Biomedical subjects

R D Burk

Publications and source records attributed to R D Burk.

At least 109 records · Page 6Linked to original sources

PubMed1992

Self-administered home cervicovaginal lavage: a novel tool for the clinical-epidemiologic investigation of genital human papillomavirus infections.

OBJECTIVE: Our objective was to evaluate a self-administered cervicovaginal irrigation apparatus (MY-PAP, Medtech, Bohemia, N.Y.) for the detection of cervicovaginal human papillomavirus infection. STUDY DESIGN: Twenty-five women referred to a colposcopy clinic because of a recent abnormal Papanicolaou smear were studied. Human papillomavirus infection test results detected by Southern blot hybridization and polymerase chain reaction from physician-administered and MY-PAP self-administered cervicovaginal lavage were paired for comparison. RESULTS: Seventeen (68%) patients returned home samples by mail a mean of 13 days after the clinic visit. All clinic samples and 16 of 17 (94%) home samples yielded adequate deoxyribonucleic acid for human papillomavirus infection analyses. Human papillomavirus infection was detected by polymerase chain reaction in 14 of 16 (88%) samples with complete concordance of viral detection in paired samples from the clinic and home. Southern blot detected human papillomavirus infection in 13 of 25 clinic samples (52%) and 7 of 16 home samples (44%), with concordance in 12 of 16 paired samples (75%). Specific viral type was the same in all positive paired samples (6/6). Concordance was high when the initial sample had a strong (2+ to 4+) human papillomavirus infection signal (5/6, 83%) or a negative result (5/6) or when a dysplastic (cervical intraepithelial neoplasia grade 1 to 3) lesion (9/11, 82%) was seen on cervical biopsy. CONCLUSION: Self-administered lavage represents an extremely promising technique for obtaining cervicovaginal lavage samples for human papillomavirus infection analyses.

Blotting, Southern↗

PubMed1992

Follow-up evaluation of cervicovaginal human papillomavirus infection in adolescents.

We performed a second examination for human papillomavirus (HPV) DNA on 51 sexually experienced 13- to 21-year-old (mean = 17.8 years) female patients seen at an urban teaching hospital. Cervicovaginal lavages were performed 6 to 36 months apart (median = 13.3 months) to collect cells for HPV DNA detection and typing by Southern blot hybridization. At the first and second visits, 39.2% (20/51) and 25.5% (13/51) of patients, respectively, were infected with HPV. Collectively, 56.9% (29/51) of patients had at least one positive HPV test result. Although 7.8% (4/51) were infected with HPV at both visits, only one patient had infection with the same HPV type. These findings suggest that although HPV infection is a common sexually transmitted disease, genotype-specific HPV infection detected by Southern blot at two visits was rare.

Adolescent↗

PubMed1992

Immune tolerance to a defined heterologous antigen after intrasplenic hepatocyte transplantation: implications for gene therapy.

Development of a host immune response against gene products expressed by genetically modified cells could be a serious limitation for gene therapy. During examination of whether site-specific differences in antigen presentation could regulate the host immune response, we observed an absence of antibodies against hepatitis B virus surface antigen (HBsAg) when HBsAg producing transgenic hepatocytes were transplanted into the spleen. Intrasplenic transplantation resulted in translocation of a large number of cells into the portal vascular bed and liver sinusoids. In these recipients, HBsAg secreted by the transplanted hepatocytes circulated indefinitely in the blood. In contrast, subcutaneous or intraperitoneal transplantation of the transgenic hepatocytes induced an anti-HBs response, followed by clearance of serum HBsAg. Rechallenge with HBsAg in a highly immunogenic form failed to break the tolerance in intrasplenic hepatocyte recipients even though these animals responded to another antigen (keyhole limpet hemocyanin). Immunization with HBsAg in intraperitoneal recipients of HBsAg producing hepatocytes further elevated anti-HBs titers. Our results indicate that hepatocyte transplantation into the portal vascular bed via injection into the spleen can confer immune tolerance to secreted heterologous antigens. This finding should have important implications for human gene therapy as well as for analyzing the mechanisms of immune tolerance.

Animals↗

PubMed1992

Phylogenetic classification of human papillomaviruses: correlation with clinical manifestations.

Human papillomaviruses (HPVs) are a heterogeneous group of small dsDNA viruses which cause a variety of proliferative epithelial lesions at specific anatomical sites. Although more than 65 different virus types have been cloned and characterized, no uniform classification system exists. In order to classify HPV DNA types, phylogenetic trees were constructed based on nucleotide sequence alignments using parsimony and distance matrix algorithms. The resulting phylogenetic trees provide a classification of the HPVs into specific groups encompassing the known tissue tropism and oncogenic potential of each HPV type. The implications of a phylogenetic taxonomy on the diagnostic detection of HPVs and the concept of different HPV species are discussed.

