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E Zintzaras

Publications and source records attributed to E Zintzaras.

At least 19 recordsLinked to original sources

DHLAS: A web-based information system for statistical genetic analysis of HLA population data.

DHLAS (database HLA system) is a user-friendly, web-based information system for the analysis of human leukocyte antigens (HLA) data from population studies. DHLAS has been developed using JAVA and the R system, it runs on a Java Virtual Machine and its user-interface is web-based powered by the servlet engine TOMCAT. It utilizes STRUTS, a Model-View-Controller framework and uses several GNU packages to perform several of its tasks. The database engine it relies upon for fast access is MySQL, but others can be used a well. The system estimates metrics, performs statistical testing and produces graphs required for HLA population studies: (i) Hardy-Weinberg equilibrium (calculated using both asymptotic and exact tests), (ii) genetics distances (Euclidian or Nei), (iii) phylogenetic trees using the unweighted pair group method with averages and neigbor-joining method, (iv) linkage disequilibrium (pairwise and overall, including variance estimations), (v) haplotype frequencies (estimate using the expectation-maximization algorithm) and (vi) discriminant analysis. The main merit of DHLAS is the incorporation of a database, thus, the data can be stored and manipulated along with integrated genetic data analysis procedures. In addition, it has an open architecture allowing the inclusion of other functions and procedures.

Databases, Genetic↗

A heterogeneity-based genome search meta-analysis for autism-spectrum disorders.

Autism and autism-spectrum disorders exhibit high heritability, although specific susceptibility genes still remain largely elusive. We performed a heterogeneity-based genome search meta-analysis (HEGESMA) of nine genome scans on autism or autism-spectrum disorders. Each genome scan was separated in 30 cM bins and the maximum linkage statistic from each bin was ranked. Significance for each bin's average rank and for between-scan heterogeneity (dis-similarity in the average ranks) was obtained through Monte Carlo tests. For autism, data from 771 affected sibpairs were synthesized across six separate genome scans. Region 7q22-q32 reached genome-wide significance both in weighted and unweighted analyses, with evidence for significantly low between-scan heterogeneity. The flanking chromosomal region 7q32-qter reached the less stringent threshold of suggestive significance, with no evidence for low between-scan heterogeneity. For autism-spectrum disorders (634 affected sibpairs from five separate scans), no chromosomal region reached genome-wide significance. However, suggestive significance was reached for the chromosomal regions 17p11.2-q12 and 10p12-q11.1 in weighted analyses. There was evidence for significantly high between-scan heterogeneity for the former region. The meta-analysis suggests that the 7q22-q32 region should be further scrutinized for autism susceptibility genes, while autism-spectrum disorders seem to have quite diverse linkage signals across scans, possibly suggesting genetic heterogeneity across subsyndromes and subpopulations.

Asperger Syndrome↗

Methylenetetrahydrofolate reductase gene and susceptibility to breast cancer: a meta-analysis.

The methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms have been linked to the risk of developing breast cancer. A meta-analysis of 18 case-control studies investigating the association between the C677T and the A1298C polymorphisms of the MTHFR gene and breast cancer (BC) was carried out. The meta-analysis included genotype data on 5467/7336 and 3768/5276 cases/controls for C677T and A1298C, respectively. In the meta-analysis, the consistency of genetic effects across different ethnicities and the effect of menopausal status for various genetic contrasts were investigated. The overall analysis for investigating the association between the C677T allele T and the risk of developing BC showed significant heterogeneity (p = 0.08, I2 = 34%) and non-significant association [odds ratio (OR) 1.02; 95% confidence interval (0.95-1.10)]. The allele contrast was not significant in Caucasians (nine studies) and in East Asians (four studies) [OR 1.03 (0.93-1.14) and OR 0.96 (0.81-1.15), respectively] or in pre-menopausal (five studies) and post-menopausal (four studies) groups [OR 1.10 (0.94-1.29) and OR 1.06 (0.95-1.18), respectively]. The genotype contrast of the homozygotes (TT vs CC) produced significant results only for pre-menopausal cases [OR 1.46 (1.05-2.03)]. The recessive model for allele T produced significant association only in pre-menopausal cases [OR 1.49 (1.09-2.03)]. The dominant model for the effect of allele T produced no significant results, overall and in each subgroup. For the A1298C polymorphism, all genotype contrasts showed lack of association, overall and in Caucasians. In summary, the accumulated evidence supports an association in pre-menopausal women. BC is a complex disease with multifactorial etiology, and therefore, case-control studies that investigate gene-environment interaction might elucidate further the genetics of the disease.

