Harmonisation of rat fetal skeletal terminology and classification. Report of the Third Workshop on the Terminology in Developmental Toxicology. Berlin, 14-16 September 2000

The initial efforts of the Federal Institute for Health Protection of Consumers and Veterinary Medicine (BgVV) and the Free University of Berlin to standardise terminology in the field of developmental toxicology began in 1995. Procedures were undertaken to harmonise the terminology used by the International Federation of Teratology Societies (IFTS) and the International Programme on Chemical Safety (IPCS). This article reflects these activities and is a report on the Third Workshop on the Terminology in Developmental Toxicology held in September 2000. This Workshop served as a forum to discuss the results of a survey on the classification of skeletal anomalies that had been previously sent to scientists active in the field. Although high agreement was reached among the evaluators for several terms, the use of a number of terms was rather variable. Therefore, the discussions at the workshop among the experts from research institutions, regulatory agencies, and industry were mainly focussed on those terms for which there was disagreement and/or uncertainties and the possible reasons. Pictures provided by the participants for the illustration of "grey zone" anomalies constituted the basis for detailed discussions. In many of the cases with lower agreement, decisions were facilitated by the provision of the corresponding picture. The main reasons for lower agreement were imprecise terms, insufficient knowledge on postnatal consequences, theoretical terms that are unlikely to occur in isolation, and the possibility of observing a range of severity that might be decisive for the classification of either a malformation or variation. The attendees concluded that "grey-zone" anomalies will never disappear completely and that for the assessment, the grade of severity and/or the frequency of the observation can be decisive for the terminology chosen. A Joint IPCS/IFTS Project was proposed to further consensus of terminology and classification and to link these anomalies to pictures at different skeletal sites. In order to support the harmonisation of regulatory decisions, it was proposed to establish a "Clearinghouse" System under the umbrella of the IPCS. The Clearinghouse could be contacted either by the regulatory authorities or by any company to clarify their queries, particularly with regard to registration or authorisation processes. Finally, it was recommended to also carry out a similar survey on "soft tissue anomalies" and "external findings." The results of this survey will be discussed at a Joint IPCS/IFTS Workshop in Berlin in 2002.

First-principles predictions of yet-unobserved ordered structures in the Ag-Pd phase diagram

The complexity of first-principles total energy calculations limits the pool of structure types considered for a ground-state search for a binary alloy system to a rather small, O(10), group of "usual suspects." We conducted an unbiased search of fcc-based Ag(1)-(x)Pd(x) structures consisting of up to many thousand atoms by using a mixed-space cluster expansion. We find an unsuspected ground state at 50%-50% composition-the L1(1) structure, currently known in binary metallurgy only for the Cu(0.5)Pt(0.5) alloy system. We also provide predicted short-range-order profiles and mixing enthalpies for the high temperature, disordered alloy.

Farbhelligkeit L*, Hämpigment- und Eisengehalt im <i>Musculus longissimus dorsi</i> bei Thüringer Schweineherkünften

Abstract. Title of the paper: Colour brightness L*, haem pigment and iron content in the musculus longissimus dorsi at Thuringian pig origins To the Identification of the Situation at the meat quality trait „meat colour" were the colour brightness L*, the reflection spectrum between 400 and 750 nm, the haem pigment content and the iron content at the musculus longissimus dorsi of 278 pigs from the Thuringian Performance testing center determined. While at the colour brightness L* measuring 24 h post mortem 90 % of the animals corresponded to the quality requirements at intact muscles the same samples of minced meat measuring 25 h post mortem presented a lower level of colour brightness L* predominantly. The haem pigment as well as the iron content (n = 104) showed means average values (1,06 mg/g resp. 4,18 mg/kg) which were too low in comparison with bibliographical references.The reflection at 525 nm was correlated with R = 0.7 to the extractive determined haem pigment content,

[Pathobiology of dysplasia in chronic inflammatory bowel disease: Current recommendations for surveillance of dysplasia]