Algorithms↗

PubMed1992

Polymerase chain reaction detection of human papillomavirus: quantitation may improve clinical utility.

A case-control study compared detection by polymerase chain reaction (PCR) specific for human papillomavirus (HPV) type 16 with restriction enzyme analysis and Southern blot hybridization detection of HPV type 16. Cervicovaginal lavage samples from 64 women with histopathologic evidence of a cervical squamous intraepithelial lesion and 55 samples from cytologically healthy women were studied. Several methods of PCR product analysis, including radioactive and nonradioactive probing, were compared. The sensitivity of HPV detection by PCR when the amplified DNA fragment was visualized on a gel was equivalent to those of detection by restriction enzyme and Southern blot analyses. Hybridization of the PCR product with radioactively or nonradioactively labeled oligonucleotide probes increased the sensitivity of HPV detection by 100-fold. However, an increase in the sensitivity of the assay preferentially identified low levels of the virus in cytologically healthy women. Therefore, the value of HPV detection in identifying women with cervical neoplastic disease was greater, and the odds ratio for the presence of a cervical squamous intraepithelial lesion was higher when the less sensitive modalities were used. These results suggest that quantitation of HPV by PCR may maximize the clinical significance of a positive test result. Further studies will be needed to determine the optimal level of virus detection which has the highest positive predictive value of clinical disease.

Base Sequence↗

PubMed1991

Human papillomavirus infection and other risk factors for cervical neoplasia: a case-control study.

A case control design has been used to investigate risk factors associated with the development of cervical squamous intraepithelial lesions (SIL) in a population of urban women in which non-affluent minority groups were heavily represented. Eighty-five women with histologically confirmed SIL were compared to a control group of 70 cytologically normal women. HPV infection was determined using both Southern blot hybridization and polymerase chain reaction (PCR) amplification specific for HPV types 16, 18, and 33. When Southern blot was used to detect HPV, logistic regression analysis identified HPV infection (odds ratio (OR) = 17.9, 95% confidence interval (CI) = 6.2-51.6) and low educational achievement (OR = 3.4, 95% CI = 1.2-10.1) as major independent risk factors. When PCR was employed to detect HPV, the logistic regression model suggested that HPV infection (OR = 10.4, 95% CI = 3.6-30.4) and Hispanic ethnicity (OR = 5.0, 95% CI = 1.2-20.5) represented independent risk factors; low educational achievement and Black ethnicity were risk factors of borderline significance. PCR detection of simultaneous co-infection with more than one HPV type was associated with a very high risk of SIL (OR for one type = 7.2, 95% CI = 2.4-21.9; OR for greater than I type = 43.0, 95% CI = 6.9-266.6). Furthermore, increased viral load determined by either method carried an increased risk of disease. HPV infection with viral types previously reported to be related to neoplastic or dysplastic lesions carried the highest risk of SIL. The association of HPV detected by Southern blot and SIL in women less than 35 years old had an OR of 10.1, whereas in women greater than or equal to 35 the OR was 74.5 (p = 0.09 for homogeneity of ORs). We conclude that infection with HPV is the major risk factor for cervical SIL and suggest that targeted HPV screening of women over age 35 may represent an innovative strategy to detect women at high risk of cervical neoplasia.

Age Factors↗

PubMed1991

Permanent engraftment and function of hepatocytes delivered to the liver: implications for gene therapy and liver repopulation.

To examine the distribution of intrasplenically transplanted hepatocytes, we used HBsAg-producing G7 HBV transgenic hepatocytes or cells labeled with 111In. Most hepatocytes translocated to the liver (55% +/- 7%; mean +/- S.D.); the spleen retained a smaller fraction (15% +/- 3%); and some transplanted cells localized in lungs (3%) or pancreas (1%). Transplanted hepatocytes were rapidly assimilated into the liver lobule. Morphometrical quantitation indicated that the numbers of transplanted hepatocytes in the liver at 48 hr and at 9 mo after transplantation were similar. Serum HBsAg was detected in recipients of the G7 HBV hepatocytes during the 1-yr experiment. These results indicate that a large number of hepatocytes can be reproducibly delivered to the liver by transplantation into the spleen. Transplanted hepatocytes engraft rapidly, assimilate into host liver, maintain normal function and survive permanently. Systems for safe delivery and localization of hepatocytes in the liver represent a critical step toward successfully accomplishing hepatocyte-directed gene therapy and repopulation of the acutely devastated liver.