Breast Neoplasms↗

IL-1RN and IL-1B gene polymorphisms and cerebral hemorrhagic events after traumatic brain injury.

OBJECTIVE: To investigate the association of (variable number tandem repeat) interleukin (IL) 1RN and (-511) IL-1B gene polymorphisms with brain hemorrhagic events after traumatic brain injury (TBI). METHODS: Data from brain CT, Glasgow Coma Scale (GCS) at admission, and 6-month Glasgow Outcome Scale (GOS) and modified Rankin Scale (mRS) were collected for 151 prospectively recruited patients with TBI. IL-1RN and IL-1B genotypes were determined using standard methods. Presence vs absence of any type of brain hemorrhage was the main outcome. Type of brain hemorrhage, GCS at admission, and 6-month GOS and mRS were secondary outcomes. Odd ratios (ORs) and corresponding 95% CI were calculated using logistic regression analyses. In adjusted models, the associations were controlled for age, gender, diffuse brain edema, volume of intracranial hematoma, neurosurgical intervention, and GCS at admission. p values less than 0.01 were considered significant. RESULTS: Compared with noncarriers, IL-1RN allele 2 carriers had higher odds of having cerebral hemorrhages after TBI (adjusted OR = 4.57; 95% CI = 1.67 to 12.96; p = 0.004). The associations for (-511) IL-1B polymorphism were not significant. CONCLUSION: There is an association between the presence of interleukin-1RN allele 2 and posttraumatic brain hemorrhage.

Adult↗

Correlation of estrogen receptor beta gene polymorphisms with spinal bone mineral density in peri- and post-menopausal Greek women.

Estrogens play a significant role in bone physiology. Their action is mainly exerted through their receptors. Estrogen receptor alpha (ERalpha) plays a major role in bone homeostasis and there is evidence suggesting that estrogen receptor beta (ERbeta) has also an effect on BMD. We investigated the possible effect of two ERbeta gene polymorphisms on spinal bone mineral density (BMD) and metabolic bone markers in Greek women. Spine BMD as well as biochemical bone markers were measured in 147 healthy peri- and post-menopausal women [mean age (S.D.) 54 (7.9) years]. Genotyping was performed for two restriction fragment length polymorphisms (RFLPs) of ERbeta gene, RsaI in exon 5 and AluI in exon 8. For each polymorphism studied the cohort was divided into two groups: the "wild-type" group (RR and AA, respectively) and the "carrier" group including subjects with at least one allele with the restriction site (Rr&rr and Aa&aa, respectively). The distribution of RsaI genotypes was RR: 91.2% (n = 134), Rr: 8.2% (n = 12), and rr: 0.6% (n = 1) and of AluI genotypes AA: 36.7% (n = 54), Aa: 57.2% (n = 84), and aa: 6.1% (n = 9). No linkage disequilibrium was found between the two polymorphic sites studied. Spine BMD did not differ significantly in the two groups of either polymorphism, after adjusting for age, weight, height, and years since menopause [mean BMD (S.D.) for RR 0.841 (0.17) g/cm(2) versus Rr&rr 0.798 (0.13) g/cm(2), p = 0.25, and mean BMD (S.D.) for AA 0.828 (0.16)g/cm(2) versus Aa&aa 0.848 (0.17) g/cm(2), p = 0.32]. No significant differences were noted in metabolic bone markers except for a marginal difference of RR versus Rr/rr in urinary hydroxyproline/creatinine ratio [median (IQR) 3.88 (6.04) micromol/mmol in RR versus 8.2 (4.32) micromol/mmol in Rr/rr, p = 0.05]. Furthermore, no interaction between the two polymorphisms on BMD was found. In conclusion, in a Greek female post-menopausal population, the two ERbeta gene polymorphisms were not associated with BMD, or metabolic bone markers.

