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Biomedical subjects

M Polak

Publications and source records attributed to M Polak.

At least 55 records · Page 3Linked to original sources
PubMed2001

Artificial life simulation of living alga cells and its sorption mechanisms.

Resistance mechanisms of organisms against toxic metals are based on a few different mechanisms provided by algae cells. These mechanisms can be localized on the cell wall, on the cell wall and cytoplasm membrane, and intracellular localized mechanisms. Due to these mechanisms, algae populations could be used for sorption of arsenic from contaminated waters. This process takes a long time and it's not very variable. With artificial life simulation based on multi-agent simulation system we are preparing a simulation that could at least partially substitute the real experiments with real cells. Artificial life simulation of alga Chlorella kessleri is based on real biological parameters and together with partial implementation of other mathematical models of algae population growth it will be used for simulating the process of absorbing heavy metals from contaminated water. Model implementation is done is Swarm--multi agent object based simulation system and it's libraries. Simulation is still in testing and debugging phase and it is not yet available for public.

Adsorption↗
PubMed2001

Identification of the gene altered in Berardinelli-Seip congenital lipodystrophy on chromosome 11q13.

Congenital generalized lipodystrophy, or Berardinelli-Seip syndrome (BSCL), is a rare autosomal recessive disease characterized by a near-absence of adipose tissue from birth or early infancy and severe insulin resistance. Other clinical and biological features include acanthosis nigricans, hyperandrogenism, muscular hypertrophy, hepatomegaly, altered glucose tolerance or diabetes mellitus, and hypertriglyceridemia. A locus (BSCL1) has been mapped to 9q34 with evidence of heterogeneity. Here, we report a genome screen of nine BSCL families from two geographical clusters (in Lebanon and Norway). We identified a new disease locus, designated BSCL2, within the 2.5-Mb interval flanked by markers D11S4076 and D11S480 on chromosome 11q13. Analysis of 20 additional families of various ethnic origins led to the identification of 11 families in which the disease cosegregates with the 11q13 locus; the remaining families provide confirmation of linkage to 9q34. Sequence analysis of genes located in the 11q13 interval disclosed mutations in a gene homologous to the murine guanine nucleotide-binding protein (G protein), gamma3-linked gene (Gng3lg) in all BSCL2-linked families. BSCL2 is most highly expressed in brain and testis and encodes a protein (which we have called seipin) of unknown function. Most of the variants are null mutations and probably result in a severe disruption of the protein. These findings are of general importance for understanding the molecular mechanisms underlying regulation of body fat distribution and insulin resistance.

Acanthosis Nigricans↗
PubMed2001

Acromicric dysplasia: long term outcome and evidence of autosomal dominant inheritance.

Acromicric dysplasia is a rare bone dysplasia characterised by short stature, short hands and feet, normal intelligence, mild facial dysmorphism, and characteristic x ray abnormalities of the hands. Only a very small number of children with this condition have been reported so far. Here we report on a series of 22 patients including 10 boys and 12 girls with acromicric dysplasia. Length was normal at birth and height fell progressively off the centiles postnatally. The mean adult height was 130 cm (133 cm in males, 129 cm in females). The hands, feet, and limbs were short and OFC was normal. Intelligence was normal and mild dysmorphic features were noted. Other occasional features included well developed muscles, a hoarse voice, generalised joint limitation in some patients, frequent ear, tracheal, and respiratory complication, and spine abnormalities. Long term follow up showed that facial dysmorphism was less obvious in adults and that carpal tunnel syndrome was frequent in older patients. Apart from short metacarpals and phalanges, internal notch of the second metacarpal, external notch of the fifth metacarpal, and internal notch of the femoral heads, there were no major x ray abnormalities. No major complications, such as cardiac disease or major orthopaedic problems, occurred in the course of the disease. The condition appeared to be sporadic in 16 cases but the observation of vertical transmission in three families was consistent with an autosomal dominant mode of inheritance.

Abnormalities, Multiple↗
PubMed2001

Biochemical investigation of foetal and neonatal thyroid function using the ACS-180SE analyser: clinical application.

