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J Pontén

Publications and source records attributed to J Pontén.

At least 19 recordsLinked to original sources
PubMed2002

Interpretation of radial pulse contour during fentanyl/nitrous oxide anesthesia and mechanical ventilation.

BACKGROUND: Peripheral arterial blood pressure is not a reliable substitute for proximal aortic pressure. Recognition of this phenomenon is important for correct appreciation of cardiac afterload. Our aim was to evaluate the utility of the radial pulse wave to better understand ventriculo-vascular coupling during anesthesia. METHODS: We observed the differences between aortic systolic pressure (AoSAP, tipmanometry) and radial systolic pressure in 15 patients, (including two women) aged 53-78 years, before coronary artery bypass surgery. We studied the induction of anesthesia with fentanyl (20 microg kg-1), moderate volume loading, and thereafter the addition of 70% nitrous oxide. The circulatory effects of mechanical ventilation were studied by doubling the tidal volumes. Pulse wave contours were assessed by calculation of radical and aortic augmentation indices (AI), which measure the second systolic pressure peak. RESULTS: Radial systolic pressure was higher than AoSAP in the control situation (8+/-2 mmHg), and this SAP gradient increased further with fentanyl (12+/-2 mmHg). The gradient persisted throughout the study, but was partially reduced by volume loading and nitrous oxide, respectively. Radial augmentation index was the only parameter remaining in a stepwise multivariate model to explain the variance in the SAP gradient (r2=0.48). Radial augmentation index also correlated with aortic pulse pressure (r2=0.71). Mechanical ventilation had significant and similar effects on pulse wave augmentation both in the aorta and in the radial artery, and did not affect the radial to aortic SAP gradient. CONCLUSION: These elderly coronary patients had stiff vasculature (high aortic AI) and considerable pulse wave reflection, which was beneficially delayed by fentanyl. Changes in the radial pulse wave augmentation during mechanical ventilation were mainly a result of cyclic changes in the stroke volume, and were seldom associated with an increased systolic pressure gradient from the aorta to the radial artery.

Aged↗
PubMed2002

Can a clinically useful aortic pressure wave be derived from a radial pressure wave?

BACKGROUND: The information contained in arterial pressure waveforms is probably underused by most clinicians who manage critically ill patients. It is not generally known that an aortic pressure wave can be synthesized by applying a generalized transfer function to the radial arterial pressure wave. We validated a commercially available system, SphygmoCo (PWV Medical, Sydney). METHODS: Ascending aortic pressure waves were synthesized and comparisons were made between the synthesized aortic waveforms, the measured aortic and radial arterial waveforms. Ascending aortic pressure waves (catheter-tip manometer) and radial artery pressure waves (short fluid-filled catheter) were recorded simultaneously in 12 patients with angina pectoris (age 62-76 years) undergoing cardiac catheterization. Patients were studied at rest, following midazolam, sublingual nitroglycerin and during Valsalva manoeuvres. RESULTS: Both midazolam and nitroglycerin lowered mean arterial pressure but nitroglycerin caused a more selective decrease in the measured and synthesized aortic systolic pressures than in the radial artery pressure. The synthesized aortic systolic pressure was less, by 6-8 mm Hg (SD 2-3) and the synthesized aortic diastolic pressure greater, by 4 mm Hg (SD 2). Despite these differences in pulse pressure, the synthesized waveform tracked the measured waveform before and during interventions. CONCLUSIONS: By deriving an aortic waveform from the radial pulse, monitoring of left ventricular afterload can improve without more invasive means.

Angina Pectoris↗
PubMed2001

HPV16 E6 gene variations in invasive cervical squamous cell carcinoma and cancer in situ from Russian patients.

