A missense mutation in SLC26A3 is associated with human male subfertility and impaired activation of CFTR

Chloride absorption and bicarbonate excretion through exchange by the solute carrier family 26 member 3 (SLC26A3) and cystic fibrosis transmembrane conductance regulator (CFTR) are crucial for many tissues including sperm and epithelia of the male reproductive tract. Homozygous SLC26A3 mutations cause congenital chloride diarrhea with male subfertility, while homozygous CFTR mutations cause cystic fibrosis with male infertility. Some homozygous or heterozygous CFTR mutations only manifest as male infertility. Accordingly, we studied the influence of SLC26A3 on idiopathic infertility by sequencing exons of SLC26A3 in 283 infertile and 211 control men. A heterozygous mutation c.2062 G > C (p.Asp688His) appeared in nine (3.2%) infertile men, and additionally, in two (0.9%) control men, whose samples revealed a sperm motility defect. The p.Asp688His mutation is localized in the CFTR-interacting STAS domain of SLC26A3 and enriched in Finland, showing a significant association with male infertility in comparison with 6,572 Finnish (P < 0.05) and over 120,000 global alleles (P < 0.0001) (ExAC database). Functional studies showed that while SLC26A3 is a strong activator of CFTR-dependent anion transport, SLC26A3-p.Asp688His mutant retains normal Cl⁻/HCO₃⁻ exchange activity but suppresses CFTR, despite unaffected domain binding and expression. These results suggest a novel mechanism for human male infertility─impaired anion transport by the coupled SLC26A3 and CFTR.

The Abl-1 Kinase is Dispensable for NK Cell Inhibitory Signalling and is not Involved in Murine NK Cell Education

Natural killer (NK) cell responsiveness in the mouse is determined in an education process guided by inhibitory Ly49 and NKG2A receptors binding to MHC class I molecules. It has been proposed that inhibitory signalling in human NK cells involves Abl-1 (c-Abl)-mediated phosphorylation of Crk, lowering NK cell function via disruption of a signalling complex including C3G and c-Cbl, suggesting that NK cell education might involve c-Abl. Mice deficient in c-Abl expression specifically in murine NK cells displayed normal inhibitory and activating receptor repertoires. Furthermore, c-Abl-deficient NK cells fluxed Ca²⁺ normally after triggering of ITAM receptors, killed YAC-1 tumour cells efficiently and showed normal, or even slightly elevated, capacity to produce IFN-γ after activating receptor stimulation. Consistent with these results, c-Abl deficiency in NK cells did not affect NK cell inhibition via the receptors Ly49G2, Ly49A and NKG2A. We conclude that signalling downstream of murine inhibitory receptors does not involve c-Abl and that c-Abl plays no major role in NK cell education in the mouse.

TLR-Stimulated Eosinophils Mediate Recruitment and Activation of NK Cells In Vivo

Eosinophils like many myeloid innate immune cells can provide cytokines and chemokines for the activation of other immune cells upon TLR stimulation. When TLR-stimulated eosinophils were inoculated i.p. into wild-type mice, and NK cells were rapidly recruited and exhibited antitumour cytotoxicity. However, when mice depleted of CD11c⁺ cells were used, a marked decrease in the number of recruited NK cells was observed. We postulated that CpG or LPS from the injected eosinophils could be transferred to host cells, which in turn could recruit NK cells. However, by inoculating mice deficient in TLR4 or TLR9 with LPS or CpG-stimulated eosinophils respectively, NK cell recruitment was still observed alongside cytotoxicity and IFNγ production. CpG stimulation of eosinophils produced the pro-inflammatory cytokine IL-12 and the chemokine CXCL10, which are important for NK cell activation and recruitment in vivo. To demonstrate the importance of CXCL10 in NK cell recruitment, we found that CpG-stimulated eosinophils pretreated with the gut microbial metabolite butyrate had reduced expression and production of CXCL10 and IL-12 and concomitantly were poor at recruitment of NK cells and inducing IFNγ in NK cells. Therefore, eosinophils like other innate immune cells of myeloid origin can conceivably stimulate NK cell activity. In addition, products of the gut microbiota can be potential inhibitors of NK cell.

Circulation stabilizing therapy and pulmonary high-resolution computed tomography in a porcine brain-dead model

BACKGROUND

Currently 80% of donor lungs are not accepted for transplantation, often due to fluid overload. Our aim was to investigate if forced fluid infusion may be replaced by a new pharmacological therapy to stabilize circulation after brain death in an animal model, and to assess therapy effects on lung function and morphology trough blood gas parameters and state-of-the-art High-resolution CT (HRCT).

METHODS

Brain death was caused by surgical decapitation. To maintain mean aortic pressure > 60 mmHg, pigs were treated with forced electrolyte solution infusion (GI; n = 6) or the pharmacological therapy (GII; n = 11). GIII (n = 11) were non-decapitated controls. Lung function was investigated with blood gases and lung morphology with HRCT.

RESULTS

GI pigs became circulatory instable 4-6 h after brain death in spite of forced fluid infusion, five pigs showed moderate to severe pulmonary edema on HRCT and median final PaO2 /FiO2 was 29 kPa (Q1; Q3; range 26; 40; 17-76). GII and GIII were circulatory stable (mean aortic pressure > 80 mmHg) and median final PaO2 /FiO2 after 24 h was 72 kPa (Q1; Q3; range 64; 76; 53-91) (GII) and 66 kPa (55; 78; 43-90) (GIII). On HRCT, only two pigs in GII had mild pulmonary edema and none in GIII. More than 50% of HRCT exams revealed unexpected lung disease even in spite of PaO2 /FiO2 > 40 kPa.

CONCLUSION

Pharmacological therapy but not forced fluid infusion prevented circulatory collapse and extensive HRCT verified pulmonary edema after acute brain death. HRCT was useful to evaluate lung morphology and revealed substantial occult parenchymal changes justifying efforts toward a more intense use of HRCT in the pre-transplant evaluation.

Gender aspects of survival after surgical treatment for rectal cancer

AIM

Longer survival in women than men after rectal cancer surgery has been reported. Our hypothesis was that after correction for their longer life expectancy a survival benefit for women would still remain.

METHOD

We studied 2792 patients diagnosed with rectal cancer in the southern part of Sweden between 1996 and 2006. The following parameters were included in a prespecified multivariable Cox regression analysis: age at diagnosis, gender, preoperative radiotherapy, stage, year and type of surgery. In addition to overall survival, relative survival was calculated using the Hakulinen approach utilizing an age-, gender- and calendar year-matched Swedish control cohort.

