Groove-binding unsymmetrical cyanine dyes for staining of DNA: dissociation rates in free solution and electrophoresis gels

The rates of dissociation of three non-intercalative unsymmetrical cyanine dyes, BEBO, BETO and BOXTO from mixed-sequence DNA have been studied with the DNA either free in solution or in confining porous agarose gels. The properties of the new dyes were compared to the related intercalating dyes BO, BO-PRO, TO-PRO and YO-PRO. With DNA in solution, BEBO dissociates more slowly than the monovalent BO and interestingly also more slowly than the divalent dye BO-PRO. Similarly, both BETO and BOXTO exhibit considerably slower dissociation than TO-PRO. The new dyes show biexponential dissociation kinetics in mixed-sequence DNA. The average rate of dissociation increases with increasing ionic strength, but the salt dependence of the dissociation is weaker than for the corresponding intercalating dye. The rate of dye-dissociation decreases by a factor of about 10(5) in the gel. The rates for the dyes generally follow the pattern that we observe with the DNA in free solution, however a more accentuated stabilization was seen for intercalators than for groove-bound dyes. The results show that, in particular, BOXTO is a promising candidate as a preferentially groove-bound DNA-stain with a large enhancement of the fluorescence quantum yield upon binding to DNA, and which exhibits slow and salt-insensitive dissociation compared to corresponding intercalative dyes.

Groove-binding unsymmetrical cyanine dyes for staining of DNA: syntheses and characterization of the DNA-binding

Two new crescent-shaped unsymmetrical cyanine dyes have been synthesised and their interactions with DNA have been investigated by different spectroscopic methods. These dyes are analogues to a minor groove binding unsymmetrical cyanine dye, BEBO, recently reported by us. In this dye, the structure of the known intercalating cyanine dye BO was extended with a benzothiazole substituent. To investigate how the identity of the extending heterocycle affects the binding to DNA, the new dyes BETO and BOXTO have a benzothiazole group and a benzoxazole moiety, respectively. Whereas BEBO showed a heterogeneous binding to calf thymus DNA, linear and circular dichroism studies of BOXTO indicate a high preference for minor groove binding. BETO also binds in the minor groove to mixed sequence DNA but has a contribution of non-ordered and non-emissive species present. A non-intercalative binding mode of the new dyes, as well as for BEBO, is further supported by electrophoresis unwinding assays. These dyes, having comparable spectral properties as the intercalating cyanine dyes, but bind in the minor groove instead, might be useful complements for staining of DNA. In particular, the benzoxazole substituted dye BOXTO has attractive fluorescence properties with a quantum yield of 0.52 when bound to mixed sequence DNA and a 300-fold increase in fluorescence intensity upon binding.

Phantom study of radiation doses outside the target volume brachytherapy versus external radiotherapy of early breast cancer

BACKGROUND AND PURPOSE

Brachytherapy is sometimes suggested as an adjuvant treatment after surgery of some tumours. When introducing this, it would be useful to have an estimate of the dose distribution to different body sites, both near and distant to target, comparing conventional external irradiation to brachytherapy. The aim of the present study was to determine radiation doses with both methods at different body sites, near and distant to target, in an experimental situation on an operated left sided breast cancer on a female Alderson phantom.

METHODS

Five external beam treatments with isocentric tangential fields were given by a linear accelerator. A specified dose of 1.0 Gy was given to the whole left sided breast volume. Five interstitial brachytherapy treatments were given to the upper, lateral quadrant of the left breast by a two plane, 10 needles implant. A dose of 1.0 Gy specified according to the Paris system was administered by a pulsed dose rate afterloading machine. Absorbed dose in different fixed dose points were measured by thermoluminescence dosimeters.

RESULTS

Both methods yielded an absorbed dose of the same size to the bone marrow and internal organs distant to target, 1.0-1.4% of the prescribed dose. There was a trend of lower doses to the lower half of the trunk and higher doses to the upper half of the trunk, respectively, by brachytherapy. A 90% reduction of absorbed dose with brachytherapy compared to external irradiation was found in the near-target region within 5 cm from target boundary where parts of the left lung and the heart are situated. If an adjuvant dose of 50 Gy is given with the external radiotherapy and brachytherapy, the absorbed dose in a part of the myocardium could be reduced from 31.8 to 2.1 Gy.