Absorptiometry, Photon↗

The value of a single combined measurement of VEGF, glycodelin, progesterone, PAPP-A, HPL and LIF for differentiating between ectopic and abnormal intrauterine pregnancy.

BACKGROUND: To evaluate whether serum concentrations of the non-placental markers vascular endothelial growth factor (VEGF), glycodelin (GLY) and progesterone (P) and the novel placental markers pregnancy-associated plasmaprotein A (PAPP-A), human placental lactogen (HPL) and leukaemia inhibiting factor (LIF) differ in ectopic pregnancy (EP) when compared with abnormal intrauterine pregnancy (aIUP). METHODS: A prospective clinical study was conducted at the University Hospital of Larissa, Greece. The study included 50 patients admitted with failed pregnancy and suspected ectopic pregnancy that were treated with curettage or laparoscopy and classified as histologically confirmed EPs (n = 27) or histologically confirmed aIUPs (n = 21) (mean gestational age of 7.15 and 7.3 weeks, respectively). Two suspected EPs proved to be normal IUPs and were excluded. VEGF, GLY, P, beta-HCG, PAPP-A, HPL and LIF were measured by enxyme-linked immunosorbent assay (ELISA) methods in a single pre-operative blood sample. RESULTS: The median VEGF concentration was 227.2 pg/ml in the EP group versus 107.2 pg/ml in the aIUP group (P < 0.001), with a suggested threshold value of 174 pg/ml for their differential diagnosis. LIF, P, PAPP-A, HPL and GLY serum measurements did not differ significantly between EP and aIUP. CONCLUSION: VEGF serum levels might be a useful marker in differentiating between EPs and aIUPs.

Biomarkers↗

Lupus thrombocytopenia: clinical implications and prognostic significance.

OBJECTIVES: To clarify clinical manifestations, association with disease activity, and prognostic impact of thrombocytopenia using simple and reliable indices. METHODS: 632 patients were reviewed retrospectively. Fifty patients with thrombocytopenia were included as cases and matched with 100 control patients. Clinical manifestations at first thrombocytopenic episode were recorded. Classification criteria at diagnosis, basic immunological profiles, disease activity (ECLAM), and end organ damage (SLICC) were recorded. RESULTS: 29/50 (58%) had thrombocytopenia at diagnosis of lupus. Haemorrhagic manifestations were associated with the degree of thrombocytopenia (p<0.001). Anticardiolipin antibodies were not related to the degree of thrombocytopenia or the severity of haemorrhagic manifestations. Megakaryocytes were normal or increased in 26/28 (93%) bone marrow specimens, indicating peripheral platelet destruction. Patients with high disease activity were more thrombocytopenic than controls (OR = 2.61, 95% CI 1.13 to 5.96, p = 0.009). Patients with low C3 or CH50 were more likely to be thrombocytopenic (OR = 2.36, 95% CI 1.05 to 5.26, p = 0.029). Median SLICC for lupus patients with thrombocytopenia was 2 (range 0-11) compared with 1 (range 0-12) for controls (p<0.001). No deaths occurred during thrombocytopenic episodes. CONCLUSIONS: Thrombocytopenia is not directly associated with end organ damage and mortality, but defines a subgroup of patients with higher morbidity and is thus a major complication of systemic lupus erythematosus, affecting overall prognosis.

Adult↗

Objective biophysical findings in patients with sensitive skin.

