Light-induced nuclear import of phytochrome-A:GFP fusion proteins is differentially regulated in transgenic tobacco and Arabidopsis

Phytochromes (phy) are a family of photoreceptors that control various aspects of light-dependent plant development. Phytochrome A (phyA) is responsible for the very low fluence response (VLFR) under inductive light conditions and for the high irradiance response (HIR) under continuous far-red light. We have recently shown that nuclear import of rice phyA:GFP is regulated by VLFR in transgenic tobacco. The import is preceded by very fast, light-induced formation of sequestered areas of phyA:GFP in the cytosol. Here we report that expression of the Arabidopsis phyA:GFP fusion protein in phyA-deficient Arabidopsis plants complements the mutant phenotype. In these transgenic Arabidopsis lines, both light-dependent cytosolic formation of sequestered areas of the phyA:GFP as well as VLFR or HIR-mediated nuclear import of the fusion protein was observed. By contrast, light-dependent nuclear import of the same fusion protein was induced only by continuous far-red light (HIR) but not by pulses of far-red light (VLFR) in transgenic tobacco. These results demonstrate that photoregulation of intracellular partitioning of the Arabidopsis phyA:GFP differs significantly in different genetic backgrounds.

Quality changes of onion (Allium cepa L.) as affected by the drying process

Thin layer drying experiments of sliced onion were carried out under different controlled conditions using a laboratory dryer. Quality changes of the dried product were evaluated by analysis of colour, pyruvate, chemical and sensory parameters. The results obtained proved that drying temperatures above 65 degrees C exert a pronounced influence on colour changes. The pyruvate content decreased with increasing of temperature and slice thickness. The sugar content was also found to be significantly influenced by the drying temperature. The rate of ascorbic acid degradation decreased with increasing temperature and slice thickness. Significant correlations were obtained between chemically determined pyruvate content and sensory evaluated odour of the dried onion.

Papillomavirus detection: demographic and behavioral characteristics influencing the identification of cervical disease

OBJECTIVE

This study was undertaken to assess the association between detection of high-risk types of human papillomavirus and various demographic and behavioral characteristics and to further relate this association to cervical histopathologic findings.

STUDY DESIGN

A total of 1007 patients with a Papanicolaou test result reported as high-grade squamous intraepithelial lesion or with 2 results reported as atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion were referred from city and county clinics to a colposcopic clinic. All women had a cervical smear obtained, underwent colposcopically directed biopsy and endocervical curettage, and had a specimen taken for human papillomavirus deoxyribonucleic acid detection by polymerase chain reaction. Demographic information was obtained from each patient.

RESULTS

Human papillomavirus deoxyribonucleic acid was identified in 655 (66%) of the specimens. High-risk human papillomavirus types (16, 18, 31, 33, and 35) were detected in 463 (70.7%) of these specimens. The prevalence of evidence of human papillomavirus (koilocytosis) and grade 1 cervical intraepithelial neoplasia in the biopsy specimen decreased significantly with age, whereas the prevalence of grade 2 or 3 cervical intraepithelial neoplasia in the biopsy specimen increased with age. There was a significant age-dependent decreasing trend in detection of high-risk human papillomavirus deoxyribonucleic acid among women who had human papillomavirus-associated changes, grade 1 cervical intraepithelial neoplasia, and grade 2 or 3 cervical intraepithelial neoplasia in the biopsy specimen. The prevalences of high-risk human papillomavirus among patients with grade 1 cervical intraepithelial neoplasia and grade 2 or 3 cervical intraepithelial neoplasia were similar, and both were significantly higher than among women with no evidence of cervical intraepithelial neoplasia or koilocytosis in the biopsy specimen. Risk factors associated with grade 2 or 3 cervical intraepithelial neoplasia were different from those associated with human papillomavirus-associated changes and with grade 1 cervical intraepithelial neoplasia.

CONCLUSION

The detection of high-risk human papillomavirus was age-dependent for all histologic categories. Patients with grade 2 or 3 cervical intraepithelial neoplasia had a prevalence of high-risk human papillomavirus that was similar to that among women with grade 1 cervical intraepithelial neoplasia but significantly higher than that among women whose biopsy specimens appeared normal or demonstrated only the presence of human papillomavirus-induced changes (koilocytosis). This suggests that separation of human papillomavirus-associated changes only from grade 1 cervical intraepithelial neoplasia may be of significance in tissue diagnosis.

