear heterogeneity in the characteristics of comparable trials, pooling of data was undertaken where possible and appropriate. MAIN RESULTS: Forty four trials, examining 23 treatment comparisons, met the inclusion criteria of this review. These involved a total of 3193 mainly female and older patients with generally displaced, often comminuted and potentially or evidently unstable fractures. Half of the trials compared surgery with plaster cast immobilisation. Summarising the outcomes was hampered by the variation between the studies in participant characteristics, interventions, quality of trial methodology and reporting, and methods of outcome measurement. Surgical methods were usually associated with better anatomical appearance after fracture healing, but there was inadequate evidence to confirm that these had resulted in better functional and clinical outcomes for the patients. REVIEWER'S CONCLUSIONS: The 44 randomised trials do not provide robust evidence for most of the decisions necessary in the management of these fractures. Although, in particular, there is some evidence to support the use of external fixation or percutaneous pinning, their precise role and methods are not established. It is also unclear whether surgical intervention of most fracture types will produce consistently better long-term outcomes. There is a need for good quality evidence for the surgical management of these fractures.

Adult↗

PubMed2002

Identification of novel bovine RPE and retinal genes by subtractive hybridization.

PURPOSE: Understanding of the specialized function of the retinal pigment epithelium (RPE) can be aided by the identification and characterization of genes that are preferentially expressed in the RPE. With this aim, we undertook a systematic effort to identify and begin characterization of such genes. METHODS: A subtracted bovine RPE cDNA library was generated through subtractive hybridization using a single-stranded circular bovine RPE cDNA library as target and biotinylated mRNA from bovine heart and liver as alternate drivers. Approximately one thousand of the resulting subtracted cDNA clones were partially sequenced and analyzed, and a non-redundant set of one hundred of these cDNAs were examined for tissue expression pattern using a mini-Northern blot procedure and for identity by sequence analysis. RESULTS: The subtraction method successfully allowed the enrichment of cDNAs that are preferentially expressed in the RPE. Out of the analyzed clones, expression of forty-five clones was verifiable by Northern blotting. Of these, a significant proportion of cDNAs were preferentially expressed in the RPE. We observed that the expression of some subtracted cDNAs was restricted to the retina and no expression was detected in the RPE. These retinal clones were obtained in addition to RPE clones presumably because the initial RPE RNA population was contaminated with a small proportion of retinal RNA. Two thirds of the identified RPE and retinal cDNAs are likely to represent novel genes because they do not have homology to known genes in the databases. CONCLUSIONS: Genes that are specifically or predominantly expressed in the RPE/retina are likely to be important for retinal function. We have identified novel cDNAs from bovine RPE and retina by subtractive hybridization. These cDNAs can be used as starting material for the identification of corresponding human genes expressed in the RPE and retina. The human genes thus identified are likely to contain good candidate genes for retinal disease.

Animals↗

PubMed2006

Generation of high density protein microarrays by cell-free in situ expression of unpurified PCR products.

Due to the success of DNA microarrays and the growing numbers of available protein expression clones, protein microarrays have become more and more popular for the high throughput screening of protein interactions. However, the widespread applicability of protein microarrays is currently hampered by the large effort associated with their production. Apart from the requirement for a protein expression library, expression and purification of the proteins themselves and the lacking stability of many proteins remain the bottleneck. Here we present an approach that allows the generation of high density protein microarrays from unbound DNA template molecules on the chip. It is based on the multiple spotting technique and comprises the deposition of a DNA template in a first spotting step and the transfer of a cell-free transcription and translation mixture on top of the same spot in a second spotting step. Using wild-type green fluorescent protein as a model protein, we demonstrated the time and template dependence of this coupled transcription and translation and showed that enough protein was produced to yield signals that were comparable to 300 microg/ml spotted protein. Plasmids as well as unpurified PCR products can be used as templates, and as little as 35 fg of PCR product ( approximately 22,500 molecules) were sufficient for the detectable expression of full-length wild-type green fluorescent protein in subnanoliter volumes. We showed that both aminopropyltrimethoxysilane and nickel chelate surfaces can be used for capture of the newly synthesized proteins. Surprisingly we observed that nickel chelate-coated slides were binding the newly synthesized proteins in an unspecific manner. Finally we adapted the system to the high throughput expression of libraries by designing a single primer pair for the introduction of the required T7 promoter and demonstrated the in situ expression using 384 randomly chosen clones.