Despite sonographic detection of foetal goitre, uncertainty persists in the initial diagnosis of thyrotoxicosis and hypothyroidism. The aim of this study was to establish foetal and neonatal iodothyronine and thyrotrophin reference values for the ACS-180SE analyser. From 22 to 36 weeks of gestation, median foetal serum free thyroxine (FT4) levels increased from 6.0 pmol/L to 143 pmol/L, while free tri-iodothyronine (FT3) levels increased from 0.7 pmol/L to 1.9 pmol/L and mean thyrotrophin (TSH) levels remained stable (10.2 +/- 3.8mU/L; n = 33). At birth, concentrations were independent of gender and gestational age. Among the 10 cases of sonographically detected foetal goitre, serum TSH and FT4 were measured in five, showing hypothyroidism (3/5) or hyperthyroidism (2/5). Cord blood TSH levels reflected the efficacy of prenatal therapy. Measurement of foetal FT4 and TSH can be used to confirm foetal thyroid dysfunction, whereas treatment efficacy can be assessed sonographically and confirmed by measurement of TSH assay at birth.

Female↗
PubMed2001

Nineteen years of national screening for congenital hypothyroidism: familial cases with thyroid dysgenesis suggest the involvement of genetic factors.

Although a few familial forms of congenital hypothyroidism (CH) due to thyroid dysgenesis (TD) have been reported, this disorder is usually considered to be sporadic. Recently, we reported that 2% of CH patients with TD have a positive familial history. The aim of this study was to describe the clinical characteristics of these familial cases and to compare them with sporadic cases. We used the French national population-based registry of the first 19-yr screening program, which included 14,416,428 screened neonates with a 100% recovery rate. Familial history of CH with TD was investigated by means of a questionnaire sent to the pediatricians (n = 592) who provided ongoing clinical care for the 4049 CH patients detected during this period, including 2863 CH cases due to TD. Information was obtained from 73% of these pediatricians who were following up 2472 CH patients with TD (86%). In all, 67 patients with a positive family history of CH with TD were referred, belonging to 32 multiplex families (i.e. including at least 2 affected members). Families were identified with ectopic gland (n = 12), athyreosis (n = 7), or both (n = 13). Comparison of familial with isolated cases showed a similar etiological diagnosis distribution of CH (40% vs. 33% for athyreosis and 60% vs. 67% for ectopic thyroid gland, respectively), whereas a significantly lower predominance of females was found in familial than in isolated cases (1.4 vs. 2.7; P < 0.03). Extrathyroidal congenital malformations were found with a similarly higher incidence in familial and isolated CH populations compared with the general population (respectively, 9% and 8.2% vs. 2.5%). In conclusion, although familial cases represent a minority of cases of congenital hypothyroidism caused by thyroid dysgenesis, they were observed in a significantly higher proportion (>15-fold) than would be expected from chance alone. This familial clustering, including athyreosis and ectopic thyroid gland, strongly suggests that genetic factors could be involved in thyroid dysgenesis with a common underlying mechanism for both etiological groups. Moreover, the high proportion of extrathyroidal congenital malformations in a population affected by CH due to TD suggests that the potential genetic factors involved in thyroid gland organogenesis are also involved in the development of other organs.

Congenital Hypothyroidism↗
PubMed2001

The quantitative genetics of fluctuating asymmetry.

Fluctuating asymmetry (subtle departures from identical expression of a trait across an axis of symmetry) in many taxa is under stabilizing selection for reduced asymmetry. However, lack of reliable estimates of genetic parameters for asymmetry variation hampers our ability to predict the evolutionary outcome of this selection. Here we report on a study, based on analysis of variation within and between isofemale lines and of generation means (line-cross analysis), designed to dissect in detail the quantitative genetics of positional fluctuating asymmetry (PFA) in bristle number in natural populations of Drosophila falleni. PFA is defined as the difference between the two sides of the body in the placement or position of components of a meristic trait. Heritability (measured at 25 degrees C) of two related measures of PFA were 13% and 21%, both of which differed significantly from zero. In contrast, heritability estimates for fluctuating asymmetry in the total number of anterior (0.7%) and transverse (2.4%) sternopleural bristles were smaller, not significant, and in quantitative agreement with previously published estimates. Heritabilities for bristle number (trait size) were considerably greater than that for any asymmetry measure. The experimental design controlled for the potentially confounding effects of common familial environment, and repeated testing revealed that PFA differences between lines were genetically stable for up to 16 generations in the laboratory at 25 degrees C. We performed line cross analysis between strains at the extremes of the PFA distribution (highest and lowest values); parental strains, F1, F1r (reciprocal), F2, backcross, and backcross reciprocal generations were represented. The inheritance of PFA was described best by additive and dominance effects localized to the X-chromosomes, whereas autosomal dominance effects were also detected. Epistatic, maternal, and cytoplasmic effects were not detected. The inheritance of trait size was notably more complex and involved significant autosomal additive, dominance, and epistatic effects; maternal dominance effects; and additive and dominance effects localized to the X-chromosomes. The additive genetic correlation between PFA and its associated measure of trait size was negative (-0.049), but not statistically significant, indicating that the loci contributing additive genetic effects to these traits are probably different. It is suggested that PFA may be a sensitive measure of developmental instability because PFA taps the ability of an organism to integrate interconnected developmental pathways.