CONCLUSIONS

Near target, brachytherapy yielded a considerably lower absorbed dose which is of special importance when considering radiation effects on the myocard and lungs. We could not demonstrate any difference of importance, in absorbed dose to dose points distant to target.

A new minor groove binding asymmetric cyanine reporter dye for real-time PCR

The minor groove binding asymmetric cyanine dye 4-[(3-methyl-6-(benzothiazol-2-yl)-2,3-dihydro- (benzo-1,3-thiazole)-2-methylidene)]-1-methyl-pyridin ium iodide (BEBO) is tested as sequence non- specific label in real-time PCR. The fluorescence intensity of BEBO increases upon binding to double-stranded DNA allowing emission to be measured at the end of the elongation phase in the PCR cycle. BEBO concentrations between 0.1 and 0.4 micro M generated sufficient fluorescence signal without inhibiting the PCR. A comparison with the commonly used reporter dye SYBR Green I shows that the two dyes behave similarly in all important aspects.

Synthesis and DNA binding studies of a new asymmetric cyanine dye binding in the minor groove of [poly(dA-dT)]2

A new asymmetric cyanine dye has been synthesised and its interaction with different DNA has been investigated. In this dye, BEBO, the structure of the known intercalating cyanine dye BO has been extended with a benzothiazole substituent. The resulting crescent-shape of the molecule is similar to that of the well-known minor groove binder Hoechst 33258. Indeed, comparative studies of BO illustrate a considerable change in binding mode induced by this structural modification. Linear and circular dichroism studies indicate that BEBO binds in the minor groove to [poly (dA-dT)](2), but that the binding to calf thymus DNA is heterogeneous, although still with a significant contribution of minor groove binding. Similar to other DNA binding asymmetric cyanine dyes, BEBO has a large increase in fluorescence intensity upon binding and a relatively large quantum yield when bound. The minor groove binding of BEBO to [poly (dA-dT)](2) affords roughly a 180-fold increase in intensity, which is larger than to that of the commonly used minor groove binding probes DAPI and Hoechst 33258.

Vitamin B12 in primary health care and geriatrics--attitudes, knowledge and competence

OBJECTIVES

The objective of the study was to test attitudes, knowledge and competence of Swedish general practitioners and geriatricians concerning B12-associated problems in 1998.

METHODS

Postal questionnaires were sent to a random sample of 485 GPs and a total sample of 613 geriatricians. The response rates were 70% in the GP group and 69% in the geriatrician group. The questionnaire contained 24 statements to be evaluated by a visuo-analogue scale.

RESULTS

There were small numerical differences between the two physician groups. The geriatricians were more aware of risk groups for B12 deficiency. GPs were less categorical concerning low hit rate in the laboratory testing of clinical conclusions. There were statistical differences in both directions for statements on pitfalls in laboratory diagnostics. GPs were somewhat less prone to give risk groups prophylactic B12 therapy.

CONCLUSIONS

GPs and geriatricians appeared to be familiar with the current debate on B12-associated problems, suggesting that health care quality will be unaffected by patient transfer from hospital care to primary health care.

["Target groups 1-3" must be granted priority access to health care services. Health care needs of somatically and mentally disabled persons in Robetsfors]

People with serious functional disabilities do not always call attention to their needs for care, and are therefore a vulnerable group in our society. In Sweden, The Act Concerning Support and Service for Persons with Certain Functional Impairments (LSS) is intended to provide for them. Our research found that people with serious physical or psychiatric disability suffer more often from intercurrent disease and have more problems with their eyesight, hearing and dental health than do other individuals. The responsibility for their respective health care needs must be clarified, so that the group is given priority access to the health care system and services for rehabilitation.

