Emotional, coping factors and personality traits that influenced alcohol consumption in Romanian students during the COVID-19 pandemic. A cross-sectional study

BACKGROUND

During the COVID-19 pandemic, after 3 months from the installation of the state of emergency on the territory of Romania, data were collected from 677 students and master's students, to explore the problematic alcohol consumption (AC).

METHODS

The evaluation was done with: Alcohol Use Disorders Identification Test, Depression, Anxiety and Stress Scales, Strategic Coping Approach Scale and The Freiburg Personality Inventory. The statistical methods used were linear regression with bootstrap procedure, Spearman's rank correlation, and the Mann-Whitney U test.

RESULTS

More than half were affected by depression or anxiety of moderate to extremely severe intensity. The prevalence of problematic alcohol consumption was low: (Hazardous and Extremely Hazardous (2.3) and Medium Risk (10.2). Early onset increases the subsequent risk of problematic AC, compared to women, men recorded a higher AC (p <.01). Anxiety, antisocial action, personality traits Aggressiveness and Somatic complaints had the effect of increasing the alcohol consumption score (p <.01). Significant but weak positive correlations between AC on one hand, and depression, anxiety, stress and antisocial action on the other hand were found (p <.01).

CONCLUSIONS

Probably the prevalence of AC was low as a result of the fact that most respondents were studying in the field of health promotion and as a result of the closure of entertainment venues. This study advocates for the education of youngsters to clearly express their opinions without violating the boundaries of others' feelings (assertive action) and to act prudently in dangerous or uncertain situations (cautious action) since these coping mechanisms were not associated with problematic alcohol consumption. The promotion of positive, achievement-oriented, life attitudes is equally important, as these characteristics of the Life Satisfaction personality dimensions were also found as non-determinants of alcohol-induced problems. The association of problematic AC with antisocial actions as a coping mechanism and high scores on Aggressiveness calls for interventions to educate the younger generation how to acquire and adopt healthy mechanisms to control tensions without resorting to alcohol consumption, more so as the two variables reinforce each other. Drinking as a means of gaining courage must be carefully reconsidered since anxiety generally hits back, often in increased levels.

The Involvement of Age, Gender, and Personality Variables in Alcohol Consumption during the Start of the COVID-19 Pandemic in Romanian University Students

This study aimed to explore the age, gender, and personality variables involved in alcohol consumption (AC) at the start of the COVID-19 pandemic in Romania among 210 bachelor's and master's students aged between 19 and 25 years. The results of the Freiburg Personality Inventory-Revised and the Alcohol Use Disorders Identification Test were examined using a logistic model and cluster analysis. The prevalence of problematic AC was relatively low (10.5%). The risk of males being part of the problematic AC cluster was 5.223 times higher than that of females (p < 0.001). Increasing age was associated with a decrease in the risk of belonging to the problematic cluster by a factor of 0.733 (p = 0.001). Increasing scores on the Frankness and Somatic Complaints personality scales were associated with a decreased risk of belonging to the problematic cluster of AC, with factors of 0.738 (95% CI, 0.643 to 0.848), Wald χ²(1) = 18.424, and p < 0.001 and 0.901 (95% CI, 0.813 to 0.999), Wald χ²(1) = 3.925, and p = 0.048, respectively. More action to prevent AC is needed in men, especially in those at the beginning of their university studies. It is necessary to intervene to decrease the interest in making a good impression (low scores on the Frankness Scale) so as to increase healthy autonomy using critical thinking and find a balance between the internal and external loci of control. Students from faculties with profiles that deal with health and its promotion are less vulnerable to problematic alcohol consumption, even if they have a withdrawn, pessimistic personality (low scores on Somatic Complaints).

Diagnosis and Psychotherapeutic Needs by Early Maladaptive Schemas in Patients With Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is chronic and incurable. Imperious diarrhea, rectal bleeding, fatigue, and weight loss, the main manifestations, cause a decrease in the quality of the patient's personal and professional life. The objectives of this study were to identify a possible relationship between early maladaptive schemas and disease activity status using logistic regression, to identify the prevalence of early maladaptive schemes in patients and to propose a psychotherapeutic intervention plan. The following were found in a sample of 46 patients aged 16-76 years. An increase in the domain overvigilance and inhibition score had a significant effect (Wald = 6.583, p = 0.010), with an increase of 1.137 CI95% [1.031, 1.254] of the risk of the disease being diagnosed as active. High and very high scores were observed for the emotional deprivation scheme (nearly three-quarters) and dependence/incompetence, vulnerability to harm and illness and subjugation schemas (over 80%). The results show that the proposed model could predict and reconfirm the diagnosis; patients have specific psychotherapeutic needs. The therapeutic goal would be to offer care, empathy and protection, to strengthen self-confidence, to make patients realize that they have the ability to cope, to provide permission, encourage the patient to experiment, and guide the patient to express their anger healthily. The therapy scheme's intervention could lead to increased long-term disease management capacity and, consequently, reduce costs directly and indirectly caused by this condition.

