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Biomedical subjects

S Jansen

Publications and source records attributed to S Jansen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Influence of the SstI polymorphism at the apolipoprotein C-III gene locus on the plasma low-density-lipoprotein-cholesterol response to dietary monounsaturated fat.

The plasma lipid response to changes in dietary fat and cholesterol can vary between individuals. The SstI polymorphism, arising from a cytosine to guanosine substitution in the 3' untranslated region of the APOC3 gene distinguishes between two alleles--S1 and S2. The S2 allele has been associated with elevated plasma triacylglycerol, cholesterol, and apolipoprotein (apo) C-III concentrations. In 90 young men we examined the effect of the same mutation on the response of low-density-lipoprotein (LDL) cholesterol to dietary monounsaturated fat. The frequency for the S2 allele was 0.14. Subjects were fed a low-fat diet for 25 d, followed by a diet rich in monounsaturated fatty acid (22% MUFA, 38% total fat) for 28 d; lipoproteins were measured at the end of each diet. There were no significant differences in initial total cholesterol between subjects with the APOC3*S1/APOC3*S1 (S1/S1) and APOC3*S1/APOC3*S2 (S1/S2) genotypes. After consumption of the diet high in MUFA, significant increases in LDL cholesterol (0.13 mmol/L, P < 0.027) were noted in the S1/S1 subjects whereas a significant decrease was observed in the S1/S2 subjects (-0.18 mmol/L, P < 0.046). Significant genotypic effects were seen for diet-induced changes in LDL cholesterol (P < 0.00034), total cholesterol (P < 0.009), and apo B (P < 0.0014). A study of the effect of the interaction between this mutation with that present in position -76 of the APOA1 gene promoter region (G/A) revealed that both mutations had an additive effect on changes in total cholesterol, LDL cholesterol, and apo B induced by diets. Plasma LDL-cholesterol responsiveness to the diet may be explained, at least in part, by variation at the APOC3 gene locus.

Adult↗
PubMed1997

Effect of 347-serine mutation in apoprotein A-IV on plasma LDL cholesterol response to dietary fat.

Lipid response to dietary fat and cholesterol is, to a large extent, genetically controlled. Apoprotein (apo) A-IV has been related to fat absorption and to the activation of some of the enzymes involved in lipid metabolism. One mutation has been described in the apo A-IV gene that causes substitution of Ser for Thr at position 347. To study the influence of this mutation on the plasma LDL cholesterol (LDL-C) response in diets of various fat content and fatty acid saturation, 41 healthy male subjects were studied, 25 of whom were homozygous for the Thr allele (347Thr) and the rest who were either homozygous (n = 2) or heterozygous carriers of the Ser allele (347Ser). They consumed three consecutive diets, each of 4 weeks' duration: one rich in saturated fat (SFA diet: 38% fat, 20% saturated), a National Cholesterol Education Program (NCEP) type 1 diet (28% fat, 10% saturated), and a third rich in monounsaturated fat (MUFA diet; 38% fat, 22% monounsaturated). Carriers of the 347Ser allele presented a greater decrease in total cholesterol (-0.7 vs -0.44 mmol/L, P < .034), LDL-C (-0.62 vs -0.31 mmol/L, P < .012), and apo B (-14 vs -8 mg/dL, P < .01) levels when they were switched from the SFA to the NCEP type 1 diet than homozygous carriers of the 347Thr allele. The change from the NCEP type 1 to the MUFA diet resulted in a greater increase in total cholesterol (0.18 vs -0.05 mmol/L, P < .028) and apo B (5 vs -1 mg/dL, P < .006) levels in the 347Ser than in the 347Thr individuals. In a previous study, we demonstrated that the G-->A polymorphism at position -76 of the gene promoter of apo A-I affects the LDL-C response to dietary fat. We therefore decided to study the effect of the interaction between these mutations on this response. We found that both mutations have an additive effect on total cholesterol, LDL-C, and apo B dietary-induced changes. Our results suggest that total cholesterol and LDL-C response to dietary fat is influenced by the 347Ser mutation of apo A-IV.

Adult↗
PubMed1997

Dietary fat clearance in normal subjects is modulated by genetic variation at the apolipoprotein B gene locus.