The term sensitive skin has been used to describe a clinical phenomenon of hyperreactivity of the human skin, which develops exaggerated reactions when exposed to external factors. The aim of this study was to determine objective biophysical findings in patients with sensitive skin compared to those individuals with nonsensitive skin. Thirty-two patients with sensitive skin and 30 healthy volunteers with nonsensitive skin were studied. The testing methods included in vivo and in vitro tests: epicutaneous testing (Patch tests); measurement of sebum and hydration of the skin; alkali resistance test; stinging test with lactic acid; reaction to aqueous solution of methyl nicotinate 0.5%, 1.4% and acetyl-b-methylcholine chloride 1:1000; pH measurement; dermographism; and measurement of total and specific IgE. Significant results were observed in the measurement of sebum (p < 0.01) and hydration (p < 0.05) of the skin, in the alkali resistance test (p < 0.05), in the vascular reaction to methyl nicotinate (p < 0.01) and to acetyl-b-methylcholine chloride (p < 0.01) and in the skin response to allergens of the European standard (p < 0.01) and cosmetic series (p < 0.05). In addition, the subjective findings of stinging test produced significant results (p < 0.001) as was anticipated. Patients with sensitive skin possess very dry skin with low fatness, which leads to a disturbance of the protective skin barrier function. They also present a hyperreaction of the skin blood vessels, increased transcutaneous penetration of water-soluble chemicals, enhanced immune responsiveness, significant decrease of alkali resistance and a heightened neurosensory stimulation.

Adult↗

Psychiatric factors in patients with sensitive skin.

The term sensitive skin has been used to describe a clinical phenomenon of skin hyperreactivity induced after exposure to different external factors. The diagnosis is mainly based on patient's self-assessment because of the lack of objective clinical signs of the disease. The aim of this study was to investigate psychiatric factors in patients with sensitive skin and to estimate the possible need for psychological intervention to these patients. Thirty-seven patients with sensitive skin and 38 individuals with nonsensitive skin were studied. The psychometric instruments used were the Symptom Checklist-90 (SCL-90) and the Delusions-Symptoms-States Inventory/states of Anxiety and Depression (DSSI/sAD). Statistically significant differences in subjects with sensitive skin compared to those with nonsensitive skin were observed in the SCL-90 subscales of somatization, phobic anxiety, hostility, interpersonal sensitivity and the DSSI/sAD subscale of anxiety. Our findings suggest that somatization, anxiety, phobic anxiety, hostility and interpersonal sensitivity symptoms may be associated with hypersensitivity of human skin. Psychological factors should be taken into consideration in the treatment of patients with sensitive skin.

Adult↗

Impaired elastic properties of ascending aorta in patients with giant cell arteritis.

OBJECTIVE: To investigate the elastic properties of the ascending aorta in untreated patients with giant cell arteritis compared with age and sex matched normal controls. METHODS: Distensibility of the ascending aorta and aortic strain were measured in 22 patients with a recent diagnosis of giant cell arteritis (documented by a positive temporal artery biopsy) before initiation corticosteroid treatment, and in 44 age and sex matched healthy subjects. Aortic distensibility was calculated as 2x[pulsatile change in aortic diameter]/[(diastolic aortic diameter)x(aortic pulse pressure)], and aortic strain as [pulsatile change in aortic diameter]/[diastolic aortic diameter]. Aortic diameters were measured by echocardiography. Aortic pressures were obtained by external sphygmomanometry. RESULTS: Distensibility of the ascending aorta and aortic strain were both lower in patients with giant cell arteritis than in the controls (p<0.01). In the patients with giant cell arteritis, aortic distensibility was inversely correlated with white blood cell count (p<0.05), but not with erythrocyte sedimentation rate or C reactive protein. CONCLUSIONS: Compared with healthy subjects, aortic distensibility and aortic strain are decreased in patients with giant cell arteritis before initiation of corticosteroid treatment. There was an association between the degree of reduction of aortic distensibility and the white blood cell count in the patient group.

Aged↗

Changes in pituitary sensitivity to GnRH in estrogen-treated post-menopausal women: evidence that gonadotrophin surge attenuating factor plays a physiological role.