RESULTS

Female patients were significantly older, received neoadjuvant treatment less often and were more often operated on by local excision. Overall survival was significantly longer in women. In the multivariable analysis of relative survival, controlling for neoadjuvant treatment, Dukes stage and year and type of surgery, no significant effect of gender [hazard ratio (HR) 1.10 for men, P = 0.114] was found, whereas an improved relative survival with increased age (HR 0.96 per year, P < 0.001) was seen. In contrast, using the same multivariable model with no correction for underlying mortality in the population, male gender (HR 1.38, P < 0.001) and greater age (HR 1.05 per year, P < 0.001) increased the risk of death.

CONCLUSION

The results show that after correction for the underlying longer survival in women and some known confounders, survival after surgical treatment for rectal cancer appears to be gender neutral.

Are 25 SNPs from the CARDIoGRAM study associated with ischaemic stroke?

BACKGROUND AND PURPOSE

The Coronary Artery Disease Genome-Wide Replication and Meta-Analysis Study (CARDIoGRAM) reported 25 single-nucleotide polymorphisms (SNPs) on 15 chromosomes to be associated with coronary artery disease (CAD) risk. Because common vascular risk factors are shared between CAD and ischaemic stroke (IS), these SNPs may also be related to IS overall or one or more of its pathogenetic subtypes.

METHODS

We performed a candidate gene study comprising 3986 patients with IS and 2459 control subjects. The 25 CAD-associated SNPs reported by CARDIoGRAM were examined by allelic association analysis including logistic regression. Weighted and unweighted genetic risk scores (GRSs) were also compiled and likewise analysed against IS. We furthermore considered the IS main subtypes large-vessel disease (LVD), small-vessel disease and cardioembolic stroke [according to Trial of Org 10172 in Acute Stroke Treatment (TOAST)] separately.

RESULTS

SNP rs4977574 on chromosome 9p21.3 was associated with overall IS [odds ratio (OR) = 1.12; 95% confidence interval (CI): 1.04-1.20; P = 0.002] as well as LVD (OR = 1.36; 95% CI: 1.13-1.64; P = 0.001). No other SNP was significantly associated with IS or any of its main subtypes. Analogously, the GRSs did not show any noticeable effect.

CONCLUSIONS

Besides the previously reported association with SNPs on chromosome 9p21, this study did not detect any significant association between IS and CAD-susceptible genetic variants. Also, GRSs compiled from these variants did not predict IS or any pathogenetic IS subtype, despite a total sample size of 6445 participants.

Clinical implementation of systematic medication reconciliation and review as part of the Lund Integrated Medicines Management model--impact on all-cause emergency department revisits

WHAT IS KNOWN AND OBJECTIVE

Interventions involving medication reconciliation and review by clinical pharmacists can reduce drug-related problems and improve therapeutic outcomes. The objective of this study was to examine the impact of routine admission medication reconciliation and inpatient medication review on emergency department (ED) revisits after discharge. Secondary outcomes included the combined rate of post-discharge hospital revisits or death.

METHODS

This prospective, controlled study included all patients hospitalized in three internal medicine wards in a university hospital, between 1 January 2006 and 31 May 2008. Medication reconciliation on admission and inpatient medication review, conducted by clinical pharmacists in a multiprofessional team, were implemented in these wards at different times during 2007 and 2008 (intervention periods). A discharge medication reconciliation was undertaken in all the study wards, during both control and intervention periods. Patients were included in the intervention group (n = 1216) if they attended a ward with medication reconciliation and review, whether they had received the intervention or not. Control patients (n = 2758) attended the wards before implementation of the intervention.

RESULTS AND DISCUSSION

No impact of medication reconciliation and reviews on ED revisits [hazard ratio (HR), 0.95; 95% confidence interval (CI), 0.86-1.04]or event-free survival (HR, 0.96; 95% CI, 0.88-1.04) was demonstrated. In the intervention group, 594 patients (48.8%) visited the ED, compared with 1416 (51.3%) control patients. In total, 716 intervention (58.9%) and 1688 (61.2%) control patients experienced any event (ED visit, hospitalization or death). Because the time to a subsequent ED visit was longer for the control as well as the intervention groups in 2007 than in 2006 (P < 0.05), we re-examined this cohort of patients; the proportion of patients revisiting the ED was similar in both groups in 2007 (P = 0.608).

WHAT IS NEW AND CONCLUSION

Routine implementation of medication reconciliation and reviews on admission and during the hospital stay did not appear to have any impact on ED revisits, re-hospitalizations or mortality over 6-month follow-up.

Follow-up of a child with congenital chloride diarrhoea caused by a novel mutation

Congenital chloride diarrhoea (CLD) is a rare autosomal recessive disease with chronic secretory diarrhoea and a need for lifelong salt replacement therapy. We describe a male newborn of consanguineous parents with CLD. Postnatally, frequent watery diarrhoea and electrolyte disturbances were noted from the day 8 of his life. At molecular level, a homozygous mutation was detected in the solute carrier family 26 member A3 gene (SLC26A3), confirming the clinical diagnosis of CLD.

CONCLUSION

The relatively late onset of persistent clinical and laboratory signs may demonstrate a new clinical course of CLD. These findings support the need of a tight follow-up and monitoring if such a diagnosis is considered.

Time trends in risk and risk determinants of non-Hodgkin lymphoma in solid organ transplant recipients

Organ transplantation increases risk of non-Hodgkin lymphoma (NHL), but long-term risk and time trends have seldom been evaluated. Immunosuppressive drug load is an important risk determinant, but the details are unclear. We studied NHL risk in a nationwide Swedish cohort of 11 081 graft recipients transplanted 1970-2008. Relative risks (RRs) were estimated within the cohort and versus the general population by age, sex, follow-up time and calendar period. NHL risk was also assessed by cumulative and average doses of immunosuppressive treatments in a nested case-control design throughout 1997 using conditional logistic regression. We observed 153 NHL cases during 97 853 years of follow-up. Compared with the general population, NHL risk was eightfold increased (RR 7.9; 95% confidence interval [CI] 6.6-9.4), and increased risks persisted after ≥15 years of follow-up among kidney (6.1; 95% CI 3.5-10) and nonkidney recipients (44; 14-103). Among nonkidney recipients, NHL risk was lower in the 2000s compared with the 1990s (0.5; 95% CI 0.3-1.0; p = 0.04). A high average dose of antithymocyte immunoglobulin (ATG) conferred an eightfold increased risk of NHL (OR 8.5; 95% CI 1.9-38). To conclude, posttransplant NHL risk decreased during the last decade among nonkidney recipients, possibly because of a more careful use of ATG, the introduction of new drugs, or both.

