Biomedical subjects

Christoph Schmitt

Publications and source records attributed to Christoph Schmitt.

8 recordsLinked to original sources

PubMed2006

Acrylic/cyclodextrin hydrogels with enhanced drug loading and sustained release capability.

The influence of the proportion of acrylamidomethyl-gamma-cyclodextrin (gamma-CD-NMA) on loading and release of the hydrophobic triamcinolone acetonide (TA) and the hydrophilic propranolol (PR) by acrylic acid hydrogels was evaluated. gamma-CD-NMA was synthesized by condensation of gamma-cyclodextrin (gamma-CD) with N-(hydroxymethyl) acrylamide. Hydrogels were prepared with gamma-CD-NMA and sodium acrylate (3 M or 4 M), using N,N'-methylen(bisacrylamide) (BIS) as cross-linker, by free radical polymerization into glass moulds of 2 mm wide and were cut as discs (10 mm diameter). gamma-CD-NMA did not modify the pH-dependent swelling of the hydrogels, but significantly increased the swelling degree in the 40:60 ethanol:water, medium in which TA can be dissolved. Hydrogels prepared with gamma-CD-NMA above 5% (w/w of total monomers) showed a remarkably higher capacity to load TA, e.g., 33 mg/g dry hydrogel versus 0.6 mg/g dry hydrogel without gamma-CD-NMA. This is explained by the formation of 1:1 inclusion complexes of TA with gamma-CD mers that overcomes the lack of interactions with the acrylic groups of the network. The release of TA in water, 0.1 N HCl, or pH 6.8 phosphate buffer was sustained for at least 24 h, whatever the pH and the composition of the medium used. In contrast, loading of PR from the water solutions was greater for hydrogels prepared with 3 M acrylate than with 4 M acrylate, irrespective to their content in gamma-CD-NMA, and in less than 2 h ca. 80% PR was released. The lower affinity of PR for the gamma-CD cavities, compared to the strong intensity of the electrostatic interactions with the acrylic acid groups, explains why the incorporation of gamma-CD-NMA did not increased the loading and control release capacity of the hydrogels of this hydrophilic drug. In summary, the copolymerisation of CD with acrylic monomers can provide highly hydrophilic pH-sensitive networks which load large amounts of hydrophobic drugs and release them in a sustained way.

Calorimetry, Differential Scanning↗

PubMed2005

Aberrant, highly hyperdiploid cells in human papillomavirus-positive, abnormal cytologic samples are associated with progressive lesions of the uterine cervix.

BACKGROUND: Infection with oncogenic-type human papillomavirus (HPV) and consecutive cytologic abnormalities of the uterine cervix precede the evolution of carcinoma. However, the specificity of both changes is too low to predict the true malignant potential of the change in a given time point, because the majority of the HPV infections revert to normal with time. In preliminary studies, the authors demonstrated that, among many dysregulatory phenomena at the cytologic level, the occurrence of significant DNA content aberrations were in good correlation with progressive cervical changes; and, as a marker for this, the significance of cells with nuclear DNA content > 9c (9c cells) was investigated using slide-based cytometry. The objective of the current study was to determine whether 9c cells in cytologic samples that presented with dysplasia and with high-risk HPV types were associated with the development of higher grade cervical intraepithelial neoplasia (CIN II+). METHODS: Samples with positive cytologic diagnoses (atypical squamous cells of undetermined significance, low-grade squamous intraepithelial lesion [LSIL], and high-grade squamous intraepithelial lesion [HSIL]) were evaluated for both parameters and were related to outcomes and, if available, to histology results over a follow-up of up to 4 years. RESULTS: Although the presence of high-risk HPV was demonstrable in almost all samples with CIN II+ (96.7%), the virus genome alone proved to have a poor positive predictive value (56.1%) for higher grade CIN. Cytology and the demonstration of 9c cells resulted in less sensitivity compared with the occurrence of high-risk HPV (70.4% and 73.7%, respectively) but in significantly greater specificity (91.3% and 89.2%, respectively). Moreover, a positive predictive value of 81.8% for CIN II+ could be calculated for 9c cells. HSIL morphology, unfavorable HPV type, and DNA cytometry together excluded the highest rate of CIN > or = II with 100% sensitivity and 91.3% specificity. CONCLUSIONS: Biologic parameters, in addition to cytology, help to define the nature of cervical dysplasias more accurately. Oncogenic HPV types and hyperdiploid cells with DNA content > 9c disclosed cytologic changes with the greatest malignant potential. Cancer

DNA↗

PubMed2005

Validity of combined cytology and human papillomavirus (HPV) genotyping with adjuvant DNA-cytometry in routine cervical screening: results from 31031 women from the Bonn-region in West Germany.