HPV16 is frequently seen in invasive cervical cancer (ICC) and cervical intraepithelial neoplasia (CIN). Its E6 gene has frequent sequence variations. Although some E6 variants have been reported to have different biochemical or biological properties, they do not show geographical identity. Moreover, the definition of 'variant' has been a source of confusion because it has been based on all departures from the 'prototype' once isolated randomly from an ICC case. We amplified the HPV16 E6 gene by PCR from fresh-frozen tissue of 104 cases of ICC and CIN from Russian patients and sequenced it in positive cases. We found that 32 of 55 (58.2%) ICC cases and 18 of 49 (36.7%) CIN cases were HPV 16-positive and we could identify 3 groups of E6 variants: group A was characterized by G at nt 350 where group B had T, and group M was a heterogeneous mixture of unique E6 variants; no significant difference existed in the distribution of the different groups between ICC and CIN; the clinically malignant (as defined by FIGO stage) order between the groups was M > A > B in ICC; in the cases with a single HPV16 E6 sequence, coexisting ICC, CIN and normal epithelium in the same patient shared the E6 variant; and 4 cases of ICC had double/multiple E6 variants. The results did not show any importance of E6 variants for ICC progression in Russian women. The results also indicated that the original HPV16 variant persisted during ICC progression, and that at a low frequency, double infections and/or mutation of variants might occur.

Adult↗
PubMed2001

Oncogene lineages of human papillomavirus type 16 E6, E7 and E5 in preinvasive and invasive cervical squamous cell carcinoma.

Human papillomavirus (HPV)16 accounts for about 60% of the HPV infections in invasive cervical cancer (ICC). There are many sequence variations within HPV16, some of which have been associated with different biological properties, although no definite correlations have yet been established. However, the definition 'variant' has been a source of confusion in research and diagnosis, since it is based on all sequence deviations from a randomly selected prototype. This study has sequenced the HPV16 oncogenes E6, E7 and E5 from 61 Swedish cases with cervical intraepithelial neoplasia grade III (CIN III) or ICC. Clustering the sequence variations at the three common sites of variation (nucleotide 350 in E6, which has previously been associated with the progression from CIN III to ICC, and nucleotides 3979 and 4042 in E5) resulted in the distinction of three major oncogene lineages encompassing more than 95% of the cases, and two minor oncogene lineages. Simple comparison of the distribution of the individual variations or oncogene lineages between CIN III and ICC showed no significant difference, but the number of variations in addition to the three common ones was significantly higher in ICC. This novel classification scheme, based on the variations in the E6, E7 and E5 region, is considered to be a major improvement over the classical 'prototype-variant' classification, and can help to clarify the interpretation of HPV sequence data in relation to the progression of cervical cancer.

Carcinoma, Squamous Cell↗
PubMed2001

Cell biology of precancer.

This article explores the possibilities of understanding the natural history of human cancers. In particular it attempts to understand precancer in cell biological or molecular rather than clinical or pathological terms. The questions discussed on the relevance of precancer in the neoplastic development are: are all cancers preceded by precancer? Is a precancer in the cell lineage characterised by hypermutability? Is there a direct DNA lineage from precancer to cancer? How many mutations have been added as a function of a number of DNA generations in the process to neoplastic transformation? Is precancer reversible? Can analysis of precancer provide a short cut to assessment of carcinogenic risk? The present data addressing these questions are discussed and the still unexplained phenomena are highlighted.

Carcinoma in Situ↗
PubMed2001

Analysis of intratumoral heterogeneity of chromosome 3p deletions and genetic evidence of polyclonal origin of cervical squamous carcinoma.