Three cases of a rare disease, congenital chloride diarrhea, summons up the variation in the clinical course and significance of early diagnosis and adequate treatment in the prevention of intellectual disability

Congenital chloride diarrhea (CLD) (OMIM #214700) is a rare, autosomal recessive disease that is characterized by increased chloride loss in stool. As a result of electrolyte loss, surviving patients might have some complications, one of them being mental retardation. Here, we present three new Turkish patients with new mutations in the SLC26A3 gene. Although the clinical picture of the patients might be similar, consequences of the disease and complications might differ greatly among patients. Pediatricians should be aware of CLD as a potentially fatal or disabling disease if untreated. History of polyhydramnios, watery diarrhea, failure to thrive, poor growth, soiling, metabolic alkalosis and hypokalemia/hypochloremia should be an alarming set of findings for the diagnosis. Salt substitution therapy started early in life prevents early complications, allows normal growth and development, and favors good long-term prognosis.

Mortality from peptic ulcer bleeding: the impact of comorbidity and the use of drugs that promote bleeding

BACKGROUND

Use of drugs promoting peptic ulcer bleed has increased several folds.

AIM

To make a time-trend analysis of peptic ulcer bleed patients and evaluate the impact of age, gender, comorbidity and use of drugs promoting peptic ulcer bleed on outcome.

METHODS

Retrospective review of hospitalizations for peptic ulcer bleed at Lund University Hospital during 1984, 1994 and 2004. Univariate analyses between years and multivariable logistic regression for risk factors of fatal outcome.

RESULTS

Incidence decreased from 62.0 to 32.1 per 100 000 inhabitants between 1984 and 2004. Mortality rates were stable. Median age (70–77 years; P = 0.001), number of comorbidities (mean +/- s.d.: 0.88 +/- 0.96 to 1.16 +/- 0.77; P = 0.021), use of aspirin (16–57%; P < 0.001) and warfarin (5–17%; P = 0.02) increased. Pharmacological and endoscopic therapy improved. Age above 65 years (OR: 1.11, 95% CI: 1.02–1.23) and number of comorbidities (OR: 6.00, 95% CI: 2.56–17.4) were independent risk factors for in-hospital mortality. Bleeding promoting drugs did not influence outcome negatively. Aspirin decreased the risk of fatal outcome (OR: 0.12, 95% CI: 0.012–0.67).

CONCLUSIONS

Incidence of peptic ulcer bleed decreased despite higher prescription rates of bleeding promoting drugs. The in-hospital mortality remained unchanged. The effect of improved therapy against peptic ulcer bleed is probably outweighed by older and more comorbid patients. The decreased risk of fatal outcome in aspirin users warrants further investigations.

Pharmacokinetics of thalidomide in patients with impaired renal function and while on and off dialysis

There is a renewed interest in thalidomide for use in malignancies and systemic inflammatory diseases. Reduced renal function is not uncommon among patients with these disease states but the pharmacokinetics has not been fully investigated. The aim of this study was to investigate the pharmacokinetics of thalidomide in haemodialysis patients while on and off dialysis and in myeloma patients with varying degrees of renal function.

Two studies were performed. To establish the pharmacokinetics of thalidomide in patients with mild to moderate renal failure, blood samples were taken over 12 weeks from 40 patients with multiple myeloma. A second study was performed in six patients with end-stage renal disease both on a non-dialysis day and before and during a haemodialysis session. Thalidomide concentration was determined by HPLC. A one-compartment open model with first-order absorption and elimination was used to fit total thalidomide concentration to population pharmacokinetics and statistical models using the NONMEM program. Clearance and volumes were slightly below 10 L h−1 and 1 L kg−1, respectively, in both patient groups. The inter- and intra-patient variability was low. Clearance was doubled during dialysis. There was no correlation between thalidomide clearance and renal function. In conclusion, the pharmacokinetics of thalidomide in patients with renal failure are very similar to values reported by others for patients with normal renal function. Although clearance during dialysis is doubled, thalidomide dose need not be changed for patients with decreased kidney function. There is also no need for a supplementary dose due to haemodialysis.

Review article: the clinical management of congenital chloride diarrhoea

BACKGROUND

Congenital chloride diarrhoea in a newborn is a medical emergency, requiring early diagnostics and treatment to prevent severe dehydration and infant mortality. While most of the 250 cases reported arise from Finland, Poland and Arab countries, single cases with this autosomal recessive disorder appear worldwide. Such congenital chloride diarrhoea rarity makes diagnosis difficult. Life-long salt substitution with NaCl and KCl stabilizes fluid, electrolyte and acid-base balance diagnosis. When properly treated, the long-term outcome is favourable.

AIM

To summarize data on congenital chloride diarrhoea diagnosis, pathophysiology and treatment, and to provide guidelines for both acute and long-term management of congenital chloride diarrhoea.

METHODS

Data are based on MEDLINE search for 'chloride diarrhoea', in addition to clinical experience in the treatment of the largest known series of patients.

RESULTS

Treatment of congenital chloride diarrhoea involves (i) life-long salt substitution; (ii) management of acute dehydration and hypokalaemia during gastroenteritis or other infections; and (iii) recognition and treatment of other manifestations of the disease, such as intestinal inflammation, renal impairment and male subfertility.

CONCLUSIONS

This review summarizes data on congenital chloride diarrhoea and provides guidelines for treatment. After being a mostly paediatric problem, adult patients constitute a rare challenge for gastroenterologists worldwide.

Four novel mutations in the lactase gene (LCT) underlying congenital lactase deficiency (CLD)

Background

Congenital lactase deficiency (CLD) is a severe gastrointestinal disorder of newborns. The diagnosis is challenging and based on clinical symptoms and low lactase activity in intestinal biopsy specimens. The disease is enriched in Finland but is also present in other parts of the world. Mutations encoding the lactase (LCT) gene have recently been shown to underlie CLD. The purpose of this study was to identify new mutations underlying CLD in patients with different ethnic origins, and to increase awareness of this disease so that the patients could be sought out and treated correctly.

Methods

Disaccharidase activities in intestinal biopsy specimens were assayed and the coding region of LCT was sequenced from five patients from Europe with clinical features compatible with CLD. In the analysis and prediction of mutations the following programs: ClustalW, Blosum62, PolyPhen, SIFT and Panther PSEC were used.

Results

Four novel mutations in the LCT gene were identified. A single nucleotide substitution leading to an amino acid change S688P in exon 7 and E1612X in exon 12 were present in a patient of Italian origin. Five base deletion V565fsX567 leading to a stop codon in exon 6 was found in one and a substitution R1587H in exon 12 from another Finnish patient. Both Finnish patients were heterozygous for the Finnish founder mutation Y1390X. The previously reported mutation G1363S was found in a homozygous state in two siblings of Turkish origin.