Cell-Free System↗

PubMed2003

A comparative study of culture-independent, library-independent genotypic methods of fecal source tracking.

Culture-independent fecal source tracking methods have many potential advantages over library-dependent, isolate-culture methods, but they have been subjected to limited testing. The purpose of this study was to compare culture-independent, library-independent methods of fecal source tracking. Five laboratories analysed identical sets of aqueous samples that contained one or more of the following sources: sewage, human feces, dog feces, cattle feces and gull feces. Two investigators used methods based on PCR amplification of Bacteroidetes marker genes and both successfully discriminated between samples that did or did not contain human fecal material. One of these investigators was also able to identify the remaining sources, except for gull, with a low rate of false positives. A method based on E. coli toxin genes successfully identified samples containing sewage and cattle feces, but missed some samples with human feces because of low marker prevalence in individual human fecal samples. Researchers who used community terminal restriction fragment length polymorphism (T-RFLP) were limited by the amount of DNA recovered from samples, but they correctly identified human and cattle fecal contamination when sufficient DNA was obtained. Culture independent methods show considerable promise; further research is needed to develop markers for additional fecal sources and to understand the correlation of these source-tracking indicators to measures of human and environmental health.

Animals↗

PubMed1983

The human erythrocyte anion-transport protein. Partial amino acid sequence, conformation and a possible molecular mechanism for anion exchange.

The N-terminal 72 residues of an integral membrane fragment, P5, of the human erythrocyte anion-transport protein, which is known to be directly involved in the anion-exchange process, was shown to have the following amino acid sequence: Met-Val-Pro-Lys-Pro-Gln-Gly-Pro-Leu-Pro-Asn-Thr-Ala-Leu-Leu-Ser-Leu-Val-Leu-Met -Ala-Gly-Thr-Phe-Phe-Phe-Ala-Met-Met-Leu-Arg-Lys-Phe-Lys-Asn-Ser-Ser-Tyr-Phe-Pro-Gly-Lys-Leu-Arg-Arg-Val-Ile-Gly-Asp-Phe-Gly-Val-Pro-Ile-Ser-Ile-Leu-Ile-Met-Val-Leu-Val-Asp-Phe-Phe-Ile-Gln-Asp-Thr-Tyr-Thr-Gln- The structure of this fragment was analysed, with account being taken of the constraints that apply to the folding of integral membrane proteins and the topographical locations of various sites in the sequence. It was concluded that this sequence forms two transmembrane alpha-helices. These are probably part of a cluster of amphipathic transmembrane alpha-helices, which could comprise that part of the protein responsible for transport activity. The presently available evidence relating to the anion-exchange process was considered with the structural features noted in this study and a possible molecular mechanism is proposed. In this model the rearrangement of a network of intramembranous charged pairs mediates the translocation of an anion between anion-binding regions at each surface of the membrane, which are composed of clusters of positively charged amino acids. This model imposes a sequential exchange mechanism on the system. Supplementary material, including Tables and Figures describing the compositions of peptides determined by amino acid analysis and sequence studies, quantitative and qualitative data that provide a residue-by-residue justification for the sequence assignment and a description of modifications to and use of the solid-phase sequencer has been deposited as Supplementary Publication SUP 50123 (12 pages) with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained as indicated in Biochem. J. (1983) 209, 5.

Amino Acid Sequence↗

PubMedDate not supplied

Calcium phosphate cement: review of mechanical and biological properties.

