Disease associated balanced chromosome rearrangements: a resource for large scale genotype-phenotype delineation in man.

Disease associated balanced chromosomal rearrangements (DBCRs), which truncate, delete, or otherwise inactivate specific genes, have been instrumental for positional cloning of many disease genes. A network of cytogenetic laboratories, Mendelian Cytogenetics Network (MCN), has been established to facilitate the identification and mapping of DBCRs. To get an estimate of the potential of this approach, we surveyed all cytogenetic archives in Denmark and southern Sweden, with a population of approximately 6.6 million. The nine laboratories have performed 71 739 postnatal cytogenetic tests. Excluding Robertsonian translocations and chromosome 9 inversions, we identified 216 DBCRs ( approximately 0.3%), including a minimum estimate of 114 de novo reciprocal translocations (0.16%) and eight de novo inversions (0.01%). Altogether, this is six times more frequent than in the general population, suggesting a causal relationship with the traits involved in most of these cases. Of the identified cases, only 25 (12%) have been published, including 12 cases with known syndromes and 13 cases with unspecified mental retardation/congenital malformations. The remaining DBCRs were associated with a plethora of traits including mental retardation, dysmorphic features, major congenital malformations, autism, and male and female infertility. Several of the unpublished DBCRs defined candidate breakpoints for nail-patella, Prader-Willi, and Schmidt syndromes, ataxia, and ulna aplasia. The implication of the survey is apparent when compared with MCN; altogether, the 292 participating laboratories have performed >2.5 million postnatal analyses, with an estimated approximately 7500 DBCRs stored in their archives, of which more than half might be causative mutations. In addition, an estimated 450-500 novel cases should be detected each year. Our data illustrate that DBCRs and MCN are resources for large scale establishment of phenotype-genotype relationships in man.

Particle size distribution of workplace aerosols in manganese alloy smelters applying a personal sampling strategy.

Air samples were collected by personal sampling with five stage Sioutas cascade impactors and respirable cyclones in parallel among tappers and crane operators in two manganese (Mn) alloy smelters in Norway to investigate PM fractions. The mass concentrations of PM collected by using the impactors and the respirable cyclones were critically evaluated by comparing the results of the parallel measurements. The geometric mean (GM) mass concentrations of the respirable fraction and the <10 µm PM fraction were 0.18 and 0.39 mg m(-3), respectively. Particle size distributions were determined using the impactor data in the range from 0 to 10 µm and by stationary measurements by using a scanning mobility particle sizer in the range from 10 to 487 nm. On average 50% of the particulate mass in the Mn alloy smelters was in the range from 2.5 to 10 µm, while the rest was distributed between the lower stages of the impactors. On average 15% of the particulate mass was found in the <0.25 µm PM fraction. The comparisons of the different PM fraction mass concentrations related to different work tasks or different workplaces, showed in many cases statistically significant differences, however, the particle size distribution of PM in the fraction <10 µm d(ae) was independent of the plant, furnace or work task.

High resolution comparative genomic hybridisation analysis reveals imbalances in dyschromosomal patients with normal or apparently balanced conventional karyotypes.

A sensitive technique is needed for screening whole genome imbalances in dyschromosomal patients when G-banding shows normal karyotypes or apparently balanced translocations. In this study we performed highly sensitive comparative genomic hybridisation analysis on a number of such cases and revealed chromosomal imbalances in all.

Molecular cytogenetic detection of 9q34 breakpoints associated with nail patella syndrome.

