Initial evaluation of a novel multibending backward-oblique viewing duodenoscope in endoscopic retrograde cholangiopancreatography

A novel multibending backward-oblique viewing duodenoscope was developed to overcome the difficult technical aspect of deep cannulation into the bile duct during endoscopic retrograde cholangiopancreatography (ERCP). The aim of the present study was to evaluate the initial experience of a novel multibending backward-oblique viewing duodenoscope (M-D scope) for ERCP. This was a retrospective review of 23 patients with native papilla who received biliary ERCP with the M-D scope between April and December 2010. The procedures were performed by two well-experienced endoscopists. In all patients, biliary cannulation and therapeutic procedure were successfully completed. In two patients with Billroth I gastrectomy, ERCP were initially attempted with a conventional single-bending duodenoscope, but biliary cannulations were unsuccessful. However, with the use of the M-D scope, biliary cannulation and therapeutic procedures were successfully completed. A novel multibending backward-oblique viewing duodenoscope is safe and feasible for therapeutic and diagnostic ERCP.

Plasma fatty acids profile and estimated elongase and desaturases activities in Tunisian patients with the metabolic syndrome

This study aimed to determine plasma fatty acids pattern and to estimate desaturases activities in Tunisian subjects with metabolic syndrome (MetS). A total of 1975 adults were randomly selected from the Great Tunis region (Tunisia). MetS was defined according to the International Diabetes Federation criteria. Saturated and monounsaturated fatty acids levels and delta 9 desaturase activity were increased, but polyunsaturated fatty acids (PUFA) levels and delta 5 desaturase activity were decreased in patients with MetS. Using multivariate analysis, MetS was found inversely associated with PUFA; compared to first quartile, multi-adjusted odd ratios (95% confidence interval) of MetS were 0.80 (0.54-1.17), 0.47 (0.27-0.81) and 0.32 (0.15-0.68) for second, third and fourth quartiles of PUFA, respectively. Altered fatty acids pattern in MetS is likely related to both dietary and metabolic changes.

The G3057A LEPR polymorphism is associated with obesity in Tunisian women

OBJECTIVES

The aim of this study was to evaluate the effect of the G3057A (rs62589000) LEPR polymorphism on obesity risk and plasma leptin, insulin, and lipid levels in a sample of the Tunisian population.

DESIGN AND METHODS

Three hundred and ninety-three obese patients and 317 controls participated in this study. The G3057A genotype was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

In the entire study sample, no significant differences in genotype frequencies were observed between obese patients and controls. However, stratified analysis by gender revealed a quantitative increase in the variant allele (33.3% vs. 25.8%; χ(2)=4.90, p=0.026) in obese women (but not men) compared to controls. When a dominant model of inheritance was assumed, the GA+AA genotypes were more prevalent in these obese female patients than in controls (58.3% vs. 47.8%; χ(2)=4.08, p=0.044). Unconditional logistic regression showed that in women only, obesity risk was significantly higher for homozygotes for the variant allele (OR=2.73, 95% CI 1.03-7.21) and for carriers of GA+AA genotypes (OR=1.53, 95% CI 1.01-2.31) compared with homozygotes for the normal allele. The association between the G3057A LEPR variant and obesity remained statistically significant even after adjustment for age. No relationship was found between the G3057A LEPR polymorphism and leptin and insulin levels. Additionally, this LEPR gene variant had no effect on plasma lipid concentrations.

CONCLUSION

There is evidence in this study that the G3057A LEPR polymorphism is associated with obesity in Tunisian women.

The Relationship between Blood Lactate and Survival following the Use of Adrenaline in the Treatment of Septic Shock

This prospective observational study evaluates the relationship between adrenaline, lactate and intensive care unit survival in septic shock. Forty patients requiring adrenaline therapy for a first episode of septic shock acquired >24 hours after admission to the intensive care unit had blood lactate levels measured two-hourly over a 24-hour period. Adrenaline therapy was escalated until target mean arterial pressure was reached. The lactate index was calculated as the ratio of maximum lactate increase to the adrenaline increase. Lactate increased from 2.3 to 2.9 mmol.l-1 (P=0.024) and the mean adrenaline increase was 0.14 μg.kg-1.minute-1. Peak lactate correlated with peak adrenaline (rho=0.34, P=0.032). Lactate index was the only independent predictor of survival after controlling for age and Acute Physiological and Chronic Health Evaluation II score (odds ratio 1.14, 95% confidence interval 1.03 to 1.26, P=0.009). A high lactate following adrenaline administration may be a beneficial and appropriate response.