PURPOSE: Calcium phosphate cement is a bioactive and biodegradable grafting material in the form of powder and liquid, which when mixed, sets as primarily hydroxyapatite, sometimes mixed with unreacted particles and other phases. This material has been extensively investigated due to its excellent biological properties, potential resorbability, molding capabilities, and easy manipulation. Because the material can potentially be replaced with bone after a period of time, it could retain the short-term biological advantages of hydroxyapatite without the long-term disadvantages. Although little is known about this material in the dental community, in vivo and in vitro studies show calcium phosphate cement as a promising material for grafting applications. In the following article, the authors review the biological and mechanical properties of calcium phosphate cement, as well as its potential use in clinical applications. MATERIALS AND METHODS: A Medline search was performed (timeline: 1980 to 2003) using the following keywords: calcium phosphate cement, hydroxyapatite cement, HA cement, and hydroxyapatite. The search was limited to the English language. The patent literature as well as a limited number of master's theses and books were reviewed after using the electronic database search service from a dental school library. RESULTS: Calcium phosphate cement appears to have excellent biological properties. At only 2 weeks, spicules of living bone with normal bone marrow and osteocytes can be seen. Excellent moldability is a desired clinical characteristic; however, further research is necessary in order to improve the mechanical properties of the cement. The resorption/replacement by bone capability of the cement remains controversial. Further research is needed to clarify this issue. Due to poor mechanical properties, clinical applications are currently limited to craniofacial applications. Further research is necessary to take advantage of the excellent biological properties of this cement under clinical applications. CONCLUSION: Further research is necessary to understand and improve the behavior of this type of cement under clinical situations.

Absorbable Implants↗

PubMed2025

Impact of RNA extraction on respiratory microbiome analysis using third-generation sequencing.

BACKGROUND: The respiratory microbiome, which comprises bacteria, fungi, and viruses, plays a crucial role in respiratory health and disease. However, its study is limited by the low microbial biomass in respiratory samples and the dominance of host RNA. Metatranscriptomics offers comprehensive insights into active microbial communities and their interactions with the host but requires optimized RNA extraction protocols for robust and unbiased analysis. This study evaluated two RNA extraction kits—one employing chemical lysis (CL) and another combining chemical and mechanical lysis (CML)—to determine their effectiveness for metatranscriptomic analysis of respiratory samples. RESULTS: The CML protocol significantly increased double-stranded DNA (dsDNA) library yields, leading to higher sequencing read counts for both sample types (p < 0.0001). The read length was unaffected by the lysis protocol for the BAL and NPS samples. Taxonomic profiling revealed that CML enhanced the detection of robust microorganisms, such as gram-positive bacteria and fungi, without compromising viral detection. CONCLUSIONS: The CML protocol demonstrated superior recovery of genetic material, particularly for fungi and gram-positive bacteria, making it better suited for comprehensive metatranscriptomic analyses. These findings underscore the need for tailored RNA extraction strategies on the basis of sample type and research objectives. Optimized metatranscriptomic protocols are pivotal for advancing our understanding of the respiratory microbiome and its role in health and disease.

Microbiota↗

PubMed1998

Erotized, AIDS-HIV information on public-access television: a study of obscenity, state censorship and cultural resistance.

This study analyzes court records of a county-level obscenity trial in Austin, Texas, and the appeal of the guilty verdict beginning with a Texas appellate court up to the U.S. Supreme Court of two individuals who broadcast erotized AIDS and HIV safer sex information on a public-access cable television. The trial and appellate court decisions are reviewed in terms of argument themes, and the nature of sexual value controversy is outlined. Erotic materials often conflict with broad-based sexual and community values, and providing erotized HIV and AIDS information products can be a form of radical political action designed to force societal change. This study raises question as to how this trial and this type of informational product might affect the programs and activities of information resource centers, community-based organizations, libraries, and the overall mission of public health education.

Acquired Immunodeficiency Syndrome↗

PubMed1976

[Practice of computer use in radiotherapy planning].

