Transgenic and gene-targeted mouse lines for toxicology studies

This unit contains an extensive tabular listing of transgenic and gene-targeted mice useful in toxicological studies. Each listing contains a brief description of the phenotype, relevant references, and where applicable, commercial sources.

The 2nd to 4th digit ratio and autism

It has been suggested that autism may arise as the result of exposure to high concentrations of prenatal testosterone. There is evidence that the ratio of the lengths of the 2nd and 4th digit (2D:4D) may be negatively correlated with prenatal testosterone. We measured 2D:4D in 95 families recruited via the National Autistic Society, UK. The sample comprised a total 72 children with autism (62 males, 10 females; age range 2 to 14 years), including 23 children (20 males, three females) with Asperger syndrome (AS), 34 siblings, 88 fathers, 88 mothers and sex- and age-matched control participants. We found that the 2D:4D ratios of children with autism, their siblings, fathers and mothers were lower than population normative values. Children with AS, who share the social and communicative symptoms of autism but have normal or even high IQ, had higher 2D:4D ratios than children with autism but lower ratios than population normative values. There were positive associations between 2D:4D ratios of children with autism and the ratios of their relatives. Children with autism had lower than expected 2D:4D ratios and children with AS higher ratios than expected in relation to their fathers' 2D:4D ratio. It was concluded that 2D:4D ratio may be a possible marker for autism which could implicate prenatal testosterone in its aetiology.

Prepubescent children show the adult relationship between dermatoglyphic asymmetry and performance on sexually dimorphic tasks

The dermatoglyphic pattern of dermal ridges that constitutes the human fingerprint is complete by the 16th foetal week and its development is thought to be influenced by prenatal hormones. Finger ridge count (FRC) is asymmetrical with the majority having more ridges on the finger tips of the right hand (R >) while the minority have more on the left (L >). In adults, the R > condition has been associated with male-typical, and the L > condition with female-typical, performance on sexually dimorphic tasks. Here we report that 60 prepubescent children showed the same sex difference and the same relationship as adults between FRC and task performance: girls and L > children performed a female-favouring task better while boys and R > children performed a male-favouring task better. This finding indicates that these sex-related task performance differences are not dependent on the activational effects of adult gonadal steroids. The implications of these findings for prenatal influences on neuropsychological development are discussed.

Regionally specific sensitivity differences in fMRI and PET: where do they come from?

In this paper we report three neuroimaging studies of language that investigate potential sources of inconsistency in measured hemodynamic responses: (1) between sessions for fMRI, including differences in hormonal status, (2) between sessions for PET, and (3) between scanning modalities (PET and fMRI). Differences in evoked responses between sessions of the same modality were small. In particular we did not find any effect of hormone levels when testing during the first and third weeks of the menstrual cycle (although we cannot exclude the possibility that activation in the temporoparietal regions is sensitive to hormonal status). Comparing the two modalities showed that prefrontal regions were more activated in fMRI than in PET. This may relate to task switching between blocks in fMRI that is not induced by PET paradigms or increased error variance in these regions for PET. In contrast, temporal activations were found in PET more than in fMRI. We attribute the lack of temporal activations, in fMRI, to a combination of factors, including susceptibility artifacts, anticipatory activity during the control condition, discontinuous sampling of peristimulus time, and differences in the source, acquisition, and analysis of the measured signals. It is concluded that although there is sufficient reproducibility of results for these paradigms within each modality, the regionally specific differences in sensitivity found between modalities warrant further investigation. These regionally specific differences are important for a properly qualified interpretation of activation profiles in fMRI.