Animals↗

PubMed1991

High risk of human papillomavirus infection and cervical squamous intraepithelial lesions among women with symptomatic human immunodeficiency virus infection.

We investigated the relationship of human papillomavirus (by cervicovaginal lavage and Southern blot), human immunodeficiency virus, and squamous intraepithelial lesions in 96 high-risk women in the Bronx, New York. Antibodies for human immunodeficiency virus were detected in 51 (53%) women. Of the 33 women with symptomatic human immunodeficiency virus infection, 23 (70%) had human papillomavirus infection compared with 4 of 18 (22%) asymptomatic women who were human immunodeficiency virus seropositive and 10 of 45 (22%) uninfected women (p less than 0.0001). The rate of squamous intraepithelial lesions was 52% (14 of 27) for women with both viruses detected, 18% (6 of 34) for women with either virus detected, and 9% (3 of 35) for uninfected women. Among symptomatic human immunodeficiency virus-infected women, a strong association between human papillomavirus infection and squamous intraepithelial lesions was demonstrated (odds ratio, 12; 95% confidence interval, 1.3 to 108). Risk was highest for younger women from ethnic or racial minority groups. Advanced human immunodeficiency virus-related disease, with its associated immunosuppression, seems to exacerbate human papillomavirus-mediated cervical cytologic abnormalities. Public health measures are needed to provide Papanicolaou smear screening and appropriate clinical follow-up and treatment for women at high risk for human immunodeficiency virus infection.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Type-specific and cross-reactive epitopes in human papillomavirus type 16 capsid proteins.

Genital human papillomavirus (HPV) 16 infection is frequently associated with cancer of the uterine cervix, as well as with precancerous lesions. In order to generate serologic reagents which might be useful in the diagnosis of HPV 16 infection, rabbit polyclonal and mouse monoclonal antisera were raised to carboxy terminal peptides from the HPV 16 L1 and L2 open reading frames (ORFs). Anti-L1 and -L2 peptide sera recognized HPV 16 L1 and L2 fusion proteins in Western blots and by immunoprecipitation. In Western blot analysis of L1 proteins from different HPV types, antisera to the L1 peptide reacted only with HPV 16, thus identifying an HPV 16 type-specific linear epitope. Anti-L2 peptide sera reacted with L2 fusion proteins from HPVs 6 and 16, but not from BPV, thus identifying a partially cross-reactive epitope in the HPV 16 L2. Computer analysis of carboxy terminal amino acid sequences of the L1 and L2 ORFs of multiple HPV types supported the Western blot findings. Despite the HPV 16 type specificity found in Western blots, anti-L1 peptide sera identified nuclear antigen by immunocytochemistry in cervical biopsies infected with HPV 16, as well as other genital HPV types. Anti-L2 peptide sera failed to recognize antigen in infected tissue.

Amino Acid Sequence↗

PubMed1991

Cervicovaginal human papillomavirus infection in suburban adolescents and young adults.

To investigate the prevalence rates of and risk factors for genital human papillomavirus (HPV) infection in white, middle-class adolescents, we obtained specimens for HPV from 107 patients undergoing pelvic examination at a suburban adolescent health service. Specimens were obtained by means of cervicovaginal lavage and were analyzed for HPV DNA by Southern blot analysis. The subjects' mean age was 18.5 (+/- 2.0 SD) years; 47% of the subjects were seen for contraception, 36% for possible pregnancy, 12% for a gynecologic complaint, and 5% for a general examination. We detected HPV in 32% of patients; HPV types included 6/11 (6%), 16 (3%), 18 (15%), 31 (3%), 42 (6%), 45 (18%), and 56 (6%). The DNA type was classified as uncharacterized in 47%, and 3% had more than one type. Univariate analysis revealed that patients found to have HPV were more likely to have more than two sexual partners, to have been sexually active for more than 2 years, to have had menarche before 12 years of age, and to have a history of sexually transmitted disease; logistic regression multivariate analysis demonstrated that number of partners and age at menarche were independent risk factors for HPV. These data indicate that HPV is common among sexually active teenagers regardless of ethnicity or socioeconomic status. The association of cervicovaginal HPV infection with sexual activity further supports the notion of the sexual transmission of this agent.

Adolescent↗

PubMed1991

Human papillomavirus, gonorrhea, syphilis, and cervical dysplasia in jailed women.