Evidence of SV40 infections in hospitalized children

Simian virus 40 (SV40) is known to have contaminated poliovirus vaccines used between 1955 and 1963. Accumulating reports have described the presence of SV40 DNA in human tumors and normal tissues, although the significance of human infections by SV40 is unknown. We investigated whether unselected hospitalized children had evidence of SV40 infections and whether any clinical correlations were apparent. Serum samples were examined for SV40 neutralizing antibody using a specific plaque reduction test; of 337 samples tested, 20 (5.9%) had antibody to SV40. Seropositivity increased with age and was significantly associated with kidney transplants (6 of 15 [40%] positive, P < .001). Many of the antibody-positive patients had impaired immune systems. Molecular assays (polymerase chain reaction and DNA sequence analysis) on archival tissue specimens confirmed the presence of SV40 DNA in 4 of the antibody-positive patients. This study, using 2 independent assays, shows the presence of SV40 infections in children born after 1980. We conclude that SV40 causes natural infections in humans.

HIV-1 tat transcriptional activity is regulated by acetylation

The human immunodeficiency virus (HIV) trans- activator protein, Tat, stimulates transcription from the viral long-terminal repeats (LTR) through an RNA hairpin element, trans-activation responsive region (TAR). We and others have shown that trans-activator protein (Tat)-associated histone acetyltransferases (TAHs), p300 and p300/CBP-associating factor (PCAF), assist functionally in the activation of chromosomally integrated HIV-1 LTR. Here, we show that p300 and PCAF also directly acetylate Tat. We defined two sites of acetylation located in different functional domains of Tat. p300 acetylated Lys50 in the TAR RNA binding domain, while PCAF acetylated Lys28 in the activation domain of Tat. In support of a functional role for acetylation in vivo, histone deacetylase inhibitor (trichostatin A) synergized with Tat in transcriptional activation of the HIV-1 LTR. Synergism was TAR-dependent and required the intact presence of both Lys28 and Lys50. Mechanistically, acetylation at Lys28 by PCAF enhanced Tat binding to the Tat-associated kinase, CDK9/P-TEFb, while acetylation by p300 at Lys50 of Tat promoted the dissociation of Tat from TAR RNA that occurs during early transcription elongation. These data suggest that acetylation of Tat regulates two discrete and functionally critical steps in transcription, binding to an RNAP II CTD-kinase and release of Tat from TAR RNA.

Light quality-dependent nuclear import of the plant photoreceptors phytochrome A and B

The phytochrome (phy) family of plant photoreceptors controls various aspects of photomorphogenesis. Overexpression of rice phyA-green fluorescent protein (GFP) and tobacco phyB-GFP fusion proteins in tobacco results in functional photoreceptors. phyA-GFP and phyB-GFP are localized in the cytosol of dark-adapted plants. In our experiments, red light treatment led to nuclear translocation of phyA-GFP and phyB-GFP, albeit with different kinetics. Red light-induced nuclear import of phyB-GFP, but not that of phyA-GFP, was inhibited by far-red light. Far-red light alone only induced nuclear translocation of phyA-GFP. These observations indicate that nuclear import of phyA-GFP is controlled by a very low fluence response, whereas translocation of phyB-GFP is regulated by a low fluence response of phytochrome. Thus, light-regulated nucleocytoplasmic partitioning of phyA and phyB is a major step in phytochrome signaling.

Is human papillomavirus testing of value in clinical practice?

The objective of this review was to evaluate the current status of human papillomavirus testing in predicting the presence of high-grade or invasive disease in the cervix in women with Papanicolaou smears reported as atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesion. This is a review of many of the studies already published evaluating the utility of human papillomavirus testing as part of the triage for patients whose Papanicolaou smears were reported as ASCUS or low-grade squamous intraepithelial lesion. Two triage approaches for follow-up of such patients are presented, and recommendations are made as to which is most cost-effective and safe. Data related to human papillomavirus testing were obtained with both currently available commercial kits for detection of high-risk human papillomavirus and the polymerase chain reaction. There was variation in results reported, possibly related to populations studied. The approach to management by cytologic screening and colposcopy, when indicated, appeared over the long term to be equal to human papillomavirus testing. In our opinion current human papillomavirus testing is of little clinical use to the practitioner. Its use should be limited to appropriately designed and implemented research studies.

