Biased estimators of quantitative trait locus heritability and location in interval mapping

In many empirical studies, it has been observed that genome scans yield biased estimates of heritability, as well as genetic effects. It is widely accepted that quantitative trait locus (QTL) mapping is a model selection procedure, and that the overestimation of genetic effects is the result of using the same data for model selection as estimation of parameters. There are two key steps in QTL modeling, each of which biases the estimation of genetic effects. First, test procedures are employed to select the regions of the genome for which there is significant evidence for the presence of QTL. Second, and most important for this demonstration, estimates of the genetic effects are reported only at the locations for which the evidence is maximal. We demonstrate that even when we know there is just one QTL present (ignoring the testing bias), and we use interval mapping to estimate its location and effect, the estimator of the effect will be biased. As evidence, we present results of simulations investigating the relative importance of the two sources of bias and the dependence of bias of heritability estimators on the true QTL heritability, sample size, and the length of the investigated part of the genome. Moreover, we present results of simulations demonstrating the skewness of the distribution of estimators of QTL locations and the resulting bias in estimation of location. We use computer simulations to investigate the dependence of this bias on the true QTL location, heritability, and the sample size.

Percutaneous coronary intervention triggers a systemic inflammatory response in patients treated for in-stent restenosis -- comparison with stable and unstable angina

OBJECTIVE AND DESIGN

It is believed that the magnitude of the systemic inflammatory response induced by percutaneous coronary intervention (PCI) impacts on the long-term outcomes in patients with stable angina (SA) and unstable angina (UA). We aimed to determine whether an inflammatory response appears in in-stent restenosis (ISR) patients undergoing balloon angioplasty and to assess its pattern and magnitude in relation to SA and UA subjects.

SUBJECTS

80 patients (59 with SA, 10 with UA, 11 with ISR) were enrolled into the prospective study.

TREATMENT

SA and UA patients undergoing single vessel coronary balloon angioplasty followed by stenting versus ISR subjects in whom only balloon angioplasty was performed.

METHODS

C-reactive protein (CRP), serum amyloid A (SAA), tumor necrosis factor alpha (TNF-alpha) and interleukin 10 (IL-10) were measured in blood samples collected before and 6, 24 h and 1 month after the procedure.

RESULTS

A comparable pattern of inflammatory response in terms of CRP and SAA concentrations in subjects undergoing PCI due to ISR and SA was discovered while in unstable patients its magnitude was substantially higher. CRP and SAA levels increased significantly in each group with the peak value at 24 h and the baseline levels remarkably correlated with the highest markers' concentrations. In contrast, preprocedural TNF-alpha concentrations were higher in ISR group when compared with SA and UA patients. Additionally, in ISR group a twofold increase in their values of borderline significance at 6 h was noted. SA and UA subjects were found to have significantly lower TNF-alpha levels at 6 and 24 h after the intervention though the marker concentrations markedly increased with peak values at 1 month. The levels of IL-10 did not differ at any time point between the groups.

CONCLUSIONS

We suggest that PCI triggers a systemic inflammatory response in patients with ISR and considerable differences in its pattern when compared with SA and UA patients were demonstrated. Moreover, a high preprocedural TNF-alpha level and its increase provoked by PCI in the ISR group warrant the need for further investigation of its possible involvement in the restenosis process.

[Hepatic actinomycosis--pseudotumoral form]

Hepatic actinomycosis is a pretty rare anatomo-clinical entity that often induces a wrong pre-operative diagnosis. By presenting a case of hepatic actinomycosis, apparently primitive and diagnosed pre-operatively as a neoplastic lesion, the authors discuss the diagnosis and treatment of this disease, mentioning that in the solid, tumoral forms, the hepatic resection is necessary. The authors consider that the post-operative addition of antibiotherapy (mega doses of penicillin) is useful for the eradication of inflammatory residual hepatic parenchyma as well as for the cicatrisation of the parietal fistulae.

Inclusion complex of fenbufen with ?-cyclodextrin

An inclusion complex of fenbufen with beta-cyclodextrin (beta-CD) in aqueous solution was characterized by (1)H-NMR spectroscopy. The [1:1] stoichiometry was determined and a stability constant of several 1000s (M(-1)) was calculated. The geometry of the inclusion complex was established based on MM(+) molecular mechanics calculations.

The importance of connections: joining components of the Hutterite pedigree

We analyzed a quantitative trait (serum IgE levels), and a binary trait (asthma), in four Hutterite sub-pedigrees. A genome screen for asthma was performed using GENEHUNTER, and interesting regions were followed up using extended pedigrees and the FASTLINK package. Markov chain Monte Carlo (MCMC) methods were used to assess haplotype sharing among affected individuals (MORGAN/AUTOZYG), and to perform a combined oligogenic segregation and linkage analysis (LOKI) for log10(IgE). We found evidence for at least two susceptibility loci for asthma on chromosome 5, and a QTL for log10(IgE) on chromosome 1. Our analyses demonstrate that using the most complete pedigree structure possible is advisable, with attention to the possibility of heterogeneity among subunits of a very large pedigree.