The dermatoglyphic characteristics of transsexuals: is there evidence for an organizing effect of sex hormones

It has been proposed that gender identity and sexual orientation are influenced by the prenatal sex steroid milieu. Human dermatoglyphics and brain asymmetry have also been ascribed to prenatal hormone levels. This study investigated dermatoglyphics (total ridge count and finger ridge asymmetry) in 184 male-to-female transsexuals and 110 female-to-male transsexuals. In a subgroup, the relationship between dermatoglyphic asymmetry and spatial ability was tested. All investigations included controls. For all subjects hand preference and sexual orientation were noted. We hypothesized that the dermatoglyphics of male-to-female transsexuals would show similarities with control women and those of female-to-male transsexuals with control men. Our results showed a trend for a sex difference in total ridge count (P<.1) between genetic males and females, but no difference in directional asymmetry was found. Contrary to our expectations, the total ridge count and finger ridge asymmetry of transsexuals were similar to their genetic sex controls. Additionally, directional asymmetry was neither related to sexual orientation, nor to different aspects of spatial ability. In conclusion, we were unable to demonstrate that our chosen dermatoglyphic variables, total ridge count and finger ridge asymmetry are related to gender identity and sexual orientation in adult transsexuals. Hence, we found no support for a prenatal hormonal influence on these characteristics, at least insofar as dermatoglyphics may be regarded as a biological marker of organizing hormonal effects.

Improved PCR detection of Campylobacter jejuni from chicken rinses by a simple sample preparation procedure

Many food samples and enrichment media are inhibitory to the PCR, thereby lowering its detection capacity. A simple sample preparation method based on buoyant density centrifugation was examined for its application in PCR detection of Campylobacter jejuni from chicken rinse samples. Bacterial cells were spiked at different levels in a mixture of Preston broth and chicken rinse (4:1 ratio) and 0.9 ml of these mixtures were layered over 0.6 ml of gradient medium made from Percoll. PCR sensitivity for bacterial samples treated with this procedure was approximately 10-100 times higher than for samples without treatment. This sample preparation method allowed for the detection of C. jejuni from 26 of 31 naturally contaminated chicken samples after a 20-24-h enrichment period in Preston broth, compared with only 14 positives for untreated samples. In addition, the effect of Oxyrase on the growth and PCR detection of C. jejuni was examined. While Oxyrase significantly enhanced the growth and the PCR signals of C. jejuni in pure culture, it appeared not to improve the PCR detection of C. jejuni in naturally contaminated chickens.

Left hand advantage in a self-face recognition task

Subjects were exposed to pictures of self and others (e.g., friend, stranger, and famous people) to determine if there was an advantage in reaction time and accuracy in identifying the self. It was found that upright and inverted self-faces were identified more rapidly than non-self faces when subjects responded with their left hand, which in other tasks has corresponded with contralateral hemispheric dominance. These data suggest that self-recognition may be correlated with neural activity in the right hemisphere, and that the differences observed may not be unique to self-face recognition. These results are in agreement with previous research indicating that self-directed awareness is correlated with right prefrontal activity.

Paralemmin, a prenyl-palmitoyl-anchored phosphoprotein abundant in neurons and implicated in plasma membrane dynamics and cell process formation

We report the identification and initial characterization of paralemmin, a putative new morphoregulatory protein associated with the plasma membrane. Paralemmin is highly expressed in the brain but also less abundantly in many other tissues and cell types. cDNAs from chicken, human, and mouse predict acidic proteins of 42 kD that display a pattern of sequence cassettes with high inter-species conservation separated by poorly conserved linker sequences. Prenylation and palmitoylation of a COOH-terminal cluster of three cysteine residues confers hydrophobicity and membrane association to paralemmin. Paralemmin is also phosphorylated, and its mRNA is differentially spliced in a tissue-specific and developmentally regulated manner. Differential splicing, lipidation, and phosphorylation contribute to electrophoretic heterogeneity that results in an array of multiple bands on Western blots, most notably in brain. Paralemmin is associated with the cytoplasmic face of the plasma membranes of postsynaptic specializations, axonal and dendritic processes and perikarya, and also appears to be associated with an intracellular vesicle pool. It does not line the neuronal plasmalemma continuously but in clusters and patches. Its molecular and morphological properties are reminiscent of GAP-43, CAP-23, and MARCKS, proteins implicated in plasma membrane dynamics. Overexpression in several cell lines shows that paralemmin concentrates at sites of plasma membrane activity such as filopodia and microspikes, and induces cell expansion and process formation. The lipidation motif is essential for this morphogenic activity. We propose a function for paralemmin in the control of cell shape, e.g., through an involvement in membrane flow or in membrane-cytoskeleton interaction.