Factors Associated with Depression in Middle-Aged and Elderly People in Romania

The objectives of this study were the determination of the prevalence of self-reported depressive symptoms by the Geriatric Depression Scale and the influences of variable income, physical activity, socialization and sexual activity. A total of 601 patients aged 55–93 years with a mean age of 67.32 years and a median age of 67 years participated in this study between 2016 and 2017. Non-cooperative people and individuals with strong auditory or visual sensory deficits, severe cognitive deficits, or disorders accompanied by psychotic elements with serious somatic pathology were excluded from the interviews. Employing the SPSS GENLIN procedure, an ordinal logistic model was used. Over ½ of the respondents are within the categories of moderate and severe depression, almost half of the respondents feel that their family incomes are not enough or make it hard to meet their needs, approximately 10% think they are sedentary, over ½ participate in no sexual activity, and over ¼ do not frequently respond with pleasure to partner-initiated sexual relationships. Those who were in the higher depression category perceived their income to be extremely low (p = .001), perceived themselves as sedentary (p < .001), infrequently met with friends or neighbours in their leisure time (p = .002), and had lower sexual interest (p < .001). Middle-aged adults and older adults should learn about the health benefits of physical activity, socialization and sexual activity. Social policies must take into account this low-income segment. Poverty itself can be a contributor to depressive states, and additionally, due to their low incomes, elderly people are at risk of benefiting less from pharmacotherapy and psychotherapy.

[Ankle-brachial index screening for peripheral artery disease in high cardiovascular risk patients. Prospective observational study of 370 asymptomatic patients at high cardiovascular risk]

INTRODUCTION

Peripheral arterial disease is a marker of systemic atherosclerosis; it is associated with a high risk of cardiovascular disease. The aim of our study was to assess the prevalence of peripheral arterial disease by measuring the ankle-brachial pressure index in patients at high cardiovascular risk and to study the risk factors associated with this disease.

METHODOLOGY

This was a descriptive and analytic cross-sectional study which focused on 370 patients seen at the medical consultation for atherosclerosis prevention. The ankle-brachial index was measured with a portable Doppler (BIDOP 3) using 4 and 8Hz dual frequency probes. The standards were: normal ankle-brachial index 0.9 to 1.3; peripheral artery obstructive disease ankle-brachial index less than 0.9; poorly compressible artery (medial arterial calcification) ankle-brachial index greater than 1.3. Cardiovascular risk factors were also studied.

RESULTS

Three hundred and seventy subjects (mean age 65.5±8.7years) were screened Cardiovascular risk factors were: sedentary lifestyle (91.5 %), hypertension (68.1 %), elevated LDL-cholesterolemia (36.3 %), diabetes (48.3 %) and tobacco smoking (33.8 %). The prevalence of peripheral artery disease was 32.4 % of which 77.5 % were asymptomatic. We found a significant correlation with smoking, diabetes, dyslipidemia and the presence of coronary artery disease or vascular cerebral disease. Screening for peripheral arterial disease (PAD) with the ankle-brachial index has increased the percentage of polyvascular patients from 6.2 to 29 %. Factors independently associated with PAD were advanced age, presence of cardiovascular disease, smoking and glycated hemoglobin.

CONCLUSION

PAD is a common condition in people at high cardiovascular risk, the frequency of asymptomatic forms justifies the screening with pocket Doppler which is a simple, inexpensive and effective test to assess the overall cardiovascular risk.

Alcohol consumption and accentuated personality traits among young adults in Romania: a cross-sectional study

Background

Alcohol consumption (AC) has negative social and economic consequences, affects health, and can create dependence. As dependence is particularly difficult to cure, prevention is important. This study aimed to identify the frequency, quantity, occasions, reasons, type of AC, and correlation with accentuated personality traits among young adults in Romania.