Epithelial glycoprotein-2 expression is subject to regulatory processes in epithelial-mesenchymal transitions during metastases: an investigation of human cancers transplanted into severe combined immunodeficient mice

The human cell-surface antigen epithelial glycoprotein-2 recognized by the monoclonal antibody MOC-31 is an epithelial tumour-associated glycoprotein expressed in non-squamous carcinomas. MOC-31 immunoreactivity was investigated in human breast, colon, ovarian and lung cancer cell lines, grown either in vitro or in severe combined immunodeficient (SCID) mice as solid tumours and/or metastases. Three of four small-cell lung cancer cell lines (NCI-H69, OH3 and SW2) and three of four ovarian cancer cell lines (SoTu 1, 3 and 4) expressed epithelial glycoprotein-2. In contrast, all three breast (MCF-7, BT20, T47D) and all three colon (HT29, CACO2, SW480) cancer cell lines strongly reacted with monoclonal antibody MOC-31. A notable difference in MOC-31 immunoreactivity was observed in spontaneously formed lung metastases of HT29 colon cancer cells. Whereas larger metastases (> 30 cells) reacted with a similar staining pattern to the primary tumour, smaller metastases did not. These findings indicate that differentiation processes during the epithelial-mesenchymal transition occur in metastases, which lead to a transient loss of epithelial glycoprotein-2 expression during the migratory and early post-migratory period. This loss of antigen expression indicates that the process of metastases formation is a regulatory event, and this transient loss of antigen expression might represent a potential obstacle to antibody-based therapy in the setting of minimal residual disease.

Cancer risk in women exposed to diethylstilbestrol in utero

CONTEXT

The association between in utero exposure to diethylstilbestrol (DES) and clear cell adenocarcinoma (CCA) of the vagina and cervix is well known, yet there has been no systematic study of DES-exposed daughters to determine whether they have an increased risk of other cancers. As many as 3 million women in the United States may have been exposed to DES in utero.

OBJECTIVE

To determine whether women exposed to DES in utero have a higher risk of cancer after an average of 16 years of follow-up.

DESIGN

A cohort study with mailed questionnaires and medical record review of reported cancer outcomes.

PARTICIPANTS

A cohort of 4536 DES-exposed daughters (of whom 81% responded) and 1544 unexposed daughters (of whom 79% responded) who were first identified in the mid-1970s.

MAIN OUTCOME MEASURES

Cancer incidence in DES-exposed daughters compared with population-based rates and compared with cancer incidence in unexposed daughters.

RESULTS

To date, DES-exposed daughters have not experienced an increased risk for all cancers (rate ratio, 0.96; 95% confidence interval [CI], 0.58-1.56) or for individual cancer sites, except for CCA. Three cases of vaginal CCA occurred among the exposed daughters, resulting in a standardized incidence ratio of 40.7 (95% CI, 13.1-126.2) in comparison with population-based incidence rates. The rate ratio for breast cancer was 1.18 (95% CI, 0.56-2.49); adjustment for known risk factors did not alter this result.

CONCLUSIONS

Thus far, DES-exposed daughters show no increased cancer risk, except for CCA. Nevertheless, because exposed daughters included in our study were, on average, only 38 years old at last follow-up, continued surveillance is warranted to determine whether any increases in cancer risk occur during the menopausal years.

Is human papillomavirus testing an effective triage method for detection of high-grade (grade 2 or 3) cervical intraepithelial neoplasia?

OBJECTIVE

Our purpose was to assess the usefulness of the polymerase chain reaction assay for detection of human papillomavirus infection for prognostic value in the triage strategies for high-grade (grade 2 or 3) cervical intraepithelial neoplasia in women referred for colposcopy after abnormal Papanicolaou smears.

STUDY DESIGN

A total of 1007 women referred to a colposcopic clinic providing care for an indigent population were studied. Four hundred fifty-four women were referred after two Papanicolaou smears reported as atypical squamous cells of undetermined significance or low grade-squamous cervical intraepithelial lesion, and 553 were referred after a single smear reported as high-grade squamous intraepithelial lesion. All women had a cervical smear, colposcopy-directed biopsy, and endocervical curettage performed. A sample for human papillomavirus deoxyribonucleic acid detection by polymerase chain reaction was obtained.