Animals↗
PubMed2001

beta Cell autoimmunity in a child with M.O.D.Y. (Maturity Onset Diabetes in the Young).

We present the case of a well characterised M.O.D.Y. type 2 diabetes family in which one of the children associated beta cell autoimmunity and a HLA DQB1 at risk for immune-mediated type 1 diabetes mellitus. The search for autoantibodies against beta cell should be considered in cases of genetically defined form of diabetes mellitus to exclude the possibility of a concomitant risk to develop type 1 diabetes mellitus.

Autoantibodies↗
PubMed2001

Cystic fibrosis-related diabetes mellitus: clinical impact of prediabetes and effects of insulin therapy.

UNLABELLED: In patients with cystic fibrosis (CF), glucose intolerance preceding diabetes (prediabetes) may have adverse effects on nutritional status and respiratory function, which are reversible after the start of insulin therapy. Respiratory function (forced vital capacity and forced expiratory volume in one second) and body mass index (BMI) were compared retrospectively in a French cohort of 14 patients during the 5 y preceding insulin therapy for diabetes and in 14 age- and sex-matched controls with normal oral glucose tolerance tests. In the diabetic group, all three parameters deviated increasingly from the values in the controls; the differences became statistically different during the 6 mo before insulin therapy. The effect was more important in patients for whom diabetes mellitus was diagnosed on the basis of symptoms of hyperglycaemia than in patients for whom it was diagnosed by systematic screening, but still present in the latter. After insulin was started, respiratory function improved and the BMI returned to normal within 1 y. The annual insulin requirement increased from 0.62 during the first year to 1.25 during the fifth year. Glycosylated haemoglobin (HbAIc) values ranged from 6.6 to 7.8%. Only 2 episodes of severe hypoglycaemia were recorded over 42 patient-years of follow-up. The insulin regimen most often used was two daily injections of a mixture of short- and intermediate-acting insulin (n = 10) given with an insulin pen. CONCLUSION: The clinical status of CF patients who will need insulin therapy deteriorates before the start of insulin. In patients with CF-related diabetes, with or without fasting hyperglycaemia, insulin therapy improves anabolism and provides good glycaemic control with few severe hypoglycaemic episodes.

Adolescent↗
PubMed2001

Emergence of type 2 diabetes in an hospital based cohort of children with diabetes mellitus.

OBJECTIVES: Increasing awareness of the heterogeneity of diabetes mellitus (DM) at presentation is changing our approach to this disease. We used the 1999 American Diabetes Association (ADA) criteria to determine the distribution of DM patterns in a large pediatric cohort with the aim of documenting the emergence of type 2 diabetes mellitus. MATERIAL AND METHODS: Charts of diabetic children aged 1 to 16 years and admitted to our center between 1993 and 1998 were reviewed for data needed to achieve classification of the type of diabetes mellitus. RESULTS: Of the 382 study patients, 327 (85.6%) had autoimmune type 1 DM (clinical insulin-treated type 1 DM with immunologic and/or genetic evidence of autoimmunity) and 6 (1.6%) had idiopathic type 1 DM (clinical insulin-treated type 1 DM without evidence of autoimmunity). Four (1.0%) patients met all the criteria for type 2 DM; all were obese and three had acanthosis nigricans; in one the diagnosis was changed from type 1 to type 2 DM during follow-up. Four patients could be classified as lean patients with type 2 DM. In keeping with recent reports of a rise in the incidence of type 2 DM, 6 of these type 2 cases were diagnosed in the last year of the study. CONCLUSION: The ADA classification helps to understand the pathophysiology of pediatric DM, thus providing useful therapeutic guidance. At presentation, most cases of pediatric DM are type 1, but we show here that type 2 DM becomes now a diagnosis to consider although in children. Our study, from a one large study center is not an epidemiological one but is consistent with population studies. Systematic or targeted screening for type 2 in children should be discussed.

Adolescent↗
PubMed2001

[Congenital cholesteatoma in children--case reports].

The authors present three cases of congenital cholesteatoma in children. In two cases primary surgery was curative, in third patient one year after first surgery the residual cholesteatoma was diagnosed, and second surgery was performed. Finally in all cases good anatomical and functional effect was obtained. The natural history of congenital cholesteatoma, as well as surgical techniques which can be applied depending on type and location of congenital cholesteatoma are discussed. The authors emphasise the importance of early recognition of the disease. Exploratory tympanotomy, or CT scan should be applied in all cases where suspected changes are observed during otoscopy.