Methods

Participants were 1359 young adults aged 18–30 years (average age, 22.67 years; standard deviation [SD], 3.02 years) from urban environments including the main university centers. Several questionnaires covering issues such as health risk behavior (smoking, alcohol abuse, unprotected sex, sedentary lifestyles, unhealthy eating), aggression, personality, adaptability, cohesion, and communication were administered to participants between 2013 and 2014. Pearson’s chi-square tests and z-tests were used for the analyses.

Results

Common reasons young adults first tried AC were curiosity (67.8 %), to be like peers (17.9 %), and adult influence (6.5 %). In terms of AC frequency, 72.5 % consumed alcohol only on special occasions/holidays, 19.4 % on weekends, 4.8 % three to four times per week, and 0.4 % on a daily basis. To overcome sexual/emotional inhibitions or for courage, 2.1 % of participants drank frequently and 23.5 % drank from time to time. AC most often occurred with a group of friends (62.3 %). For 9.7 % of participants, AC was a reason for poor concentration, or problems at work/school. At the time of interview, participants had consumed an average of 319.48 ml beer (SD, 1223.02 ml), 82.75 ml wine (SD, 385.39 ml) and 25.62 ml spirits (SD, 131.34 ml) in the previous week. AC was significantly higher in males (p < 0.01), and in participants aged 23–30 years (p < 0.05). AC was influenced by six accentuated personality traits: Demonstrativeness, Hyper-perseverance, Uncontrollability, Hyperthymia, Cyclothymia, and Exaltation (p < 0.01).

Conclusions

AC was relatively high, especially among young men, peer groups, and young adults who had problems socializing. AC also correlated with some accentuated personality traits. Therefore, public health education programs should be targeted for these categories.

Sexual behaviour and sexual and reproductive health education: a cross-sectional study in Romania

BACKGROUND

Up-to-date, genuine sexual and reproductive health (SRH) education programmes have been possible in Romania only since communism collapsed in 1990. Since 2006, Romania has had no national strategy in this field. Under current global circumstances (high labour mobility, internationally mixed marriages), issues previously considered solely national have become worldwide concerns.

METHODS

In 2011-2012, 1215 respondents homogeneously distributed on background, gender, educational level and age group (18-74) were sampled. This article uses a 96-item questionnaire about family and SRH, presenting results on nine items: first intercourse (FI), virginity, knowing first sexual partner, safe sex, number of sexual partners and sexual education. The data were analysed using Pearson chi-square tests and latent class analysis.

RESULTS

Some participants (7.2%) engaged in FI at age 15 or earlier. The average age at FI was lower for men (18.08), for individuals with a lower education level (18.07) and for those in rural areas (18.27), compared with that for women, those with more education and those in urban areas, respectively. The average age at FI was over 2.5 years lower for people aged 18-24 (16.99) than for those aged 60-74 (p < 0.001). More than 60% were not married or partnered with their FI partner, and 17.8% engaged in FI less than a month after meeting their partner. Less than one-fourth practiced safe sex at FI, with higher proportions for the urban sample, those with an average level of education and those aged 18-35 (p < 0.001). Higher average numbers of sexual partners were found among men (6.56, compared with 2.37 among women), in urban areas (5.07, compared with 3.75 in rural areas) and among those with higher levels of education (p < 0.005). On average, subjects first received information on SRH at 15.39 years of age, with only 10% listing the school, doctors or medics as a source.

CONCLUSIONS

Unsafe sex, early initiation of sexual activity and poor SRH education from schools, experts and parents require a multidisciplinary approach within prevention programmes, especially among the populations at risk: rural residents, those with low levels of education and youth.

Violence against women by male partners and against children within the family: prevalence, associated factors, and intergenerational transmission in Romania, a cross-sectional study

Background

Domestic violence is a public health problem with negative consequences. We aimed to determine the prevalence of violence between parents and by parents against children, types of intimate partner violence against women, the intergenerational transmission of violence, and to identify a profile of beliefs and judgements regarding violent behaviour.