RESULTS

High-risk human papillomavirus types were detected in 463 (46%) of 1007 women studied. There was a significant increase of the frequency of high-risk human papillomavirus by the increasing severity of biopsy findings ranging from 32.7% in women without cervical intraepithelial neoplasia on biopsy to 60% in women having grade 2 or 3 on the biopsy specimen. Women having a negative Papanicolaou smear found to have high-risk human papillomavirus deoxyribonucleic acid at the time of colposcopy had a significantly higher rate of grade 2 or 3 cervical intraepithelial neoplasia on the biopsy specimen than did women without high-risk human papillomavirus. There was no such difference observed in women with a cytologic finding of low- or high-grade squamous intraepithelial lesions at the time of colposcopy. The polymerase chain reaction assay appears to be more sensitive than the commercial human papillomavirus profile test. The positive predictive value for grade 2 or 3 cervical intraepithelial neoplasia of both tests was similar (21.7% and 22.8%, respectively).

CONCLUSION

The human papillomavirus is associated with high-grade cervical intraepithelial neoplasia, but the screening for human papillomavirus deoxyribonucleic acid does not have prognostic value in women reported as having atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesions on two precolposcopy Papanicolaou smears.

Rest and exercise hemodynamics after the Ross procedure: an echocardiographic study

BACKGROUND

Aortic prosthetic valves with superior hemodynamic performance are associated with more complete regression of left ventricular hypertrophy and better left ventricular function postoperatively. The near normal function of the pulmonary autografts at rest is well documented, however, exercise data has been seldom reported. The purpose of this study is to evaluate the hemodynamic performance of pulmonary autografts in the aortic position and the homografts used to reconstruct the right ventricular outflow tract during conditions of high cardiac output by means of dobutamine stress echocardiography.

METHODS

Between May 1995 and February 1998, 67 patients were submitted to a Ross operation at our institution. Twenty of these patients had a mean age of 28.6+/-8.3 years and a mean follow-up time of 15.7+/-5.9 months. They were studied by dobutamine stress echocardiography to evaluate rest and exercise hemodynamics of the pulmonary autografts as well as of the aortic and pulmonary homografts used to reconstruct the right ventricular outflow tract. Dobutamine infusion was started at 5 microg/kg with incremental doses up to 40 microg/kg in every case.

RESULTS

With dobutamine infusion, heart rate increased from 71+/-10 to 142+/-11 beats/min, left ventricular systolic volume from 86.8+/-33.9 mL to 115.9+/-52.6 mL, and cardiac output from 6.3+/-2.9 L/min to 16.8+/-7.4 L/min. Left ventricular function was considered satisfactory at rest and during exercise in all patients. The mean gradient across the autograft increased from 1.03+/-0.95 mmHg to 4.03+/-2.05 mmHg and maximal instantaneous gradient from 2.45+/-2.21 mmHg to 9.54+/-4.85 mmHg. The mean effective orifice area for the autografts were 3.5+/-1.3 cm2 at rest and 3.3+/-1.4 cm2 during exercise. The patients with mild aortic insufficiency at rest had no increase in the degree of regurgitation with exercise. In the right ventricular outflow tract, the mean gradient across the homograft increased from 9.06+/-5.29 mmHg to 17.55+/-9.76 mmHg and maximal instantaneous gradient from 21.4+/-12.5 mmHg to 41.5+/-23.1 mmHg.

CONCLUSIONS

Pulmonary autografts exhibit normal hemodynamic performance at rest and during exercise after the Ross operation. However, mild-to-moderate gradients are common at the right ventricular outflow tract and should be carefully monitored.