Our aim was to improve the accuracy of routine cervical screening by a risk-adapted multimodal protocol with special focus on possible reduction and prognostic assessment of false positive results. A cohort of 31031 women from the Bonn-region in West Germany, median age 36 years, were screened by cytology (conventional or liquid-based), followed by PCR-based HVP detection with genotyping and adjuvant DNA image cytometry, if indicated, in a sequential manner. The true prevalence of high-grade cervical intraepithelial neoplasia and carcinoma (>/=CIN2) was 0.32% in the population as projected from cervical biopsies of 123 women (0.4%), of whom 100 showed >/=CIN2. Sensitivity of the cytology screening program at PapIIID/HSIL threshold for detecting histologically confirmed >/=CIN2 cases was 81%, with specificity, positive predictive value (PPV) and negative predictive value (NPV) of 99, 20.9 and 99.9%, respectively. Of 38 women receiving the complete screening protocol, all the 31 >/=CIN2 cases were correctly detected by cytology alone, 30 by positive high-risk HPV genotype and 30 by aneuploid DNA profile. The combination of the three methods resulted in an up to 6.9% increase in PPV for >/=CIN2 at practically unchanged detection rate with the additional benefit of being able to predict the probable outcome of CIN1 lesions detected as false positives with any single test. Multimodal cervical screening might permit identification of those women with low-grade squamous intraepithelial lesions likely to progress at an earlier and curable stage of disease and lengthen the screening interval in those with transient minor lesions caused by productive HPV infection.

Adult↗

PubMed2004

Human papillomavirus (HPV) study of 2916 cytological samples by PCR and DNA sequencing: genotype spectrum of patients from the west German area.

Human papillomaviruses (HPVs) are aetiological agents for cervical cancer. More than 70 different HPV types that infect genital mucosa have been found. In order to develop a sensitive and specific detection and typing assay, a PCR/direct sequencing approach was used. Two pairs of consensus primers were used for amplification of HPV DNA and the PCR products obtained were analysed by automated sequencing. Sequences were compared with those in GenBank by using the BLAST program. In this study, 2916 cytological samples were screened for HPV, as well as for triage. Nine hundred and forty-eight (32.5%) samples were positive for HPV, of which 134 harboured more than one HPV type. Of the 948 PCR-positive samples, 648 were typed. Thirty-nine different HPV types were identified by sequencing. The two most frequently found HPV types, 16 and 31, together accounted for 36.3% of the sequences (26.2 and 10.1%, respectively). This group was followed by HPV types 6 (5.7%), 18 (5.3%), 58 (4.5%), 61 (4.5%), 53 (4.4%), 42 (4.3%) and 51 (4.0%). All other types were detected at frequencies <4% and eight types were detected only once. PCR/direct sequencing is a reliable method for routine detection of HPV in cytological samples. The data presented here suggest a complex distribution of HPV types in the population tested. The results accentuate the importance of PCR-based techniques in HPV diagnosis, as hybridization-based methods can only detect a limited number of infections. This method can also be applied easily to the analysis of tissue samples and it therefore also allows type-specific follow-up of women who have been treated for cervical intraepithelial neoplasia.

Adolescent↗

PubMed2003

Determination of features indicating progression in atypical squamous cells with undetermined significance: human papillomavirus typing and DNA ploidy analysis from liquid-based cytologic samples.

BACKGROUND: The Bethesda System of cervical cytologic findings introduced the term ASCUS (atypical squamous cells of undetermined significance) to cover the broad zone separating normal cytomorphology from definitive squamous intraepithelial lesions (SILs). The management of patients with ASCUS is particularly problematic as approximately 10% of ASCUS patients develop SIL and 1 per 1000 develop cervical carcinoma. METHODS: Our aim was to demonstrate the combined use of polymerase chain reaction for human papillomavirus (HPV) typing and laser scanning cytometry for DNA content measurements in the subcategorization of ASCUS cases according to the risk for progression toward cancer. Liquid- based monolayer preparation (ThinPrep, Cytyc, Boston, MA) of the cytologic material was used for cytomorphologic analysis. DNA content measurements using laser scanning cytometry and direct sequencing of HPV using the consensus primers GP5+/GP6+ and MY09/MY11 were performed from the same material. RESULTS: Twelve of the 44 cases (27.2%) with ASCUS carried a high-risk HPV genome whereas only 3 of the 195 normal control cases (1.5%) showed positivity for a high-risk HPV genome. Six of 12 (50%) of the high-risk HPV-positive ASCUS cases presented isolated cells with a DNA content above 5c, whereas cells with a DNA content above 9c were found in 3 of 12 cases (25%) and were exclusively found in combination with high-risk HPV infection. In these three cases, the histologic follow-up resulted in cervical intraepithelial neoplasia (CIN) I (one case) and CIN III (two cases). None of the other ASCUS or normal cases displayed DNA aneuploidy above 9c. They returned to normal cytology (within normal limits/benign cellular changes) in the follow-up. CONCLUSIONS: Human papillomavirus typing and DNA content measurements may delineate a distinct group of ASCUS. Our preliminary data suggest that ASCUS cases with high-risk HPV positivity and with rare cells with abnormally high DNA content represent similar biologic features as high-grade SIL and are at elevated risk to develop cancer.