BACKGROUND: The purpose of this study was to investigate changes in pituitary response to GnRH in post-menopausal women during substitution treatment with exogenous estrogen and progesterone. METHODS: Seven healthy post-menopausal women (group 1) were treated with various doses of E2 valerate for 43 days, so as the serum concentrations of E2 mimicked those of a follicular (FP-1), a luteal (LP) and a second follicular (FP-2) phase. During the LP, progesterone was also administered. The 30 min response of LH (DeltaLH) and FSH (DeltaFSH) to GnRH (10 microg i.v.) (pituitary sensitivity) was investigated every 24 h in group 1 and also in seven normally cycling women (group 2) during a spontaneous (control) follicular phase (FP). Based on the hormone profiles, day 32 in group 1 (FP-2) corresponded to day 2 in the spontaneous FP of group 2. RESULTS: Basal FSH concentrations were significantly higher in FP-2 than in the control FP (P < 0.05), while basal LH concentrations were similar in the two phases with higher values in FP-2 towards the end of the experiment (corresponding to days 10 and 11, P < 0.05). However, an LH surge was seen only in the control FP. DeltaFSH values remained stable in both phases and increased only in the control FP on days 12 and 13. DeltaLH values remained stable in the control FP and only increased on days 12 (P < 0.05) and 13 (P < 0.05), but in FP-2, DeltaLH values increased earlier (corresponding to day 7, P < 0.05). CONCLUSIONS: The present study demonstrates for the first time that in the absence of ovarian function, follicular phase E2 concentrations sensitize the pituitary to GnRH at an earlier stage (corresponding to the midfollicular phase) than in the normal menstrual cycle (late follicular phase). It is suggested that during the early to midfollicular phase the ovaries produce a gonadotrophin surge attenuating factor (GnSAF) that antagonizes the pituitary-sensitizing effect of E2 to GnRH.

Adult↗

Autoimmune phenomena in myelodysplastic syndromes: a 4-yr prospective study.

OBJECTIVE: To determine the clinical aspects and evolution of autoimmune inflammatory manifestations (AIMs) in patients with myelodysplastic syndrome (MDS) and ascertain the prognostic implications of these manifestations in MDS. METHODS: Seventy patients diagnosed for MDS were enrolled in a prospective cohort study of 4-yr duration. Thirteen patients with AIMs were identified (group A). The remaining 57 MDS patients without AIMs constituted the control group (group B). Demographic, clinical features, laboratory data, treatment and outcome of all these cases were recorded. RESULTS: On comparing features between the two groups we were unable to identify any particular difference (P > or = 0.05) concerning bone marrow blast count [odds ratio (OR) = 0.68], international prognostic scoring system (IPSS) (OR = 1.36), favourable cytogenetic abnormalities (OR = 0.52), leukaemic transformation (OR = 1.30) and survival (P = 0.76). Furthermore there was a significant difference in survival between low vs non-low IPSS patients for both groups (P<0.01). CONCLUSION: In a 4-yr prospective study the prognosis of MDS patients with AIMs appeared to be closely related to the IPSS subcategory of the underlying haematological malignancy and not to the autoimmune process.

Adult↗

Infliximab Therapy for Patients With Active and Refractory Spondyloarthropathies at the Dose of 3 mg/kg: A 20-Month Open Treatment.

BACKGROUND: : Infliximab at the dose of 5 mg/kg per infusion has been shown effective for the treatment of active spondyloarthropathies. It is not clear if the 5 mg/kg is required in most patients. OBJECTIVE: : To evaluate the long-term efficacy and safety of infliximab at the lower dose of 3 mg/kg in patients with active and refractory ankylosing spondylitis (AS) and psoriatic arthritis (PsA). METHODS: : Thirty patients were enrolled in a 78-week, single-center, prospective, open-label pilot study, including 16 patients with severe and active AS and 14 patients with active and refractory PsA. Infliximab (3 mg/kg, in combination with a stable dose of methotrexate was administered intravenously at 0, 2 and 6 weeks, and q8 weeks thereafter (schedule-A) and the improvement of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI; for AS patients) and Patient Global Assessment of Disease Activity (PDA; for PsA patients) was monitored at baseline and at every visit (primary variables). Patients who did not respond sufficiently at 14 weeks, as well as patients who relapsed at any time during follow-up, received infliximab every 4 weeks (treatment schedule-B). Three different statistical approaches (per-protocol, last observation carried forward and by intention-to-treat) were applied. RESULTS: : Ten patients discontinued treatment for various reasons, including 3 (10.0%) because of allergic reactions. Twenty patients (66.7%, 9 with AS and 11 with PsA) had completed 78 weeks of treatment (schedule-A, 11 patients; schedule-B, 9 patients). Of these patients, 18 (90.0%) showed optimal response (improvement >/=50%), including 13 (65.0%) with improvement >/=70%. ASsessments in AS (ASAS) 50% was attained by 7/9 AS patients (77.8%). At 78 weeks of treatment, statistically significant improvement of indices of disease activity, function and quality of life was observed by all statistical approaches applied. CONCLUSIONS: : Infliximab at 3 mg/kg every 8 weeks or, if needed, every 4 weeks appears to be an effective and rather safe treatment of patients with active and refractory AS and PsA after 78 weeks of treatment.