Investigation on intratumoral genetic heterogeneity provides an important insight into the roles of genetic alterations in human carcinogenesis and clues to clonal origin of tumors. Intratumoral heterogeneity of genetic changes of cervical cancer has not been described so far. In this study, we analyzed the intratumoral heterogeneity of chromosome 3p deletions and X-chromosome inactivation patterns in multiple microdissected samples from each individual cervical cancer, attempting to understand the roles of 3p deletions in development of cervical cancer and its clonal origin. Totally, 120 normal and lesional samples from 14 cases of fresh cervicalcancers were analyzed. Frequency and patterns of allelic losses of 3p were assessed by polymerase chain reaction (PCR) amplification of 12 microsatellite markers flanking the frequently deleted regions of 3p, followed by Genescan analysis in an ABI 377 DNA sequencer. Loss of heterozygosity was recorded as heterogeneous pattern (LOH present in parts of samples or LOH involving different alleles among different samples) and homogeneous pattern (LOH involving identical alleles in all samples from the tumor). Allelic loss affecting at least one marker was detected in 8 of 14 cases (57%). Allelic losses, both homogeneous and heterogeneous, were frequently detected at FHIT gene region (D3S1300, 40% and 60%; D3S4103, 27.3% and 54.6%), 3p21.3-21.2 (D3S1478, 27.3% and 45.5%), and 3p24.2-22 (D3S1283, 30% and 50%). Seven of eight LOH-positive tumors exhibited homogeneous allelic loss involving at least one of these three 3p loci. Allelic losses were present in the CIN lesions synchronous with invasive lesions positive for LOH. Our findings suggest essential roles of genes on these 3p loci, particularly the FHIT gene in participating in clonal selection and early development of cervical cancer. Most interestingly, with the combination of LOH analysis and X-chromosome inactivation analysis, we provided the first clear genetic evidence of polyclonal origin of cervical invasive cancer in two of eight cases. This finding strongly suggests the importance of field defect (possible human papilloma virus) in cervical carcinogenesis.

Adult↗
PubMed2001

Epidermal p53 response and repair of thymine dimers in human skin after a single dose of ultraviolet radiation: effects of photoprotection.

A cellular p53 response, DNA repair enzymes and melanin pigmentation are important strategies utilized by skin keratinocytes against impairment caused by ultraviolet radiation (UVR). In this study a double-immunofluorescence technique was used to investigate UVR-induced thymine dimers and p53 protein simultaneously. Four healthy volunteers were irradiated on both sides of their buttock skin with a single dose of solar-simulating UVR. One side was pretreated with a topical sunscreen. Biopsies from different time-points were immunostained for visualization of thymine dimers, p53 and proliferation. One single physiological dose of UVR generated widespread formation of thymine dimers throughout the epidermis 4h after irradiation. The level of thymine dimers decreased over time and was followed by a p53 response in the same cells. A late proliferative response was also found. The formation of thymine dimers, the p53 response and the late proliferative response were partially blocked by topical sunscreen. Large inter-individual differences in the kinetics of thymine dimer formation and repair as well as in the p53 response were evident in both sunscreen-protected and unprotected skin.

Adult↗
PubMed2001

HPV-related cancer susceptibility and p53 codon 72 polymorphism.

Conflicting results regarding the association of a polymorphism at codon 72 of the p53 tumour suppressor gene and susceptibility to develop human papilloma virus (HPV)-associated cervical cancer have been published over the last year, implicating differences in ethnic background, sample origin, sample size and/or detection assay. The material for this study was collected in the identical geographical region as for 2 previous reports with contradictory results regarding the association of codon 72 genotype with squamous cell cancer (SCC). We have used an alternative detection assay, based on pyrosequencing technology, that interrogates the variable position by the accuracy of DNA polymerase. In addition to cervical clinical specimens from SCC, HPV16- and HPV18-infected adenocarcinoma cases as well as cervical intraepithelial neoplasia (CIN) were investigated. No significant association was found between p53 codon 72 genotype and the risk to develop adenocarcinoma, SCC or CIN in the Swedish population.

Adenocarcinoma↗
PubMed2000

Analysis of p53 mutations in single cells obtained from histological tissue sections.