Methods

The data used for this article were sourced from three cross-sectional studies performed in Romania in 2009–2011. We sampled 869 respondents (male and female) with a homogenous distribution between environment, gender, educational level, and age group (18 to 75). From a 96-item questionnaire regarding family and reproductive health, this article refers to four items: (1) feelings relating to the family in which they were raised; (2) whether they witnessed violence between parents or were victims of violence by parents or other family members during childhood or the teenage years; (3) opinions relating to 10 statements on violence from Maudsley Violence Questionnaire; (4) the manifestation of psychological, emotional, and sexual abuse from the partner in the family of procreation (FOP). The data were analysed by Pearson chi-square tests and latent class analysis.

Results

During childhood, 35% of respondents witnessed parental violence and 53.7% were victims of family violence. Psychological abuse by men against women was the most common type of violence reported in the FOP (45.1%). Violence in childhood and adolescence correlated with the perception of the family of origin as a hostile environment and of violence against women as a corrective measure, and that insults, swearing, and humiliation by their partner within the FOP is acceptable (p < 0.05). A profile of beliefs and judgements about violent behaviour indicated that the Impulsive reactive cluster is represented by men in rural areas, and by subjects who witnessed parental violence or were victims of violence during childhood (p < 0.001).

Conclusions

In Romania, the use of violence as a form of discipline or instruction of children and women remains a significant problem, with a higher rate of intimate partner violence than in other developed countries. Furthermore, implementing intervention mechanisms for psychological abuse is urgently required, as are education and intervention in high-risk populations.

Age at initiation of sexual life, protection at first intercourse and sources of information regarding sexual and reproductive health

OBJECTIVES

this study is intended to determine: age at initiation of sexual life, protection at first intercourse and sources of information regarding sexual and reproductive health. The trends identified by this study can form the basis of public health programmes.

MATERIAL AND METHODS

between 2011 and 2012, 564 subjects, 18-35 years old, from urban and rural environment, have responded to a questionnaire with 96 items on family-related topics. In the present study we focused on three items. The Pearson chi-square tests were employed using the statistical programs SPSS.

RESULTS AND DISCUSSION

most of the subjects had engaged in their first intercourse at 17-18 years old (48.58%). The number of individuals who had started their sexual life earlier than at 17 years of age was higher in males and in young subjects (p < 0.001). The protection at first intercourse was very low (38.4%) and the condom was the main method (34%). The protection was significantly higher in urban environment and in case of people with average and high educational level (p < 0.001). As for the information on the subject of sexual behavior, the smallest contribution came from doctors and sanitary staff (12.6%), from the school (15.2%), from parents, relatives (17%). Friends and acquaintances contributed to the largest extent--45.7%, and the contribution of Internet was 41%.

CONCLUSIONS

Diminishing the pregnancy rate in teenagers and the unwanted pregnancy rate, as well as the rate of sexually transmitted infections, requires a multidisciplinary approach in the prevention programmes. The school and parents are crucial factors within the education programmes.

Evaluation of women knowledge and attitude regarding cervical cancer early detection

At European level, Romania unfortunately comes first as far as mortality due to cervical cancer is concerned, mortality rate recording a continuous increase due to disease detection in advanced stages. In this context, we followed an assessment of women's cognitive and attitudinal fund in relation to early detection of cervical cancer, through the application of a questionnaire on a batch of 617 women with ages from 18 to 75-year-old, with various levels of education, residents of Craiova City and communes from Dolj County. Statistic processing of their answers indicates that 43.3% of the inquired subjects have not had a routine gynecological exam for at least seven years (or even never), which is more often found in the subgroup of women from the rural environment, with ages over 35 years and with an elementary educational level (p<0.001). 65.8% of the women have not done a Babes-Papanicolau test for seven years or even never, residence area, age and education level being once again discrimination factors between the subgroups. The reasons usually put forward as a justification for the failure to do the cytological test for the past three years are negligence (23.8%), the lack of information on the existence of such an investigation (18.2%), the absence of a genital pathology (12.8%) or of a medical recommendation (11.8%). Results suggest the need to provide uniform accessibility of the population to health services, by developing and implementing new strategies of educational and sanitary intervention mainly in rural communities.

[Food intake--family income in a group of teenagers from Iaşi "Dimitrie Cantemir" High School]

Food intake is influenced by a series of factors, including family, income, school and mass-media.

MATERIAL AND METHOD

A group of 78 teenagers were investigated using a food intake questionary, correlating the results with family income.

RESULTS

Our results show that the food intake is influenced more by family dietary habits rather than family income, with no significant differences between families with different socio-economic status.