Conclusion

This is the first report of CLD mutations in patients living outside Finland. It seems that disease is more common than previously thought. All mutations in the LCT gene lead to a similar phenotype despite the location and/or type of mutation.

Self-esteem in a clinical sample of morbidly obese children and adolescents

AIM

To study self-esteem in clinical sample of obese children and adolescents.

METHODS

Obese children and adolescents aged 8-19 years (n = 107, mean age 13.2 years, mean BMI 32.5 [range 22.3-50.6], mean BMI z-score 3.22 [range 2.19-4.79]; 50 boys and 57 girls) were referred for treatment of primary obesity. Self-esteem was measured with a validated psychological test with five subscales: physical characteristics, talents and skills, psychological well-being, relations with the family and relations with others. A linear mixed effect model used the factors gender and adolescence group, and the continuous covariates: BMI z-scores, and BMI for the parents as fixed effects and subjects as random effects.

RESULTS

Age and gender, but neither the child's BMI z-score nor the BMI of the parents were significant covariates. Self-esteem decreased (p < 0.01) with age on the global scale as well as on the subscales, and was below the normal level in higher ages in both genders. Girls had significantly lower self-esteem on the global scale (p = 0.04) and on the two subscales physical characteristics (p < 0.01) and psychological well-being (p < 0.01).

CONCLUSION

Self-esteem is lower in girls and decreases with age. In treatment settings special attention should be paid to adolescent girls.

Cl- is required for HCO3- entry necessary for sperm capacitation in guinea pig: involvement of a Cl-/HCO3- exchanger (SLC26A3) and CFTR

Our previous study demonstrated the involvement of cystic fibrosis transmembrane conductance regulator (CFTR) in transporting bicarbonate that is necessary for sperm capacitation; however, whether its involvement is direct or indirect remains unclear. The present study investigated the possibility of a Cl-/HCO3- exchanger (solute carrier family 26, number 3 [SLC26A3]) operating with CFTR during guinea pig sperm capacitation. Incubating sperm in media with various concentrations of Cl- resulted in varied percentages of capacitated sperm in a concentration-dependent manner. Depletion of Cl-, even in the presence of HCO3-, abolished sperm capacitation and vice versa, indicating the involvement of both anions in the process. Capacitation-associated HCO3--dependent events, including increased intracellular pH, cAMP production, and protein tyrosine phosphorylation, also depend on Cl- concentrations. Similar Cl- dependence and inhibitor sensitivity were observed for sperm-hyperactivated motility and for sperm-egg fusion. The expression and localization of CFTR and SLC26A3 were demonstrated using immunostaining and Western blot analysis. Taken together, our results indicate that Cl- is required for the entry of HCO3- that is necessary for sperm capacitation, implicating the involvement of SLC26A3 in transporting HCO3-, with CFTR providing the recycling pathway for Cl-.

Phenotypic consequences of genetic variation at hemizygous alleles: Sotos syndrome is a contiguous gene syndrome incorporating coagulation factor twelve (FXII) deficiency

PURPOSE

We tested the hypothesis that Sotos syndrome (SoS) due to the common deletion is a contiguous gene syndrome incorporating plasma coagulation factor twelve (FXII) deficiency. The relationship between FXII activity and the genotype at a functional polymorphism of the FXII gene was investigated.

METHODS

A total of 21 patients including those with the common deletion, smaller deletions, and point mutations, and four control individuals were analyzed. We examined FXII activity in patients and controls, and analyzed their FXII 46C/T genotype using direct DNA sequencing.

RESULTS

Among 10 common deletion patients, seven patients had lower FXII activity with the 46T allele of the FXII gene, whereas three patients had normal FXII activity with the 46C allele. Two patients with smaller deletions, whose FXII gene is not deleted had low FXII activity, but one patient with a smaller deletion had normal FXII. Four point mutation patients and controls all had FXII activities within the normal range.

CONCLUSION

FXII activity in SoS patients with the common deletion is predominantly determined by the functional polymorphism of the remaining hemizygous FXII allele. Thus, Sotos syndrome is a contiguous gene syndrome incorporating coagulation factor twelve (FXII) deficiency.

Expression of ion transport-associated proteins in human efferent and epididymal ducts

Appropriate intraluminal microenvironment in the epididymis is essential for maturation of sperm. To clarify whether the anion transporters SLC26A2, SLC26A6, SLC26A7, and SLC26A8 might participate in generating this proper intraluminal milieu, we studied the localization of these proteins in the human efferent and the epididymal ducts by immunohistochemistry. In addition, immunohistochemistry of several SLC26-interacting proteins was performed: the Na+/H+exchanger 3 (NHE3), the Cl−channel cystic fibrosis transmembrane conductance regulator (CFTR), the proton pump V-ATPase, their regulator Na+/H+exchanger regulating factor 1 (NHERF-1), and carbonic anhydrase II (CAII). Our results show that SLC26A6, CFTR, NHE3, and NHERF-1 are co-expressed on the apical side of the nonciliated cells, and SLC26A2 appears in the cilia of the ciliated cells in the human efferent ducts. In the epididymal ducts, SLC26A6, CFTR, NHERF-1, CAII, and V-ATPase (B and E subunits) were co-localized to the apical mitochondria rich cells, while SLC26A7 was expressed in a subgroup of basal cells. SLC26A8 was not found in the structures studied. This is the first study describing the localization of SLC26A2, A6 and A7, and NHERF-1 in the efferent and the epididymal ducts. Immunolocalization of human CFTR, NHE3, CAII, and V-ATPase in these structures differs partly from previous reports from rodents. Our findings suggest roles for these proteins in male fertility, either independently or through interaction and reciprocal regulation with co-localized proteins shown to affect fertility, when disrupted.

Long-term clinical outcome in patients with congenital chloride diarrhea

OBJECTIVES

Congenital chloride diarrhea (CLD) is a rare, autosomal recessive disorder of intestinal Cl/HCO3 exchange caused by mutations in the SLC26A3 gene and characterized by persistent Cl rich diarrhea from birth. Treatment is symptomatic and replacement therapy with NaCl and KCl has been shown to be effective in children, but the long-term prognosis remains unclear. We studied the largest known cohort of patients to evaluate the long-term outcome of CLD and to search for extraintestinal manifestations.

METHODS

This is a cross-sectional clinical evaluation and retrospective analysis of medical history of 36 Finnish patients with CLD, born in the 1960s (n = 8), 1970s (n = 7) and 1980s (n = 21).