Secondary acute myeloid leukemia after successful treatment for osteosarcoma

Secondary acute myeloid leukemia (sAML) is a rare complication following chemotherapy for osteogenic sarcoma. However, the exact offending drug is difficult to prove as there is no consistent data. It usually develops 2 years after completion of therapy. We report a case of sAML that developed within 8 months of completing the treatment. The patient was treated with cisplatin, doxorubicin and high-dose methotreaxate followed by surgery (amputation). Eight months after completion of therapy, while on follow-up, he presented with leukocytosis and thrombocytopenia and confirmed to have AML.

A pilot study of EUS-guided hot saline injection for induction of pancreatic tissue necrosis

BACKGROUND AND STUDY AIMS

Hot saline may be potentially useful for inducing necrosis of pancreatic tissue. However, the local and systemic effects are largely unknown. This pilot study aimed to evaluate the feasibility and safety of EUS-guided injection of hot saline into the pancreas in the porcine model.

METHODS

Boiling hot saline was injected into the tail of normal porcine pancreas under EUS guidance in six pigs via a transgastric approach. Three pigs were killed 4 hours later to study the acute effect of the hot saline injection (acute study). The remaining three pigs were killed after 7 days of clinical observation (survival study).

RESULT

Injection of 5 mL, 2 mL and 1 mL of hot saline produced localized necrosis (7 - 10 mm) of pancreatic tissue in the acute study. However, there was pooling of hot saline on the surface of the pancreas when 5mL was injected. On the basis of the results of the acute study, the volume of hot saline injected in the survival study was 1 mL. One milliliter of hot saline produced localized or sporadic necrosis of pancreatic tissue without any signs of pancreatitis in all three pigs in the survival study; hot saline was observed to pool on the pancreatic surface of one pig. There was no histological evidence of necrosis in the pancreatic tissue adjacent to the pooled hot saline in either the acute or the survival study.

CONCLUSION

EUS-guided hot saline injection of pancreatic tissue in the porcine model was technically successful and led to localized necrosis of pancreatic tissue without any sign of pancreatitis.

Clinical spectrum of SIX3-associated mutations in holoprosencephaly: correlation between genotype, phenotype and function

BACKGROUND

Holoprosencephaly (HPE) is the most common structural malformation of the human forebrain. There are several important HPE mutational target genes, including the transcription factor SIX3, which encodes an early regulator of Shh, Wnt, Bmp and Nodal signalling expressed in the developing forebrain and eyes of all vertebrates.

OBJECTIVE

To characterise genetic and clinical findings in patients with SIX3 mutations.

METHODS

Patients with HPE and their family members were tested for mutations in HPE-associated genes and the genetic and clinical findings, including those for additional cases found in the literature, were analysed. The results were correlated with a mutation-specific functional assay in zebrafish.

RESULTS

In a cohort of patients (n = 800) with HPE, SIX3 mutations were found in 4.7% of probands and additional cases were found through testing of relatives. In total, 138 cases of HPE were identified, 59 of whom had not previously been clinically presented. Mutations in SIX3 result in more severe HPE than in other cases of non-chromosomal, non-syndromic HPE. An over-representation of severe HPE was found in patients whose mutations confer greater loss of function, as measured by the functional zebrafish assay. The gender ratio in this combined set of patients was 1.5:1 (F:M) and maternal inheritance was almost twice as common as paternal. About 14% of SIX3 mutations in probands occur de novo. There is a wide intrafamilial clinical range of features and classical penetrance is estimated to be at least 62%.

CONCLUSIONS

Our data suggest that SIX3 mutations result in relatively severe HPE and that there is a genotype-phenotype correlation, as shown by functional studies using animal models.