Pathobiology of dysplasia in chronic inflammatory bowel disease: Current recommendations for surveillance of dysplasia. Patients with ulcerative colitis and Crohn's disease bear an about 10- and 4-fold increased risk, respectively, for developing colorectal carcinoma. Apart from typical locations of colorectal carcinoma in the sigmoid colon and rectum other locations were also often observed, e. g. right hemicolon or multifocal distribution. Histologically colorectal neoplasms frequently present as mucinous adenocarcinoma (signet-ring cell carcinoma). The risk for neoplasm depends on extension, severity, duration and therapeutic responsiveness of chronic colonic inflammation, and it seems pathogenetically to be similar in ulcerative colitis and Crohn's disease. Colorectal carcinoma in inflammatory bowel disease arises from epithelial dysplasia. Since there are no reliable biological markers available to date, surveillance-programs continue to rely on the discovery of dysplasia (unequivocal intraepithelial neoplasia). Detection of dysplasia by colonoscopy achieves 70-85 % sensitivity.Endoscopic surveillance should start after 8 years of disease's duration in pancolitis, after 10-12 years in left- sided colitis and after 12 years in Crohn's disease of the colon, with regular intervals every 1-2 years. 3-5 biopsies should be done every 10 cm from mucosa free of inflammation. Additionally, every fine or discrete alteration of the mucosal surface should be recorded. Multiple biosies should also be taken from such minimal lesions as well as from more macroscopically suspicious areas like plaques, nodular lesions or stenosis. The clinical consequence of a positive screening for dysplasia is colectomy because of an assumed risk of cancer of about 40-70 %. Dysplasia in macroscopically suspect areas bear the highest risk of cancer (non-adenoma like dysplasia), followed by multiple high-grade lesions without a macroscopic lesion, and multiple low-grade dysplasias. Detection of single dysplastic lesions in flat mucosa should be followed by a control endoscopy after 2-6 months, and if dysplasia is seen again, colectomy is recommended.

Cortical activation in patients with functional hemispherectomy

Functional hemispherectomy, a safe and effective therapeutical procedure in medically intractable epilepsy, offers the chance to investigate a strictly unilateral cortical activation in ipsilateral limb movement. We assessed the pattern of cortical activation in a group of patients following functional hemispherectomy. We measured regional cerebral blood flow (rCBF) in 6 patients postoperatively and 6 normal subjects with positron emission tomography using 15[O]H2O as a tracer. Brain activation was achieved by passive elbow movements of the affected arm. Analysis of group results and between-group comparisons were performed with statistical parametric mapping, (SPM96). In normal subjects brain activation was found contralaterally in the cranial sensorimotor cortex and the supplementary motor area and ipsilaterally in the inferior parietal cortex. In patients significant rCBF increases were found in the inferior parietal cortex, caudal sensorimotor cortex and the supplementary motor area ipsilaterally. The activation was weaker than in normal subjects. Compared with normal subjects patients showed additional activation in the premotor cortex, caudal sensorimotor cortex and the inferior parietal cortex of the remaining hemisphere. Less activation compared with normal subjects was found in the cranial sensorimotor cortex and the supplementary motor area. A functional network connecting the inferior parietal cortex, premotor cortex and the supplementary motor area as well as the existence of ipsilateral projections originating from these regions may explain why these areas are predominantly involved in reorganization confined to a single hemisphere.

Metaplasia, intraepithelial neoplasia and early cancer of the stomach are related to dedifferentiated epithelial cells defined by cytokeratin-7 expression in gastritis

