Reinforced versus standard stapler transection on postoperative pancreatic fistula in distal pancreatectomy: multicentre randomized clinical trial.

BACKGROUND: Postoperative pancreatic fistula is the leading cause of morbidity after distal pancreatectomy. Strategies investigated to reduce the incidence have been disappointing. Recent data showed a reduction in postoperative pancreatic fistula with the use of synthetic mesh reinforcement of the staple line. METHODS: An RCT was conducted between May 2014 and February 2016 at four tertiary referral centres in Sweden. Patients scheduled for distal pancreatectomy were eligible. Enrolled patients were randomized during surgery to stapler transection with biological reinforcement or standard stapler transection. Patients were blinded to the allocation. The primary endpoint was the development of any postoperative pancreatic fistula. Secondary endpoints included morbidity, mortality, and duration of hospital stay. RESULTS: Some 107 patients were randomized and 106 included in an intention-to-treat analysis (56 in reinforced stapling group, 50 in standard stapling group). No difference was demonstrated in terms of clinically relevant fistulas (grade B and C): 6 of 56 (11 per cent) with reinforced stapling versus 8 of 50 (16 per cent) with standard stapling (P = 0.332). There was no difference between groups in overall postoperative complications: 45 (80 per cent) and 39 (78 per cent) in reinforced and standard stapling groups respectively (P = 0.765). Duration of hospital stay was comparable: median 8 (range 2-35) and 9 (2-114) days respectively (P = 0.541). CONCLUSION: Biodegradable stapler reinforcement at the transection line of the pancreas did not reduce postoperative pancreatic fistula compared with regular stapler transection in distal pancreatectomy. Registration number: NCT02149446 (http://www.clinicaltrials.gov).

Impact of delay between imaging and treatment in patients with potentially curable pancreatic cancer.

BACKGROUND: Locoregional pancreatic ductal adenocarcinoma (PDAC) may progress rapidly and/or disseminate despite having an early stage at diagnostic imaging. A prolonged interval from imaging to resection might represent a risk factor for encountering tumour progression at laparotomy. The aim of this study was to determine the therapeutic window for timely surgical intervention. METHODS: This observational cohort study included patients with histologically confirmed PDAC scheduled for resection with curative intent from 2008 to 2014. The impact of imaging-to-resection/reassessment (IR) interval, vascular involvement and tumour size on local tumour progression or presence of metastases at reimaging or laparotomy was evaluated using univariable and multivariable regression. Risk estimates were approximated using hazard ratios (HRs). RESULTS: Median IR interval was 42 days. Of 349 patients scheduled for resection, 82 had unresectable disease (resectability rate 76.5 per cent). The unresectability rate was zero when the IR interval was 22 days or shorter, and was lower for an IR interval of 32 days or less compared with longer waiting times (13 versus 26.2 per cent; HR 0.42, P = 0.021). It was also lower for tumours smaller than 30 mm than for larger tumours (13.9 versus 32.5 per cent; HR 0.34, P < 0.001). Tumours with no or minor vascular involvement showed decreased rates of unresectable disease (20.6 per cent versus 38 per cent when there was major or combined vascular involvement; HR 0.43, P = 0.007). However, this failed to reach statistical significance on multivariable analysis (P = 0.411), in contrast to IR interval (P = 0.028) and tumour size (P < 0.001). CONCLUSION: Operation within 32 days of diagnostic imaging reduced the risk of tumour progression to unresectable disease by half compared with a longer waiting time. The results of this study highlight the importance of efficient clinical PDAC management.

Reassuringly low carriage of enteropathogens among healthy Swedish children in day care centres.

OBJECTIVES: Infectious gastroenteritis is one of the most common diseases among children and has a considerable impact on health and socio-economy. Day care centres are high-risk environments for infections. The aim of this study was to investigate if asymptomatic preschool children constitute a reservoir for potential enteropathogens. STUDY DESIGN: In total, 438 individual diapers were collected from day care centres in Uppsala, Sweden, during spring and autumn, and molecular techniques were used to estimate the prevalence of asymptomatic carriage of multiple enteropathogens. METHODS: Faecal samples were analysed with multiplex polymerase chain reaction (PCR) (xTAG® Gastrointestinal Pathogen Panel; Luminex Corporation, Toronto, Canada) targeting 21 different pathogens. Samples with a median fluorescence intensity above threshold were re-analysed with a second PCR assay. RESULTS: Sixteen of the 438 samples were positive for enteropathogens, 1.6% for enteric adenovirus, 0.7% for Campylobacter spp., and 0.7% for norovirus. CONCLUSIONS: Preschool children in Uppsala constitute a limited reservoir for potential enteropathogens.