RESULTS

Early diagnosis and aggressive salt replacement therapy were associated with normal growth and development, in addition to significantly reduced mortality rates among the groups of patients born in the different decades, respectively (P = 0.001). No deaths due to CLD were observed after 1972. Enuresis, slight soiling and hospitalizations for gastroenteritis were common, especially in childhood, but 92% of the patients found their health excellent or good. Complications documented were end-stage renal disease (n = 1) and hyperuricemia (n = 4), novel findings possibly associated with CLD being male subfertility (n = 3), spermatoceles (n = 3), intestinal inflammation (n = 2), inguinal hernias (n = 4) and increased concentrations of sweat Cl in 12% of the patients.

CONCLUSIONS

When early diagnosed and adequately treated, the long-term prognosis of CLD is favorable. A putative role of a primary anion exchange defect of SLC26A3 in male subfertility and the decline of renal function due to chronic dehydration deserve further characterization.

Expression of SLC26A3, CFTR and NHE3 in the human male reproductive tract: role in male subfertility caused by congenital chloride diarrhoea

Congenital chloride diarrhoea (CLD) is a rare inherited disease caused by mutations in the solute carrier family 26 member 3 (SLC26A3) gene. Disruption of intestinal Cl(-)/HCO(3)(-) exchange causes watery Cl(-) rich diarrhoea from birth, and recently male subfertility was observed as a novel manifestation. Expression of SLC26A3, together with interacting proteins cystic fibrosis transmembrane conductance regulator (CFTR) and Na(+)/H(+) exchanger 3 (NHE3), was studied using immunohistochemistry in the testis (n = 2) and efferent ducts (ED) (n = 1) of patients with CLD (V317del genotype) and in the testis and epididymis (n = 11), seminal vesicle (n = 9) and prostate (n = 4) of the controls. SLC26A3 was immunolocalized in the head of the elongating spermatids (stages III-VI) and CFTR in the elongating spermatids (stages III and IV) and pachytene (stages III-V) and diplotene spermatocytes. In the non-ciliated cells of the ED, apical expression of all three proteins was observed, but only SLC26A3 and CFTR were detected on the luminal border of the apical mitochondria-rich cells (AMRC) of the ductus epididymis and in the epithelium of the seminal vesicle. Only CFTR was present in the epithelium of the prostatic duct. In the patient with CLD, the expression of both SLC26A3 and CFTR was absent in the ED, but testicular expression was identical to that of the controls. These results suggest a primary role for SLC26A3 in male reproduction. Tissue-specific co-expression with CFTR and NHE3 supports diverse functions of SLC26A3 and may have an impact on pathophysiology of male subfertility both in CLD and in cystic fibrosis (CF), as well as spermatoceles.

SLC26A3 and congenital chloride diarrhoea

Congenital chloride diarrhoea (CLD, OMIM214700) is a rare genetic disease caused by mutations in a plasma membrane protein, the solute-linked carrier family 26 member A3 (SLC26A3) protein, which encodes for an epithelial anion exchanger for Cl- and HCO3-. The main clinical symptom is a lifetime watery diarrhoea with a high Cl- content and low pH, causing dehydration and hypochloremic metabolic alkalosis. CLD may be fatal, if not adequately treated by substitution of NaCl, KCl and fluid lost in the faeces. Long-term prognosis is generally favourable, but complications such as renal disease, inflammatory bowel disease, hyperuricemia, inguinal hernias, spermatoceles and male subfertility are possible. The role of dysfunctional SLC26A3 in the pathogenesis of these complications is poorly known. Altogether 30 different mutations of the SLC26A3 gene are currently known among patients with CLD; the most common of them being the three founder mutations present among Finns (V317del), Polish (I675676ins) and Arabic (G187X) populations. Individual variation in the clinical picture of CLD is common, but not known to associate with the genotype.

Disruption of the SLC26A3-mediated anion transport is associated with male subfertility

Male subfertility in congenital chloride diarrhea (CLD) was possible after identification of expression of an epithelial Cl-/HCO3- exchanger SLC26A3 in the male reproductive tract and by the observation that adult men with CLD had very few children. A prospective clinical and laboratory study among eight adult Finnish men with CLD revealed constant oligoasthenoteratozoospermia but normal spermatogenesis, high chloride and low pH in seminal plasma, and three spermatoceles, suggesting that male subfertility is a clinical manifestation of CLD and could be caused by an analogous defect in the epithelial Cl-/HCO3- and water transport, as described for the CLD intestine.

NK cells in autoimmune disease

The role of NK cells in autoimmunity has not been extensively studied. Speaking for a disease-promoting role for NK cells in autoimmune diseases are recent results suggesting that IFN-gamma production by NK cells may help adaptive immune responses diverge in the direction of a Th1 response. NK cells may also be involved in direct killing of tissue cells, which could lead to acceleration of autoimmunity. However, NK cells have also been shown to protect from some autoimmune diseases. A possible reason for this discrepancy may lie in the capacity of NK cells also to produce Th2 cytokines, which could downregulate the Th1 responses that are common in autoimmune disorders. Thus there is at present no coherent view on the role of NK cells in autoimmunity, and more work is needed to clarify why NK cells in some cases aggravate disease and in some cases protect from disease.

Gastrointestinal complications after cardiac surgery

BACKGROUND

Gastrointestinal complications after cardiac surgery are often difficult to diagnose, and are associated with high morbidity and mortality rates. The aim of this study was to determine risk factors for these complications.

METHOD

Between 1996 and 2001 data were collected prospectively from 6119 patients who underwent 6186 cardiac surgical procedures. Data from patients who experienced major gastrointestinal complications were analysed retrospectively by univariate and multivariate analysis.

RESULTS

Fifty major gastrointestinal complications were identified in 47 patients (incidence 0.8 per cent). Thirteen of these patients died within 30 days. The most common complication was upper gastrointestinal bleeding (16 patients). Intestinal ischaemia was the most lethal complication (eight of ten patients died). Abdominal surgical operations were performed in 12 patients. Multivariate analysis identified nine variables that independently predicted major gastrointestinal complications: age over 80 years, active smoker, need for preoperative inotropic support, New York Heart Association class III-IV, cardiopulmonary bypass time more than 150 min, postoperative atrial fibrillation, postoperative heart failure, reoperation for bleeding and postoperative vascular complications.

CONCLUSION

Nine risk factors for the development of major gastrointestinal complications after cardiac surgery were identified. Gastrointestinal complications were often lethal but did not independently predict death within 30 days.