Shifts in B12 opinions in primary health care of Sweden

AIMS

The diagnosis and management of vitamin B12 deficiency varies between countries and within countries. The aim of the study was to map current attitudes and values behind clinical decision-making in Swedish primary health care, which has a unique B12 tradition: two patients out of three are treated with oral high-dose cyanocobalamin. Most patients with B12-associated problems are managed in primary health care by general practitioners (GPs).

METHODS

The study was designed to elucidate possible opinion shifts among GPs during the period 1996-1998. GPs (n=499), stratified and randomized, received a questionnaire with 24 statements on B12-associated clinical and laboratory problems, to be evaluated by a visuo-analogue scale.

RESULTS

The majority of GPs in primary health care in Sweden accepted homocysteine and methylmalonic acid (MMA) as markers for functional deficiency of vitamin B12. The evaluation of classical markers of B12 deficiency was wary and balanced. There was a consensus of the need for B12 therapy to risk groups such as patients with atrophic gastritis or previous gastric surgery. The answers also appeared to reflect an improvement of professional knowledge and competence concerning B12-associated problems among Swedish GPs between 1996 and 1998.

CONCLUSIONS

The overriding conclusion was that B12-associated opinions of Swedish GPs were stable within the period studied, with marginal improvements of knowledge and competence.

[Experiences from the county of Norrbotten: screening of hearing at the age of four crucial for detecting mild hearing impairment]

Since the eighties the formerly well established hearing screening performed at the age of four has been debated, partly for economic reasons. One quarter of Sweden's counties have since then abolished it. But how many children do we detect by this screening? What significance does it have for a child that those around it are aware of a mild hearing impairment? In Norrbotten, in all, we found 123 children born 1989-1992 with a hearing impairment. The prevalence was 7.9 per thousand. 30 percent of the children were detected at the 4-years hearing screening, and of these 0.9/1,000 had a hearing impairment that was bilateral, 1.0/1,000 unilateral and 0.5/1,000 impairment only in the high frequencies. Also children with mild bilateral or unilateral hearing impairment can experience difficulties in school and among friends, especially in noisy surroundings, and benefit by knowing early about their hearing impairment.

Free-probe fluorescence of light-up probes

The fluorescence enhancement of light-up probes (thiazole orange (TO) conjugated peptide nucleic acids (PNAs)) upon hybridization to target nucleic acid depends on the probe sequence, mainly due to large variations in free-probe fluorescence. Here we study three probes where the fluorescence in free state varies more than 50-fold. We find that this variation is due to a fraction that has TO intramolecularly "back-bound" to the PNA bases. The intramolecular affinity constant for this unimolecular interaction was determined by temperature titrations using absorption spectroscopy, and the fluorescence quantum yields of the probes in back-bound conformation were calculated. The molar ratio of probes in back-bound conformation was 0.70-0.96 at 30 degrees C and 0.40-0.73 at 60 degrees C, and the fluorescence quantum yield in back-bound conformation varied between 0.0020 and 0.077 at 30 degrees C, and 0.00065-0.029 at 60 degrees C. These data show that the variation in free-probe fluorescence depends mainly on the fluorescence quantum yield of the probe in back-bound conformation and to a much lesser extent on the tendency of the probe to adopt the back-bound conformation. With increasing temperature the free-probe fluorescence decreases owing to both reduced degree of back-binding and a decrease of the fluorescence quantum yield in back-bound conformation.

Rapid and specific detection of PCR products using light-up probes

Newly developed light-up probes offer an attractive tool for PCR product detection. The light-up probe, which consists of a thiazole orange derivative linked to a peptide nucleic acid oligomer, hybridizes specifically to complementary nucleic acids. Upon hybridization the thiazole orange moiety interacts with the nucleic acid bases and the probe becomes brightly fluorescent. This eliminates the need to separate bound from unbound probes and reduces the risk of cross contamination during sample handling. We demonstrate here the applicability of light-up probes in two different PCR assays, one directed towards the human beta-actin gene and the other towards the invA gene of Salmonella. The probes do not interfere with the PCR reaction and can either be included in the sample mixture or added after completed amplification. The specificity of the probe is found to be excellent: a single-base mismatch in the target sequence is sufficient to prevent probe binding as indicated by the lack of fluorescence increase. Furthermore, a clear correlation is found between the intensity of gel bands and the measured probe fluorescence in solution, which suggests that the amount of PCR products can be quantified using light-up probes.