Immunophenotype of human HT29 colon cancer cell metastases in the lungs of scid mice: spontaneous versus artificial metastases

The aim of this study was to compare the immunophenotype of the human colon cancer cell line HT29 tumour deposits in the lung which occurred spontaneously after subcutaneous implantation with those which arose after intravenous injection into severe combined immunodeficient (scid) mice. Irrespective of the route of implantation the colon cancer cells were readily observed in the lungs of the scid mice. Similar patterns of immunoreactivity for the proliferative markers (MiB-1, PCNA), and for the tumour suppressor gene (p53) were detected in both groups, and for carcinoembryonic antigen, with only minor quantitative differences in levels of marker expression. Whereas the marker CD44 variant 6 gave very little reaction after either route, cytokeratin expression varied amongst the different cytokeratins (CK 7, 18 or 20), and with the route of implantation. CA125 and E-cadherin were weakly expressed after intravenous injection, but generally not after subcutaneous implantation. Vimentin was not demonstrated in any of the specimens examined. In general, the expression of proliferative markers, and of oncogenes, appears to be independent of the implantation route, whilst expression of cell adhesion molecules can be dependent on the route of implantation.

Phosphorylation of bovine leukemia virus Tax protein is required for in vitro transformation but not for transactivation

The Tax proteins of the oncovirinae viruses are phosphorylated transcriptional activators that exhibit oncogenic potential. The role of phosphorylation in their functional activities remains unknown. As a model for the Human T-cell leukemia virus type I (HTLV-I), Bovine Leukemia Virus (BLV) permits the characterization of viral replication and leukemogenesis in vivo. Here, we show that the BLV Tax protein is phosphorylated on serine residues 106 and 293 both in insect and in mammalian cells. These sites can also be efficiently phosphorylated by the cdc2 and MAP kinases in vitro. Mutation of these residues does not affect the capacity of the Tax protein to function as a transactivator. Indeed, the Tax proteins mutated at one or both serines increase LTR-directed viral transcription at levels similar to those obtained with wild-type Tax in cell culture. Moreover, inhibition of Tax phosphorylation by W7, a calmodulin antagonist, does not alter its transactivation activity. Thus, phosphorylation on serines 106 and 293 is not required for transactivation by Tax. However, simultaneous substitution of both serines into alanine residues destroys the capacity of Tax to cooperate with the Ha-ras oncogene to transform primary rat embryo fibroblasts and induce tumors in nude mice. When the serines were replaced with aspartic acid residues, the oncogenic potential of Tax was maintained indicating that the negative charge rather than the phosphate group itself was required for Tax oncogenicity. Finally, to assess the role of the serine residues in vivo, recombinant viruses which express the Tax mutants were constructed and injected into sheep. It appeared that the mutated proviruses replicate at levels similar to the wild-type virus in vivo. We conclude that Tax phosphorylation is dispensable for transactivation and viral replication in vivo but is required for its oncogenic potential in vitro.

Cytochrome c biogenesis is involved in the transposon Tn5-mediated bleomycin resistance and the associated fitness effect in Escherichia coli

The transposon Tn5 ble gene and the Escherichia coli alkylation-inducible aidC locus are co-operatively involved in the resistance to the anti-cancer drug and DNA-cleaving agent bleomycin and enhance fitness of bacteria in the absence of the drug. In this report, we demonstrate that the aidC locus is identical to nrfG, the last gene of the nrf operon involved in the periplasmic formate-dependent nitrite reduction. In the presence of Ble, NrfG expression is specifically induced and restores both bleomycin resistance and its associated beneficial growth effect in an aidC- strain. In vitro DNA protection assays reveal that purified Ble prevents bleomycin-mediated DNA breakage, as do bleomycin-binding proteins. Similarities between haems of the cytochrome c biogenesis nrf pathway and iron bleomycin suggest a DNA repair-independent molecular mechanism for both bleomycin resistance and increased viability. The Ble protein binds bleomycin and prevents DNA breakage. It also induces the nrf locus that may assimilate bleomycin into haem for extracellular transport or inactivate bleomycin. Inactivation of potent DNA oxidants confers a better fitness to the bacterium carrying the transposon, suggesting a symbiotic relationship between host and transposon.