The main problems of radiotherapy planning are discussed with respect to use of computers now being available for a greater number of centers. One of the most essential premises is apart from clear ideas on a modern target volume concept - a sufficiently high speed in producing realistic summarized isodose contours for any radiation therapy arrangement in any individual patient's cross section outline. This problem being solved, those individual summarized isodose figures have to be critically evaluated and therefore the importance of applicable meaningful optimization criteria come into account. The properties of such criteria, which must be quantifiable, generally applicable and really relevant for judgement on quality of a plan, had to be accepted, before automatic optimization procedures could be developed; principles involved are presented. By means of a short series of examples, namely 60Co fixed field combinations with and without use of wedges, combinations of arc therapy for a number of clinical tasks. It has been pointed out, that most experienced estimate by the eye would have been by far insufficient when compared to the automized computer optimization when using such simple criteria as 1. homogeneity of absorbed dose within target volume, 2. numerically limited absorbed dose within areas of risk, 3. as low as possible radiation effects to all "outside areas". It seems to be a real danger, that so called isodose libraries, how high their merits might be estimated, may change into an "isodose bcemetery", unless we'll be successful for each individual clinical case by use of computers, which are now prepared to supply the best possible variant of the standard plan or the primary radiotherapy idea. Regular use of computers in such a way will furthermore give an incomparable documentation material.

Breast Neoplasms↗

PubMed1997

Potential of high-performance liquid chromatography with photodiode array detection in forensic toxicology.

The potentials and limitations of high-performance liquid chromatography-photodiode array detection are highlighted in respect to its use in the analysis of different biological matrices followed by the identification of unknowns. The logical analytical approach used in clinical and forensic toxicology, vital for the identification of one or more toxic substances as a cause of intoxication, is largely based on both simple and fast "general unknown screening" methods which cover most relevant drugs and potentially hazardous chemicals. In this field of systematic toxicological analysis, a literature overview shows that HPLC can play a substantial role. Both column packing material and eluent composition have their impact on intra- and interlaboratory reproducibility. In view of the sometimes different retention characteristics of various HPLC columns, several possibilities are addressed to enhance the discriminating power of primary retention parameters. The advantages of photodiode array detection as compared to UV detection have been of paramount importance to the success of HPLC in toxicological analysis. Dedicated libraries with spectral information and searching software are powerful tools in the process of identification of an unknown substance. In the present paper, these aspects are also verified in a number of real cases, i.e., trazodone and dothiepin, azide, chloroquine and cocaine, in which we illustrate from our own experience the potentials of HPLC-photodiode array detection in systematic toxicological analysis.

Adult↗

PubMed2005

Pseudoachalasia: a case series and analysis of the literature.

OBJECTIVE: Pseudoachalasia frequently cannot be distinguished from idiopathic achalasia by manometry, radiologic examination or endoscopy. Mechanisms proposed to explain the clinical features of pseudoachalasia include a circumferential mechanical obstruction of the distal esophagus or a malignant infiltration of inhibitory neurons within the myenteric plexus. MATERIAL AND METHODS: Between January 1980 and December 2002, the clinical features of 5 patients with pseudoachalasia and 174 patients with primary achalasia, diagnosed in a single center, were compared. A literature analysis of the etiology of pseudoachalasia for the time period 1968 to December 2002 was performed. The search concentrated on the databases and online catalogues PubMed, Web of Science, Cochrane Library and Current Contents Connect. RESULTS: In our case series, patients with pseudoachalasia reported a shorter duration of symptoms and tended to be older than patients with primary achalasia. Conventional manometry, endoscopy and radiologic examination of the esophagus proved to be of little value in distinguishing between the diseases. In the majority of cases only surgical exploration revealed the underlying cause. A coincidence of primary achalasia and disorders of the gastroesophageal junction was excluded by showing return of peristalsis following treatment. The analysis of the literature showed a total of 264 cases of pseudoachalasia in 122 publications. Most cases of were due to malignant disease (53.9% primary and 14.9% secondary malignancy), followed by benign lesions (12.6%) and sequelae of surgical procedures at the distal esophagus or proximal stomach (11.9%). In rare instances, the disease was an expression of a paraneoplastic process due to distant neuronal involvement rather than to local invasion with destruction of the myenteric plexus (2.6%). CONCLUSIONS: The diagnosis of pseudoachalasia is difficult to establish by conventional diagnostic measures. The main distinguishing feature of secondary versus primary achalasia is the complete reversal of pathologic motor phenomena following successful therapy of the underlying disorder.

Adult↗