Journal Article↗

Morning levels of fibrinogen in children with sleep-disordered breathing.

Elevated fibrinogen level is a predictor of cardiovascular disease in adults, and it is associated with sleep-disordered breathing. Levels of fibrinogen in adults are affected by other co-existing cardiovascular risk factors, which are not usually present in children. To investigate the association between fibrinogen and sleep-disordered breathing, a case-control study was carried out in children with and without habitual snoring. All snoring children underwent polysomnography. Morning fibrinogen values in 30 children with snoring and an apnoea-hypopnoea index (AHI) > or =5 episodes x h(-1) (median (interquartile range) 318 mg x dL(-1) (290-374)) were similar to values in 61 children with snoring and an AHI <5 episodes x h(-1) (307 (269-346)). Both groups had higher fibrinogen values than those in 23 controls without snoring (271 mg x dL(-1) (244-294)). There was no correlation between fibrinogen values and AHI, respiratory movement/arousal index or haemoglobin desaturation index. In conclusion, fibrinogen values are higher in children with snoring than in controls, but there is no association between these values and polysomnography indices.

Case-Control Studies↗

Incidence and prognostic value of positive peritoneal cytology in colorectal cancer.

PURPOSE: This study was conducted to investigate the incidence of free cancer cells in the peritoneal washings of patients who had undergone surgery for colorectal cancer and to evaluate its influence as a prognostic factor of the disease. METHODS: From 1990 to 1996, intraoperative washing cytology was performed in 110 patients who underwent surgery for colorectal cancer. All patients had curative resections. Immediately after the abdomen was opened and before exploration and mobilization of the tumor, 100 ml of saline was injected over the tumor site. Washings were then aspirated and taken for cytologic examination. RESULTS: Twenty-two (20 percent) of 110 patients examined were found to have positive cytology for intraperitoneal free malignant cells. The site of tumor in the colon or rectum, tumor size, nodal status, degree of differentiation, mucinous characteristics, and vascular or neural invasion were found not to affect the incidence of free cancer cells. Conversely, tumor penetration was found to affect the incidence of positive cytology. The degree of association among the stages of tumor penetration was indicated by the contingency coefficient, which was 0.42. Patients with positive cytology had a significantly higher rate of local recurrence and peritoneal carcinomatosis (22.8 vs. 8 percent, P = 0.05) than patients with negative cytology. Mortality rate was not found to be related to the presence of free cancer cells. CONCLUSION: Cytologic examination of peritoneal lavage at the time of surgery could be a useful prognostic indicator for local and peritoneal recurrence rate. However, it was not found to be a predictor of survival.

Adenocarcinoma↗

The Th1/Th2 cytokine balance changes with the progress of the immunopathological lesion of Sjogren's syndrome.