We assessed the prevalence of human papillomavirus (HPV) by cervicovaginal lavage and Southern blot and inquired about behavioral risk factors for cervical disease and sexually transmitted diseases by interview in 114 female detainees at a large New York City jail. Of the women screened, 8% had abnormal Pap smears, 35% had HPV, 7% had gonorrhea, and 22% had serologic syphilis. Given the high rates of HPV infection and cervical cytology, Pap smears should be a routine intake procedure for incarcerated women.

Adult↗

PubMed1991

Plasma ascorbic acid and beta-carotene levels in women evaluated for HPV infection, smoking, and cervix dysplasia.

The association of the plasma levels of the essential micronutrients, ascorbic acid and beta-carotene, with smoking and human papillomaviruses (HPV) infection has been studied in 75 women referred to a colposcopy clinic for an abnormal Pap smear. Each patient had a repeat Pap smear and a colposcopically directed biopsy of a visually perceived cervix abnormality. Cervicovaginal lavage specimen and peripheral venous blood sample were obtained for HPV DNA hybridization studies and nutrient analyses, respectively. Samples were obtained and analyzed without knowledge of each woman's clinical status. A group of 45 subjects had histopathologically diagnosed dysplasias of varying grades of severity. Among women with dysplasias, 53.3% were smokers. Of subjects with and of subjects without dysplasias, 66 and 34%, respectively, were positive for HPV infection. The mean plasma reduced ascorbic acid, retinol, and beta-carotene levels between the dysplastic groups were comparable. A strong association with smoking history and plasma reduced ascorbic acid level was note independent of cervical dysplasias or HPV status. The findings underscore the importance of smoking, ascorbic acid, and beta-carotene as nutritional variables, and HPV infection in the pathogenesis of cervical dysplasias.

Adult↗

PubMed1990

Genetic screening with exfoliated cervicovaginal cells collected by a noninvasive lavage technique performed during routine gynecologic cancer screening.

We have investigated and established the feasibility of the use of exfoliated cervicovaginal cells as an abundant source of genetic material. We routinely use this material for the detection by molecular hybridization of human papillomavirus infection of the cervix. We have analyzed deoxyribonucleic acid isolated from cervicovaginal cells by Southern blot hybridization to detect a common restriction fragment length polymorphism on chromosome 13. We suggest that in the near future most, if not all, major human genetic disease loci will be cloned and their mutations will be identified. With this knowledge and innovative methods, such as the polymerase chain reaction, it will be possible to distinguish normal individuals who harbor a variety of recessive genetic mutations that may place them at risk to produce offspring with serious genetic diseases. We propose that both genetic and cancer screening can be performed during the same office visit. Such testing offers the advantage of identification of women at risk for genetic disease with a noninvasive procedure before or concurrent with childbearing. Easily accessible genetic material extracted from exfoliated cervicovaginal cells can also be used for population genetic studies.

Adult↗

PubMed1990

The rat hepatocyte plasma membrane organic anion binding protein is immunologically related to the mitochondrial F1 adenosine triphosphatase beta-subunit.

A 55-kD organic anion binding protein (OABP) was identified previously in liver cell plasma membrane sinusoidal subfractions. Although this protein was localized to the surface of hepatocytes by immunofluorescence, immunoblot analysis revealed reactivity toward both plasma membrane and mitochondrial fractions. To clarify these findings, an immunoreactive clone from a rat liver cDNA expression library was isolated, the 1,500-base pair cDNA insert was sequenced, and the corresponding beta-galactosidase fusion protein was expressed and purified. The resulting sequence corresponded to that of the rat mitochondrial F1-adenosine triphosphatase (F1-ATPase) beta-subunit. This protein and OABP are of similar size and are mutually immunologically cross-reactive. That the antigen was present on the cell surface as well as in mitochondria was suggested from studies of immunoprecipitation after cell-surface iodination, and light- and electron-microscopic immunocytochemistry. Photoaffinity labeling of bovine F1-ATPase with high-specific-activity [35S]sulfobromophthalein revealed binding only to the beta-subunit. Hepatocyte uptake of bilirubin and sulfobromophthalein requires cellular ATP and mitochondria also transport these organic anions, which at high doses inhibit respiration. The presence of an organic anion binding site on the F1-ATPase beta-subunit suggests that it may play a role in these processes.

Affinity Labels↗

PubMed1990

Cervical cytologic abnormalities and papillomavirus in women infected with human immunodeficiency virus.