Serological evaluation of possible exposure to Ljungan virus and related parechovirus in autoimmune (type 1) diabetes in children.

Exposure to Ljungan virus (LV) is implicated in the risk of autoimmune (type 1) diabetes but possible contribution by other parechoviruses is not ruled out. The aim was to compare children diagnosed with type 1 diabetes in 2005-2011 (n = 69) with healthy controls (n = 294), all from the Jämtland County in Sweden, using an exploratory suspension multiplex immunoassay for IgM and IgG against 26 peptides of LV, human parechoviruses (HPeV), Aichi virus and poliovirus in relation to a radiobinding assay (RBA) for antibodies against LV and InfluenzaA/H1N1pdm09. Islet autoantibodies and HLA-DQ genotypes were also determined. 1) All five LV-peptide antibodies correlated to each other (P < 0.001) in the suspension multiplex IgM- and IgG-antibody assay; 2) The LV-VP1_31-60-IgG correlated with insulin autoantibodies alone (P = 0.007) and in combination with HLA-DQ8 overall (P = 0.022) as well as with HLA-DQ 8/8 and 8/X subjects (P = 0.013); 3) RBA detected LV antibodies correlated with young age at diagnosis (P < 0.001) and with insulin autoantibodies (P < 0.001) especially in young HLA-DQ8 subjects (P = 0.004); 4) LV-peptide-VP1_31-60-IgG correlated to RBA LV antibodies (P = 0.009); 5) HPeV3-peptide-IgM and -IgG showed inter-peptide correlations (P < 0.001) but only HPeV3-VP1_1-30-IgG (P < 0.001) and VP1_95-124-IgG (P = 0.009) were related to RBA LV antibodies without relation to insulin autoantibody positivity (P = 0.072 and P = 0.486, respectively). Both exploratory suspension multiplex IgG to LV-peptide VP1_31-60 and RBA detected LV antibodies correlated with insulin autoantibodies and HLA-DQ8 suggesting possible role in type 1 diabetes. It remains to be determined if cross-reactivity or concomitant exposure to LV and HPeV3 contributes to the seroprevalence.

Hospital teaching status and volume related to mortality after pancreatic cancer surgery in a national cohort.

BACKGROUND: The association between hospital teaching status and mortality after pancreatic resection is not well explored. Although hospital volume is related to short-term mortality, the effect on long-term survival needs investigation, taking into account hospital teaching status and selective referral patterns. METHODS: This was a nationwide retrospective register-based cohort study of patients undergoing pancreatic resection between 1990 and 2010. Follow-up for survival was carried out until 31 December 2011. The associations between hospital teaching status and annual hospital volume and short-, intermediate- and long-term mortality were determined by use of multivariable Cox regression models, which provided hazard ratios (HRs) with 95 per cent c.i. The analyses were mutually adjusted for hospital teaching status and volume, as well as for patients' sex, age, education, co-morbidity, type of resection, tumour site and histology, time interval, referral and hospital clustering. RESULTS: A total of 3298 patients were identified during the study interval. Hospital teaching status was associated with a decrease in overall mortality during the latest interval (years 2005-2010) (university versus non-university hospitals: HR 0·72, 95 per cent c.i. 0·56 to 0·91; P = 0·007). During all time periods, hospital teaching status was associated with decreased mortality more than 2 years after surgery (university versus non-university hospitals: HR 0·86, 0·75 to 0·98; P = 0·026). Lower annual hospital volume increased the risk of short-term mortality (HR for 3 or fewer compared with 4-6 pancreatic cancer resections annually: 1·60, 1·04 to 2·48; P = 0·034), but not long-term mortality. Sensitivity analyses with adjustment for tumour stage did not change the results. CONCLUSION: Hospital teaching status was strongly related to decreased mortality in both the short and long term. This may relate to processes of care rather than volume per se. Very low-volume hospitals had the highest short-term mortality risk.

Diagnostic value of abdominal drainage in individual risk assessment of pancreatic fistula following pancreaticoduodenectomy.