Estrogen and memory in a transsexual population

The association between administered estrogen and performance on verbal memory and other cognitive tasks was examined. Male-to-female transsexuals undergoing estrogen treatment for sex reassignment (n = 29) scored higher on Paired Associate Learning (PAL) compared to a similar transsexual control group, awaiting estrogen treatment (n = 30) (P < 0.05). No differences between groups receiving and not receiving estrogen were detected on a control memory task (Digit Span) or on other cognitive tasks including Mental Rotations and Controlled Associations. There were no group differences in age. Group differences in mood or in general intellectual ability also did not explain the findings. Results suggest a specific influence of estrogen in men on verbal memory tasks, similar to that seen in prior studies of women. They are discussed in terms of differential processing demands of the two memory tasks and possible differences between estrogenic influences on Mental Rotations and Controlled Associations in men versus women.

Verbal and music dichotic listening tasks reveal variations in functional cerebral asymmetry across the menstrual cycle that are phase and task dependent

Two dichotic listening tests, one a verbal consonant-vowel identification task, the other a musical chord recognition task, were administered to 32 women at two points during the menstrual cycle, menses (when oestrogen is low) and the midluteal phase (when oestrogen is high), in a counterbalanced repeated measures design. The degree of asymmetry changed across the cycle for both syllables and music. The right ear advantage recorded for the verbal task was greater during the midluteal phase than during menses. The left ear advantage recorded for the music task was greater during menses than during the midluteal phase. These reciprocal changes in asymmetry were the result of consistent changes in ear performance. From menses to the midluteal phase, left ear (right hemisphere) performance fell significantly for both tasks whereas right ear (left hemisphere) performance showed a small, but non-significant, increase. The findings are discussed in the light of evidence for phasic activational effects of gonadal steroids on both asymmetry and cognition which provide an explanation for the sometimes elusive nature and small effect size of sex differences in these characteristics. The relationships between sex differences in asymmetry and cognition are re-examined.

Survival and recovery of Escherichia coli O157:H7 in inoculated bottled water

A methodology used to isolate Escherichia coli O157:H7 from water and survival of this pathogen in inoculated water is described. The methodology used in the isolation of E. coli O157:H7 included the use of selective plating on Sorbitol MacConkey agar (supplemented with potassium tellurite [2.5 mg/liter], cefixime [0.05 mg/liter], and cefsulodin [10 mg/liter], and modified hemorrhagic colitis agar (also supplemented with potassium tellurite [2.5 mg/liter]) and cefsulodin [10 mg/liter]). There were no significant differences (P < 0.05) between the recoveries of E. coli O157:H7 on these two selective media. Direct plating on these selective agars was used to determine the length of time that E. coli O157:H7 was able to grow, remain viable, and be resistant to the selective agents. E. coli O157:H7 survived in inoculated water for up to > 300 days, depending on the type of water. Observation by scanning electron microscopy indicated that E. coli O157:H7 cells attached to, and multiplied on, the container walls.

Thin aggregative fimbriae enhance Salmonella enteritidis biofilm formation

Salmonella enteritidis enteropathogens produce a variety of potentially adherent fimbrial types including SEF14, SEF17, SEF18 and SEF21 (type I). In a simplified, pure culture, biofilm generating system the virulent isolate, S. enteritidis 3b, readily adhered to Teflon (polytetrafluoroethylene) and stainless steel forming thick cell aggregates. The inability of an isogenic SEF17-deficient mutant to form thick biofilms suggested a role for SEF17 in stabilizing cell-cell interactions during biofilm formation. Epifluorescent detection of SEF17 in biofilms confirmed the association of these fimbriae with aggregated cells but not with adherent mutants unable to produce SEF17. The reduced adherence observed with an isogenic SEF14/SEF21-deficient strain implicated the involvement of additional cell surface adherence factors, possibly including SEF21 (type I) fimbriae in the adherence of S. enteritidis to stainless steel or Teflon. The role of SEF17 fimbriae in biofilm formation and the contributions of SEF17 to the persistence of Salmonellae on surfaces and in food are discussed.