Cancer presumably arises from stem cells, preserved in an undifferentiated status since fetal development, or from a dedifferentiation of mature cells that return into a fetal phenotype with the potential for proliferation and renewal. Dedifferentiation in this context could represent a transient phase, passed through by cells, before they switch to redifferentiation, metaplasia or neoplasia. Cytokeratin-7 (CK7) is present in fetal, largely absent in normal adult, and transiently neoexpressed in metaplastic and neoplastic epithelial cells of the stomach according to previous observations. CK7 neoexpression in the stomach could, hence, define a fetal-like, dedifferentiated, cellular phenotype during the development of metaplasia and neoplasia. To test this hypothesis, we investigated CK7 expressions in fetal stomachs, non-neoplastic control stomachs, and neoplastic stomachs exhibiting metaplasia, intraepithelial neoplasia, and early cancer. Proliferation and beta-catenin expression of CK7-positive cells were also evaluated. The chronology of CK7 expression was studied during the experimental gastritis-cancer sequence in Mongolian gerbils. Our results show that metaplastic and neoplastic changes in the gastritis-cancer sequence are related to dedifferentiated epithelial cells which are defined by CK7 expression and can phenotypically be linked to fetal cells at the start of gastric pit development. The dedifferentiated cells exhibit a low proliferation and beta-catenin accumulation, similar to stem cells. Thus, the "stem cell" and "dedifferentiation" hypotheses for cancer origin could complement one another, and dedifferentiation-redifferentiation processes might be decisive for carcinogenesis in the stomach.

[Esophageal manometry: equipment cleaning and disinfection with glutaraldehyde]

BACKGROUND

Many publications have emphasized the need of proper cleaning, disinfection and sterilization process for reused materials intended to prevent cross infections. As the endoscope the esophageal manometry catheters are considered as semicritical materials and must be free of microrganisms.

AIM

To standardize the esophageal manometry materials cleaning and disinfection process to guarantee the safety of patients when reusing semicritical materials. It was based on international protocols and according to recommendations of the Hospital Infection Control Commission of the "Hospital de Clinicas de Porto Alegre", Porto Alegre, RS, Brazil.

MATERIALS AND METHODS

Enzymatic detergent was used for catheter cleaning, followed by immersion with 2% glutaraldehyde solution during 20 minutes for high-level disinfection. The water reservatory was kept clean and dry to prevent microorganisms proliferation.

CONCLUSIONS

The high level disinfection with 2% glutaraldehyde, preceded by enzymatic detergent cleaning, is a safe and simple technique that avoids cross infection in the esophageal manometry equipment. This care must be taken after each manometric procedure. The transducers must be resterilized in ethylene oxide. The professionals of this area must work in concordance with the Hospital Infection Control Commission, being acquainted with the country laws and regulations and keeping sterilizing process and materials updated.

[Thalidomide in the treatment of cutaneous and systemic sarcoidosis]

The clinical courses of two patients suffering from generalized or disseminated cutaneous sarcoidosis are described. Both were treated with thalidomide 2 x 100 mg/day, later 100 mg/day. After 8 to 12 months of treatment the skin and systemic lesions had resolved almost completely.

Predictive value of radiological criteria for disintegration rates of extracorporeal shock wave lithotripsy

OBJECTIVE

To evaluate routinely applicable criteria to predict fragmentation of renal calculi by extracorporeal shock wave lithotripsy (ESWL).

PATIENTS AND METHODS

Two hundred and two consecutive patients (121 men, 81 women), median age 48 (range 19-81) years, were treated with the original Dornier HM-3 lithotriptor at a single stone center. Inclusion criteria were: solitary stones, 10-30 mm in greatest diameter, located in renal pelvis or calyces. Based on plain radiographs, the calculi were classified according to their size, form, location, density (compared to the 12th rib), structure and surface. Furthermore, age of the patient, gender and body mass index were also considered for evaluation. Disintegration was documented on day 1 after ESWL by plain X-ray. A multivariate regression analysis was applied to all preoperative parameters, based on the dual variable stone free versus residual fragments.

RESULTS

The overall disintegration rate was 95.5%; 42 patients (20.8%) were completely stone free, and 151 patients (74.7%) had clinically insignificant residual fragments (5 mm or smaller). 14.9% of men and 29.6% of women were stone free (p = 0.01). All other parameters did not reach statistical significance.