BACKGROUND: The use of prophylactic abdominal drainage following pancreaticoduodenectomy (PD) is controversial as its therapeutic value is uncertain. However, the diagnosis of postoperative pancreatic fistula (POPF), the main cause of PD-associated morbidity, is often based on drain pancreatic amylase (DPA) levels. The aim of this study was to assess the predictive value of DPA, plasma pancreatic amylase (PPA) and serum C-reactive protein (CRP) for diagnosing POPF after PD. METHODS: Patients undergoing PD with prophylactic drainage between 2008 and 2012 were studied prospectively. DPA, PPA and CRP levels were obtained daily. Differences between groups with clinically relevant POPF (International Study Group on Pancreatic Fistula (ISGPF) grade B/C) and without clinically relevant POPF (no POPF or ISGPF grade A) were evaluated. Receiver operating characteristic (ROC) analyses were performed to determine the value of DPA, PPA and CRP in prediction of POPF. Risk profiles for clinically relevant POPF were constructed and related to the intraoperative pancreatic risk assessment. RESULTS: Fifty-nine (18.7 per cent) of 315 patients developed clinically relevant POPF. DPA, PPA and CRP levels on postoperative day (POD) 1-3 differed significantly between the study groups. In predicting POPF, the DPA level on POD 1 (cut-off at 1322 units/l; odds ratio (OR) 24.61, 95 per cent confidence interval 11.55 to 52.42) and POD 2 (cut-off at 314 units/l; OR 35.45, 14.07 to 89.33) was superior to that of PPA on POD 1 (cut-off at 177 units/l; OR 13.67, 6.46 to 28.94) and POD 2 (cut-off at 98 units/l; OR 16.97, 8.33 to 34.59). When DPA was combined with CRP (cut-off on POD 3 at 202 mg/l; OR 16.98, 8.43 to 34.21), 90.3 per cent of postoperative courses could be predicted correctly (OR 44.14, 16.89 to 115.38). CONCLUSION: The combination of serum CRP and DPA adequately predicted the development of clinically relevant pancreatic fistula following PD.

Assessing surgical quality: comparison of general and procedure-specific morbidity estimation models for the risk adjustment of pancreaticoduodenectomy outcomes.

INTRODUCTION: The use of outcomes to evaluate surgical quality implies the need for detailed risk adjustment. The physiological and operative severity score for the enumeration of mortality and morbidity (POSSUM) is a generally applicable risk adjustment model suitable for pancreatic surgery. A pancreaticoduodenectomy (PD)-specific intraoperative pancreatic risk assessment (IPRA) estimates the risk of postoperative pancreatic fistula (POPF) and associated morbidity based on factors that are not incorporated into POSSUM. OBJECTIVE: The aim of the study was to compare the risk estimations of POSSUM and IPRA in patients undergoing PD. METHODS: An observational single-center cohort study was conducted including 195 patients undergoing PD in 2008-2010. POSSUM and IPRA data were recorded prospectively. Incidence and severity of postoperative morbidity was recorded according to established definitions. The cohort was grouped by POSSUM and IPRA risk groups. The estimated and observed outcomes and morbidity profiles of POSSUM and IPRA were scrutinized. RESULTS: POSSUM-estimated risk (62 %) corresponded with observed total morbidity (65 %). Severe morbidity was 17 % and in-hospital-mortality 3.1 %. Individual and grouped POSSUM risk estimates did not reveal associations with incidence (p = 0.637) or severity (p = 0.321) of total morbidity or POPF. The IPRA model identified patients with high POPF risk (p < 0.001), but was even associated with incidence (p < 0.001) and severity (p < 0.001) of total morbidity. CONCLUSION: The risk factors defined by a PD-specific model were significantly stronger predictive indicators for the incidence and severity of postoperative morbidity than the factors incorporated in POSSUM. If available, reliable procedure-specific risk factors should be utilized in the risk adjustment of surgical outcomes. For pancreatic surgery, generally applicable tools such as POSSUM still have to prove their relevance.

Identification of tryptic peptides unique to a 110,000-molecular weight polyprotein encoded by the T-8 isolate of murine leukemia virus.