Apolipoprotein B (apo B) plays a dominant role in cholesterol homeostasis. Several polymorphic sites within or adjacent to the gene locus for apo B have been detected. The X+ allele (XbaI restriction site present) of the XbaI restriction fragment polymorphism on the apo B gene has been found in some studies to be associated with higher serum cholesterol and/or triglyceride levels and with greater dietary response. The present study was designed to evaluate whether the apo B XbaI polymorphism was associated with the interindividual variability observed during postprandial lipemia. Fifty-one healthy young male volunteers [20 X-/X- (X-), and 31 X+/X- or X+/X+ (X+)], homozygotes for the apo E3 allele, were subjected to a vitamin A-fat load test. Subjects with the X- genotype had significantly greater retinyl palmitate (RP) and apo B-48 postprandial responses on both the large and the small TRL lipoprotein fractions compared with X+ subjects. In summary, subjects with the X-/X- genotype at the apo B locus have a greater postprandial response than X+ subjects. These differences observed in postprandial lipoprotein metabolism could explain some of the reported associations of this polymorphism to coronary heart disease risk.

Adolescent↗
PubMed1997

Preoperative ultrasound to predict conversion in laparoscopic cholecystectomy.

Laparoscopic cholecystectomy (LC) is the established treatment for symptomatic cholelithiasis. With its decreased postoperative stay, it is being performed increasingly in short-stay or outpatient settings. It is particularly important to identify preoperative factors that may predict conversion to open cholecystectomy (OC) at LC, with its concomitantly prolonged hospital recovery. In this series of 738 patients, the ultrasound features of stone size, gallbladder wall thickness, diameter of the common bile duct, number of stones, and the appearance of a contracted gallbladder were assessed preoperatively in all patients. The overall conversion rate was 3.5% (26 of 738). By logistic regression analysis, factors found to increase significantly the risk of conversion were patient age > 70 years (p < 0.01), a stone at least 20 mm in diameter (p < 0.05), a gallbladder wall thicker than 4 mm (p < 0.05), a common bile duct wider than 6 mm (p < 0.05), and contracted gallbladder on ultrasound (p < 0.02). The number of stones in the gallbladder was not significant. Using these risk factors, it was possible to divide patients into high- and low-risk groups. The 118 patients in the high-risk group had 18 of the 26 conversions, for a conversion rate of 15.3%. The 620 patients in the low-risk group had eight of the 26 conversions, for a conversion rate of 1.3%. This low-risk subgroup represented 84% of the series of 738 LC procedures and may have been suitable for outpatient LC. Using preoperative ultrasound, it is possible to predict patients who are at low risk of conversion and are suitable for ambulatory surgery.

Age Factors↗
PubMed1997

Effect of 360His mutation in apolipoprotein A-IV on plasma HDL-cholesterol response to dietary fat.

In order to determine whether genetic variability of apolipoprotein (apo) A-IV is responsible for the improvement in lipid profile when dietary saturated fats are replaced by carbohydrates or monounsaturated fats, 41 healthy male subjects were studied: 33 were homozygous for the 360Gln allele and 8 were heterozygote carriers of the 360His allele. These were administered three consecutive 4-week diets. The first was a diet rich in saturated fat (SAT diet, with 38% fat, 20% saturated. This was followed by a low fat diet (NCEP-I, with < 30% fat, < 10% saturated). The final diet was rich in monounsaturated fat (MUFA diet, with 38% fat, 22% monounsaturated). There was no difference in plasma lipid and apolipoprotein levels of both groups of individuals after consuming the SAT diet. Switching from this diet to the NCEP-I diet, carriers of the 360His allele presented a greater decrease in high density lipoprotein-cholesterol (HDL-C) (-10 vs. -1 mg/dL, P < 0.004) and apoA-I levels (-19 vs. -8 mg/dL, P < 0.037). Similarly, replacement of carbohydrates by monounsaturated fats produced a greater increase in HDL-C (9 vs. 1 mg/dL, P < 0.003) and apoA-I levels (9 vs. 2 mg/dL, P < 0.036) in carriers of the 360His mutation. Lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) activities and apoA-IV levels were also measured. However, no genotype-related differences were observed for these parameters. Our results suggest that variability in HDL-C and apoA-I response to diet is, at least partially, determined by the 360His mutation of apoA-IV.

Adult↗
PubMed1996

Novel mutations and polymorphisms in the Fanconi anemia group C gene.