Light-up probes: thiazole orange-conjugated peptide nucleic acid for detection of target nucleic acid in homogeneous solution

We have constructed light-up probes for nucleic acid detection. The light-up probe is a peptide nucleic acid (PNA) oligonucleotide to which the asymmetric cyanine dye thiazole orange (TO) is tethered. It combines the excellent hybridization properties of PNA and the large fluorescence enhancement of TO upon binding to DNA. When the PNA hybridizes to target DNA, the dye binds and becomes fluorescent. Free probes have low fluorescence, which may increase almost 50-fold upon hybridization to complementary nucleic acid. This makes the light-up probes particularly suitable for homogeneous hybridization assays, where separation of the bound and free probe is not necessary. We find that the fluorescence enhancement upon hybridization varies among different probes, which is mainly due to variations in free probe fluorescence. For eight probes studied the fluorescence quantum yield at 25 degrees C in the unbound state ranged from 0.0015 to 0.08 and seemed to depend mainly on the PNA sequence. The binding of the light-up probes to target DNA is highly sequence specific and a single mismatch in a 10-mer target sequence was readily identified.

Sense of coherence in different stages of health and disease in northern Sweden--gender and psychosocial differences

OBJECTIVE

To investigate "Sense of Coherence" (SOC) and its relation to perceived health, different stages of disease, and different psychosocial factors in a population-based study.

DESIGN

Postal survey of a population-based sample, the MONICA study (1994).

SETTING

Norrbotten and Västerbotten, the two northernmost counties in Sweden, with a total population of 510000 inhabitants.

SUBJECTS

837 men and 882 women in three mutually-exclusive groups: stomach trouble of many years' standing, identified disease (stroke, cardiac infarction, diabetes, anti-hypertension treatment) and no reported disease.

MAIN OUTCOME MEASURES

SOC scores in relation to sociodemographic variables and perceived health.

RESULTS

We found a relationship between low SOC scores and poor perceived health, low social support and low emotional support on a population level. When comparing persons with stomach trouble with those without disease, or with established diseases, we found similar relationships between low mean SOC scores in all strata for both women and men. "Perceived health", however, was only significantly correlated for women, and women had an overall stronger relationship.

CONCLUSIONS

In a study in northern Sweden, female patients with stomach trouble comprise a vulnerable group. The concept of SOC introduces a new dimension for perceiving health and disease. In clinical practice, care providers can identify and elaborate on the relationship between SOC scores and sociodemographic data.

Prevalence of sexualized violence among women. A population-based study in a primary healthcare district

In order to estimate the prevalence of sexual and physical abuse, postal questionnaires were sent to a random sample of 251 adult women in a primary care district. Three yes/no-questions were asked on these topics, and a fourth inquired into effects on health. Space was left for open-ended answers in which yes-responders were invited to write about their experiences. A total of 175 women (70%) answered, and 25 (14%) of these reported abuse. Nine (5%) had experienced women battering. Thirteen (7.5%) reported sexual abuse as an adult, and 12 (7%) as a child. Many told their stories. Methodological shortcomings in this study might explain why the rates are somewhat lower than in other investigations. However, our figures verified that abuse of women is a common social phenomenon. They also confirmed abuse as a major health problem for women. One-third of respondents explicitly reported effects on health. Others, though negating such effects, described them in written narratives. In order to study this contradiction, in-depth interviews with abused women are recommended.

The impact of patients' influence on recovery in a group of patients with dyspepsia

BACKGROUND

The approach to health and disease can either be salutogenic (origins of health) or pathogenic (disease causing), which thus makes recovery a concept featuring several different angles. Antonovsky, with his concept of salutogenesis, tried to reach a more complete understanding of its favourable effects on health.