The nail patella syndrome (NPS1) is an autosomal dominant disorder characterised by dysplasia of the finger nails and skeletal abnormalities. NPS1 has been mapped to 9q34, to a 1 cM interval between D9S315 and the adenylate kinase gene (AK1). We have mapped the breakpoints within the candidate NPS1 region in two unrelated patients with balanced translocations. One patient [46,XY,t(1;9)(q32.1;q34)] was detected during a systematic survey of old cytogenetic files in Denmark and southern Sweden. The other patient [46,XY,t(9;17)(q34.1;q25)] was reported previously. D9S315 and AK1 were used to isolate YACs, from which endclones were used to isolate PACs. Two overlapping PAC clones span the 9q34 breakpoints in both patients, suggesting that NPS1 is caused by haploinsufficiency due to truncation or otherwise inactivation of a gene at or in the vicinity of the breakpoints.

Tetrasomy 18p de novo: parental origin and different mechanisms of formation.

We have used eight PCR-based DNA polymorphisms to determine the parental origin and mechanisms of formation in 9 patients with de novo nonmosaic tetrasomy 18p. The 9 patients, 4 girls and 5 boys, had clinical features characteristic of i(18p) syndrome. The supernumerary marker chromosome was identified by fluorescence in situ hybridization (FISH) analysis using centromeric probes and a flow-sorted 18p-specific library. The isochromosome was of maternal origin in all 9 cases. The formation of tetrasomy 18p cannot be explained by a single model. In 6 cases, meiosis II nondisjunction, followed by subsequent postzygotic misdivsion, and in 1 case postzygotic nondisjunction and postzygotic misdivision were the most likely mechanisms of formation. Alternative mechanisms are suggested in the remaining 2 cases.

Origin of nondisjunction in trisomy 8 and trisomy 8 mosaicism.

Causes of chromosomal nondisjunction is one of the remaining unanswered questions in human genetics. In order to increase our understanding of the mechanisms underlying nondisjunction we have performed a molecular study on trisomy 8 and trisomy 8 mosaicism. We report the results on analyses of 26 probands (and parents) using 19 microsatellite DNA markers mapping along the length of chromosome 8. The 26 cases represented 20 live births, four spontaneous abortions, and two prenatal diagnoses (CVS). The results of the nondisjunction studies show that 20 cases (13 maternal, 7 paternal) were probably due to mitotic (postzygotic) duplication as reduction to homozygosity of all informative markers was observed and as no third allele was ever detected. Only two cases from spontaneous abortions were due to maternal meiotic nondisjunction. In four cases we were not able to detect the extra chromosome due to a low level of mosaicism. These results are in contrast to the common autosomal trisomies (including mosaics), where the majority of cases are due to errors in maternal meiosis.

Monozygotic twins discordant for gastroschisis: case report and review of the literature of twins and familial occurrence of gastroschisis.

We describe a pair of monozygotic (MZ) female twins discordant for gastrochisis. To our knowledge, this is the first such case reported. The zygosity was verified by DNA analysis using highly polymorphic microsatellites. There was no family history of gastroschisis. During pregnancy there was no suspicion of any exposure responsible for the malformation. The number of twin cases described so far does not allow any conclusion as to hereditary factors in the cause of gastroschisis, but the number of families reported with familial gastroschisis suggests that the recurrence risk is higher than previously thought.

Obstetrical and gynecological complications in fragile X carriers: a multicenter study.

We have conducted a multicenter obstetrical and gynecological survey of women in fragile X families. Included in the study were 131 gene carriers (39 with a full mutation and 92 with a premutation) and 109 noncarriers. Analysis indicated that higher numbers of fragile X gene carriers reported having irregular menses and other gynecological complications. As a group they also experienced cessation of menses prior to age 40 years at a significantly higher rate. The data appear to indicate that the FMR1 gene may play a role in the development and proliferation of oogonia.

Early outcome and graft patency in mammary artery grafting of left anterior descending artery with sternotomy or anterior minithoracotomy.