We have previously reported on direct sequence analysis of the p53 gene in laser-dissected single cells from tissue sections, where each allele of two fragments (exons 7 and 8) could be accurately analyzed in only 14% of the cells due to the high frequency of exon and allele dropout. Here in an effort to minimize this problem, we have investigated various approaches for sample preparation and gene amplification. By pinpointing some critical steps in the procedure, we could increase the number of investigated exons and substantially improve the genetic analysis of single cells obtained from histochemically stained frozen tissue sections. The biggest improvement was achieved by minimizing DNA degradation using EDTA as a nuclease inhibitor in all sample preparation steps. Efforts to increase primer annealing, by increasing the concentration of template and primers, in addition to prolonging the annealing and extension times, also improved the amplification efficiency. With these measures we can now amplify six individual exons of the p53 gene (exons 4-9) in 70% of the cells and in 50% of these cells both alleles are amplified. This allows application of the method in various investigations such as within the field of tumor pathology.

Alleles↗
PubMed2000

A prospective study showing long-term infection with human papillomavirus 16 before the development of cervical carcinoma in situ.

Human papillomavirus 16 (HPV16) is a predominant cause of cervical neoplasia. However, no population-based study with long-term follow-up has clarified the temporal relationship between HPV16 infection and occurrence of carcinoma in situ, or the importance of recurrent or persistent infection. This nested case-control study was carried out in a population-based cohort of women participating in cytological screening whose initial smear, taken in 1969-1995, was normal. During up to 26 years of follow-up, carcinoma in situ was diagnosed in 484 eligible women. Archival smears from these women were compared with smears from 619 individually matched controls. After DNA extraction, a highly sensitive PCR system was used to detect HPV16. Among case women, the prevalence of HPV16 positivity was 56% at the time of diagnosis. The relative risk of cervical carcinoma in situ increased from 3.6 (95% confidence interval, 1.2-11.0) 13 years before diagnosis to 11.1 (95% confidence interval, 5.5-22.2) 1 year before diagnosis. Having a positive smear at entry to the cohort increased risk >5-fold, whereas having persistent infection with HPV in two subsequent smears increased risk 30-fold. We estimated that among HPV16-positive women, the median incubation period from infection to carcinoma in situ was 7-12 years. We conclude that evidence of persistent and/or recurrent infection is associated with a drastically higher risk of cervical carcinoma in situ than occasional infection with HPV16.

Adolescent↗
PubMed2000

Consistent high viral load of human papillomavirus 16 and risk of cervical carcinoma in situ: a nested case-control study.

BACKGROUND: Persistent infection with certain types of human papillomavirus (HPV) is believed to be a prerequisite for the development of cervical neoplasia. Persistence may depend on certain characteristics, such as viral load, which has so far been given little attention. We investigated the association between HPV 16 viral load and cervical carcinoma in situ. METHODS: We did a nested case-control study of women participating in cytological screening in Sweden. We used a sensitive quantitative PCR assay to estimate HPV 16 load in multiple smears for each woman, taken during a period of up to 26 years before diagnosis. We calculated C, values, which decrease as the number of viral DNA copies increases. FINDINGS: 2081 smears from 478 cases and 1754 smears from 608 controls were tested. Among cases, we found a consistently increased load of HPV 16 already 13 years or more before diagnosis, and when many smears were still cytologically normal. Women with high HPV 16 viral loads were at least 30 times the relative risk of HPV-16-negative women more than a decade before diagnosis. The increase in relative risk was constant over time. About 25% of women (95% CI 0.12-0.32) infected with a high viral load before age 25 years developed cervical carcinoma in situ within 15 years. INTERPRETATION: Cervical carcinoma in situ associated with HPV 16 occurs mainly in HPV-16-positive women who have consistently high viral loads long term. Women at high risk could be identified by use of a quantitative HPV test in addition to cytological screening.

Actins↗
PubMed2000

Comparison of chromosome 3p deletions between cervical precancers synchronous with and without invasive cancer.