Lattice parameter determination using a curved position-sensitive detector in reflection geometry and application to Smx/2Ndx/2Ce1–xO2–δceramics

X-ray diffractometers with curved position-sensitive (CPS) detectors have become popular for their ability to perform fast data collection over a wide 2θ range, enabling kinetics studies of chemical reactions and measurement of other time-resolved solid-state phenomena. While the effect of sample displacement onhkl-specific apparent lattice parameters has been explored for a transmission-mode Debye–Scherrer geometry, such effects for a reflection-mode Debye–Scherrer geometry are not yet well understood. The reflection-mode Debye–Scherrer geometry for CPS detectors is unique in the sense that the angle for the incident X-ray beam is kept fixed with respect to the normal of a flat diffracting sample, while the diffracted beams are measured at multiple angles with respect to the sample normal. An efficient method for precise lattice parameter determination using linear extrapolation of apparent lattice parameters calculated from differenthkldiffraction peaks is proposed for such geometries. The accuracy involved with this method is investigated for an Si powder standard. The extrapolation method is then applied to develop an empirical relationship between composition (x) and the lattice parameter (ao) of Smx/2Ndx/2Ce1−xO2−δceramics for solid oxide fuel cell electrolytes. In this system, the empirical relationship betweenxandaois compared with a previous theoretical prediction.

Magnifying endoscopy with narrow band imaging for predicting the invasion depth of superficial esophageal squamous cell carcinoma

The invasion depth of superficial esophageal squamous cell carcinoma is important in determining therapeutic strategy. The aim of this study was to prospectively investigate the clinical utility of magnifying endoscopy with narrow band imaging compared with that of non-magnifying high-resolution endoscopy or high-frequency endoscopic ultrasonography in predicting the depth of superficial esophageal squamous cell carcinoma. The techniques were carried out in 72 patients with 101 superficial esophageal squamous cell carcinomas, which were then resected by either endoscopic mucosal resection or esophagectomy. The histological invasion depth was divided into two: mucosal or submucosal carcinoma. We investigated the relationship between endoscopic staging and histology of tumor depth. Non-magnifying high-resolution endoscopy, magnifying endoscopy with narrow band imaging, and high-frequency endoscopic ultrasonography had overestimation/underestimation rates of 7/5, 4/4 and 8/3%, respectively. The sensitivity rates for the three techniques were 72, 78, and 83%, respectively, and the specificity rates were 92, 95, and 89%, respectively. There were no statistically significant differences among the three endoscopic techniques. Clinical utility of magnifying endoscopy with narrow band imaging does not seem to be significantly different from that of non-magnifying high-resolution endoscopy or high-frequency endoscopic ultrasonography in predicting the depth of superficial esophageal squamous cell carcinoma. Magnifying endoscopy with narrow band imaging may have potential to reduce overestimation risks of non-magnifying high-resolution endoscopy or high-frequency endoscopic ultrasonography.

Endoscopic ultrasound-guided drainage of abdominal abscesses and infected necrosis

Traditionally abdominal abscesses have been treated with either surgical or radiologically guided percutaneous drainage. Surgical drainage procedures may be associated with considerable morbidity and mortality, and serious complications may also arise from percutaneous drainage. Endoscopic ultrasound (EUS)-guided drainage of well-demarcated abdominal abscesses, with adjunctive endoscopic debridement in the presence of solid necrotic debris, has been shown to be feasible and safe. This multicenter review summarizes the current status of the EUS-guided approach, describes the available and emerging techniques, and highlights the indications, limitations, and safety issues.

[XbaI polymorphism of apolipoprotein B gene in a Tunisian population: alleles frequencies and relationship with plasma lipid parameters]

Apolipoprotein B (Apo B) is a component of chylomicrons, low-density lipoproteins (LDL), very low density lipoproteins (VLDL), and intermediate-density lipoproteins (IDL) and is the ligand for the LDL receptor. Thereby, Apo B plays a central role in lipoprotein metabolism and in maintaining the normal homeostasis of serum cholesterol levels. Several Apo B restriction fragment length polymorphisms (XbaI, EcoRI, MspI) have been reported to be associated with variation in lipid levels, obesity and/or coronary artery disease. To date, no data are available on relationship between XbaI Apo B polymorphism and lipid levels in Tunisian population. Here, we report frequencies of the XbaI polymorphism of the Apo B gene and we assess the effect of this polymorphism on lipid and lipoprotein concentrations in Tunisian population. Blood samples from 296 Tunisian individuals (112 women and 184 men, aged 51.4+/-9.6 years), were analysed for total cholesterol, triglycerides, HDL-cholesterol and apolipoproteins A1 and B. In parallel, genotyping by means of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) was performed. The XbaI polymorphism was associated with differences in plasma cholesterol (p=0.04), triglyceride (p=0.02) and apolipoprotein A1 (p=0.004), individuals with the genotype X1X1 have the lowest mean levels and those with the genotype X2X2 have the highest, with the individuals heterozygous for the polymorphism having intermediate levels. According to sex, the XbaI polymorphism effect was only observed for triglyceride in men. Thus, the results demonstrate an influence of XbaI polymorphism of Apo B gene on serum total-cholesterol, triglycerides and apolipoprotein A1 concentrations among Tunisian population.