Sexual orientation differences in cerebral asymmetry and in the performance of sexually dimorphic cognitive and motor tasks

With each of the tasks in the present studies we expected to find the reported sex difference between heterosexual women and heterosexual men and we predicted a sexual orientation effect with the performance of homosexual men being similar to that of heterosexual women and different from that of heterosexual men. Study 1 aimed to replicate earlier findings by recording the performance of a group of homosexual men on a visuospatial task, the Vincent Mechanical Diagrams Test (VMDT), a dot detection divided visual field measure of functional cerebral asymmetry, and on five subtests of the Wechsler Adult Intelligence Scale (WAIS). For each task the profile of scores obtained for the homosexual men was similar to that of heterosexual women in that they scored lower than heterosexual men on the VMDT, they showed less asymmetry, and they recorded a higher Verbal than Performance IQ on the WAIS. In Study 2, a male-biased targeted throwing task favored heterosexual men while, in contrast, on the female-biased Purdue Pegboard single peg condition heterosexual men were outperformed by heterosexual women and homosexual men. On neither of these two tasks did the performances of homosexual men and heterosexual women differ. One task, manual speed, yielded neither sex nor sexual orientation differences. Another, the Purdue Pegboard assemblies condition, revealed a sex difference but no sexual orientation difference. Failure to obtain a sexual orientation difference in the presence of a sex difference suggests that the sexual orientation effect may be restricted to a subset of sexually dimorphic tasks.

Characteristics of individuals with Huntington disease in long-term care

This is a retrospective review of 97 Huntington disease (HD) patients living in long-term care facilities in the Twin Cities. The purpose of the study was to describe the demographic features, patterns of behavior, weight change, nursing issues, medication use, and hospitalization in this population. On admission to the nursing home, the "average" HD patient was of either sex, 45 years old, previously employed, a high school graduate, and not married. One third had severe behavior problems. Half gained and half lost weight; weight loss was not a predictor of death. Almost all used central nervous system-active drugs, most commonly neuroleptics. Eighty-four percent were ambulatory on admission, but 88% of those who died were nonambulatory at the time of death. We concluded that (a) HD patients are demographically different from other residents of long-term care facilities, (b) weight gain can occur in some late-stage patients, (c) negative behavior is a significant problem but is restricted to a subset of patients, and (d) adapting creatively to increasing multifaceted disability is the greatest challenge to the staff in facilities caring for HD patients.

The role of methotrexate in the management of steroid-dependent asthma

Severe asthma often requires high-dose corticosteroid therapy. However, steroid therapy is fraught with many side effects. There are conflicting reports in the literature regarding the role of methotrexate in reducing the steroid requirements of these patients. This study examined the role of low-dose methotrexate in the management of steroid-dependent asthma. Eleven subjects with stable steroid-dependent asthma were enrolled in a placebo-controlled double-blind crossover trial. Patients received methotrexate, 15 mg/wk, or placebo each for two 12-week periods. There was significant improvement of pulmonary function and reduction of prednisone requirement in both placebo and methotrexate treatment periods. However, methotrexate was not superior to placebo. Only 3 of 11 patients responded to methotrexate. Although low-dose methotrexate therapy may have a role in a small select group of steroid-dependent asthmatics, it provided no additional benefit overall.