Inhibition of the Proteasome Reduces Transfer-Induced Diabetes in Nonobese Diabetic Mice

Inhibition of the 26S proteasome reduces the severity of several immune-mediated diseases. Here, we report that the proteasome also regulates transfer-induced diabetes in nonobese mice. Treatment of recipient mice with the proteasome inhibitor N(alpha)-benzyloxycarbonyl-l-leucyl-l-leucyl-l-leucinal (MG132) resulted in a 76% reduction in transfer-induced diabetes. The closely related inhibitor carbobenzoxy-l-leucyl-l-leucinal that inhibits calpains but not the proteasome had no protective effect, suggesting that MG132 acted via inhibition of the proteasome. MG132 decreased proliferation of transferred T cells in the pancreatic lymph nodes in vivo and prevented their expansion in a dose-dependent manner in vitro, consistent with a direct effect by MG132 on the T cells. MG132 did not prevent migration of transferred T cells into the islets but reduced the number of mice with severe infiltration. We suggest that MG132 prevents transfer-induced diabetes by directly targeting the autoreactive T cells and lowering their diabetogenic potential.

Low Number of H-2Dd-Negative Haematopoietic Cells in Mixed Bone Marrow Chimeras Convey In Vivo Tolerance to H-2Dd-Negative Cells But Fail to Prevent Resistance to H-2Dd-Negative Leukaemia

Natural killer (NK) cells kill cells lacking self major histocompatibility complex (MHC) class I. This missing self reactivity is beneficial in haploidentical bone marrow transplantations to cure leukaemia, in which donor-derived NK cells reject MHC disparate leukaemia cells and prevent relapse. To understand the role of NK cells in transplantation, we have studied NK cell tolerance in mice receiving mixed bone marrow transplants with limiting number of the MHC disparate component. Using an MHC class I (Dd) transgenic mouse model, we generated bone marrow chimeras carrying mixtures of Dd-positive and -negative cells. NK reactivity against Dd-negative cells (missing self) was assayed by outgrowth of lymphoma cells, stability of the chimerism in vivo and killing of Concanavalin A blasts in vitro. Up to 20% Dd-negative haematopoietic cells reduced, but did not abrogate, rejection of Dd-negative tumours and killing of Dd-negative T-cell blasts. In contrast, the ratios between Dd-positive and -negative cells were stable in vivo, suggesting tolerance to normal cells. Our data suggest that NK cell tolerance to normal cells and tumours in mixed MHC environments is differentially regulated, tolerance to normal cells being more easily induced. These results are important in relation to the role of NK cells in antileukaemic reactions after bone marrow transplantation.

Interstitial 1q25.3-q31.3 deletion in a boy with mild manifestations

We describe a 4-year-old boy with an accessory right thumb, short and broad toes, cryptorchidism, micrognathia, abnormally modeled ears, and delayed speech development. The chromosome analysis of patient's peripheral blood lymphocytes by conventional GTG banding demonstrated a small deletion in the long arm of chromosome 1. Confirmation and defined localization of the deleted segment to chromosomal bands 1q25.3-q31.3 was obtained by high resolution prometaphase analysis. Molecular studies, using a set of polymorphic chromosome 1q specific microsatellite markers, localized the deletion between the markers D1S2127 and D1S1727 on the paternally inherited chromosome 1. The maximum physical distance between these markers is approximately 21 Mb. The previously described two patients with 1q25-q31 deletions both had severe clinical manifestations, just as the other 10 patients with the proposed "intermediate 1q deletion syndrome," associated with 1q25-q32 deletions. Distinct from all these patients, the clinical picture of our patient is markedly milder, i.e., without growth retardation, microcephaly, or clear mental retardation.

High-dose methotrexate: on the relationship of methotrexate elimination time vs renal function and serum methotrexate levels in 1164 courses in 264 Swedish children with acute lymphoblastic leukaemia (ALL)

PURPOSE

The objectives of the present study were to determine the relationship between methotrexate (MTX) elimination time and various aspects of renal function and to evaluate the prognostic value of elevated serum MTX and creatinine for delayed MTX elimination.

PATIENTS AND METHODS

The majority of the 264 children were being treated for ALL. According to the NOPHO-92 protocol, 5 or 8 g MTX/m(2) was administered over 24 h. Serum creatinine was assessed daily. In 11 patients from one centre, renal function was studied in more detail using serum cystatin C, iohexol clearance, and urinary albumin, IgG and protein HC.

RESULTS

Increased serum creatinine correlated significantly with the elimination time of MTX, whereas no indications were found of tubular or barrier function damage. Of the 1164 courses, 44 had delayed elimination of MTX (>/=120 h). Serum MTX >150 microM at the end of infusion had a sensitivity of 0.27 and a specificity of 0.94 to predict delayed MTX elimination, and >/=50% increase in serum creatinine during the first treatment day (creatinine ratio) had a sensitivity of 0.32 and a specificity of 0.99. The corresponding risk ratios were 5 and 19 for MTX >150 micro M and creatinine ratio, respectively. In courses with a normal elimination time (<72 h), 99% of the courses had a rise in serum creatinine of less than 50%.

CONCLUSIONS

Elevation of serum creatinine by more than 50% is a better predictor of delayed elimination than the level of serum MTX at the end of MTX infusion, especially if information on previous creatinine measurements is used to reduce the impact of an occasionally low serum creatinine value before the start of the MTX infusion.

SLC26A3 mutations in congenital chloride diarrhea

Congenital chloride diarrhea (CLD) is an autosomal recessive disorder of intestinal electrolyte absorption. It is characterized by persistent secretory diarrhea resulting in polyhydramnios and prematurity prenatally, and dehydration, hypoelectrolytemia, hyperbilirubinemia, abdominal distention, and failure to thrive immediately after birth. CLD is caused by mutations in the solute carrier family 26, member 3 gene (SLC26A3, alias CLD or DRA), which encodes a Na+-independent Cl-/HCO3- (or OH-) exchanger. SLC26A3 is a member of the SLC26 sulfate permease/anion transporter family and it is expressed mainly in the apical brush border of intestinal epithelium. The only extraintestinal tissues showing SLC26A3 expression are eccrine sweat glands and seminal vesicles. A wide variety of different mutations in the SLC26A3 gene have been associated with CLD with no apparent evidence of phenotype-genotype correlation. The clinical course of CLD, however, is variable and may rather depend on environmental factors and compensatory mechanisms than mutations. In this report, we present a summary of all published and two novel SLC26A3 mutations and polymorphisms, and review them in the context of their functional consequences and clinical implications.