[457 inguinal and femoral hernioplasties with synthetic prosthetic materials]

The authors retrospectively analyse 457 inguinal and femural hernioplasties with synthetic prosthesis materials, during a period of 10 years. There have been discussions going on about the prosthesis utilisation indications (advanced stages, complex inguinal hernia), type of prosthesis that has been used, the modalities of inserting a prosthesis and the surgical techniques employed. In 164 (34%) of the operations the mesh has been used as an reinforcement and 293 (64%) of the interventions were "tension-free" operations. The average reccurrence was approximately 1%, during a period ranging between 1 to 5 years.

[Giant cavernous hemangiomas of the caudal lobe. Clinical and therapeutically considerations]

The authors present two cases of giant hepatic cavernous hemangiomas with rare topography--caudate lobe. The article debates at length the natural evolution of disease, the diagnosis and the treatment. It give emphasis to the fact that, at present, we are witnessing the limitation of surgical indications far these benign vascular tumors. On the other hand, when operation is indicated, the authors prefer tumorectomy by enucleating or enucleoresection (which are limited) instead of major hepatic resections.

[Retrospective analysis of prognostic factors for annual mortality in 97 patients with chronic congestive heart failure]

The aim of our study was to find clinical and biochemical factors, which are prognostically important for the annual mortality in patients with chronic congestive heart failure (CHF). The studied group consisted of 97 people with CHF (31 females and 66 males, mean age--61). The causes of the heart failure were: coronary artery disease or/and hypertension (80 patients), valvular mitral heart disease--(12 patients), dilated cardiomyopathy--(5 patients). On the first day of the hospitalization patients were classified as functional class II-IV according to NYHA classification. Patients were divided into: group 'A'--34 patients, who had died during the 1st year of observation, and group 'B'--63 patients who have survived the 1st year of observation. According to the results of our study patients from group A had lower concentration of plasma sodium, lower left ventricular ejection fraction, lower mean heart rate, higher frequency of ventricular arrhythmias (according to 3&4 Lown class).

Urinary cGMP concentrations in severe primary pulmonary hypertension

BACKGROUND

Prognostic evaluation of patients with primary pulmonary hypertension (PPH) requires right heart catheterisation. The development of accurate non-invasive methods for monitoring these patients remains an important task. Cyclic guanosine monophosphate (cGMP) is an indicator of the action of natriuretic peptides and nitric oxide on target cells. Plasma and urinary cGMP concentrations are raised in patients with congestive heart failure in whom they correlate closely with haemodynamic parameters and disease severity. The aim of the present study was to determine whether the urinary concentration of cGMP could be used as a non-invasive marker of haemodynamic impairment in patients with severe PPH.

METHODS

Urinary cGMP concentrations were measured in 19 consecutive patients with PPH, seven with acute asthma, and 30 normal healthy controls.

RESULTS

Patients with PPH had higher urinary cGMP concentrations than asthmatic patients or normal healthy controls (p = 0.001). Urinary cGMP concentrations were higher in patients with severe haemodynamic impairment--that is, those with a cardiac index (CI) of < or = 2 l/min/m2 (p = 0.002)--and urinary cGMP concentrations were inversely correlated with CI (r = -0.69, p = 0.002) and venous oxygen saturation (r = -0.65, p = 0.003).

CONCLUSION

Urinary cGMP concentrations may represent a non-invasive indicator of the haemodynamic status of patients with severe PPH.

[Pulmonary aspergilloma successfully operated on in a patient with the pentalogy of Fallot]

Fallot disease occurs in 10% of congenital heart diseases. This case showed a clinical association between Fallot disease and a pulmonary aspergilloma. A 44-years male, with a history of Fallot disease (diagnosed in childhood) and a normal life, was admitted for repeated hemoptysis during last three months. Clinical examination revealed signs of Fallot disease: cyanosis, finger clubbing. CT scan and chest X-ray revealed a cavitary image in the right upper lobe. The CT image revealed a typical aspect of cavitary aspergilloma. The patient was referred to the thoracic surgeon, a right upper lobectomy was performed, which confirmed the presence of aspergilloma. Postoperative evolution was good.