Cervical cancers are considered to originate from a series of pre-malignant lesions (cervical intra-epithelial neoplasia, CIN). The mechanisms behind these events are unknown. In addition to HPV infection, deletions of chromosome 3p have been found to be a frequent event in cervical cancer and likely play an important role in the transition of CIN to invasive cancer. To classify the potential role of 3p deletions in early-stage cervical carcinogenesis, we analyzed LOH of 3p in cervical precancers. Thirty cases with single or multiple CIN lesions were selected for the study, including 20 cases without and 10 cases with synchronous invasive cancers. Allelic losses on 1 or more 3p loci were recorded in 33% (3/9) of CIN II and 36% (5/14) of CIN III lesions from 20 cases without co-existing invasive cancer, whereas an increasing percentage of LOH was observed in the 10 precancerous lesions synchronous with invasive cancer, with 71% (5/7) CIN II and 76% (13/17) CIN III lesions. This result implies that 3p deletions have selective roles in early transition of pre-malignancy to invasive cancer. Comparing the LOH patterns between the 2 groups, genetic deletions in cases with invasive cancers involved extensive regions of 3p but were more localized in precancer cases without concomitant invasive cancer. Two interstitial regions, 3p22-21.3 around marker D3S1260 and 3p21.1 around markers D3S1289 and D3S1076, were most frequently deleted in both groups, suggesting that these 2 regions are novel tumor-suppressor loci which may play a role in early transition of cervical precancer to invasive cancer. Identical LOH patterns between multiple CIN lesions and synchronous invasive cancer in the same case suggests that different cervical precancers and invasive cancer are genetically linked and most likely originate from a single precursor cell.

Chromosome Deletion↗
PubMed2000

Clonality analysis of multifocal carcinoid tumours of the small intestine by X-chromosome inactivation analysis.

The clonality of intestinal carcinoids and the relationship between different tumour deposits of multiple intestinal carcinoids were investigated in this study. Six cases of multiple ileal carcinoids were selected for analysis and three independent carcinoid lesions from each case were microdissected. Clonality of the lesions was determined by polymerase chain reaction (PCR)-based X-chromosome inactivation of the human androgen receptor gene. Four out of six cases were heterozygous for microsatellite repeats within the androgen receptor gene and thus informative for the study. The results showed that all 12 lesions analysed had non-random X-chromosome inactivation (monoclonal) patterns, compared with the background normal intestinal mucosal tissues. This finding proves for the first time the monoclonal origin of human intestinal carcinoids, by X-chromosome inactivation analysis. More interestingly, identical X-chromosome inactivation patterns were found in different carcinoid lesions from each individual case. This evidence strongly indicates that multiple carcinoids of the small intestine were generated by metastasis of a primary tumour to different locations in the intestine, rather than being of multiple origin. This study provides an important insight into the carcinogenesis of intestinal carcinoids.

Carcinoid Tumor↗
PubMed2000

Clonality of precursors of cervical cancer and their genetical links to invasive cancer.

Two problems were the focus of this study. (1) Is precancer and/or invasive cancer of the human cervix a poly- or monoclonal proliferation of neoplastic cells? (2) Are simultaneously present precancers and cancers of the cervix clonally related, or do they arise independently? Microdissection of 37 neoplastic lesions with different degrees of histologic severity in 22 patients followed by polymerase chain reaction-based analysis of X-chromosome inactivation was used as a principal method. Invasive cancers were interpreted as monoclonal because samples invariably showed monoclonal signals. In two thirds of these cases, simultaneously present precursors had the identical X-chromosome inactivation pattern, but in one third the pattern was different. Polyclonality was seen in a subgroup of precursors, where there was no simultaneous presence of invasive cancer. In contrast, when invasive cancer was present, no precursor signaled polyclonality. Data taken together indicate that the pathogenesis of cervical cancer is probably even more complicated than that of other cancers involving selection of subclones from originally polyclonal precursors and possibility of coexistence of precursors of different monoclonal composition. The study also observed that a large field of normal cervical squamous epithelium (approximately 500 basal squamous epithelial cells) with nonrandom X-chromosome inactivation was present. It remains to be further investigated whether this phenomenon represents an embryologic lyonization pattern of X-chromosome inactivation or postembryologic clonal expansion of submorphologically transformed cells.

Clone Cells↗
PubMed1999

HPV typing and HPV16 E6-sequence variations in synchronous lesions of cervical squamous-cell carcinoma from Swedish patients.