CONCLUSIONS

The disintegration rate of the HM-3 is excellent for kidney stones; women did significantly better than men. However, because of this high disintegration rate, a much larger series would be necessary to define possible differences between preinterventional parameters, if there were any at all.

Structural characterization of human recombinant and bone-derived bone sialoprotein. Functional implications for cell attachment and hydroxyapatite binding

Human bone sialoprotein (BSP) comprises 15% of the total noncollagenous proteins in bone and is thought to be involved in bone mineralization and remodeling. Recent data suggest a role for BSP in breast cancer and the development of bone metastases. We have produced full-length recombinant BSP in a human cell line and purified the protein from human bone retaining the native structure with proper folding and post-translational modifications. Mass spectrometry of bone-derived BSP revealed an average mass of 49 kDa and for recombinant BSP 57 kDa. The post-translational modifications contribute 30-40%. Carbohydrate analysis revealed 10 different complex-type N-glycans on both proteins and eight different O-glycans on recombinant BSP, four of those were found on bone-derived BSP. We could identify eight threonines modified by O-glycans, leaving the C terminus of the protein free of glycans. The recombinant protein showed similar secondary structures as bone-derived BSP. BSP was visualized in electron microscopy as a globule linked to a thread-like structure. The affinity for hydroxyapatite was higher for bone-derived BSP than for recombinant BSP. Cell adhesion assays showed that the binding of BSP to cells can be reversibly diminished by denaturation.

Mammalian cells express two VPS4 proteins both of which are involved in intracellular protein trafficking

The yeast Vps4 protein (Vps4p) is a member of the AAA protein family (ATPases associated with diverse cellular activities) and a key player in the transport of proteins out of a prevacuolar endosomal compartment. In human cells, we identified two non-allelic orthologous proteins (VPS4-A and VPS4-B) of yeast Vps4p. The human VPS4-A and VPS4-B proteins display a high degree of sequence identity to each other (80 %) and to the yeast Vps4 protein (59 and 60 %, respectively). Yeast cells lacking a functional VPS4 gene exhibit a temperature-sensitive growth defect and mislocalise a carboxypeptidase Y-invertase fusion protein to the cell surface. Heterologous expression of human VPS4 genes in vps4 mutant yeast strains led, in the case of human VPS4-A, to a partial and, in the case of human VPS4-B, to a complete suppression of the temperature-sensitive growth defect. The vacuolar protein sorting defect of vps4 mutant yeast cells was complemented completely by heterologous expressed human VPS4-B protein, and partially by the human VPS4-A protein. Expression of mutant human VPS4-A (E228Q) and VPS4-B (E235Q) proteins, harbouring single amino acid exchanges in their AAA domains, induced dominant-negative vacuolar protein sorting defects in wild-type yeast cells in both cases. Two-hybrid experiments suggest that the human VPS4-A and VPS4-B proteins can form heteromeric complexes, and subcellular localisation experiments indicate that both human VPS4 proteins associate with endosomal compartments in yeast. Based on these results, we conclude that both human VPS4 proteins are involved in intracellular protein trafficking, presumably at a late endosomal protein transport step, similar to the Vps4p in yeast.

Detection of a conformational change in G gamma upon binding G beta in living cells

Interaction induced changes in the conformation of proteins are frequently the molecular basis for the modulation of their activities. Although proteins perform their functions in cells, surrounded by many potential interaction partners, the studies of their conformational changes have been mainly restricted to in vitro studies. Ste4p (G beta) and Ste18p (G gamma) are the subunits of a heterotrimeric G-protein in the yeast Saccharomyces cerevisiae. A split-ubiquitin based conformational sensor was used to detect a major structural rearrangement in Ste18p upon binding to Ste4p. Based on these in vivo results and the solved structure of the mammalian G beta gamma, we propose that G gamma of yeast adopts an equally extended structure, which is only induced upon association with G beta.