Upregulation of CFTR expression but not SLC26A3 and SLC9A3 in ulcerative colitis

In inflamed colonic mucosa, the equilibrium between absorptive and secretory functions for electrolyte and salt transport is disturbed. We compared the expression of three major mediators of the intestinal salt transport between healthy and inflamed colonic mucosa to understand the pathophysiology of diarrhea in inflammatory bowel disease. Expression levels of the cystic fibrosis transmembrane regulator (CFTR) (Cl- channel), SLC26A3 (Cl-/HCO exchanger) and SLC9A3 (Na+/H+ exchanger) mRNAs were measured by real-time quantitative RT-PCR in peroperative colonic samples from controls (n = 4) and patients with ulcerative colitis (n = 10). Several samples were obtained from each individual. Tissue samples were divided into three subgroups according to their histological degree of inflammation. Expression of CFTR and SLC26A3 proteins were determined by immunohistochemistry and Western blotting from the same samples, respectively. Increased expression of CFTR mRNA was observed in all three groups of affected tissue samples, most pronounced in mildly inflamed colonic mucosa (5-fold increase in expression; P < 0.001). The expression of the CFTR protein was detected from health and inflamed colon tissue. Although the expression of the SLC26A3 mRNA was significantly decreased in severe ulcerative colitis (P < 0.05), the SLC26A3 protein levels remained unchanged in all groups. The expression of SLC9A3 mRNA was significantly changed between the mild and severe groups. Intestinal inflammation modulates the expression of three major mediators of intestinal salt transport and may contribute to diarrhea in ulcerative colitis both by increasing transepithelial Cl- secretion and by inhibiting the epithelial NaCl absorption.

Gastrectomized rats respond with exaggerated hypercalcemia to oral and intravenous calcium loads because of impaired ability of bone to take up Ca2+

BACKGROUND

Gastrectomy (Gx) causes osteopenia. The hypothesis tested in the present study is that Gx affects Ca homeostasis and that an impaired ability to handle Ca contributes to the Gx-evoked osteopenia.

METHODS

SHAM-operated and Gx rats were compared with respect to changes in blood Ca2+ after oral or intravenous loads of CaCl2 1-2 weeks or 2-4 months after the operations.

RESULTS

Different doses of oral CaCl2 raised blood Ca2+ more in Gx than in SHAM rats, more so after 2-4 months than after 1-2 weeks. The rise was greater in fasted (48 h) rats than in fed rats regardless of whether they were SHAM or Gx. While SHAM rats tolerated high doses of CaCl2 well, Gx rats died when exposed to quite modest doses, particularly 2-4 months after Gx. Intravenous infusion of CaCl2 (2,500 micromol/kg/h) induced a greater and steeper rise in blood Ca2+ in Gx rats than in SHAM rats. Kinetic analysis of the blood Ca2+ data showed Gx rats to display: 1) a decreased Ca2+ elimination clearance from the central distribution compartment (blood), 2) a reduced size of the peripheral distribution compartment (the so-called bone fluid compartment). and 3) a spectacular decrease in the intercompartmental clearance (transfer of Ca2+ from blood to bone). These effects were notably apparent after 2-4 months. At sacrifice, the Gx-evoked osteopenia was confirmed by planimetric analysis of the calvariae. revealing 40% reduction of bone tissue after 2-4 months.

CONCLUSIONS

Based on the present data we argue that Gx rats respond with exaggerated hypercalcemia to oral and intravenous CaCl2 loads because of a greatly impaired transfer of Ca+ from blood to bone. We suggest that with time this impairment results in osteopenia.

Acquisition of external major histocompatibility complex class I molecules by natural killer cells expressing inhibitory Ly49 receptors

Murine natural killer (NK) cells express inhibitory Ly49 receptors specific for major histocompatibility complex (MHC) class I molecules. We report that during interactions with cells in the environment, NK cells acquired MHC class I ligands from surrounding cells in a Ly49-specific fashion and displayed them at the cell surface. Ligand acquisition sometimes reached 20% of the MHC class I expression on surrounding cells, involved transfer of the entire MHC class I protein to the NK cell, and was independent of whether or not the NK cell expressed the MHC class I ligand itself. We also present indirect evidence for spontaneous MHC class I acquisition in vivo, as well as describe an in vitro coculture system with transfected cells in which the same phenomenon occurred. Functional studies in the latter model showed that uptake of H-2D(d) by Ly49A+ NK cells was accompanied by a partial inactivation of cytotoxic activity in the NK cell, as tested against H-2D(d)-negative target cells. In addition, ligand acquisition did not abrogate the ability of Ly49A+ NK cells to receive inhibitory signals from external H-2D(d) molecules. This study is the first to describe ligand acquisition by NK cells, which parallels recently described phenomena in T and B cells.

A new liposomal liver-specific contrast agent for CT: first human phase-I clinical trial assessing efficacy and safety

In this first clinical trial liposome-encapsulated iodixanol, CT particles (CTP) were studied. The aims of the present trial were to assess the efficacy of CTP in CT and to determine the safety of different doses of CTP. A total of 47 healthy volunteers were enrolled in the present study. The CTP was administered at doses 10, 30, 70 and 100 mg encapsulated I/kg bw. Efficacy was assessed using single-slice CT of the abdomen and evaluated by dose-response attenuation curves over time in liver, spleen, and abdominal vessels. Safety was assessed by blood tests, clinical examinations and recording of subjective adverse events (AE). The attenuations in liver tissue increased with the dose and maximal values above baseline were 20, 39 and 45 HU at the doses 30, 70 and 100 mg encapsulated I/kg bw, respectively. Maximal increases were seen 12.5 min after contrast administration. As for liver, the attenuations in spleen increased with the dose, but higher attenuations were obtained. In early images clinically significant enhancement was seen in abdominal vessels. Mild and moderate subjective AE were encountered at the doses 70 and 100 mg encapsulated I/kg bw. The CTP is efficacious in enhancing hepatic and splenic tissues and in early imaging of abdominal vessels. Adverse event precludes a clinical use of CTP in the current formulation.

Identification of seven novel mutations including the first two genomic rearrangements in SLC26A3 mutated in congenital chloride diarrhea

Congenital chloride diarrhea (CLD) is an autosomal recessive disorder characterized by defective intestinal electrolyte absorption, resulting in voluminous osmotic diarrhea with high chloride content. A variety of mutations in the solute carrier family 26, member 3 gene (SLC26A3, previously known as CLD or DRA) are responsible for the disease. Since the identification of the SLC26A3 gene and the determination of its genomic structure, altogether three founder and 17 private mutations have been characterized within miscellaneous ethnic groups. We screened for mutations in seven unrelated families with CLD. The diagnoses were confirmed by fecal chloride measurements. The combined PCR-SSCP and sequencing analyses revealed altogether seven novel mutations including two missense mutations (S206P, D468V), two splicing defects (IVS12-1G>C, IVS13-2delA), one nonsense mutation (Q436X), one insertion/deletion mutation (2104-2105delGGins29-bp), and an intragenic deletion of SLC26A3 exons 7 and 8. Two previously identified mutations were also found. This is the first report of rearrangement mutations in SLC26A3. Molecular features predisposing SLC26A3 for the two rearrangements may include repetitive elements and palindromic-like sequences. The increasingly wide diversity of SLC26A3 mutations suggests that mutations in the SLC26A3 gene may not be rare events.