Control of protein splicing by intein fragment reassembly

Inteins are protein splicing elements that mediate their excision from precursor proteins and the joining of the flanking protein sequences (exteins). In this study, protein splicing was controlled by splitting precursor proteins within the Psp Pol-1 intein and expressing the resultant fragments in separate hosts. Reconstitution of an active intein was achieved by in vitro assembly of precursor fragments. Both splicing and intein endonuclease activity were restored. Complementary fragments from two of the three fragmentation positions tested were able to splice in vitro. Fragments resulting in redundant overlaps of intein sequences or containing affinity tags at the fragmentation sites were able to splice. Fragment pairs resulting in a gap in the intein sequence failed to splice or cleave. However, similar deletions in unfragmented precursors also failed to splice or cleave. Single splice junction cleavage was not observed with single fragments. In vitro splicing of intein fragments under native conditions was achieved using mini exteins. Trans-splicing allows differential modification of defined regions of a protein prior to extein ligation, generating partially labeled proteins for NMR analysis or enabling the study of the effects of any type of protein modification on a limited region of a protein.

Lectin histochemistry reveals the appearance of M-cells in Peyer's patches of SCID mice after syngeneic normal bone marrow transplantation

Peyer's patches in the intestinal mucosa are characterized by the presence of several lymphatic follicles and interfollicular T-cell regions. Luminal antigens are transported across the intestinal epithelium to stimulate the Peyer's patch pre-B-cells in the follicles that proliferate and migrate to distant sites. Evidence suggests that antigen priming of B-lymphocytes is responsible for the number and location of Peyer's patches during postnatal life, but little is known about the histogenesis of Peyer's patches and their overlying membranous (M) cells. To examine whether T- and B-lymphocytes in Peyer's patches have an influence on M-cell generation, we studied the development of Peyer's patches and M-cells in severe combined immunodeficient (SCID) mice reconstituted with bone marrow cells from normal syngeneic mice. Our experiments demonstrate that the donor bone marrow cells in the host scid mice repopulate to form single (primary) follicles and aggregates of lymphoid nodules, the Peyer's patches. Use of the lectins Anguilla anguilla (AAA) and Ulex europaeus I (UEA-I) as positive markers of mouse Peyer's patch M-cells revealed that M-cells develop in the dome epithelium overlying the single primary follicles and Peyer's patches of reconstituted scid mice. This experimental system therefore allows the study of the histogenesis of Peyer's patches and M-cells.

Immunohistochemical detection of the MUC1 gene product in human cancers grown in scid mice

Alterations in mucin expression have been detected in many clinically relevant cancers and, in particular, the polymorphic epithelial mucin, encoded by the MUC1 gene, has attracted considerable attention. We investigated its expression in human breast, colon, ovarian, lung, and skin cancer cells and their metastases grown in severe combined immunodeficient (scid) mice using three different monoclonal antibodies (HMFG-1, HMFG-2, and SM3). Four of five breast cancer cell lines, three of five colon cancer cell lines, two of three small-cell carcinoma of the lung cell lines, and A 431 cells all expressed the MUC1 gene product. Neuraminidase predigestion often enhanced HMFG-1 immunoreactivity, which was more widespread and stronger than SM3 immunoreactivity. A considerable heterogeneity of MUC1 gene product expression was observed in the same tumors grown in different mice. The binding pattern between single-cell/small-cell clusters (up to 10 cells) and larger cell number aggregates varied. The results indicate that the MUC1 gene expression both in primary tumors and metastases is not tightly controlled within a particular tumor cell line. Because of this heterogeneous antigen expression in vivo, it appears impossible to target all metastatic deposits by a single monoclonal antibody directed against the MUC1 gene product. (J Histochem Cytochem 46:127-134, 1998)

Human papillomavirus testing as triage for atypical squamous cells of undetermined significance and low-grade squamous intraepithelial lesions: sensitivity, specificity, and cost-effectiveness

OBJECTIVE

Our purpose was to evaluate the cost-effectiveness of the use of a Food and Drug Administration-approved human papillomavirus test in triaging patients with Papanicolaou smears showing atypical squamous cells of undetermined significance or a low-grade squamous intraepithelial lesion for colposcopy compared with an algorithm that used cytologic follow-up.

STUDY DESIGN

Four hundred sixty-two women referred to our Colposcopy Clinic with a Papanicolaou smear report of atypical squamous cells of undetermined significance or a low-grade squamous intraepithelial lesion underwent repeat Papanicolaou smear, cervical colposcopy, directed cervical biopsy, and endocervical curettage. In addition, human papillomavirus testing by the Food and Drug Administration-approved HPV Profile (Digene Diagnostics, Silver Spring, Md.) test was done. A comparison of sensitivity, specificity, and cost-effectiveness of an algorithm determining the need for colposcopy on the basis of repeat cytologic testing versus an algorithm that incorporated repeat cytologic testing and human papillomavirus screening was done. The cost-effectiveness of both of these triage algorithms was also compared.