Fanconi anemia (FA) is an autosomal recessive disorder associated with hypersensitivity to DNA cross-linking agents and bone marrow failure. At least four complementation groups have been defined, and the FA group C gene (FAC) has been cloned. We have screened 76 unrelated FA patients of diverse ethnic and geographic origins and from unknown complementation groups for mutations in the FAC gene either by chemical cleavage mismatch analysis or by single-strand conformational polymorphism (SSCP). Five mutations were detected in four patients (5.3%), including two novel mutations (W22X and L496R). Nine polymorphisms were detected, seven of which have not been described previously (663A-->G, L190F, IVS6 + 30C-->T, I312V, V449M, Q465R, and 1974G-->A). Six of the nine polymorphisms occurred in patients or controls from the Tswana or Sotho chiefdoms of South Africa and were not found in 50 unrelated European controls. Restriction site assays were established for all 8 pathogenic mutations identified in the FAC gene to date and used to screen a total of 94 unrelated FA patients. This identified only one other group C patient, who was homozygons for the mutation IVS4 + 4A-->T. This study indicates that the proportion of FA patients from complementation group C is generally likely to be less than 10%. Guidelines for the selection of FA patients for FAC mutation screening are proposed.

Cell Cycle Proteins↗
PubMed1996

Distribution and transmission of Pseudomonas aeruginosa and Burkholderia cepacia in a hospital ward.

Genotyping and antibiotic susceptibility testing were used to analyze Pseudomonas aeruginosa and Burkholderia cepacia strains from sink drain from 14 pediatric patients with cystic fibrosis (CF) and from hospital personnel as part of a 4 week prospective study of strain transmission in a pediatric ward. A total of 87.5% of all washbasin drains were contaminated with P. aeruginosa [10(2) to 10(5) colony forming units (CFU)/ml sink fluid], whereas B. cepacia was found only once in a sink drain. From the eight CF patients already infected with P. aeruginosa upon entering the ward, we isolated six genotypes that were identical with strains found in sink drains of the ward. Four of the 16 members of the personnel had one positive P. aeruginosa hand culture. B. cepacia was never found in patients or on personnel hands. Hand washing in contaminated sinks (> or = 10(3) CFU/ml) led to positive P. aeruginosa or B. cepacia hand cultures. P. aeruginosa or B. cepacia embedded in sputum were transmissable by hand shaking for up to 180 min, whereas both pathogens suspended in physiological saline were transmissable to other hands only up to 30 min. Genotyping of P. aeruginosa revealed strain transmission from CF patients or the environment to other patients or the personnel, as well as one transmission from the environment to a CF patient. The ability of CF sputum to prolong survival of P. aeruginosa and B. cepacia may be important for strain transmission. The results suggest that improved hygienic measures are required to prevent routes of bacterial transmission via the hands and sink drains.

Adolescent↗
PubMed1996

Boar sperm proacrosin infrared investigation: secondary structure analysis after autoactivation and suramin binding.

Fourier transform infrared spectroscopy was used to investigate the secondary structure of boar sperm proacrosin at p2H 5.5, to determine the structural changes following protein autoactivation to beta-acrosin at p2H 8.0 and to study the effect of suramin binding on the protein secondary structure. At p2H 5.5, proacrosin contents of alpha-helix, beta-sheet, turns, and unordered structures were estimated to be 9, 49-51, 16-18, and 24%, respectively. At p2H 8.0, the protein was partially insoluble; spectral analysis of the soluble fraction, which contained beta-acrosin, showed an overall secondary structure quite similar to that of proacrosin at p2H 5.5. However, p2H 8.0 spectra of the soluble protein (beta-acrosin), together with the thermal denaturation experiments, indicated that, compared to proacrosin, beta-acrosin showed an increased content of beta-sheets exposed to the solvent as well as a different tertiary structure. Proacrosin/suramin interaction at p2H 5.5 resulted in the formation of soluble and insoluble complexes and the relevant infrared spectra showed only minor differences with respect to the native proacrosin. However, the thermal denaturation curves revealed that suramin induced a destabilization of proacrosin structure. The data also indicated that suramin could modify the interaction characteristics of proacrosin aspartyl and glutamyl residues, thus suggesting competition of suramin with these two residues for ionic interactions.

Acrosin↗
PubMed1996

Clinical studies of multiple endocrine neoplasia type 1 (MEN1)

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the combined occurrence of parathyroid, pancreatic islet and anterior pituitary tumours. To facilitate a screening programme for MEN1, we investigated 709 people (364 males and 345 females, age range 1-84 years) from 62 MEN1 families, and 36 non-familial MEN1 patients. Of those investigated, 220 (95 males and 125 females, age range 8-79 years) suffered from MEN1. Parathyroid, pancreatic and pituitary tumours occurred in 95%, 41% and 30% of the patients, respectively. Parathyroid tumours were the first manifestation of MEN1 in 87% of patients, and amongst the pituitary and pancreatic tumours, somatotrophinomas and gastrinomas were more common in patients above the age of 40 years, whilst insulinomas occurred more frequently in patients below the age of 40 years. Biochemical screening indicated that the penetrance of MEN1 by the ages of 20, 35 and 50 years was 43%, 85% and 94%, respectively, and that the development of MEN1 was confined to first-degree relatives in 91% of patients and to second-degree relatives in 9% of patients. These findings have helped to define a proposed screening programme for MEN1.