Adolescent↗
PubMed2000

Clinical and metabolic presentation of the lipodystrophic syndrome in HIV-infected children.

OBJECTIVE: To investigate body fat distribution and glucose and lipid metabolism in HIV-infected children with the aim of describing the lipodystrophic syndrome in children. DESIGN: Cross-sectional study including 39 HIV-infected children aged 3-18 years. MAIN OUTCOME MEASURES: Clinical lipodystrophy was defined as peripheral fat wasting (facial and/or buttock and/or limb atrophy with arm skinfold thickness lower than the third percentile of the reference values for sex and age) and/or truncal adiposity (breast enlargement and/or buffalo neck and/or relative abdominal obesity with trunk : arm skinfold ratio > 2 standard deviations). Fasting serum lipid concentrations were measured and an oral glucose tolerance test was performed. RESULTS: Of 39 HIV-infected children, lipodystrophy was observed in 13 children (33.3%): eight with truncal lipohypertrophy, three with peripheral lipoatrophy and two with combined lipodystrophy. Combined lipodystrophies were observed only in adolescents with a more severe presentation than in prepubertal children. Lipodystrophic children had higher fasting insulinaemia (7.0+/-8.5 versus 3.0+/-2.3 microU/ml; P = 0.07), suggesting a certain degree of insulin-resistance. Hypercholesterolaemia (23% versus 15%; P = 0.59 ) and hypertriglyceridaemia (15% versus 11%; P = 0.76) were observed with the same proportion in the lipodystrophic as in the non-lipodystrophic groups; 23% of the non-lipodystrophic children had dyslipidaemia. CONCLUSION: The lipodystrophic syndrome prevails in HIV-infected children in the three clinical forms initially described in adults but appears less severe before the initiation of puberty. Insulin-resistance occurs in lipodystrophic children only, whereas dyslipidaemia exists in non-lipodystrophic children as well, suggesting that dyslipidaemia could reflect subclinical alteration of the adipose tissue.

Adolescent↗
PubMed2000

Management of fetal thyroid goitres: a report of 11 cases in a single perinatal unit.

Fetal thyroid goitres may reveal hormonal imbalance. This can jeopardize neurological development and fetal outcome even when early postnatal treatment is provided. We report a series of 11 goitres diagnosed antenatally in women with past or present thyroid disorders or discovered fortuitously on ultrasound scan. Fetuses presented with hyperthyroidism in three cases and hypothyroidism in eight. Hypothyroidism was iatrogenic in five cases, due to maternal anti-thyroid drugs. Hyperthyroidism was induced by transplacental transfer of thyroid stimulating antibodies (TSHrab). Accurate diagnosis of fetal thyroid status was obtained by fetal blood sampling but this invasive method was deemed necessary only in four cases as maternal clinical and biological data and ultrasound signs provided sufficient information to infer the type of thyroid disorder in the remaining patients. Fetal therapy relied on reduction of maternal antithyroid medication and, in selected cases, intra-amniotic injection of levothyroxin in hypothyroidism, and on administration of antithyroid drugs in hyperthyroidism. All newborns were healthy and none displayed consequences of severe thyroid imbalance. No caesarean section was performed for dystocia. Fetal thyroid goitres can be managed successfully with selected use of invasive diagnostic and therapeutic techniques.

Female↗
PubMed2000

Type 1 diabetic children have abnormal lipid profiles during pubertal years.

AIM/HYPOTHESIS: To study the prevalence of hypercholesterolemia, hypertriglyceridemia and the relationship between metabolic control, pubertal status and plasma lipoprotein levels in children with diabetes mellitus. SUBJECTS AND METHODS: A cross-sectional study was conducted on 126 subjects with type I diabetes followed at our institution. There were 57 boys and 69 girls (mean age: 13.4+/-3.4 yr; mean duration of diabetes: 7.3+/-2.1 yr), on whom fasting lipoprotein levels and pubertal status were determined. Mean glycated hemoglobin (HbA1c) of the preceding year was used in the analysis. Cholesterol (CT) and triglyceride (TG) levels were transformed into standard deviations (SD) using age dependent normal values. RESULTS: 1) CT levels of DM children (mean level: +0.9+/-1.2 SD) are higher for both sexes and at each age. Sixteen percent of the cases had CT level > or =2 SD. Within the range of the HbA1c observed (9.1+/-1.2%), CT levels are not correlated with the degree of metabolic control. In contrast to non-diabetic children, CT levels of the diabetic children did not vary throughout pubertal stages. CT levels correlated highly with apolipoprotein B (r=0.79; p<0.00001 and r(2)=82%, in univariate and multivariate analysis, respectively. 2) Plasma TG levels are comparable in the diabetic children (mean level: -0.11+/-0.9 SD) and non-diabetic children. Only 5% of the diabetic children have a TG level > or =2 SD. The TG levels are significantly, but weakly, positively correlated with duration of diabetes and the degree of metabolic control (r(2)=12% and 16%, respectively, p<0.0001 for both). CONCLUSIONS: Plasma CT levels of type I diabetic children are increased in comparison to non-diabetic children and do not follow the usual decreasing pattern during puberty.