Mink cells nonproductively-infected with the weakly-transforming T-8 isolate of murine leukemia virus (MuLV) express a 110,000 mol wt polyprotein designated T-8 P110. By immunoprecipitation analysis, T-8 P110 is shown to contain AKR-MuLV amino terminal gag gene-specific components (p15, p12) but to lack p30, p10, gp70, and p15(E) antigenic determinants. These observations are further substantiated by tryptic peptide analysis indicating T-8 P110 to share approximately six lysine-containing tryptic peptides with AKR-MuLV Pr65gag, and none with AKr-MuLV Pr82env. Furthermore, of seven methionine-containing T-8 P110 tryptic peptides, at least four can be conclusively shown not to be present in either AKr-MuLV Pr180gag/pol or Pr82env. A clonal mink cell line nonproductively infected by T-8, and expressing high levels of P110, although not morphologically transformed, is shown to lack elevated levels of tyrosine-specific protein kinase activity and reduction of epidermal growth factor binding sites characteristic of cells transformed by many other RNA-transforming viruses. These findings argue either that the T-8 viral genome contains acquired cellular sequences encoding a portion of P110, or that T-8 P110 represents an inphase deletion of AKR-MuLV Pr180gag/pol with extensive posttranlational modification and that an as yet unidentified protein is responsible for T-8 associated transformation.

The rapid molecular subtyping and pathotyping of avian influenza viruses.

Highly conserved nucleotide stretches flanking the cleavage site of the haemagglutinin (HA) gene of influenza type A viruses were utilised for generating PCR amplicons from a broad range of avian influenza viruses (AIV) in a one-step real-time SYBR Green RT-PCR assay. The nucleotide sequencing of the amplified PCR products simultaneously reveals both the HA subtype and the pathotype of the AIV isolates, as we demonstrated in case of H5 subtype viruses. The specificity of the assay was confirmed by investigating 66 strains of AIV and nine heterologous pathogens, including influenza B, C and various avian pathogenic viruses. This assay enables a general HA subtype identification and pathotype determination of AIV isolates providing a useful alternative tool for avian influenza diagnosis.

Evolution of human endogenous retroviral sequences: a conceptual account.

Endogenous retroviruses (ERVs) most likely are remnants of ancient retroviral infections. ERVs preserve functions of exogenous retroviruses to a varying extent, and can be parasites, symbionts or more or less neutral genetic 'junk'.Their evolution has two facets, pre- and post-endogenization. Although the two are not clearly separated, the first pertains to retroviral evolution in general and the second to the fate of repetitive DNA and the evolution of the host organism and its genome. The study of ERVs provides much material for the understanding of retroviral evolution. This sequence archive reflects the history of successes and shortcomings of antiviral resistance, but also of strategic evolutionary decisions regarding genome organization and new gene acquisition. This review discusses retroviral evolution illustrated through HERVs, bioinformatic prerequisites for ERV studies, the endogenization process and HERV evolution post-endogenization, including relation to disease. (Part of a multi-author review).

Glycosphingolipids of a green monkey kidney cell line (GMK AH-1). Evidence for a novel pentaglycosylceramide based on globotetraosylceramide.

Total non-acid glycolipid fractions have been isolated from GMK AH-1 cells grown in fetal calf serum and in horse serum. For comparison, glycolipids were also prepared from green monkey (Cercopithecus aetiops) kidney and from fetal calf serum. The major glycolipids from GMK AH-1 cells grown in fetal calf serum were isolated by silicic acid column chromatography and preparative thin-layer chromatography. These fractions were characterized mainly by thin-layer chromatography, mass spectrometry and gas chromatography. The structures of the glycolipids isolated were proposed as: Glc1 leads to 1Cer, Gal1 leads to 1Cer, Gal1 leads to 4Glc1 leads to 1Cer, Gal1 leads to 4Gal1 leads to 4Glc1 leads to 1Cer, GalNAcl leads to 3Gal1 leads to 4Gal1 leads 4Glc1 leads to 1Cer. In addition, a novel pentaglycosylceramide with the probable structure Ga1 beta 1 leads to 3GalNAc beta 1 leads to Gal alpha 1 leads to 4Gal beta 1 leads to 4Glc beta 1 leads to 1Cer was also present. THe ceramides contained mainly dihydroxy 18:1 long-chain base in combination with non-hydroxy 16:0-24:0 fatty acids. Small amounts of trihydroxy 18:0 long-chain base and hydroxy 22:0-24:0 fatty acids were also present in the mono- and diglycosylceramide fractions. The glycolipid patterns of GMK AH-1 cells grown in fetal calf serum or horse serum were identical. The pentaglycosylceramide present in the cultured cells could not be detected with certainty in the kidney tissue. The uptake of this glycolipid from the culture medium is unlikely as it seems to be lacking in calf serum.