CONCLUSION

Educational programs for changing the nutritional habits must be implemented.

[Smoking, alcohol consumption and pregnancy in a population of south-western Romania]

The purpose of the study was to evaluate the amplitude of tobacco and alcohol consumption among two populations living in urban, respectively rural areas in the South-Western part of the country. The presence of the two risky behaviours during the pregnancy was also analysed.

MATERIAL AND METHOD

A number of 1,200 people, men and women, aged 18-75 years, with different educational levels, living in urban and rural communities were asked to answer a questionnaire with 111 items regarding their knowledge and attitudes about the sexual-reproductive health; 11 items referred to tobacco smoking and alcohol drinking.

RESULTS

About half of the subjects have never smoked. The mean age of starting smoking was 16.97 years. A number of 295 subjects (24.6%) were daily active smokers, men more frequently than women (p < 0.001). A percentage of 77.3% of the subjects used to drink alcohol, 16.4% of them daily. The daily alcohol consumption was more frequent among men, low educated people and rural inhabitants comparing to women, respectively high educated or urban inhabitants (p < 0.001); 11.2% of the respondents got frequently drunk. During the last pregnancy in the couple, women and high educated people stopped smoking and drinking more frequently then men, respectively low educated people.

CONCLUSIONS

The above findings indicate the need to start in school effective health promotion campaigns to reduce tobacco and alcohol consumption and the need for support of population-based educational interventions aimed at smoking cessation in both parents.

[Fruit consumption in a group of teenagers from Iaşi]

A goal for the national nutritional education program is represented by the increase of fruit consumption.

MATERIAL AND METHOD

Using specially designed questionaries a group of 127 teenagers from two different Iaşi high schools provided date related to thei daily fruit intake.

RESULTS

Almost 40% of the teenagers use fresh fruits as part of their breakfast and a greater number use them as snacks (57.5%) or dessert (80.5%), with statistically insignificant differences between the two high schools.

CONCLUSION

The fruit intake is adequate in the studied group and the programs that promote certain food habits must take into account the existing situation.

[Anthropological study on hearing deficit]

Professional training of hearing impaired persons is conditioned by the stage of psychologic development and by educational level.

MATERIAL AND METHOD

The study was carried out on a series of 142 children (87 girls and 55 boys) aged 12 to 17 years with hearing deficit from a special school for deaf.

RESULTS

The distribution of these children according to their parents being deaf or not, skills, constitution, intensity of voice was analyzed. The goal of this study is to demonstrate that students in these special schools have to get full support for participating in joint activities with hearing students. Such activities are favorable not only for developing mutual interests, but also for improving verbal expression in a new, pleasant, lively and instructive.

[Physical development and health status in mentally disabled school children]

Mentally disabled children represent about 3% from the children population.

MATERIAL AND METHOD

102 children with mental disabilities were investigated using physical and somatometric examination.

RESULTS

The mental disabilities are associated with different diseases, in most cases correlated in intensity with de degree of mental disorder. The physical development is considered to be with average values for the majority of children; the presence of harmonic development is predominant, but we met cases in which the values for height and weight are small or even pathologic.

CONCLUSION

Mentally disabled school children physical development and health status raise many problems for the medical staff and the management of these children implies permanent monitoring.

[The medical and social impact of the gross domestic product on the life expectancy and infantile mortality in Romania]

In this study we have analyzed the correlations between the GDP reported on every inhabitant and the life expectancy respective the infantile mortality rates. Analysis cover 11 countries, divided in four categories: three former countries members of EU (France, Italy, Sweden), three countries recently admitted (2004) in E.U. (Poland, Slovenia, Hungary), two countries which will join E.U. in 2007 and other three countries none located in Europe (Canada, Japan, USA). In the countries that invest a lot in health care system the life expectancy at birth is bigger that in other countries, but this relation is not a linear one. Infantile mortality in modern society is strongly influenced by the socio-economic status.

Switch junction sequences in PMS2-deficient mice reveal a microhomology-mediated mechanism of Ig class switch recombination

Isotype switching involves a region-specific, nonhomologous recombinational deletion that has been suggested to occur by nonhomologous joining of broken DNA ends. Here, we find increased donor/acceptor homology at switch junctions from PMS2-deficient mice and propose that class switching can occur by microhomology-mediated end-joining. Interestingly, although isotype switching and somatic hypermutation show many parallels, we confirm that PMS2 deficiency has no major effect on the pattern of nucleotide substitutions generated during somatic hypermutation. This finding is in contrast to MSH2 deficiency. With MSH2, the altered pattern of switch recombination and hypermutation suggests parallels in the mechanics of the two processes, whereas the fact that PMS2 deficiency affects only switch recombination may reflect differences in the pathways of break resolution.