BACKGROUND: The main objective of this study was to retrospectively compare early outcome and graft patency in patients who underwent coronary artery bypass grafting with the internal thoracic artery to the left anterior descending artery via an anterior minithoracotomy or median sternotomy and without the use of extracorporeal circulation. METHODS: One hundred thirty consecutive patients were studied. Median sternotomy was performed in 77 patients and anterior minithoracotomy in 53 patients. RESULTS: There were no differences in early clinical data or persistent postoperative pain between the groups. Early graft patency was 88% in the thoracotomy group and 96% in the sternotomy group (p = 0.3). Five of 7 patients who presented with a significant stenosis at the first coronary angiography had a normal angiogram at the reangiography. None of the patients with nonsignificant stenosis at the early coronary angiography had any clinical signs of ischemia or chest pain. CONCLUSIONS: In our experience, anterior minithoracotomy and median sternotomy are different and distinguishable regarding early outcome and early graft patency. Most of the stenoses visualized at the early coronary angiography had vanished at a later coronary angiography, which makes the interpretation of the angiogram hazardous as a tool for the decision for redo procedure in the early postoperative period.

The impact of time after portacaval shunt in the rat on behavior, brain serotonin, and brain and muscle histology.

We investigated open field behavior, cellular fluorescence of brain serotonin and serotonin metabolism in different regions of the central nervous system (CNS), and brain and muscle histology in rats 3 weeks or 6 months after surgical end-to-side portacaval shunt (PCS). The results revealed a similar disturbance of the CNS serotonin at 3 weeks and 6 months after PCS in the rat. Progressive neurohistological changes were present between 3 weeks and 6 months after PCS. The open field behavioral impairment appeared, however, to diminish with time. There was no evidence from muscle biopsies that lesions in the muscles or in the peripheral nerves contributed to the motor disturbance.

Replacement of the ascending aorta with composite valve grafts: long term results.

BACKGROUND AND AIMS OF THE STUDY: Long term survival after replacement of the aortic root is improving. The most common cause of late death is progression of disease in the remaining aorta (dissection or atherosclerosis). The purpose of this study was to review our clinical experience with composite graft replacement of the aortic root with special reference to long term results. MATERIALS AND METHODS: One hundred twenty-six patients (mean age: 53 years) with different pathologies of the ascending aorta underwent aortic root replacement with a composite-graft prosthesis over a 12-year period. Twenty-three patients had previously undergone cardiovascular surgery. The surgical technique included resection of the ascending aorta with the aortic valve and end-to-side anastomosis between full-thickness buttons of the aortic wall with the coronary ostia and the graft. One or more associated cardiovascular procedures were performed in 24 cases. Long term follow up to July 1995 is complete. Uni- and multivariate analysis were performed to identify risk-factors for early and late mortality and reoperation. RESULTS: Twenty-three patients died during the first 30 days (18%). Sixteen of them had aortic dissection. The most common cause of early death was heart failure. Twenty-three patients died during the follow up time with heart failure, again, being the most common cause of death. Thirteen late reoperations on the composite-graft or the remaining aorta were performed in 12 patients, six of whom had Marfan's syndrome. The 30-day mortality at reoperation was 30%. CONCLUSIONS: This surgical option offers good long term results with a five-year actuarial survival of 67% or 75% when the 30-day mortality is excluded. Careful follow up of patients with Marfan's syndrome and/or aortic dissection is mandatory to increase the long term survival.

Aortic surgery in patients with marfan syndrome: long-term survival, morbidity and function.