The effect of high-dose pentaerythritol tetranitrate on the development of nitrate tolerance in rabbits

Experimental studies with therapeutic doses of pentaerythritol tetranitrate (PETN) have shown unexpected actions such as a lack of nitrate tolerance and vasoprotective effects in atherosclerosis. We investigated the effect of a 3-week treatment with low- (6 mg kg(-1) day(-1), n=10) and high-dose (100 mg kg(-1) day(-1), n=10) oral PETN given twice daily on the development of nitrate tolerance in rabbits. We measured aortic relaxation in response to acetylcholine, S-nitroso-N-acetyl-D,L-penicillamine and PETN, constriction in response to phenylephrine and production of reactive oxygen species (ROS). Mean aortic pressure (AOPmean) and heart rate were measured after a single oral dose of PETN (50 mg kg(-1), n=6) and after increasing doses of pentaerythritol dinitrate (PEDN, n=5) and pentaerythritol mononitrate (PEMN, n=5) in anaesthetized rabbits. Oral PETN, even at high dosage, was not associated with nitrate tolerance. None of the aortic ring studies showed a difference in the responses to the vasodilators, while the vasoconstriction to phenylephrine was slightly reduced in both PETN groups. The production of vascular ROS was also not different. Oral PETN reduced AOPmean transiently (-19.3+/-4.4%, P<0.01 vs. controls) and i.v. administration of both PEMN and PEDN reduced AOPmean dose dependently (P<0.05, ANOVA). These results suggest that oral PETN elicits minor nitrate tolerance. This unique feature might be due to the slow onset of vasodilator activity of the predominantly active metabolites PEDN and PEMN and might contribute to the vasoprotective activity of PETN in atherosclerosis.

Thermodynamics of HMGB1 interaction with duplex DNA

The high mobility group protein HMGB1 is a small, highly abundant protein that binds to DNA in a non-sequence-specific manner. HMGB1 consists of 2 DNA binding domains, the HMG boxes A and B, followed by a short basic region and a continuous stretch of 30 glutamate or aspartate residues. Isothermal titration calorimetry was used to characterize the binding of HMGB1 to the double-stranded model DNAs poly(dAdT).(dTdA) and poly(dGdC).(dCdG). To elucidate the contribution of the different structural motifs to DNA binding, calorimetric measurements were performed comparing the single boxes A and B, the two boxes plus or minus the basic sequence stretch (AB(bt) and AB), and the full-length HMGB1 protein. Thermodynamically, binding of HMGB1 and all truncated constructs to duplex DNA was characterized by a positive enthalpy change at 15 degrees C. From the slopes of the temperature dependence of the binding enthalpies, heat capacity changes of -0.129 +/- 0.02 and -0.105 +/- 0.05 kcal mol(-1) K(-1) were determined for box A and full-length HMGB1, respectively. Significant differences in the binding characteristics were observed using full-length HMGB1, suggesting an important role for the acid tail in modulating DNA binding. Moreover, full-length HMGB1 binds differently these two DNA templates: binding to poly(dAdT).(dTdA) was cooperative, had a larger apparent binding site size, and proceeded with a much larger unfavorable binding enthalpy than binding to poly(dGdC).(dCdG).

Head-to-head comparison of N-terminal pro-brain natriuretic peptide, brain natriuretic peptide and N-terminal pro-atrial natriuretic peptide in diagnosing left ventricular dysfunction

Brain natriuretic peptide (BNP), NT-proBNP and NT-pro-atrial natriuretic peptide (NT-proANP) were measured in blood samples from 57 patients using immunoassays and immunoradiometric assays to evaluate the usefulness as diagnostic markers for the detection of heart failure. For the detection of impaired left ventricular ejection fraction (LVEF), receiver operating characteristic curves showed that BNP had the best diagnostic performance with an area under curve (AUC) of 0.75+/-0.06. However, NT-proBNP (AUC: 0.67+/-0.07) and NT-proANP (AUC: 0.69+/-0.08) showed no significant difference to BNP. In a further analysis for the detection of resting LVEF <40%, BNP again was the best marker with an AUC of 0.83+/-0.06. NT-proBNP showed only a slightly smaller AUC (0.79+/-0.07). The AUC for NT-proANP was significantly smaller (0.65+/-0.08) compared to BNP. Additionally, BNP and NT-proBNP correlated negatively with the resting LVEF (BNP: -0.472, p<0.001; NT-proBNP: -0.306, p=0.026), whereas NT-proANP showed no significant correlation. In summary, BNP was the best marker to detect patients with impaired LVEF compared to NT-proBNP and NT-proANP. However, NT-proBNP showed no significant differences to BNP and it is therefore a new promising alternative marker for the detection of left ventricular dysfunction.