The intrinsic hypermutability of antibody heavy and light chain genes decays exponentially

Somatic hypermutation, essential for the affinity maturation of antibodies, is restricted to a small segment of DNA. The upstream boundary is sharp and is probably related to transcription initiation. However, for reasons unknown, the hypermutation domain does not encompass the whole transcription unit, notably the C-region exon. Since analysis of the downstream decay of hypermutation is obscured by sequence-dependent hot and cold spots, we describe a strategy to minimize these fluctuations by computing mutations of different sequences located at similar distances from the promoter. We pool large databases of mutated heavy and light chains and analyse the decay of mutation frequencies. We define an intrinsic decay of probability of mutation that is remarkably similar for heavy and light chains, faster than anticipated and consistent with an exponential fit. Indeed, quite apart from hot spots, the intrinsic probability of mutation at CDR1 can be almost twice that of CDR3. The analysis has mechanistic implications for current and future models of hypermutation.

In vivo and in vitro studies of immunoglobulin gene somatic hypermutation

Following antigen encounter, two distinct processes modify immunoglobulin genes. The variable region is diversified by somatic hypermutation while the constant region may be changed by class-switch recombination. Although both genetic events can occur concurrently within germinal centre B cells, there are examples of each occurring independently of the other. Here we compare the contributions of class-switch recombination and somatic hypermutation to the diversification of the serum immunoglobulin repertoire and review evidence that suggests that, despite clear differences, the two processes may share some aspects of their mechanism in common.

Memory in the B-cell compartment: antibody affinity maturation

In the humoral arm of the immune system, the memory response is not only more quickly elicited and of greater magnitude than the primary response, but it is also different in quality. In the recall response to antigen, the antibodies produced are of higher affinity and of different isotype (typically immunoglobulin G rather than immunoglobulin M). This maturation rests on the antigen dependence of B-cell maturation and is effected by programmed genetic modifications of the immunoglobulin gene loci. Here we consider how the B-cell response to antigen depends on the affinity of the antigen receptor interaction. We also compare and draw parallels between the two processes, which underpin the generation of secondary-response antibodies: V gene somatic hypermutation and immunoglobulin heavy-chain class switching.

Automated detection of point mutations using fluorescent sequence trace subtraction

The final step in the detection of mutations is to determine the sequence of the suspected mutant and to compare it with that of the wild-type, and for this fluorescence-based sequencing instruments are widely used. We describe some simple algorithms forcomparing sequence traces which, as part of our sequence assembly and analysis package, are proving useful for the discovery of mutations and which may also help to identify misplaced readings in sequence assembly projects. The mutations can be detected automatically by a new program called TRACE_DIFF and new types of trace display in our program GAP4 greatly simplify visual checking of the assigned changes. To assess the accuracy of the automatic mutation detection algorithm we analysed 214 sequence readings from hypermutating DNA comprising a total of 108 497 bases. After the readings were assembled there were 1232 base differences, including 392 Ns and 166 alignment characters. Visual inspection of the traces established that of the 1232 differences, 353 were real mutations while the rest were due to base calling errors. The TRACE_DIFF algorithm automatically identified all but 36, with 28 false positives. Further information about the software can be obtained from http://www.mrc-lmb.cam.ac.uk/pubseq/

Hot spot focusing of somatic hypermutation in MSH2-deficient mice suggests two stages of mutational targeting

Likely creation of mismatches during somatic hypermutation has stimulated interest in the effect of mismatch repair deficiency on the process. Analysis of unselected mutations in the 3' flank of VH rearrangements in germinal center B cells revealed that MSH2 deficiency caused a 5-fold reduced mutation accumulation. This might reflect ectopic effects of the Msh2 disruption; indeed, the mice exhibit other perturbations within the B cell compartment. However, that MSH2 (or factors dependent upon it) plays a role in the mechanism of mutation fixation is indicated by a strikingly increased focusing of the mutations on intrinsic hot spots. We propose two phases to hypermutation targeting. The first is hot spot focused and MSH2 independent; the second, MSH2-dependent phase yields a more even spread of mutation fixation.