Expression of type-1 and type-2 cytokines at the mRNA level in labial salivary glands (LSG) of patients with Sjogren's syndrome (SS), as reported by several groups, have generated conflicting results. In the present study we have directly examined the production of IL-4, IL-13 and IFN-gamma by lymphocytes infiltrating the LSG of 44 consecutive patients referred for SS evaluation. Cytokines production was evaluated following in vitro culture of LSG in the presence of IL-2. IFN-gamma and IL-13 were detected in the majority of SN (24/44 and 26/44, respectively) while IL-4 was present in 5/44 SN. The presence of IFN-gamma was significantly higher in SS patients, as opposed to patients who did not fulfil the criteria for SS (P < 0.01). In addition, almost all cultured lymphocytes expressed mRNA for IFN-gamma (17/19 cultures) and IL-13 (18/19) while IL-4 mRNA was also expressed at high frequency (14/19 cultures). Interestingly, the IFN-gamma mRNA copies in cultured lymphocytes correlated significantly with the intensity of lymphocytic infiltration as evaluated by Chisholm's score (P < 0.01). Furthermore, RT-PCR of RNA extracted from whole LSG from 14 SS patients also demonstrated the presence of all cytokines in the majority of the cases and the prevalence of IFN-gamma in LSG with high-grade infiltration. Because IL-13 was produced by the majority of the cultured LSG, IgE production was also evaluated. Interestingly, IgE was detected in 21/44 LSG culture SN and mainly in those biopsies that had Chisholm's score less than 0.5 (P < 0.05). We conclude that lymphocytes infiltrating the LSG are capable of producing both Th1 and Th2 cytokines and that the balance between them shifts in favour of Th1 in LSG with high infiltration score and in patients with SS.

Cells, Cultured↗

Variation in the life cycle and morphology of the tobacco host-race of Myzus persicae (Hemiptera: Aphididae) in relation to its geographical distribution.

Morphological variation and life cycle category were examined in 121 clones of Myzus persicae (Sulzer). The clones were collected from tobacco from three localities in Greece (Xanthi, Nea Efessos and Naphplion), one in Germany (Rheinstetten), one in France (Bergerac) and one in Spain (Madrid). Before morphometrics, all aphids were laboratory-reared on potato. The morphological variation was investigated using both canonical variates analysis and a novel non-parametric classification tree method. The life cycle category was examined by rearing the clones for three generations under short day conditions. In Nea Efessos a relative high proportion of clones was found to overwinter as eggs on the primary host. In the other regions all collected clones were non-holocyclic. Intermediate genotypes were found in all regions at percentages ranging from 4.0 to 24.0%. Androcyclic clones were found only in Xanthi, Greece (4.0%) and Rheinstetten, Germany (16.7%). The canonical variates analysis and the tree classification method revealed important intrapopulation polymorphisms in clones from Bergerac, Nea Efessos and Madrid. Both methods separated the populations originating from Greece from those collected elsewhere in western Europe. The observed morphological variation was probably due to genetic differences, since all clones were reared in a common environment. The results are discussed in relation to factors responsible for genetic divergence in M. persicae populations.

Animals↗

Host-correlated morphological variation of Myzus persicae (Hemiptera: Aphididae) populations in Greece.

Morphological variation in nine characters of 157 clones of Myzus persicae (Sulzer) was examined by multivariate analysis. The clones were collected from peach, Prunus persica, the primary host and the secondary hosts tobacco, Nicotiana tabacum, cabbage, Brassica oleracea, sugarbeet, Beta vulgaris and pepper Capsicum annuum. The 156 clones originated from various regions of Greece, both in the north, where a large part of the population has an annual bisexual generation on peach, and in more southerly regions, where populations are predominantly unisexual. One clone was collected from tobacco in Caserta, Italy. All clones were laboratory-reared on potato. Canonical variate analysis, hierarchical cluster analysis and a non-parametric classification tree method both revealed morphological differences associated with the host-plant on which they were collected. The scores of the first two canonical variates separated the tobacco-feeding clones from those originating from other secondary host-plants. However, in tobacco-growing areas the tobacco-feeding form predominated in spring populations on peach, and was sometimes found on other secondary hosts. In addition, using cluster analysis, the clones from tobacco which were sampled in the most southeasterly region showed a relatively large phenotypic distance from those collected further north and west. Moreover, clonal phenotypes were affected both by host plant and by long-term parthenogenetic rearing. However, in spite of these effects, the tobacco form was generally distinguishable from aphids originating from other hosts, indicating that the difference must have a genetic basis. In separate analyses of the clones originating from secondary hosts no association was found between morphology and either life cycle category or colour. Discriminant analysis showed that 89% of 1723 specimens could be correctly classified into the two groups.

Animals↗