Polychlorinated biphenyls (PCBs) in the British environment: sinks, sources and temporal trends

This paper estimates the present UK environmental loading of polychlorinated biphenyls (PCBs). Of the estimated approximately 40,000 t SigmaPCB sold in the UK since 1954, only an estimated 1% (400 t) are now present in the UK environment. Comparisons of estimated production and current environmental loadings of congeners 28, 52, 101, 138, 153 and 180 suggest that PCB persistence broadly increases with increasing chlorination. Those PCBs that are not now present in the UK environment are considered to have been destroyed--by natural or anthropogenic mechanisms, to be still in use, to reside in landfills or to have undergone atmospheric and/or pelagic transport from the UK. The dramatic fall in PCB levels in archived UK soils and vegetation between the mid-1960s and the present is evidence that the latter mechanism is the most important and that a significant proportion of PCBs released into the UK environment in the 1960s have subsequently undergone environmental transport away from the UK. The bulk (93.1%) of the estimated contemporary UK environmental burden of SigmaPCBs is associated with soils, with the rest found in seawater (3.5%) and marine sediments (2.1%). Freshwater sediments, vegetation, humans and sewage sludge combined account for 1.4% of the present burden, whilst PCB loadings in air and freshwater are insignificant. Although consideration of individual congeners does not reveal any major deviations from the relative partitioning of Sigma PCBs, the importance of sinks other than soils is enhanced for individual congeners, particularly 138 and 180. In particular, around 2% of the total UK burden of congener 180 is present in humans, implying that biodata as a whole may constitute an important sink for the higher chlorinated congeners. The contemporary flux of SigmaPCBs to the UK surface is estimated at 19 t yr(-1), compared with an estimated annual flux to the atmosphere of 44-46 t. This implies that the major sources of PCBs to the UK atmosphere have been identified and that there is currently a net loss of these compounds from the UK. These sources are: volatilisation from soils (88.1%), leaks from large capacitors (8.5%), the production of refuse-derived fuel (RDF) (2.2%), leaks from transformers (0.6%), the recovery of contaminated scrap metal (0.5%) and volatilisation from sewage sludge-amended land (0.2%). Interestingly, whilst large excesses of estimated annual fluxes to the atmosphere over deposition fluxes for individual congeners exist for congeners 28, 52 and 101, estimates of fluxes in both directions across the soil-atmosphere interface agree closely for congeners 138, 153 and 180. This suggests that lower chlorinated congeners are more susceptible to both long-range environmental transport beyond the UK and to atmospheric degradation. Retrospective analysis of dated sediment cores, vegetation and soils indicates that environmental transport from North America and continental Europe introduced PCBs into the British environment well before the onset of their commercial production in the UK in 1954. Since that time, the input of PCBs to the UK environment has essentially reflected temporal trends in UK use. After peaking in the 1960s they declined rapidly through the 1970s following restrictions on PCB use. Recent evidence, however, is that the rate of decrease has diminished and that further significant reductions in fresh environmental input will take some time to occur. Such reductions will be especially slow for humans and other biota with long life-spans. This stems partly from cross-generational transfer from parents to offspring and also because the persistence of PCBs in biota means that present body burdens will reflect past as well as current exposure.

Estimation of arterial stiffness, compliance, and distensibility from M-mode ultrasound measurements of the common carotid artery

BACKGROUND AND PURPOSE

Arterial stiffness may indicate early vascular changes that predispose to the development of major vascular disease. The repeatability of a variety of indices of arterial stiffness calculated from a standard carotid arterial M-mode ultrasound image was investigated.

METHODS

Twenty-six asymptomatic normal subjects were imaged and had blood pressure recordings on each of two separate occasions at least 1 day apart. Using a computer-assisted method, the maximum and minimum internal diameter and average wall thickness of the right common carotid artery were measured over several cardiac cycles, and the following indices of arterial stiffness and distensibility (compliance) were derived: the pressure-strain elastic modulus (Ep), Young's modulus (E), cross-sectional compliance (CC), and the distensibility coefficient (DC).

RESULTS

The repeatability of these measures, expressed as coefficients of variation, was as follows: Ep, 18%; E, 24%; CC, 14%; and DC, 13%. In another group of 20 subjects, the coefficient of variation for repeat examination by different sonographers was Ep, 19%; E, 20%; CC, 14%; and DC, 17% and for the one sonographer using two ultrasound machines was Ep, 13%; E, 13%; CC, 11%; and DC, 13%. These values indicate a moderate level of repeatability. In a univariate analysis each of these indices was significantly related to increasing age (Ep = 1.0 + 12.9 x AGE, r = .80; E = 314.5 + 13.9 x AGE, r = .48; CC = 22.6-0.26 x AGE, r = -.63; DC = 64.0-0.65 x AGE, r = -.78) but not to wall thickness (all P > .47). Using multiple regression techniques to adjust for age, wall thickness is a significant predictor of distensibility (P = .017), cross-sectional compliance (P < .001), and the pressure-strain elastic modulus (P = .019). Because Young's modulus is calculated from wall thickness, it could not be included in the multivariate analysis.