OBJECTIVE

We aimed to investigate, understand and learn from the experiences of a small group of patients about factors leading to recovery.

METHODS

A qualitative approach was used to explore patient experiences. One semi-structured interview was conducted by one of the authors (BN) with each of the 18 patients suffering from dyspepsia who had been investigated by means of gastroscopy at a university hospital clinic 12-15 years previously. The interviews were recorded either in written notes composed directly after the interviews or tape-recorded and subsequently transcribed. A modified form of grounded theory according to Strauss-Corbin was used to analyse the data.

RESULTS

A pattern featuring five types of patients' influence on their lives was discerned, ranging from "a sense of no possibility of having an influence on existence/life" to "having influence". Strategies used by patients to maintain health could be categorized into four types: "extremists", "oscillators", "leapers" and "full-scalers".

CONCLUSIONS

Listening to patients who had experiences with dyspepsia brought patient influence on their own lives and on the care process into focus. We consider that there might be a link between patients having an influence on their lives and their being healthy today. In clinical practice, patient recovery and health promotion could gain from a perspective where patient influence is treated with esteem and emphasized in the consultation. In the future, research design could benefit from taking patient influence on the care process into consideration. However, no causal linkage between patient influence and patient outcome was established in this study. In order to do that, studies with quantitative design should be undertaken in the future.

Women with false positive screening mammograms: how do they cope?

OBJECTIVES

To assess the long term psychological impact on women who were recalled for further investigation after mammography screening and to find any factors that might predict coping ability in order to identify those subjects who require additional support at an earlier stage.

SETTING

Counties of Västerbotten and Västernorrland, Sweden.

METHODS

A prospective design was used in which 252 recalled women completed questionnaires twice--once within a week of having received the all-clear and again at follow up six months later. A group of 1104 randomly selected, screen negative women were followed up in the same way for comparison. The questionnaire included the Psychological Consequences Questionnaire (PCQ) and basic sociodemographic data. The main outcome measure was the total score on the PCQ at six months.

RESULTS

Of the 252 women, 235 (93%) completed both questionnaires. In the control group, 987 (89.4%) women responded. Six months after the all-clear, recalled women were still significantly more anxious (p < 0.001) than those who had been screened but not recalled. The strongest predictor of psychological distress at six months was the PCQ score at the first measurement. Other predictors were a low level of education, living in high density urban areas, and having only one child or no children at all. Widows appeared to cope better than other women.

CONCLUSIONS

It is possible to define a group of women with false positive results who are already at risk of coping less effectively at the time of recall. Offering these women counselling or other types of support should be considered.

Cross-comparison of two quality of life instruments used in a randomized study of combination chemotherapy in advanced breast cancer

Twenty-six patients from a randomized study of combination chemotherapy in advanced breast cancer were included in a cross-comparison between two quality of life instruments: a categorical linear analogue scale (C-LASA) based on the instrument of Priestman and Baum and a Swedish instrument developed by Glimelius et al. Quality of life was assessed on day 1 and day 10 of each chemotherapy cycle and the instruments were compared using correlation and kappa analysis. For the physical dimension, the mean correlation coefficient on day 1 was 0.89 and the kappa coefficient was 0.62; and on day 10 the correlation coefficient was 0.83 and the kappa coefficient 0.62. For the emotional dimension the correlation and kappa coefficients were 0.89 and 0.71 and 0.89 and 0.61 on days 1 and 10, respectively. The corresponding values for the global dimension were 0.76 and 0.56 and 0.80 and 0.57 on days 1 and 10, respectively. A correlation was also demonstrated over time. The instruments gave similar measurements of quality of life for chemotherapy-treated patients with advanced breast cancer, but the feasibility of the C-LASA instrument was better.