On the molecular electron structure of three phosphinine-containing macrocycles

A broad set of structural models and theoretical methods has been successfully used for studying both the molecular electron structure of the silacalix[3]phosphinine and the changes of the macrocycle core under the conditions that frequently correspond to its complexes with metals. The macrocycle core of the silacalix[3]phosphinine and its neutral derivatives are strongly deviated from the main molecular plane. The phosphorous electron lone pairs and the pi-cloud of the phosphinine units give the main contribution to the electron valence structure in the silacalix[3]phosphinine and also in its both oxidized and reduced derivatives. Although the electron lone pairs of the P atoms tend to be strongly repulsive, they are either totally or partially extended above all the fragment of the phosphorous atoms depending on geometrical factors or even strongly coupled with the pi-cloud of the phosphinine units. Electronic processes that take away part of the electron density from the macrocyle favor both its planar configuration and the asymmetric distribution of the valence electrons in the silacalix[3]phosphinine and its derivatives. The limit condition to this effect is the appearance of a new in-plane sigma molecular orbital between the P atoms of two neighboring phosphinine units.

Is molecular biology the best alternative for diagnosis of malaria to microscopy? A comparison between microscopy, antigen detection and molecular tests in rural Kenya and urban Tanzania

OBJECTIVE

To assess the agreement of different diagnostic methods for the diagnosis and confirmation of the clinical suspicion of Plasmodium infection in children in Tanzania and Kenya.

METHOD

Blood samples were collected by the finger prick method from 338 children. Blood samples were collected from 338 children with the clinical suspicion of uncomplicated malaria in health clinics in Tanzania and Kenya. The presence of Plasmodium parasites was assessed with microscopy, rapid diagnostic tests (RDTs) and the molecular assays, quantitative nucleic acid sequence based amplification (QT-NASBA) and polymerase chain reaction (PCR). The results were compared and analysed for agreement.

RESULTS

There was a high degree of agreement (88.6-100%) between RDTs or molecular tests and microscopy. In rural Kenya, with a high incidence of malaria cases, the correlation coefficient ranged from 0.94 for RDTs to 0.76 for PCR. In urban Tanzania, where there was a low incidence of cases, R for RDTs was 1.0 but only 0.25 for PCR and 0.33 for NASBA.

CONCLUSION

Malaria is overestimated if the diagnosis is based solely on clinical signs. Therefore, laboratory confirmation is essential. Microscopy is a reliable method in rural areas where malaria is prevalent, but RDTs offer a good alternative with the advantage that it is an easy and rapid method. Molecular tests are more sensitive but difficult to implement in rural areas. In areas with lower incidence, molecular tests detect a significantly higher number of Plasmodium infections than RDTs or microscopy. Although implementation of molecular tools can be difficult, the prospect of an easy and cheap detection system makes them promising tools for the near future.

Primary precutting versus conventional over-the-wire sphincterotomy for bile duct access: a prospective randomized study

BACKGROUND AND STUDY AIMS

Precut is a well-known technique that is used if repeated attempts at common bile duct (CBD) cannulation fail. Opinions on the complication rate of precut are conflicting, however. The aim of the present study was to compare the efficacy and complication rate of precut used as a primary method of CBD access with the efficacy and safety of the conventional technique.

PATIENTS AND METHODS

During the 19-month study period, consecutive patients who were scheduled for first-time endoscopic sphincterotomy (ES) for a variety of biliary disorders were randomized into two groups: patients in group A underwent conventional wire-guided biliary cannulation followed by ES (with precut being performed only when this failed); in patients in group B precut was used as a primary technique to gain biliary access, followed by wire-guided ES. We used a specially designed, modified Erlangen type of sphincterotome for precutting.