Comprehensive multi-dimensional chromatographic studies on the separation of saturated hydrocarbon ring structures in petrochemical samples.

Characterization of complex petrochemical samples has been a classical subject of comprehensive two-dimensional (2D) gas chromatography (GC x GC). Macroscopic properties of these samples can be described accurately by separation of compounds in classes of identical molecular functionality. Ring structures in the carbon backbone of these compounds, which can be divided in saturated and unsaturated, are amongst the foremost functionalities affecting samples properties. Unfortunately, GC x GC tuned for separation of both saturated and unsaturated ring structures is likely to result in convoluted chromatograms when a distribution of both molecular properties is present in the sample. An independent liquid chromatographic (LC) separation preceding GC x GC could be used to resolve the mixture based on unsaturated rings, allowing saturated rings to be resolved separately in the GC x GC separation. This three-dimensional separation (abbreviated LC-GC x GC) was performed after rigorous evaluation of LC as part of a multidimensional separation using LC x GC. Group-type separation was achieved using this separation for components with either saturated or unsaturated rings. Results of this separation were used to compare information obtained by GC x GC with LC-GC x GC.

Classification of highly similar crude oils using data sets from comprehensive two-dimensional gas chromatography and multivariate techniques.

Comprehensive two-dimensional gas chromatography (GCxGC) has proven to be an extremely powerful separation technique for the analysis of complex volatile mixtures. This separation power can be used to discriminate between highly similar samples. In this article we will describe the use of GCxGC for the discrimination of crude oils from different reservoirs within one oil field. These highly complex chromatograms contain about 6000 individual, quantified components. Unfortunately, small differences in most of these 6000 components characterize the difference between these reservoirs. For this reason, multivariate-analysis (MVA) techniques are required for finding chemical profiles describing the differences between the reservoirs. Unfortunately, such methods cannot discern between 'informative variables', or peaks describing differences between samples, and 'uninformative variables', or peaks not describing relevant differences. For this reason, variable selection techniques are required. A selection based on information between duplicate measurements was used. With this information, 292 peaks were used for building a discrimination model. Validation was performed using the ratio of the sum of distances between groups and the sum of distances within groups. This step resulted in the detection of an outlier, which could be traced to a production problem, which could be explained retrospectively.

A cluster of continuous antigenic structures in the transmembrane protein of HIV-1: individual patterns of reactivity in human sera.

We investigated the antigenicity of a highly conserved region in the transmembrane protein of the human immunodeficiency virus type 1 (HIV-1). In order to identify antigenically important residues, amino-acid sequences of synthetic peptides representing this region were varied systematically: single residues were omitted from the sequence of HIV-env 583-599; threonines were substituted for pairs of residues in HIV-env 581-599; the sequences of heptadeca-peptides were shifted by single residues. The peptides were tested in an enzyme immuno-assay against fourteen HIV-1 antibody-positive human sera, which were previously found to react with HIV-env 583-599, and against rabbit antisera to the peptides HIV-env 583-599 and 586-606. Substitutions as well as deletions in the sequence 589-596 (AVERYLKD) aborgated the antigenicity of the peptides with most of the human sera. Changes outside this sequence affected the reactivities differentially. Six overlapping dodeca-peptides, shifted in the sequence by single residues, lacked antigenicity in a competition assay, suggesting antigenic dependence on an ordered peptide conformation, which the longer peptides may preferentially assume. 19- and 21-mers with overlapping sequences competed to different extents with each other for binding to the antibodies of 3 human sera, illustrating that more than one antigenic structure in this narrow region can be recognized by a single polyclonal serum.

Antibodies to a putative HIV gp41 immunosuppressive peptide, pHIVIS (583-599), do not correlate significantly with outcome in HIV infection.

We have studied the prevalence of antibodies to peptides derived from the transmembrane protein of HIV, gp41. Previous work has suggested that the presence of antibodies to the gp41 peptide known as pHIVIS (env 583-599) is associated with protection from immunosuppression in HIV infection. We studied 171 sequential sera from 55 HIV-1-infected people in various clinical stages of disease. There was no significant association between antibodies to pHIVIS and clinical status in this study. Although pHIVIS has sequence similarity to the putative immunosuppressive region of the C-type oncornaviruses (p15E), antibodies to this peptide do not appear to be associated with protection from immunosuppression in natural HIV infection.