Monitoring and interpreting the intrinsic features of somatic hypermutation

We have used both normal and transgenic mice to analyse the recruitment and targeting of somatic hypermutation to the immunoglobulin loci. We compare methods for analysing hypermutation and discuss how large databases of mutations can be assembled by PCR amplification of the rearranged V-gene flanks from the germinal centre B cells of normal mice as well as by transgene-specific amplification from transgenic B cells. Such studies confirm that hypermutation is preferentially targeted to the immunoglobulin V gene with the bcl6 gene, for example, escaping this intense mutational targeting in germinal centre B cells. We review our data concerning the nature of the hypermutation domain and the targeting of hotspots within that domain. We consider how enhancer-mediated recruitment of hypermutation to the immunoglobulin loci operates in a clonally maintained fashion and illustrate how both the degree of expression and demethylation of the transgene broadly correlate with its mutability.

The 5' hypermutation boundary of kappa chains is independent of local and neighbouring sequences and related to the distance from the initiation of transcription

The hypermutation of antibody genes targets 1-2 kb of DNA which includes the rearranged V(D)J gene segments. The precise nature, location and limits of the targeted region are of considerable interest in terms of the mechanism of hypermutation. We have analyzed the frequency and distribution of mutations in the 5' region of immunoglobulins using several modified kappa transgenes. We found that the position of the boundary, relative to the transcription initiation site, is not affected by the sequence of the V segment or by substituting the kappa chain promoter for a beta-globin promoter. Furthermore, the deletion of the leader intron (containing the hypermutation boundary) does not affect hypermutation per se, but shifts the boundary from the leader intron to the V region such that the distance between the boundary and the site of initiation of transcription remains constant. These results show that the position of the hypermutation boundary (about 185 bases downstream of the site of initiation of transcription) is not defined by the nucleotide sequence but rather by the distance to a fixed upstream position. Although mutations are also observed in the region upstream of the boundary, the frequency at which they occur is one order of magnitude lower relative to the frequency observed in the V segment. Nonetheless this upstream mutation rate remains more than two orders of magnitude higher than that of somatic genes. We discuss possible mechanisms explaining the nature and position of the boundary in the context of an error-prone DNA repair model.

The targeting of somatic hypermutation

Somatic hypermutation does not occur randomly within immunoglobulin V genes but, rather, is preferentially targeted to certain nucleotide positions (hot spots) and away from others (cold spots). Cold spots often coincide with residues essential for V gene folding. Hotspots, which appear to be strategically located to favour affinity maturation, are most frequently located in the CDRs (particularly CDR1) though conserved hotspots are also found at the base of FR3. Hotspots are in part created by local DNA sequence and the strong biases of codon usage in V genes indicate that the genes have evolved such that somatic hypermutation is targeted to those parts of the V where it is likely to prove most useful. These features of mutational hotspots and biased codon usage are also evident in V genes of lower animals suggesting that diversification by strategic targeting of non-templated mutation may have evolved early in antigen receptor evolution.

The 5' boundary of somatic hypermutation in a V kappa gene is in the leader intron

The maturation of the immune response involves the hypermutation of antibody genes and the selection of B cells expressing receptors with improved antigen binding properties. Somatic hypermutation of antibody genes is targeted to a small region approximately 1 kb surrounding the rearranged V gene. The precise definition of the 5' limit is not yet clear since the data base of somatic mutations upstream of the V region is very restricted. The available data suggest that it lies close to the promoter region and this has been used to implicate transcription in the mechanism leading to hypermutation. Here we present an extensive analysis of mutations in the 5' region of a single kappa light chain gene. A large data base from highly mutated sequences was obtained from anti-oxazolone hybridomas expressing the V kappa Ox1-J kappa 5 light chain and from polymerase chain reaction-derived clones from splenic and Peyer's patches of transgenic mice expressing the same V kappa Ox1-J kappa 5 gene combination. Although mutations were found in the 5'-flanking segment, the rate of mutation in the V-J segment was about 20-fold higher. A sharp decline between those two mutation rates is evident but the boundary was found in the leader intron of the V kappa Ox1 gene, about 150 bases downstream of the initiation of transcription site.