BACKGROUND AND AIM OF THE STUDY: The natural history of patients with Marfan syndrome is depressing, but surgical intervention on the aorta can improve the prognosis. Study results were analyzed with reference to long-term survival, morbidity and function. METHODS: Seventy-four Marfan patients (51 males, 23 females; mean age 41+/-14 years), underwent first-time aortic surgery between 1977 and 1998. Follow up information regarding mortality, morbidity and functional status was obtained from patient records and by questionnaire. The mean follow up was 5 years (range: 0-19 years). Forty-seven patients (64%) had a dissection, 27 (36%) an aneurysm, and 45 (61%) patients underwent emergency operations (<4 h from arrival at hospital). In 72 patients (97%) the disease affected the ascending aorta, and implantation of a composite graft was the most frequent operation. RESULTS: Overall 30-day mortality was 12% (3% in elective cases, 18% in emergency cases, p <0.05). Emergency operations and surgery extended to the aortic arch were risk factors for early mortality. Overall actuarial survival was 63.4+/-8% at 10 years. Age was the only risk factor for late mortality. Seventeen patients were reoperated on due to pathologies of the remaining aorta (n = 12), pseudoaneurysms (n = 4) and aortic valve endocarditis (n = 1). A total of five patients had endocarditis; one patient with a homograft required surgery, and medical treatment was successful in the other four patients. Five patients had neurological thromboembolic episodes without permanent damage, and six had minor bleeding complications. Freedom from early and late mortality, reoperation on the aorta and major cardiovascular events (endocarditis episodes, thromboembolic/hemorrhagic strokes and other major bleeding/embolic episodes) was 33.3 +/- 8.1% at 10 years. At follow up, 98% of patients were in NYHA functional class I or II, and 80% were working. CONCLUSION: Elective aortic surgery in Marfan patients can be performed with good results. Close follow up of patients undergoing surgery is important. The long-term functional status of surviving patients is satisfactory.

Serotonin metabolism in the central nervous system in portacaval shunted rats infused with fat emulsion.

Increased brain concentrations of tryptophan, and presumably thereby increased brain serotonin metabolism, have been observed following liver impairment and implicated in the etiology of portal-systemic encephalopathy (PSE). Increased plasma-free tryptophan (ie, not albumin-bound) concentrations can be expected after exogenous fat administration. This might further increase the brain serotonin metabolism in liver failure and negatively influence the PSE. We treated rats 2 weeks after end-to-side portacaval shunt (PCS) with continuous intravenous infusion of fat emulsion (Intralipid 20%) for 24 and 72 hr, respectively. The regional serotonin turnover was determined in different regions of the central nervous system (CNS) by measuring 5-hydroxyindole concentrations after NSD 1015 decarboxylase inhibition. The results revealed no further increase of the CNS serotonin turnover after fat infusion to PCS rats, compared with PCS rats given equal amounts of glucose. Thus, continuous infusion of a fat emulsion caused no major alteration of the CNS serotonin metabolism in PCS rats.

Amino acids and indoleamines in the brain after infusion of branched-chain amino acids to rats with liver ischemia.

Rats with a portacaval anastomosis and ligation of the hepatic artery 2 days later were infused for 6 hr with a 10% glucose solution (group I) or the same solution combined with 0.24 M/liter branched-chain amino acids (BCAA, group II). Control animals with portacaval anastomosis and sham-operation (group III) or two sham-operations (group IV) were infused with a 10% glucose solution. The rats were killed by decapitation and indoleamines and amino acids were determined in the brain. Rats with liver ischemia were stuporous at the end of the experiment irrespective of treatment. The concentrations in the cortex of lysine, methionine, phenylalanine, threonine, alanine, glutamine, glycine, histidine, and tyrosine were significantly increased in group I compared to group IV. Infusion of BCAA to rats with liver-ischemia (group II) resulted in significantly lower concentrations of lysine, methionine, phenylalanine, threonine, histidine and tyrosine and increased concentrations of isoleucine, leucine, valine, and arginine compared to group I. The content of serotonin in the cortex and brain stem was significantly increased in group I compared with the BCAA-treated animals (group II) and the control groups III and IV. The concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in the cortex and brain stem were higher in group I than in group IV. Infusion of BCAA to rats with liver ischemia normalized the concentrations of 5-HIAA in the cortex and brain stem.

Serotonin receptors in the brain following total hepatectomy in rats treated with branched-chain amino acids.