A survey of synthetic HIV-1 peptides with natural and chimeric sequences for differential reactivity with Zimbabwean, Tanzanian and Swedish HIV-1-positive sera.

OBJECTIVE: To determine whether the known sequence differences between African and non-African HIV-1 strains are reflected in the serological response. DESIGN AND METHODS: We investigated the antibody reactivity of 34 Swedish, 30 Tanzanian and 42 Zimbabwean HIV-1-positive sera to 67 synthetic peptides with sequences from North American and African HIV-1 isolates, mostly derived from regions of gag and env known to be antigenic. Not all sera were tested against all peptides. RESULTS: Differences in frequency of reactivity were noted with peptides covering the entire third variable domain (V3), which is a primary neutralization determinant, and the carboxyl terminus of gp120, in two regions of gp41, and the carboxyl terminus of p24. In env Tanzanian sera reacted preferentially with a V3 peptide from the strain JY1 (Zaire). Gradual substitutions in the central motif in V3 of ELI from GLGQ to GPGR, typical of many non-African strains, led to a gradual increase in reactivity of many Swedish sera, but did not affect Tanzanian and Zimbabwean sera, suggesting that the major epitopes recognized by these African sera are outside GPGR. V3 peptides from the MN and Z3 strains reacted with most sera, but missed 30% of those of Tanzanian origin. In the carboxyl terminus of gp120 both sets of African sera reacted preferentially with peptides from strains JY1 and MAL. Swedish sera reacted strongest with analogues from strains Z321 and HXB2. In gp41, Swedish sera showed a weak preference for reactivity with HXB2-derived peptides in the immunodominant region (amino acids 590-620), and further towards the carboxyl terminus (amino acids 620-665). CONCLUSION: The differences in serological reactivity were as great between Zimbabwe and Tanzania as between the two African sets and the Swedish. The geographical differences in the pattern of reactivity with HIV peptides probably depend on both host and viral variation and may be developed into a seroepidemiological tool, useful for optimization of future HIV vaccines.

PIP: The objective of this study was to determine whether the known sequence differences between African and non-African HIV-1 strains are reflected in the serological response. The authors investigated the antibody reactivity of 34 Swedish, 30 Tanzanian, and 42 Zimbabwean HIV-1 positive sera to 67 synthetic peptides with sequences from North American and African HIV-1 isolates, mostly derived from regions of gag and env known to be antigenic. Not all sera were tested against all peptides. The authors noted several results. Differences in frequency of reactivity were noted with peptides covering the entire third variable domain (V3), which is a primary neutralization determinant, and the carboxyl terminus of gp120, in 2 regions of gp41, and the carboxyl terminus of p24. In env, Tanzanian sera reacted preferentially with a V3 peptide from the strain JY1 (Zaire). Gradual substitutions in the central motif in V3 of ELI from GLGQ to GPGR, typical of many non-African strains, led to a gradual increase in reactivity of many Swedish sera, but did not affect Tanzanian and Zimbabwean sera, suggesting that the major epitopes recognized by these African sera are outside GPGR. V3 peptides from the MN and Z3 strains reacted with most sera, but missed 30% of those of Tanzanian origin. In the carboxyl terminus of gp120, both sets of African sera reacted preferentially with peptides from strains JY1 and MAL. Swedish sera reacted strongest with analogues from strains Z321 and HXB2. In gp41, Swedish sera showed a weak preference for reactivity with HXB2-derived peptides in the immunodominant region (amino acids 620-665). The differences in serological reactivity were as great between Zimbabwe and Tanzania as between the 2 African sets and the Swedish. The geographical differences in the pattern of reactivity with HIV peptides probably depend on both host and viral variation and may be developed into a seroepidemiological tool, useful for optimization of future HIV vaccines.

The long leader sequence of the mouse ornithine decarboxylase mRNA, previously suspected to be a cloning artifact, is probably a product of recombination with MuLV-like retrovirus.