CONCLUSIONS

We conclude that estimates of carotid artery distensibility and cross-sectional compliance derived from M-mode ultrasound recordings are moderately repeatable and may provide useful additional end points for trials of atherosclerotic progression.

Triplex formation inhibits HER-2/neu transcription in vitro

Triplex-forming oligonucleotides (TFOs) have been shown to bind to target DNA sequences in several human gene promoters such as the c-myc oncogene, the epidermal growth factor receptor, and the dihydrofolate reductase genes. TFOs have been shown to inhibit transcription in vitro and gene expression in cell culture of the c-myc and other genes. The HER-2/neu oncogene, which is overexpressed in breast cancer and other human malignancies, contains a purine-rich sequence in its promoter, which is favorable for purine:purine:pyrimidine (R:R:Y) triplex formation. Although its function in the HER-2/neu promoter is unknown, this purine-rich site is homologous to a protein-binding sequence in the promoter of the epidermal growth factor receptor that is necessary for efficient transcription of this gene. We have shown that this sequence is a site for nuclear protein binding by incubation with a crude nuclear extract. We describe the formation of an interstrand triplex using a purine-rich oligonucleotide antiparallel to this purine-rich target sequence of the HER-2/neu promoter. Triplex formation by the oligonucleotide prevents protein binding to the target site in the HER-2/neu promoter in vitro. We have shown that this oligonucleotide is a potent and specific inhibitor of HER-2/neu transcription in an in vitro assay. The triplex target site contains a single pyrimidine base that does not conform to the R:R:Y triplex motif. In an attempt to abrogate the potentially destabilizing effects of this pyrimidine base on triplex formation, we have substituted an abasic linker for the pyrimidine residue in the triplex forming oligonucleotide. Triplex formation with the modified oligonucleotide appears to occur with approximately equivalent binding affinity. Triplex formation in the HER-2/neu oncogene promoter prevents transcription in vitro and may represent a future modality for specific inhibition of this gene in vivo.

B-mode ultrasound images of the carotid artery wall: correlation of ultrasound with histological measurements

B-mode ultrasound is being used to assess carotid atherosclerosis in epidemiological studies and clinical trials. Recently the interpretation of measurements made from ultrasound images has been questioned. This study examines the anatomical correlates of B-mode ultrasound of carotid arteries in vitro and in situ in cadavers. Twenty-seven segments of human carotid artery were collected at autopsy, pressure perfusion fixed in buffered 2.5% glutaraldehyde and 4% paraformaldehyde and imaged using an ATL UM-8 (10 MHz single crystal mechanical probe). Each artery was then frozen, sectioned and stained with van Gieson or elastin van Gieson. The thickness of the intima, media and adventitia were measured to an accuracy of 0.01 mm from histological sections using a calibrated eye graticule on a light microscope. Shrinkage artifact induced by histological preparation was determined to be 7.8%. Digitised ultrasound images of the artery wall were analysed off-line. The distance from the leading edge of the first interface (LE1) to the leading edge of the second interface (LE2) was measured using a dedicated programme. LE1-LE2 measurements were correlated against histological measurements corrected for shrinkage. Mean values for the far wall were: ultrasound LE1-LE2 (0.97 mm, S.D. 0.26), total wall thickness (1.05 mm, S.D. 0.37), adventitia (0.35 mm, S.D. 0.16), media (0.61 mm, S.D. 0.18), intima (0.09 mm, S.D. 0.13). Ultrasound measurements corresponded best with total wall thickness, rather than elastin or the intima-media complex. Excision of part of the intima plus media or removal of the adventitia resulted in a corresponding decrease in the LE1-LE2 distance of the B-mode image. Furthermore, increased wall thickness due to intimal atherosclerotic thickening correlated well with LE1-LE2 distance of the B-mode images. B-mode images obtained from the carotid arteries in situ in four cadavers also corresponded best with total wall thickness measured from histological sections and not with the thickness of the intima plus media. In conclusion, the LE1-LE2 distance measured on B-mode images of the carotid artery best represents total wall thickness of intima plus media plus adventitia and not intima plus media alone.