Serotonin concentrations and receptor binding characteristics were investigated in rats subjected to total hepatectomy, portacaval shunt (PCS) or sham-operation. The animals were infused for 5 hr with a 10% glucose solution or the same solution enriched with 0.24 M branched-chain amino acids (BCAA). Hepatectomized animals were in grade-two coma at the end of the experiment independent of infusion. Indoleamines in mesencephalon-pons and diencephalon were analyzed by high-pressure liquid chromatography with electrochemical detection. Serotonin receptors (5-HT1 and 5-HT2) were investigated in the cortex and hippocampus by radioligand binding studies using 3H-serotonin for analysis of 5-HT1-receptors and 3H-ketanserin for analysis of 5-HT2-receptors. Concentrations of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were significantly increased after hepatectomy compared with controls. Treatment with BCAA significantly decreased 5-HT and 5-HIAA levels in hepatectomized animals. The affinity and the number of binding sites for the 5-HT1 and 5-HT2 receptors were found to be similar in all groups. The present study indicates that PCS for 1 week and the anhepatic state for 5 hr in rats do not influence brain serotonin receptors in contrast to previous studies in pigs with liver ischemia or rabbits with galactosamine-induced liver damage. In addition, infusion of BCAA for 5 hr did not alter the binding characteristics.

The "90 degrees bent" two-stage venous cannula.

A 90 degree bent two-stage venous cannula for cardiopulmonary bypass is presented and discussed. Its main advantages, compared to similar straight ones, are that it is out of the way of the surgeon, by being placed under the right sternum and also that the venous return seems uninfluenced by displacement of the heart when operating on the posterior side of the heart. No major drawbacks for the cannula have been noticed so far.

The de-airing clamp in cardiac surgery.

De-airing of the heart in open heart surgery is a necessary routine. Most of the air is evacuated from the heart before the aortic cross clamp is removed, but the de-airing may be continued even after declamping. One way to continue de-airing is to partially clamp the ascending aorta, proximally to the aortic cannula, in order to create a pocket for trapping residual air coming from the left ventricle. This paper describes a clamp specially designed and developed for this purpose. It has been used in our center since 1990 and our experience is reported. The clamp has been used on 250 patients and in 50% ultrasonography has been used to examine the heart being free from air bubbles within 20 min from releasing the aortic cross clamp.

Difficulties in the interpretation of coronary angiogram early after coronary artery bypass surgery on the beating heart.

OBJECTIVE: The major objective of this study was to evaluate the findings in early postoperative coronary angiography in patients who underwent coronary revascularization on the beating heart without cardiopulmonary bypass. METHODS: Eighty-four consecutive patients receiving 113 grafts were studied. A coronary angiography was performed 0 to 5 days postoperatively. All the grafts were reviewed and classified in the following way: grade A (unimpaired run-off); grade B1 (<50 stenosis); grade B2 (>50% stenosis); grade O (occlusion). A second coronary angiography was performed in patients with a stenosis grade B2, 4 to 30 months postoperatively. An exercise test was performed by patients with B1 stenosis. RESULTS: Overall graft patency was 96% in the 113 grafts. None of the 14 patients with B1 stenosis in the early coronary angiography had any clinical signs of ischemia. Eight of the 12 patients who exhibited B2 stenosis either at the anastomotic site, in the graft or in the distal coronary artery at the first coronary angiography had a normal angiogram at the re-angiography. CONCLUSION: A majority of stenoses visualized at the early coronary angiography could not be seen at a later coronary angiography, which makes the interpretation of the angiogram unreliable as a tool for the decision as to redo-procedure in the early postoperative period.

Primary malignant cardiac tumors.

Our experience with primary malignant cardiac tumors is reviewed. Six adult patients were treated surgically during a 10-year period. A preoperative diagnosis of cardiac "tumor" was established in all cases by means of echocardiography. Surgery was possible in each case. Adjuvant therapy was also used. All patients died between 3 weeks and 43 months from the first operation. The importance of an aggressive surgical attitude and the role of adjuvant therapy is discussed.