RESULTS

As expected, high-risk human papillomavirus deoxyribonucleic acid was detected with greater frequency in relation to increasing severity of cervical intraepithelial neoplasia. In 268 women, the follow-up smear obtained in our clinic was reported as negative. High-risk human papillomavirus types were found in 23.5% of these women. In the human papillomavirus-negative women, 5.9% had grade 2 or 3 cervical intraepithelial neoplasia confirmed on cervical biopsy. In comparison, 20.6% of those with a positive result of the human papillomavirus test had grade 2 or 3 cervical intraepithelial neoplasia on biopsy (p < 0.001). Despite this difference, the sensitivity of a positive result of a high-risk human papillomavirus test in predicting the presence of grade 2 or 3 cervical intraepithelial neoplasia was only 52%. Among the women for whom a follow-up clinic Papanicolaou smear was reported as showing atypical squamous cells of undetermined significance or a low-grade squamous intraepithelial lesion, there was no difference in the frequency of biopsy-proved grade 2 or 3 cervical intraepithelial neoplasia between those women with a positive human papillomavirus test result and those with a negative test result. Colposcopy would have been recommended for 194 women because of a repeat clinic smear revealing atypical squamous cells of undetermined significance, a low-grade squamous intraepithelial lesion, or a high-grade squamous intraepithelial lesion, and in 21.6% of these grade 2 or 3 cervical intraepithelial neoplasia was shown on biopsy (sensitivity 63%, specificity 62%). Colposcopy would have been recommended for 180 women because high-risk human papillomavirus or a high-grade squamous intraepithelial lesion was detected at the clinic visit, and in 25% of this group grade 2 or 3 cervical intraepithelial neoplasia was shown on biopsy (sensitivity 67%, specificity 66%). Sensitivity and specificity were virtually identical for the two algorithms, but the cost of human papillomavirus testing was nearly double that of triage based on repeat cytologic testing alone ($692 vs $1246 per case).

CONCLUSION

The Food and Drug Administration-approved HPV Profile test is not a cost-effective triage for patients referred with Papanicolaou smears reported as showing atypical squamous cells of undetermined significance or low-grade squamous lesions.

Cytomegalovirus infection, lipoprotein(a), and hypercoagulability: an atherogenic link?

A link between cytomegalovirus (CMV) infection and atherosclerosis has been suggested by experimental, clinical, and epidemiologic studies. We investigated the association between CMV antibody titers in serum collected in 1974 in 300 adult residents in Washington County, Md, and hemostatic parameters in plasma collected in 1987 through 1989, when these individuals participated in the baseline examination of the Atherosclerosis Risk in Communities Study. The cross-sectional association of CMV serum antibodies and hemostatic parameters was also explored in another set of Atherosclerosis Risk in Communities cases and controls. In the longitudinal analyses, CMV titers in 1974 were directly associated with 1987 through 1989 plasma levels of von Willebrand factor, factor VIII, and protein C and negatively associated with activated partial thromboplastin time. In the cross-sectional analyses, CMV titers were directly related to antithrombin III and fibrinogen levels. When the association between CMV antibodies and atherosclerosis was examined in stratified analyses, a significant association was restricted to individuals with high levels of lipoprotein(a) and fibrinogen. These results are compatible with previous evidence suggesting that CMV virus might have procoagulant properties. The possible synergism of CMV infection and resulting hypercoagulability with reduced fibrinolysis due to increased lipoprotein(a) levels deserves further investigation.