We microdissected 15 specimens of invasive cervical cancer co-existing with some of its precursors. Out of 15 cases, 10 carried HPV16, 2 HPV31, 1 HPV18 and 2 were HPV-negative. We found 3 HPV16 E6 variants among the 10 cases; one was A --> G in nt 131 (one case) and a second was A --> G in nt 276. The third, T;--> G in nt 350, was common, and was found in 5 of the 10 patients infected by HPV16. The type of HPV and the E6 variant were identical in all lesions within the same patient. Viral DNA present in normal epithelium was identical in type and E6 variant to HPV in the same patient's lesions. Multiple samples from invasive cancers with HPV were consistently positive. The data suggest that the originally infecting HPV, including its variant type in the E6 gene, persists unaltered in the whole series of CIN that precedes invasive cancer. Our data are compatible with an essential role of HPV manifested by persistence of the viral genome during the entire natural life history of cervical cancer. We did not confirm previous data on the specific association of invasive cancer with an HPV E6 variant (G at nt 350 rather than T). The discrepancy may depend on the relatively few cases investigated or selection of a special sub-set with progression from CIN to invasive cancer already manifest.

Adult↗
PubMed1999

Smoking and oral contraceptives as risk factors for cervical carcinoma in situ.

Human papillomavirus (HPV) is probably a necessary but definitely not a sufficient cause of cervical carcinoma. However, it remains unclear which factors, in addition to HPV, are important for the development of cervical carcinoma and its precursor lesions. To address this issue, we conducted a case-control study nested in a population-based cohort consisting of women participating in cytological screening in one Swedish county, any time during 1969 through 1995. Detailed information on sexual practice, smoking habits and oral contraceptive (OC) use were collected through telephone interviews with 422 case patients diagnosed with cervical carcinoma in situ and 422 control subjects. All cytological smears were analyzed for presence of HPV 16/18 by a polymerase chain reaction (PCR)-based method. Odds ratios (OR) were used as measures of relative risk. After multivariate adjustment, a 2-fold higher risk was observed among current smokers compared with never smokers [OR 1.94; 95% confidence interval (CI 1.32-2.85)], an association apparently confined to women younger than 45 years. Current use of OCs was associated with a 4-fold increased risk overall (OR 3.64; 95% CI 1.91-6.93) with a monotonic increase with increasing duration of use (p for trend < 0.001). The number of sexual partners was significantly, positively associated with risk among HPV 16/18-negative (p for trend < 0.005) but not among HPV 16/18-positive women. Our data confirm the association between smoking and cervical carcinoma in situ, which might be age-dependent. Our results further indicate a relation with OC use and the risk for cervical carcinoma in situ.

Adult↗
PubMed1999

A high frequency of sequence alterations is due to formalin fixation of archival specimens.

Genomic analysis of archival tissues fixed in formalin is of fundamental importance in biomedical research, and numerous studies have used such material. Although the possibility of polymerase chain reaction (PCR)-introduced artifacts is known, the use of direct sequencing has been thought to overcome such problems. Here we report the results from a controlled study, performed in parallel on frozen and formalin-fixed material, where a high frequency of nonreproducible sequence alterations was detected with the use of formalin-fixed tissues. Defined numbers of well-characterized tumor cells were amplified and analyzed by direct DNA sequencing. No nonreproducible sequence alterations were found in frozen tissues. In formalin-fixed material up to one mutation artifact per 500 bases was recorded. The chance of such artificial mutations in formalin-fixed material was inversely correlated with the number of cells used in the PCR-the fewer cells, the more artifacts. A total of 28 artificial mutations were recorded, of which 27 were C-T or G-A transitions. Through confirmational sequencing of independent amplification products artifacts can be distinguished from true mutations. However, because this problem was not acknowledged earlier, the presence of artifacts may have profoundly influenced previously reported mutations in formalin-fixed material, including those inserted into mutation databases.

Base Sequence↗