Sequence analysis of the first 549 nucleotides (nt) of the non-translated 5' end of the cloned mouse ornithine decarboxylase (ODC; L-ornithine carboxy-lyase, EC 4.1.1.17)-encoding sequence shows that this sequence is closely related to nt 1946-1395 of Moloney murine leukemia virus (MuLV). The viral sequence, however, is oriented anti-sense relative to the ODC sequence. This orientation makes it unlikely to be a cloning artifact mediated by reverse transcriptase, but rather a recombination between genomic DNA and a MuLV-like provirus. In the cell line, from which the cDNA clone originated, Katz and Kahana [EMBO J. 8 (1989) 1163-1167] have shown that an intragenic deletion and amplification of the ODC gene had taken place. We believe that an additional recombination also has occurred in this cell line. The cDNA clone studied was obtained after selecting for high ODC expression. It is conceivable that the retroviral sequence contains an intragenic enhancer which is also functional in the anti-sense orientation. The inserted sequence contains two repeats which share homology with known enhancer elements. The reported recombination event shows that caution is needed when selective pressure is applied for the isolation and characterization of genes.

Three-dimensional structure and antigenicity of transmembrane-protein peptides of the human immunodeficiency virus type 1. Effects of a neutralization-escape substitution.

A point mutation (Ala-589 to Thr) in the transmembrane protein of the human immunodeficiency virus type 1 (HIV-1) has been shown to decrease the sensitivity of the virus to the neutralizing effect of human HIV-1 specific antibodies [(1990) J. Virol. 64, 3240-3248]. Here 17-residue peptides with the parental and mutant sequences were compared: the parental peptide bound antibodies of sera from HIV-1 infected persons more frequently and with higher affinity than the mutant peptide. However, according to circular dichroism (CD), NMR spectroscopy and molecular modelling the peptides have indistinguishable backbone conformations under a variety of experimental conditions. These techniques showed for both peptides that no ordered helix was present in water solution. However, for both peptides in alcohol-water solutions approximately 60% alpha-helix could be induced. The three-dimensional structures of these peptides provide a basis for understanding how this mutation in the transmembrane protein may affect the interaction with both the outer envelope glycoprotein and with antibodies.

Type- and group-specific continuous antigenic determinants of HTLV. Use of synthetic peptides for serotyping of HTLV-I and -II infection.

The human T lymphotropic viruses (HTLV-I and -II) are relatively common in subpopulations of certain countries, notably intravenous drug abusers in North America. Infections with these malignancy-associated human retroviruses are hard to discriminate with currently available commercial serological tests. We studied the distribution of antigenicity and the degree of cross-reactivity of epitopes in gag and env of the two viruses. Sequences in the carboxyl terminus of the matrix protein (MA) and the middle of the outer glycoprotein (SU) reacted in a type-specific fashion, while sequences from the capsid protein (CA), the carboxyl terminus of SU, and conserved portions of the transmembrane protein (TM) mainly reacted in a group-specific fashion, correlating with the degree of sequence dissimilarity between the two viruses. The serological discrimination obtained with the peptides was evaluated in a panel of 25 sera where infection with HTLV-I or -II had been typed by competition in a p24 enzyme-linked immunosorbent assay (ELISA) or by the polymerase chain reaction (PCR). After processing peptide results in a computer program, a typing result concordant with earlier results was obtained in 21 of 25 sera. Of the remaining five sera, four were labeled "too weak for typing" and one "HTLV of uncertain type" by the program. They did not react sufficiently strongly or clearly with the peptides to allow classification. A combination of synthetic peptides may become useful for serotyping HTLV infection and become an alternative to Western blots for confirmation of HTLV positivity.

Increased incidence of Kaposi sarcoma in Sweden before the AIDS epidemic.

Clinical factors of possible importance for the greater than two-fold rise in the incidence of Kaposi sarcoma of the elderly in Sweden before the AIDS epidemic were reviewed in 63 regional patients. 5 patients had lymphoproliferative disease before or at the time of Kaposi sarcoma, and 4 patients had been receiving steroids (including 1 with lymphoma) at diagnosis. 2 of these 9 patients plus 2 additional patients had received blood transfusions 1-9 years before diagnosis. None of 17 patients tested was positive for HIV-1, and none had signs of an unexplained progressive immune defect. Of the evaluable cases, 27% had diabetes mellitus and 7% had had previous myocardial infarction. However, only the frequency of congestive heart failure (47%) was significantly greater than that of an ambulatory control group (P = 0.001) in the age group 75-84 years. Exposure to cytomegalovirus (CMV) was not more common in 15 Kaposi sarcoma patients than in an age and sex matched control group. No single factor could account for increased Kaposi sarcoma among the elderly. If the classical form has an infectious aetiology, the tumour could arise after effective transmission of the agent (as by a transfusion), especially combined with some degree of immune deficiency or perhaps congestive failure late in life.