Journal Article↗
PubMed2000

Reproductive characteristics of the flower-breeding Drosophila hibisci Bock (Drosophilidae) in eastern Australia: within-population genetic determinants of ovariole number.

Genetic variation for ovariole number in the flower-breeding Drosophila hibisci was studied within populations obtained from three separate sites in the centre of the species distribution along the east coast of Australia. Heritability for ovariole number (adjusted for body size), derived from isofemale lines from each site, was estimated to be h2+/-SE = 0.564+/-0.160. The variance of ovariole number within sites (sigma2(within) = 2.039) was comparable to the variance between sites (sigma2(between) = 2.048) obtained from an earlier study of populations sampled over 14 degrees of latitude. Two isofemale lines (from within one site) that differed by an average of 4.6 ovarioles were used to generate F1, F2 and backcross generations. Analysis of mean ovariole number for these generations showed that only additive gene effects were important and that dominance, digenic epistasis and maternal effects were not significant. This within-population result contrasted with earlier results between populations that revealed additive and digenic epistasis for the same trait. High heritability within populations and the relatively large within-population variation for ovariole number suggest that substantial microhabitat variation is influencing this fitness-related trait.

Animals↗
PubMed2000

Genetic architecture of a wing size measure in Drosophila hibisci from two populations in eastern Australia.

Two models of evolutionary change invoke either additive genetic contributions to phenotypic traits (Fisher) or epistatic as well as additive effects (Wright). An earlier study of the flower-breeding Drosophila hibisci from two sites in eastern Australia reported additive and epistatic genetic effects as well as environmental effects on ovariole number. The present study of the same flies examines the genetic architecture of wing width, a trait that is correlated phenotypically with ovariole number and body size. A generation means analysis of flies reared at 25 degrees C indicated additive and epistatic genetic effects, but no consistent maternal effects, whereas for flies reared at three temperatures (18 degrees C, 21.5 degrees C, and 25 degrees C) linear and nonlinear environmental effects interacted with additive genetic effects. The genetic correlation matrix for ovariole number and wing width suggested negative genetic correlations between additive effects on one trait and epistatic effects on the other. Both traits provide evidence of genetic effects consistent with assumptions of Wright's shifting balance theory of evolution.

Animals↗
PubMed2000

How accurate is the prenatal diagnosis of abnormal genitalia?

PURPOSE: The prenatal diagnosis of abnormal genitalia may have a major impact on prenatal counseling and postnatal outcome. We studied the accuracy and clinical implications of the prenatal diagnosis of abnormal genitalia. MATERIALS AND METHODS: Between 1991 and 1999 the prenatal and/or postnatal diagnosis of abnormal genitalia in 53 cases was made at our institution. All cases were prenatally assessed at our Obstetrics and Fetal Medicine Department. Outcome was confirmed postnatally or by a fetopathologist in the case of pregnancy termination. RESULTS: A genital anomaly was prenatally diagnosed in 43 cases and was accurate in 34, while in 9 cases anomalies were absent at birth. In 10 cases ambiguous genitalia were not detected prenatally. The primary anomalies suspected were male pseudohermaphroditism in 19 cases and female pseudohermaphroditism in 12, including 2 cases of congenital adrenal hyperplasia. Male pseudohermaphroditism was detected prenatally in 17 cases and diagnosis was confirmed at birth. Female pseudohermaphroditism was detected prenatally in 12 cases and only 5 were confirmed and the anomaly was discovered at birth in 6. The prognosis was highly altered when many malformations or aneuploidy was associated with ambiguous genitalia. Of the 15 patients with many malformations only 3 survived, and pregnancy was terminated in 3 of 4 cases of aneuploidy. CONCLUSIONS: When pseudohermaphroditism was detected in a male fetus by an experienced ultrasonographer at a tertiary center the prenatal diagnosis was accurate in 100% of cases. The prenatal diagnosis was less accurate (46% correct) in a female fetus.

Disorders of Sex Development↗