Adolescent↗
PubMed1996

[Improved organ survival in transplantation of pediatric kidneys by optimizing donor-recipient size relation].

The risk for renal allograft failure in pediatric renal transplantation (donor age below 3 years) is still high, although it has been reduced by the use of potent immunosuppressive therapies. In this study we report on experience with 80 kidneys of donors below 3 years of age (PD) transplanted at the University of California at San Francisco Hospital in accordance with the policy of minimizing donor-recipient size differences. The graft survival rates were comparable with the results for adult donors, 18-50 years of age (AD, n = 891): at 1 year PD 74.1% vs AD 85.5%, at 2 years PD 70.5% vs AD 80.2%, at 3 years PD 63.5% vs AD 76%; there were no significant differences. The policy of minimizing donor-recipient size differences seems to improve graft survival rates, avoiding the tendency for hyperfiltration phenomena and possibly being responsible for this salutary effect. We conclude that the use of pediatric donor kidneys can yield excellent long-term results independent of primary disease if the donor-recipient size difference is minimized and a potent immunosuppressive regimen is employed.

Adolescent↗
PubMed1996

[Proacrosin and acrosin--retrospect of a multifunctional complex].

Proacrosin is a molecule that is located under the acrosomal cap and that acts as a secondary ligand after acrosome reaction. Proacrosin is thought to bind to ZP2 (zona pellucida receptor 2). The high affinity is based on the interaction of the zona pellucida glycoprotein's acidic sulphate groups with basic, positively charged amino acids of the proacrosin molecule. Proacrosin is a serine protease and is capable to lyse the zona pellucida locally. Our structural analysis of proacrosin shows, that the catalytic centre is surrounded by loops containing positively charged amino acids which create the binding domain. This review is intended to describe the results that lead to the elucidation of the biochemistry of proacrosin.

Acrosin↗
PubMed1996

[The problem of breeding for fertility].

The reproductive success in domestic animals is an important factor towards the economical production of livestock. Thus, a lot of energy has been spent on the amelioration of the reproduction by means of genetics but no considerable success was achieved since the additive genetic variance is low. This communication is supposed to elucidate its molecular biological basis in reproduction and furthermore, the article should point out the way in research how to improve reproductive parameters. We propose to characterize all sorts of genes and their gene products that are involved in reproduction. This is to realize a full understanding of the sperm egg interaction and to derive benefit from effects like heterosis.

Animals↗
PubMed1995

[Possible relationship between overweightness and prevalence of hyperlipemia in the children of patients with heterozygote familial hypercholesterolemia and combined familial hyperlipemia].

BACKGROUND: Heterozygote familial hypercholesterolemia and combined familial hyperlipemia are associated to a greater risk of coronary disease. Combined familial hyperlipemia has classically been indicated to manifest after the second decade in life. The aim of this study was to establish whether a systematic search would demonstrate the existence of combined familial hyperlipemia earlier and analyze whether the antropometric parameters related with the overweightedness accompany the appearance of the lipid disorders of this disease found at an early age. PATIENTS AND METHODS: Different lipid parameters were studied in 89 subjects under the age of 18 who were children of patients with heterozygote familial hypercholesterolemia and combined familial hyperlipemia. Likewise the weight, height and waist/hip quotient were evaluated. Hyperlipemia was considered as the presence of cholesterol/LDL and/or triglicerides greater than the 95 percentile for age and sex. RESULTS: Hyperlipemia was observed in 51% and 40% of the children of patients with heterozygote familial hypercholesterolemia and combined familial hyperlipemia, respectively. The body mass index and the waist/hip quotient of the latter children significantly correlated with the cholesterol-HDL values and the LDL/HDL quotient. CONCLUSIONS: The patients with known combined familial hyperlipemia have a high percentage of children with hyperlipemia during infancy. These data suggest a possible association between obesity in the appearance of hyperlipemia in the children of patients with combined familial hyperlipemia at this age.

Adolescent↗