An immunoplaque assay distinguishing between cytopathogenic and noncytopathogenic biotypes of bovine viral diarrhoea virus

Cytopathogenic (cp) and noncytopathogenic (ncp) biotypes of bovine virus diarrhoea virus (BVDV) could be clearly distinguished by hollow plaques with peripheral immunostaining in infected fetal calf kidney (FCK) monolayers cultures or the appearance of homogenously stained immunoplaques (IPs), respectively. Of 70 BVDV isolates formerly classified as cytopathogenic according to microscopic observations in FCK cell cultures, 46 produced IPs of both types while the remaining 24 isolates induced only the IP type characteristic of the ncp BVDV biotype. The same was true for 24 additional isolates classified by light microscopy as ncp after ten blind passages in FCK cell cultures. Thus it appeared that in 1/3 of the cases changes in FCK cell cultures had been formerly misinterpreted as BVDV induced cytopathic effects (CPE). Of the 46 isolates which produced both ncp and cp immunoplaques 5 BVDV isolates were selected and successfully subjected to cloning. Clones of the cp biotype were developed by picking native plaques from unfixed FCK cell monolayers. In case of ncp IP, cloning was attempted by picking randomly in the spaces between visible native plaques. Pairs of clones from each of the field isolates proved to consist of pure plaque populations of cp BVDV and ncp BVDV biotypes, respectively, at the dilution of viral suspension which allowed the classification of a single IP according to morphology. Analysis of the clones using 15 monoclonal antibodies against the major viral glycoprotein revealed far-reaching antigenic homogeneity for each pair with only few but distinct exceptions.

Factors influencing default at a hospital colposcopy clinic

OBJECTIVE

To identify factors reducing compliance at diagnosis, treatment, and review stages among women referred with abnormal cervical smears to a hospital colposcopy clinic.

DESIGN

Retrospective analysis of sociodemographic data from hospital notes of the attenders and defaulters during one year (1989-90) and prospective collection of information by structured interviews of a sample of defaulters and attenders during five months (May-September 1990).

SETTING

One hospital colposcopy clinic.

PATIENTS

238 women defaulting on two consecutive occasions and 188 attending regularly (retrospective analysis) and a subset of 40 defaulters and 24 attenders (interview sample).

MAIN MEASURES

Sociodemographic data and interview responses about attitudes, behaviour, choice, accessibility cultural understanding, communications, and emotional response.

RESULTS

22 (12%) women defaulted at diagnosis, 24(13%) at treatment, 39(21%) at the first check up after treatment, and 84(45%) at the review stage; 19(10%) defaulted from the first check up after diagnostic examination revealed no need for treatment. Age and social class differed between the two groups. 181(76%) defaulters were under 30 compared with 91(48%) attenders; 14(6%) compared with 41(23%) were over 40(p < 0.001). The proportion of women in social classes 4 and 5 was 33%(20/60) for defaulters and 21%(25/120) for attenders (p < 0.05) and unemployed was 66%(158/238) and 36%(68/188) respectively. 63(28%) defaulters were pregnant compared with 11(6%) attenders (p < 0.001). More defaulters came from gynaecology or antenatal clinics. Most defaulters (93%) had child care responsibilities and they knew and understood less about colposcopy. Their explicit reasons for defaulting included child care commitments and fear and their implicit reasons lack of understanding, inaccessibility of information, and staff attitudes.

CONCLUSIONS

Compliance may be improved by promoting women's understanding of treatment and encouraging health professionals to develop a service more sensitive to the various needs of women in different socioeconomic groups.