[The chronology and diagnostic round of patients operated on for bronchopulmonary cancer]

37 patients with certified diagnosis, operated for lung cancer (LC) in The Central Military Hospital Bucharest, during six months period (October 1st 1996-June 1st 1997). It was a retrospective study on the patients medical files. Sex distribution, postsurgical staging and histological type were studied. We calculated the following delays: 1. Between the first medical examination and the first suspicion (chest X-ray): 6 +/- 3 days; 2. Between the first medical examination and first hospital admission: 14 +/- 11 days; 3. Between the first hospital admission and the first admission in surgical units: 43 +/- 23 days; 4. Between the first admission in surgical units and surgery: 59 +/- 26 days; 5. The delay until bronchoscopy: 23 +/- 16 days; 6. The delay until the CT examination: 26 +/- 16 days; 7. Between the first medical examination and the surgery: 78 +/- 30 days. These delays were correlated with the specialty profile of the services which referred the patients: pulmonology, internal medicine, oncology or primary services.

CONCLUSION

1. Most patients come from pulmonology units (22 out of 37 patients); 2. There are significant delays until bronchoscopy and CT scan, the availability of these services is still limited; 3. The primary care medical network is still inefficient in early diagnosis of LC; 4. The overcrowding of thoracic surgery unit (scheduling for surgical intervention). All of these are arguments for developing more efficient and faster circuits of LC diagnosis, especially for high risk patients.

[The clenbuterol treatment of patients with the chronic obstructive syndrome]

We have studied the effect of a new long acting bronchodilator: CLENBUTEROL, in 10 patients suffering from chronic obstructive diseases. All patients received 1 tablet of Clenbuterol, then we measured the following parameters in each patient, 2 and 6 hours after the drug administration: VC (vital capacity), FEV1 (forced expiratory volume in the first second of forced expiration), FEV1 x 100/VC, Raw (airways resistance), RV (residual volume). In all patients, excepting one of them, we registered a modification of all or some of the parameters 2 hours after drug administration. The bronchodilator effect was still present at 6 hours after drug administration. This data suggest that Clenbuterol induced a significant and long acting improvement of chronic obstruction; this drug might offer the advantage of sustained effect in patients suffering from chronic bronchospastic obstruction.

[Congestive heart failure and ventricular arrhythmia in relation to magnesium, potassium and sodium in serum and erythrocytes]

The aim of this study was to determine magnesium, potassium and sodium in plasma and erythrocytes in patients (14 male, 12 female; the average age 60.3) with congestive heart failure (CHF) (NYHA class II/III, III, IV) who were treated with digitalis, diuretics and vasodilators. All patients were subjected to 24 h ECG monitoring and ventricular arrhythmias classified according to LOWN, were analyzed in relation to electrolyte contents in erythrocytes and serum. Control group consisted of 20 persons (17 male; 3 female: the average age 58.7 years). Plasma and erythrocyte K and Na were determined by flame spectrophotometer; Mg was assayed by atomic absorption spectrophotometer. Statistical analysis was made by t-Student test. Results obtained suggest that patients with CHF require supplementation K+ with Mg2+ (tab. I). Our study has not revealed expected interrelationships between ventricular arrhythmias and electrolyte disturbances in patients with CHF. It should be stressed, however, that the small numbers of patients in the subgroups in our study might have blurred the possible relationship.

[Magnesium, potassium and sodium in serum and erythrocytes in acute myocardial infarction]

Serum concentration and erythrocyte contents of Mg++, K+ and Na+ was measured on day 1, 3 and 14 in patients with transmural myocardial infarction. The study group consisted of 72 patients (15 females and 57 males) with the diagnosis of myocardial infarction based on WHO criteria. The control group consisted of 52 healthy subjects (11 females and 41 males). Measurements of sodium and potassium were made using flame photometer, magnesium was measured with atom adsorption spectrophotometry. Lowest magnesium and potassium concentrations (in serum and in erythrocytes) were found on day 1 and day 3 with almost full normalization on day 14. Sodium serum concentration and erythrocyte contents varied; lowest serum concentration appeared on day 1 and day 3, erythrocyte contents was highest on day 1.

[The etiological spectrum of mitral insufficiency: a 10-year retrospective study]

The incidence, etiology and data on the severity and therapeutic implications of the mitral insufficiency were investigated in the patients admitted in the clinic during 10 years. The diagnosis was based mainly on clinical and echocardiography mode M data. 595 patients suffering from mitral insufficiency (below 2% of the total of the patients admitted) were recorded. In 65% of the cases mitral insufficiency had a rheumatic etiology (the majority associated polyvalvulopathies), in 14.8% an ischaemic origin, and in 10.9% an organic-functional one (the left ventricle was dilated). The primary prolapse of the mitral valve appeared in 6.9% of the cases (the low incidence was explained by the severe criteria applied in positive diagnosis). 4 cases of rupture of the subvalvular apparatus are described in the patients suffering from prolapse. All of them had a sudden onset, by severe cardiac insufficiency without a clear cause, appeared under conditions of seemingly complete health. Intense therapy followed by valvular prosthesis, resulted in a spectacular recovery of the heart function.