RESULTS

A total of 291 patients (100 men, 191 women; mean +/- SD age 65 +/- 17.5 years) were recruited: 146 patients were assigned to group A (conventional approach) and 145 to group B (primary precut approach). The indications for ES were comparable in the two groups. In group A, wire-guided cannulation of the CBD failed in 42 patients. Secondary precut was successful in 41 of these patients, leading to an overall success rate of 99.3 %. In group B, the ES success rate using primary precut was 100 % at the first attempt. The mean time to successful deep CBD cannulation was 8.3 +/- 2.1 minutes in group A and 6.9 +/- 1.8 minutes in group B ( P < 0.001). The incidence of mild to moderate pancreatitis was similar in the two groups (2.9 % in group A vs. 2.1 % in group B, P > 0.05). Mild bleeding occurred in only one patient (from group A) and this was controlled by epinephrine injection. None of the study patients developed severe pancreatitis or perforation.

CONCLUSIONS

In experienced hands, an approach using primary precut appears to be at least as successful and safe as a conventional approach using guide-wire-based CBD cannulation followed by ES, and might also be a quicker method.

[Iron metabolism, overview and recent insights]

The paper is an up to date overview of knowledge on iron metabolism that integrate recent findings in this field. Significant advances were made in understanding the implication of protein factors (transporters, enzymes and regulation factors) in iron metabolism, as well as related genetic abnormalities. The research highlighted the complexity of mechanisms in charge of maintaining equilibrium of Fe in the body. The iron is vital to the life of cells, but its presence in excess is rather toxic. Iron is mostly required for hemoglobin synthesis. It is recycled between reticulo-endothelial macrophages and bone marrow that is the main user of iron. Intestinal absorption is a key step in determining iron capital in the body. Its rate is tightly controlled by several factors that act under influence of signals of unknown nature, which indicate iron needs and storage. The IRP/IRE (iron regulatory protein/iron responsive element) system controls cellular uptake, stores and exportation of iron, and heme synthesis. Mitochondrion is a dynamo of iron metabolism, being vital for heme synthesis and iron sulphur cluster genesis. The recent discovery of several mitochondrial proteins involved in iron metabolism resulted in better understanding mitochondrial iron movement, storage and exchange. Nevertheless, much remains to be known on the role of some actors such as HFE protein, hepcidin, hemojuvelin and transferrin receptor 2, and to determine the nature and mechanisms of signals regulating iron level in the body.

Endoscopic mucosal resection of early esophageal squamous cell cancer using the Duette mucosectomy kit

BACKGROUND AND STUDY AIM

Endoscopic mucosal resection (EMR) is a less invasive alternative treatment strategy to surgery for intramucosal esophageal squamous cell carcinoma (SCC). This study described our initial experience with the newly introduced Duette Multiband Mucosectomy Kit (Cook Ireland Ltd, Limerick, Ireland) for the treatment of extensive early esophageal SCC.

PATIENTS AND METHODS

Five patients with extensive early esophageal SCC, covering at least half of the circumference of the esophageal wall and measuring a mean of 2.8 cm longitudinally, underwent EMR after EUS staging.

RESULTS

EMR was successfully completed in one session in five patients. Post-EMR stricture occurred in four patients but was successfully treated with bougienage. One patient did not return for follow-up after bougienage and died from ischemic heart disease 3 months later. For the remaining four patients, there was no recurrence over a mean follow up of 14.7 months.

CONCLUSION

This new device obviates the need for repeated insertion of the endoscope during the process of ligation and resection and thus facilitates EMR of extensive SCC.