We investigated the relationship of human papillomavirus (HPV) infection of the female genital tract, cervical cytology, and human immunodeficiency virus (HIV) infection in 67 women. Forty-eight women had a history of intravenous drug use, 18 were heterosexual partners of HIV-infected intravenous drug users, and one was a transfusion recipient. Patients received a Pap smear, cervicovaginal lavage for HPV determination by Southern blot, HIV serum antibody by enzyme immunoassay with Western blot confirmation, and thorough screening for other sexually transmitted diseases. Seventeen of the 35 (49%) women seropositive for HIV had HPV infection, compared with 8 of 32 (25%) seronegative women (p less than 0.05). Fourteen of 35 (40%) HIV-positive women had squamous intraepithelial lesions (SIL) on cervical cytology, compared with three of 32 (9%) HIV-negative women (p less than 0.01). Of 22 women with symptomatic HIV infection, 11 (50%) had SIL on cytology; 10 of these 11 were HPV-positive. Among 13 asymptomatic HIV-positive women, only three (23%) had such cytological lesions. Our findings strongly suggest that HIV-induced immunosuppression exacerbates HPV-mediated cervical cytologic abnormalities.

Adult↗

PubMed1990

A novel system for transplantation of isolated hepatocytes utilizing HBsAg-producing transgenic donor cells.

Hepatocytes from donor transgenic mice that produce an easily assayable circulating marker have been used to develop a novel hepatocyte transplantation system. Isolated G7 HBV transgenic donor hepatocytes secreting HBsAg were transplanted into congeneic or allogeneic mouse recipients. Serum HBsAg was present three days after hepatocyte transplantation in congeneic animals and persisted indefinitely when hepatocytes were transplanted into the spleen. Transplanted hepatocytes within the splenic pulp were identified by morphologic and histochemical analysis. Migration of hepatocytes injected into the spleen to the liver was demonstrated by in situ hybridization using an RNA probe for HBsAg. Transplantation into nonimmunosuppressed allogeneic recipients resulted in disappearance of detectable hepatocytes in the spleen within two weeks. This novel transplantation system should facilitate studies of hepatocyte engraftment and survival, modulation of allograft rejection, and development of hepatocyte-directed gene therapy.

Animals↗

PubMed1989

Inter-laboratory variation as an explanation for varying prevalence estimates of human papillomavirus infection.

Human papillomavirus (HPV) infection has been strongly implicated as a cause of genital neoplasia. Although Southern blot DNA hybridization techniques are regarded as the most accurate means of identifying HPV infection, studies using this technique to measure infection have provided varying estimates of the prevalence of HPV among healthy and diseased groups. This investigation provides a possible explanation for study-to-study differences, by demonstrating inter-laboratory variability in the detection and typing of HPV by Southern blot. Four experienced laboratories tested 40 identical, masked samples of DNA extracted from presumed infected and non-infected tissues. The pairwise percentage agreement between the laboratories in judging samples as HPV-positive or negative ranged from 66 to 97%. Among samples judged to contain HPV, agreement as to type ranged from 77 to 96%. We conclude that inter-laboratory differences are an important consideration in any discussion of HPV prevalence estimates.

Analysis of Variance↗

PubMed1989

High prevalence rate of human papillomavirus infection and association with abnormal papanicolaou smears in sexually active adolescents.

Human papillomaviruses (HPVs) are associated with neoplastic and malignant lesions of the uterine cervix. Cervical neoplasia is associated with onset of sexual activity at an early age. Therefore, this study sought to define the prevalence rates of HPV infection and cytologic abnormalities in adolescents. Sexually active females 13 to 21 years of age undergoing routine cervical cytologic screening were evaluated in the adolescent clinic of an urban hospital. Cells collected by cervicovaginal lavage from 249 subjects were analyzed for HPV DNA by Southern blot hybridization with probes for HPV types 6/11, 16, and 18. The HPV DNA was detected in 95 (38.2%) of 249 patients. Teenagers between the ages of 13 and 18 years with multiple lifetime sexual partners were at higher risk for HPV infection (38/71 [54%]) compared with patients of the same age who had only a single partner (25/74 or [34%]). Twenty (8.3%) of 241 patients had abnormal Papanicolaou smears with atypia, koilocytosis, or low-grade cervical intraepithelial neoplasia. Cytologic abnormalities were detected in 16 (17%) of 94 adolescents with HPV present, but in only 4 (2.7%) of 147 of the uninfected patients. Thus, HPV emerged as a common pathogen in female adolescents, and infected patients are at increased risk for cervical epithelial abnormalities.

Adolescent↗