Carcinoma, Squamous Cell↗

PubMed2003

Formation of a PNA2-DNA2 hybrid quadruplex.

DNA guanine (G) quadruplexes are stabilized by an interesting variation of the hydrogen-bonding schemes encountered in nucleic acid duplexes and triplexes. In an attempt to use this mode of molecular recognition, we target a dimeric G-quadruplex formed by the Oxytricha nova telomeric sequence d(G(4)T(4)G(4)) with a peptide nucleic acid (PNA) probe having a homologous rather than complementary sequence. UV-vis and CD spectroscopy reveal that a stable hybrid possessing G-quartets is formed between the PNA and DNA. The four-stranded character of the hybrid and the relative orientation of the strands is determined by fluorescence resonance energy transfer (FRET) experiments. FRET results indicate that (i) the two PNA strands are parallel to each other, (ii) the two DNA strands are parallel to each other, and (iii) the 5'-termini of the DNA strands align with the N-termini of the PNA strands. The resulting PNA(2)-DNA(2) quadruplex shows a preference of Na(+) over Li(+) and displays thermodynamic behavior consistent with alternating PNA and DNA strands in the hybrid. The formation of this novel supramolecular structure demonstrates a new high-affinity DNA recognition mechanism and expands the scope of molecular recognition by PNA.

Animals↗

PubMed2003

Human papillomavirus typing and DNA ploidy determination of squamous intraepithelial lesions in liquid-based cytologic samples.

BACKGROUND: Infection by high-risk human papillomavirus (HPV) plays a role in the evolution of cervical carcinoma. Cellular atypia and consecutive DNA content alterations in cytologic samples are consequences of a preexisting viral infection. METHODS: We analyzed the frequency and association of HPV types and the presence of rare cells with abnormally high DNA content. We also evaluated whether these findings support the cytologic diagnosis in 112 routine cases with low and high-grade squamous intraepithelial lesions (LSIL/HSIL) when performed from liquid-based cytologic samples (ThinPrep). For DNA content measurements, laser scanning cytometry was applied and at least 10,000 cells were analyzed. HPV typing was performed by a direct sequencing approach using the consensus primers GP5+/GP6+ and MY09/MY11. RESULTS: Of 112 SIL cases, 110 (98.2%) were HPV positive and 95 (84.8%) had a high-risk type HPV infection. Almost one-half of the cases (46 of 95, 48.4%) with a high-risk HPV infection presented aneuploid squamous cells with greater than 9c DNA content, whereas none of the low-risk HPV-positive or HPV-negative SIL cases showed any aneuploid cells in this range. Although 91.8% of the HSIL cases displayed greater than 9c aneuploid cells, only 7.9% of the LSIL cases were positive for such cells with abnormally high DNA content. CONCLUSIONS: HPV typing and DNA measurements help in the objectivation of cytologic atypia and both can be performed efficiently from the same liquid-based cytologic samples.

DNA, Viral↗

PubMedDate not supplied

Predicting treatment outcome in cervical diseases using liquid-based cytology, dynamic HPV genotyping and DNA cytometry.

BACKGROUND: In this study, our prospective experience with a multimodal follow-up protocol is summarized, with special emphasis on predicting the treatment outcome of cervical diseases. MATERIALS AND METHODS: Liquid-based cytology samples (ThinPrep) from 209 women exhibiting the whole spectrum of human papilloma virus (HPV)-related cervical diseases were investigated by cytology, PCR-based HPV genotyping and DNA cytometry pre-surgery. The first control cytology and type-specific HPV tests were performed at 3 months post-surgery. RESULTS: The success rate of surgery was 95% in eradicating high-grade cervical disease and 90% in eliminating the baseline HPV genotype. Treatment failure was significantly correlated with baseline cytology (p=0.011), resection margin status (p=0.016) and HPV positivity at 3 months post-surgery (p=0.04). Multivariate logistic regression analysis showed that type-specific persistent HPV infection (p=0.028), baseline cytology (p=0.039) and histology (p=0.065) were independent predictors of residual cervical neoplasias. CONCLUSION: Our results showed that our multimodal surveillance protocol may help to individually assess the anticipated clinical outcome of cervical diseases post-surgery.

Adolescent↗