Affinity maturation leads to differential expression of multiple copies of a kappa light-chain transgene

Transgenic animals containing rearranged heavy or light chains are used to study the process of hypermutation, which characterizes the maturation of the antibody response. LK6 mice contain five copies of a transgene coding for a light chain produced in response to the hapten 2-phenyloxazolone. We have selected hybridomas from secondary responses that express the transgene as the only light chain. Some of these hybridomas contain transgene copies carrying mutations known to improve antibody affinity. We have analysed the expression of the five transgene copies in those hybridomas. We report here that the somatic hypermutation process can affect the successful expression of antibody light-chain transgenes. When mutations that improve the antibody affinity appear in one transgene copy, antigenic selection favours cells that downregulate the other copies at multiple levels of gene expression, including examples where nonsense mutations correlate with a drop in messenger RNA level.

Passenger transgenes reveal intrinsic specificity of the antibody hypermutation mechanism: clustering, polarity, and specific hot spots

We have analyzed somatic hypermutation in mice carrying an immunoglobulin kappa transgene in order to discriminate mutations that reflect the intrinsic specificity of the hypermutation mechanism from those highlighted by antigenic selection. We have immunized animals with three different immunogens. With one immunogen, the antigen-specific B cells express a transgenic kappa chain, which does not form part of the antibody; the transgene is a passenger free to accumulate unselected mutations. With the other two immunogens, the transgenic kappa chain constitutes the light chain of the expressed antibody. A comparison of the transgene mutations obtained under these different circumstances allows us to identify common features that we attribute to the intrinsic specificity of the hypermutation process. In particular, it yields only base substitutions and leads to hot spots occurring in individual positions (e.g., the second base of the Ser-31 codon). The mutations preferentially accumulate around the first complementarity-determining region. The process exhibits specific base substitution preferences with transitions being favored over transversions. We propose that these substitution preferences can be used to discriminate intrinsic from antigen-selected hot spots. We also note that hypermutation distinguishes between the coding and noncoding strands since pyrimidines (particularly thymidines) mutate less frequently than purines.

Mutation and selection during the secondary response to 2-phenyloxazolone

The most characteristic feature of the mouse antibody response to the hapten 2-phenyloxazolone is the recurrent expression of the light-chain variable region Igk-VO chi 1 gene in its germ-line or mutated configuration. The analysis of somatic mutants of the Igk-VO chi 1 gene reported here indicates that, as found during the primary response, hypermutation is also activated during the secondary response. Somatic mutations in the Igk-VO chi 1 gene increased in sequences obtained at day 14 and day 21 in the primary response and again in the secondary response at days 3, 5, and 7. The ratio of replacement to silent mutations also increased, particularly between days 5 and 7, suggesting that a stage of negative selection operates on new somatic mutants generated in the secondary response. Most Igk-VO chi 1 mutants isolated in the secondary response had the features of selected memory clones (i.e., they carried mutations known to increase binding affinity for the hapten). However, some clones had chain-termination codons, and others had mutations predicting a nonfunctional light chain. At least three and possibly five of these clones also expressed the mutation characteristic of the memory response to 2-phenyloxazolone (His-34----Asn-34/Gln-34). We conclude that after a second antigenic challenge, new somatic variants, including some leading to the loss of antigen binding, are generated by hypermutation of cells derived from the memory pool.

Concerted evolution of class I genes in the major histocompatibility complex of murine rodents

Full-length cDNA sequences of two class I major histocompatibility complex molecules from the DA strain of Rattus norvegicus are reported. One codes for the classical class I restriction element RT1.Aa, which maps to the locus in the rat major histocompatibility complex homologous to H-2K in the mouse. The other probably codes for a soluble nonclassical class I molecule present in DA rat serum; a short deletion in the fifth exon implies that the translated product will terminate in the membrane-spanning region. These sequences have been compared with mouse classical class I sequences as well as with three published rat class I cDNA partial sequences. The results show, first, that "locus-specific" substitutions from the H-2K, H-2D, and H-2L data set are scrambled in the RT1.Aa molecule; a majority of these substitutions have H-2D/L-specific features. Second, the data show that the four rat sequences are strikingly similar to one another regardless of locus or haplotype of origin; they share a number of apparently species-specific features that distinguish them all from mouse classical class I sequences, which likewise share distinctive features of their own. The results suggest that segmental sequence exchange plays a major role in determining the evolution of sequence in class I major histocompatibility complex molecules.