[Homocysteinemia and coronary artery disease: a case-control study in a Tunisian population]

We have determined the prevalence of hyperhomocysteinemia and tested its relationship with coronary heart disease in Tunisian patients. The study included 70 angiogrphically proven coronary patients and 140 age- and sex-matched healthy subjects. Plasma homocysteine folate and vitamin B12 were analyzed by immunoenzymatic methods. Hyperhomocysteinemia was considered for plasma homocysteine concentration >17 micromol/L. Mean plasma homocysteine concentration and hyperhomocysteinemia prevalence were significantly (p<0.001) higher in patients (16.3 +/- 7.9 micromol/L and 29%) than controls (12.6 +/- 4.0 micromol/L and 10%). The association between hyperhomocysteinemia and coronary heart disease persisted after adjusting on main cardiovascular risk factors (multi adjusted odds ratio, 2.99; 95% CI, 1.18-7.59; p=0.02). No association was observed between hyperhomocysteinemia and coronary disease severity and extent. This study showed an independent association between hyperhomocysteinemia and coronary heart disease, suggesting a role of hyperhomocysteinemia in atherothrombogenesis. However, causal relationship is not yet established. Until results of homocysteine-lowering therapy trials become available, hyperhomocysteinemia should be researched and treated in coronary heart disease patients.

Endoscopic ultrasound-guided fine-needle aspiration biopsy for lymphadenopathy of unknown origin

BACKGROUND AND STUDY AIMS

The diagnosis of mediastinal and intra-abdominal lymphadenopathy is sometimes difficult, especially in patients who have no other primary lesions. Lymphoma is one of the main causes of this condition. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a safe and accurate diagnostic procedure for lesions surrounding the gastrointestinal tract. However, diagnosing lymphoma using the EUS-FNA technique remains a diagnostic challenge, due to limitations in the amount of material sampled. The aim of the present study was to evaluate the yield of EUS-FNA biopsy (EUS-FNAB) using a large-gauge needle in patients with mediastinal and intra-abdominal lymphadenopathy of unknown origin, especially in relation to subclassification of the lymphomas.

PATIENTS AND METHODS

Consecutive patients with mediastinal and intra-abdominal lymphadenopathy of unknown origin who were referred between October 2003 and March 2005 were enrolled in the study. EUS-FNAB was carried out using a 19-gauge needle, passing through the esophageal, gastric, and duodenal walls. Pathological diagnoses were made on the basis of histological findings, including immunopathological staining.

RESULTS

A total of 104 patients were included in the study. The locations of the lymph nodes were mediastinal in 50 patients, intra-abdominal in 48 patients, and both mediastinal and intra-abdominal in six patients. The diagnoses made using EUS-FNAB were lymphoma (n = 48), metastasis (n = 16), and benign/reactive (n = 40). The overall accuracy of EUS-FNAB for unknown lymphadenopathy was 98 %, and it was possible to classify the lymphomas in accordance with the World Health Organization classifications in 88 % of cases. No serious complications occurred with the procedure.

CONCLUSIONS

Open thoracic surgery, laparotomy, and other invasive diagnostic procedures such as mediastinoscopy and laparoscopy can now be avoided, as EUS-FNAB is potentially a safe and accurate tool for diagnosing unknown lymphadenopathy, including lymphoma.

Apolipoprotein B signal peptide polymorphism: distribution and influence on lipid parameters in Tunisian population

Apolipoprotein B (apo B) is the major protein component of LDL, VLDL and chylomicrons. Numerous polymorphisms of the apolipoprotein B gene have been described. Particularly, the insertion/deletion polymorphism located in the coding part of the signal peptide of apo B, associated with modification of lipid concentrations and the risk of cardiovascular disease, has been reported in the general population. No such study in the Tunisian population has been performed. The aim of our study was to assess the effect of insertion/deletion polymorphism of the apolipoprotein B gene on lipid levels in a sample of the Tunisian population. A total of 458 unrelated subjects (321 men and 137 women) were included. The insertion/deletion polymorphism was determined by electrophoresis on polyacrylamide gels after PCR amplification. The relative frequencies of the Ins and Del alleles were 0.74 and 0.26, respectively. These frequencies were similar to those found in other Caucasian populations. There was no significant difference in serum TC, TG, and HDL-C levels due to the influence of the genotypes. However, significant variation among the three genotypes was seen for LDL-cholesterol (p<0.001) and apo B (p<0.001) levels. Individuals homozygous for the Del allele had higher levels than individuals homozygous for the Ins allele, while individuals heterozygous for both alleles exhibited intermediate levels. When the data were analyzed in men and women separately, a similar effect was seen in both groups. Our results show that distribution of apo B insertion/deletion polymorphism in Tunisians is similar to other Caucasian population and confirm the reported association with serum LDL-cholesterol and apo B concentrations.