The meanings of pain: an exploration of women's descriptions of symptoms

A grounded theory study with repeated semi-structured interviews was conducted to explore the meaning of the illness experiences of women patients, impaired by biomedically undefined musculoskeletal pain. Twenty female patients were recruited at an urban primary health care centre in northern Sweden, where two of the researchers work as family physicians. In this paper we focus on considerations of patient pain and analyze the findings from aspects linking together body, gender, and society. Four categories of symptom description were identified: bodily presentations, explanatory models, consequences of pain for the patient's activities, and consequences for her self-perception. The bodily symptoms signaled loss of control. The explanatory models consisted of physical damage and strain injuries, but were also psychological and self-blaming. The consequences of pain were described as negative consequences for the women's everyday life that challenged their self-perception as women. The participants' search and need for legitimization of their illness experiences, and the expectations placed on doctors as legitimizing agents was evident. To achieve the desired shared understanding in consultations, doctors must be aware of and consider not only physical signs and symptoms, but also the patients' gendered concerns and psycho-social circumstances.

Shifting the distribution of risk: results of a community intervention in a Swedish programme for the prevention of cardiovascular disease

STUDY OBJECTIVE

To examine the impact of a systematic risk factor screening and counselling carried out by family physicians and family nurses within the larger framework of a community intervention programme for the prevention of cardiovascular disease (CVD).

DESIGN

Quasi-experimental study comparing trends in an intervention area with those in a reference area.

SETTING

A Northern Sweden municipality (5500 inhabitants) constituted the intervention area while the Northern Sweden region (510,000 inhabitants) served as the reference area.

PARTICIPANTS

All 30, 40, 50, and 60 year old inhabitants were invited each year from 1985 to 1992. Among 2046 eligible 1893 participated (92.5%), which formed eight independent cross sections. One cross section, 1986, was re-surveyed forming a panel.

MAIN RESULTS

In the cross sections, mean total cholesterol was reduced from 7.09 to 6.27 mmol/l for men (p < 0.001) and from 7.13 to 5.89 mmol/l for women (p < 0.001) and mean systolic blood pressure from 132.2 to 123.7 mm Hg for men (p < 0.05) and from 129.2 to 122.0 mm Hg for women (p < 0.001) during the eight years. Body mass index (BMI) increased from 25.6 to 26.2 for men (p < 0.05) and from 25.0 to 25.5 for women (NS). A corresponding reduction in cholesterol and blood pressure (for women) occurred in the panel, while BMI was unchanged. The risk for CVD, using the Framingham equation, was estimated to be reduced overall by 19% (p = 0.0021) when comparing early cross sections (1985/86) with the later cross sections (1990/91).

CONCLUSIONS

It was concluded that a long term community based CVD prevention programme that combines population and individual strategies can substantially promote a health shift in CVD risk in a high risk rural population. The individual attention and evaluation provided by the health provider survey seem to accelerate, but not increase the amount of, risk reduction.

Megestrol acetate in advanced, progressive, hormone-insensitive cancer. Effects on the quality of life: a placebo-controlled, randomised, multicentre trial

A randomised double-blind placebo-controlled multicentre trial was performed to investigate the effects of megestrol acetate (MA) on the quality of life (QoL), appetite, weight and survival of patients with advanced, incurable, hormone-insensitive cancer. QoL was assessed at the start of treatment and at 4, 8 and 12 weeks, using the EORTC-QLQ-C30 instrument. 255 patients were randomised to 320 mg of MA daily or placebo for 12 weeks. 244 patients were assessable at baseline, 190 at 4 weeks (placebo 94; MA 96), 150 at 8 weeks (placebo 69; MA 81) and 112 at 12 weeks (placebo 55; MA 57). A beneficial effect of MA on appetite loss was observed at week 4 (P < 0.0001) and possibly at week 8 (P = 0.058). Further weight loss during treatment was significant only in the placebo group. In the first 8 weeks, changes in mean global QoL were small and similar in both groups. By 12 weeks the decrease in mean global QoL was more pronounced in the MA group (P = 0.028), which was related to a deterioration in physical function, while psychosocial function was not affected. Survival was not affected by MA, and side-effects were mild. The results show that MA has a beneficial effect on appetite and that it may retard weight loss with no adverse impact on survival and with mild toxicity. However, MA does not appear to improve global QoL as measured by the EORTC QLQ-C30.