Astrocytes induce manganese superoxide dismutase in brain capillary endothelial cells

Astrocytes induce blood-brain barrier (BBB) properties in brain endothelial cells (EC)*O(2)*, generated in blood and EC, opens the BBB. Hence, high activity of superoxide dismutase (SOD) is a prerequisite for normal BBB function. Therefore, the influence of rat astrocytes on the expression of manganese (Mn)SOD in rat EC was investigated in two coculture models of the BBB, allowing either exchange of soluble factors or additionally cellular contacts. Activity, protein content and mRNA expression of endothelial MnSOD were significantly increased in both coculture models in comparison to monoculture by soluble astrocytic factors, such as cytokines. High activity of endothelial MnSOD may be considered as a further essential property of the BBB, which is induced and maintained by astrocytes.

Are some memory deficits unique to lesions of the mammillary bodies?

The role of the mammillary bodies in human memory is still in debate. A recent model of human amnesia proposes similar functions for the mammillary bodies and the hippocampus. But the main evidence for this model comes from animal studies using the delayed non-matching to sample paradigm. We describe a patient who developed a severe memory impairment after surgical removal of a germinoma. Postsurgical high resolution MRI revealed bilaterally shrunken mammillary bodies and an infarct of the left mammillary body. There were no other relevant lesions. Neuropsychological testing showed mildly impaired frontal lobe functions (executive functions, working memory and word fluency), almost intact learning and recognition, but severely impaired free and delayed recall. Experimental investigations revealed a reduced but preserved release of proactive interference and a pronounced impairment of recency and source judgments. We conclude that the mammillary bodies do play a prominent role in human memory, although the role differs slightly from that of the hippocampus.

Coordinate positive regulation of genes encoding [NiFe] hydrogenases in Methanococcus voltae

Two transcription units encoding selenium-free [NiFe] hydrogenases in Methanococcus voltae are transcribed only upon selenium deprivation. Their products replace or complement selenocysteine-containing isoenzymes. The transcription units are linked by a 453-bp intergenic region, and are subject to both positive and negative transcriptional regulation. The mechanism of positive regulation was studied in detail. Mutations in identical 11-bp putative activator recognition sites close to each promoter showed that each site is involved in the activation of both promoters. Sequence-specific DNA-affinity chromatography yielded a 55-kDa protein which specifically recognized the 11-bp sequence. We consider this protein to be a transcriptional activator for both transcription units.

Cell biology and matrix biochemistry of chondromyxoid fibroma

We studied matrix composition and gene expression pattern in chondromyxoid fibromas on the protein and the messenger RNA levels. We could clearly identify focal chondrocytic differentiation within chondromyxoid fibroma by the expression and deposition of type II collagen, which is a marker of chondrocytic cell differentiation. We also were able to show expression of collagen types I, III, and VI in the neoplasm. The major tumor portion was, however, characterized by the presence of hydrated proteoglycans and only minor amounts of collagens, a matrix composition responsible for the myxoid matrix appearance of most parts of these neoplasms. By analyzing cytoprotein expression, we found S-100 protein restricted to cells of the chondroid areas, suggesting S-100 protein staining to be of little help as a positive diagnostic marker for chondromyxoid fibroma. Our data show a specific matrix composition of chondromyxoid fibroma, not previously found in other mesenchymal neoplasms, including chondroblastoma, osteochondroma, enchondroma, and chondrosarcoma. This justifies chondromyxoid fibroma as a specific neoplastic entity, both clinically and biologically.