Clinical pharmacology of thalidomide

BACKGROUND

Thalidomide has a chiral centre, and the racemate of (R)- and (S)-thalidomide was introduced as a sedative drug in the late 1950s. In 1961, it was withdrawn due to teratogenicity and neuropathy. There is now a growing clinical interest in thalidomide due to its unique anti-inflammatory and immunomodulatory effects.

OBJECTIVE

To critically review pharmacokinetic studies and briefly review pharmacodynamic effects and studies of thalidomide in consideration of its chemical and stereochemical properties and metabolism.

METHODS

Literature search and computer simulations of pharmacokinetics.

RESULTS

Rational use of thalidomide is problematic due to lack of basic knowledge of its mechanism of action, effects of the separate enantiomers and metabolites and dose- and concentration-effect relationships. Due to its inhibition of tumour necrosis factor-alpha and angiogenesis, racemic thalidomide has been tested with good effect in a variety of skin and mucous membrane disorders, Crohn's disease, graft-versus-host disease, complications to human immunodeficiency virus and, recently, in multiple myeloma. Adverse reactions are often related to the sedative effects. Irreversible toxic peripheral neuropathy and foetal malformations are serious complications that can be prevented. The results of several published pharmacokinetic studies can be questioned due to poor methodology and the use of non-stereospecific assays. The enantiomers of thalidomide undergo spontaneous hydrolysis and fast chiral interconversion at physiological pH. The oral bioavailability of thalidomide has not been unequivocally determined, but available data suggest that it is high. Absorption is slow, with a time to maximum plasma concentration of at least 2 h, and may also be dose-dependent; however, that of the separate enantiomers may be faster due to higher aqueous solubility. Estimation of the volume of distribution is complicated by probable hydrolysis and chiral inversion also in peripheral compartments. A value of around 11/kg is however plausible. Plasma protein binding is low with little difference between the enantiomers. Elimination of thalidomide is mainly by pH-dependent spontaneous hydrolysis in all body fluids with an apparent mean clearance of 10 l/h for the (R)- and 21 l/h for the (S)-enantiomer in adult subjects. Blood concentrations of the (R)-enantiomer are consequently higher than those of the (S)-enantiomer at pseudoequilibrium. The mean elimination half-life of both enantiomers is 5 h. One hydroxylated metabolite has been found in low concentrations in the blood. Since both enzymatic metabolism and renal excretion play minor roles in the elimination of thalidomide, the risk of drug interactions seems to be low.

CONCLUSIONS

The interest in and use of thalidomide is increasing due to its potential as an immunomodulating and antiangiogenic agent. The inter-individual variability in distribution and elimination is low. Apart from this, its use is complicated by the lack of knowledge of dose- or concentration-effect relationships, possible dose-dependent oral absorption and of course by its well-known serious adverse effects.

Distinct outcomes of chloride diarrhoea in two siblings with identical genetic background of the disease: implications for early diagnosis and treatment

BACKGROUND

Congenital chloride diarrhoea (CLD, OMIM 214700) is a serious inherited defect of intestinal electrolyte absorption transmitted in an autosomal recessive fashion. The major clinical manifestation is diarrhoea with high chloride content which can be balanced by substitution. The molecular pathology involves an epithelial Cl(-)/HCO(3)(-) exchanger protein, encoded by the solute carrier family 26, member 3 gene (SLC26A3), previously known as CLD or DRA (downregulated in adenomas). To date, almost 30 different mutations in the SLC26A3 gene have been identified throughout the world. No clear genotype-phenotype correlation has been established.

PATIENTS/METHODS

Two siblings presenting with CLD were studied for disease history, supplementation, or other treatments, and for mutations in the SLC26A3 gene.

RESULTS

Mutation analysis revealed a homozygous I544N mutation in both patients. However, despite the uniform genetic background of CLD in this family, the clinical picture and outcome of the disease were remarkably different between siblings. The older sibling had a late diagnosis and chronic course of the disease whereas the younger one, who was diagnosed soon after birth and immediately received supplementation therapy, grows and develops normally.

CONCLUSION

Time of diagnosis, substitution therapy, compliance, and compensatory mechanisms are more important modulators of the clinical picture of CLD than the type of mutation in the SLC26A3 gene.

Maternal and Paternal Chromosomes 7 Show Differential Methylation of Many Genes in Lymphoblast DNA

Genomic imprinting, the differential expression of paternal and maternal alleles, involves many chromosomal regions and plays a role in development and growth. Differential methylation of maternal and paternal alleles is a hallmark of imprinted genes, and thus methylation assays are widely used to support the identification of novel imprinted genes. Either blood or lymphoblast DNAs are most often used in these assays, even though methylation levels may change in cell culture. We undertook a systematic survey of parent-of-origin-specific methylation of chromosome 7 genes and ESTs by comparing DNA samples from cases of maternal and paternal uniparental disomy for chromosome 7 using DNA from fresh blood and lymphoblast cell lines. Our results revealed that up to 41% of genes and ESTs show parent-of-origin-specific methylation differences in lymphoblast DNA after only a short time in culture, whereas methylation differences were not seen in blood DNA. The methylation changes occurred most commonly on paternal chromosome 7, whereas alterations on maternal chromosome 7 were more infrequent and weaker. These findings indicate that methylation patterns may change significantly during cell culture in a parent-of-origin-dependent manner and suggest that methylation is maintained differently on maternal and paternal chromosomes 7.

Elimination of S100B and renal function after cardiac surgery

OBJECTIVES

To determine the biologic half-life of the S100B protein and to investigate if the elimination of S100B depends on glomerular filtration rate (GFR).

DESIGN

Prospective human study.

SETTING

University hospital.

PARTICIPANTS

Sixteen patients who underwent cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

Shed mediastinal blood (autotransfusion) was returned to the patients postoperatively and used to study the kinetics of S100B. Iohexol was infused simultaneously to estimate GFR. S100B was measured at 0, 20, 40, 60, and 180 minutes after infusion. Iohexol was measured at 180 and 240 minutes after infusion.

MEASUREMENTS AND MAIN RESULTS

S100B followed first-order kinetics, and the biologic half-life for S100B was determined to be 25.3 +/- 5.1 minutes. GFR was determined to be 63.8 +/- 34.4 mL/min. No correlation was found between GFR and S100B half-life.

CONCLUSIONS

The elimination of S100B after cardiac surgery is faster than reported earlier and not affected by a moderate decrease in GFR. This finding is important when evaluating S100B levels after cardiac surgery.