Lectin histochemical HPA-binding pattern of human breast and colon cancers is associated with metastases formation in severe combined immunodeficient mice

Metastasis formation is a major clinical problem in cancer treatment, and no significant progress in the treatment of metastatic spread has been made. This apparent lack of progress is partly caused by the absence of clinically relevant animal models of metastases. The binding of the lectin Helix pomatia agglutinin (HPA) has been associated with a poor prognosis in breast and colon cancer patients. HPA-positive and -negative human breast and colon cancer cell lines were transplanted into severe combined immunodeficient (SCID) mice. HPA-positive breast cancer cell lines (MCF-7 and T47D) metastasized in SCID mice, whereas the HPA-negative ones (BT20, HS578T and HBL100) did not. The HPA-positive colon cancer cell line HT29 metastasized, while the HPA-negative ones (COLO320DM, SW480 and SW620) did not. However, in two of eight SCID mice inoculated with the HPA-negative colon cancer cell line, CACO2 metastatic deposits were found. Despite this exception, HPA binding is a good indicator of the metastasis of human breast and colon cancer cells in SCID mice: 23 out of 26 HPA-positive cancers metastasized, as opposed to only two out of 38 HPA-negative cancers. This experimental model is well suited for investigating the functional role of carbohydrate residues recognized by HPA in breast and colon cancer metastasis.

Cytomegalovirus infection and atherosclerosis

The biological properties of human cytomegalovirus are consistent with pathogenic involvement at several levels of the atherogenic process. Although the sites of latency of CMV have not been established, both smooth muscle cells and leukocytes are likely possibilities. The observations of viral antigens and nucleic acid sequences in arterial smooth muscle cells suggest that latent CMV infection of the arterial wall may be common in patients with atherosclerosis. The seroepidemiologic studies suggest that a periodically activated latent infection is present in patients with atherosclerosis. Important are the observations that in immunosuppressed heart transplant patients infected with CMV, atherosclerosis is prone to develop in the transplanted heart. This mainly circumstantial evidence of the involvement of CMV in human atherosclerosis provides an important basis for further investigation of the role of CMV in atherogenesis.

Innervation of the thymus in normal and bone marrow reconstituted severe combined immunodeficient (SCID) mice

The innervation of the thymus was studied in SCID mice: There was a relatively more dense innervation pattern in SCID mice as compared to normal BALB/c mice (from which SCID mice are derived), including nerve fibres immunoreactive for protein gene product 9.5 (PGP 9.5), tyrosine hydroxylase (TH), neuropeptide tyrosine (NPY) and vasoactive intestinal peptide (VIP), although there was no reactivity to substance P (SP) or leucine enkephalin (ENK). Only a few acetylcholinesterase (AChE)-positive nerve fibres were observed in the SCID thymus. Ten weeks after the transfer of bone marrow from normal BALB/c mice into SCID mice no immunoreactivity to the above markers was found, nor was there any AChE reaction, although histologically the thymus appeared normal and dot-blot assays demonstrated the presence of immunoglobulin indicating a return to normal bone marrow function in SCID mice. Both innervation and morphology were restored 6 months after bone marrow transfer. In conclusion, the thymus of SCID mice lacking thymocytes has visible neurotransmitter levels in the nerves, but after thymocyte repopulation by bone marrow transplantation the transmitters are generally not demonstrable. This indicates that the innervation may be more important for the establishment of the microenvironment rather than the maintenance of thymocyte differentiation.

Immunophenotype of human ovarian malignancies (cystadenocarcinomata and mixed müllerian tumor) established in SCID mice

Human ovarian malignancies from three different patients (histology: two serous cystadenocarcinomata and one mixed Müllerian tumor, homologous type) were successfully serially transplanted intraperitoneally into severe combined immunodeficient (SCID) mice where the tumor cells spread around the peritoneal cavity. If the ascites derived from cystadenocarcinoma cells engrafted in the female genital tract of the SCID mice, they formed cystic tumors resembling remarkably well the original tumors in the patients. Immunohistochemical analysis revealed that the immunophenotype of the patients' original tumor and those grown in SCID mice were similar in the case of the two cystadenocarcinomata; in addition, the marker expression in general was stable during serial transplantation. If distant metastases occurred in the lungs, they immunophenotypically resembled those grown intraperitoneally. In contrast, the cells derived from the mixed Müllerian tumor shifted during serial transplantation from a spindle cell morphology toward a morphology characterized by cuboidal cells. The transition toward a more epithelial phenotype was accompanied by a changed immunophenotype of the tumor cells which became positive for epithelial cell markers such as carcinoembryonic antigens, CA 19-9 and CA 125. Concurrently with this differentiation, the p53 immunophenotype changed from positive to negative, indicating a further mutation in the p53 gene during serial passages.