Cloning and expression of cDNAs encoding alpha1,3-fucosyltransferase homologues from Arabidopsis thaliana

The core alpha1,3-fucosyltransferases are involved in the synthesis of glycans specific to plants and invertebrates which are known to be immunogenic and allergenic. We report the identification, isolation and characterisation of the cDNAs of three genes (FucTA, FucTB and FucTC) encoding proteins similar to alpha1,3-fucosyltransferases in Arabidopsis thaliana. Reverse transcription-polymerase chain reaction was used to amplify the full length coding sequence of FucTA. The FucTA gene, which consists of seven exons, encodes a presumptive protein of 501 amino acids showing an overall sequence identity of 66% to the protein encoded by the recently isolated mung bean Fuc-T C3 cDNA. FucTA was expressed in Pichia pastoris under the control of the AOX1 gene promoter. The soluble enzyme was found to catalyse the same reaction as mung bean core alpha1,3-fucosyltransferase as judged by analyses of the products by MALDI-TOF and high-performance liquid chromatography. The FucTB cDNA was isolated from a lambda-ZAP library, but the clone used an alternative splicing site between the second and third exon resulting in a premature stop codon. The FucTC gene encodes a protein with less than 40% identity to FucTA across 115 amino acids of a total of 401 amino acids and is a member of a new sub-family of plant alpha1,3/4-fucosyltransferase homologues.

"Bar-coding" primate chromosomes: molecular cytogenetic screening for the ancestral hominoid karyotype

Two recently introduced multicolor FISH approaches, cross-species color banding (also termed Rx-FISH) and multiplex FISH using painting probes derived from somatic cell hybrids retaining fragments of human chromosomes, were applied in a comparative molecular cytogenetic study of higher primates. We analyzed these "chromosome bar code" patterns to obtain an overview of chromosomal rearrangements that occurred during higher primate evolution. The objective was to reconstruct the ancestral genome organization of hominoids using the macaque as outgroup species. Approximately 160 individual and discernible molecular cytogenetic markers were assigned in these species. Resulting comparative maps allowed us to identify numerous intra-chromosomal rearrangements, to discriminate them from previous contradicting chromosome banding interpretations and to propose an ancestral karyotype for hominoids. From 25 different chromosome forms in an ancestral karyotype for all hominoids of 2N=48 we propose 21. Probes for chromosomes 2p, 4, 9 and Y were not informative in the present experiments. The orangutan karyotype was very similar to the proposed ancestral organization and conserved 19 of the 21 ancestral forms; thus most chromosomes were already present in early hominoid evolution, while African apes and human show various derived changes.

Low prevalence of latently Epstein-Barr virus-infected cells in chronic gastritis

The association of Epstein-Barr virus (EBV) with a proportion of gastric carcinomas is well established. The role of EBV in conditions predisposing to carcinoma such as chronic gastritis has remained undefined, however. We used in situ hybridization with radioactive and nonradioactive single-stranded RNA probes specific for the EBV small latent nuclear transcripts, EBER1 and EBER2, to analyze biopsy specimens from 242 patients with mild to severe chronic gastritis of Sydney classification types A, B, and C. A small number of EBV infected lymphocytes was detected in only nine cases, even in biopsies investigated with radioactive probes. Labeling of epithelial or stromal cells was not observed. The paucity of latently EBV-infected cells in chronic gastritis biopsies differs from the previously reported higher prevalence of virus carrying cells in inflammatory conditions at other sites of the gastrointestinal tract. These findings argue against a direct involvement of EBV in the pathogenesis of chronic gastritis. The low prevalence of EBV-positive cells suggests that local factors do not favor the entry and retention of circulating EBV-infected lymphocytes in gastric mucosa. Moreover, our findings indicate that EBV infection of gastric epithelial cells is not an early event in gastric carcinogenesis.