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41.
Somatic mutation processes at a human minisatellite 总被引:6,自引:3,他引:6
Germline instability at human minisatellites frequently involves complex
inter-allelic transfers of repeat units usually restricted to one end of
the repeat array and apparently regulated by flanking DNA. In contrast,
nothing is known about the structural basis of somatic instability at
minisatellites. An electrophoretic size-enrichment strategy was therefore
developed at minisatellite MS32 (D1S8) to enable rare abnormal-length
mutants to be detected, validated and quantitated in blood DNA by single
molecule PCR. Structural analysis of rare mutant alleles in blood revealed
simple deletions/duplications of repeat unit blocks located at random along
the tandem repeat array, a mode of mutation completely different from that
seen in sperm. Furthermore, allele-specific suppression of sperm
instability at MS32 did not affect somatic instability. These data suggest
that conversion-based minisatellite mutation in sperm is completely
germline-specific and most likely meiotic in origin. Somatic instability
appears to occur by a separate pathway involving replication slippage or,
more likely, intra-allelic unequal crossing over.
相似文献
42.
Mutations in the TSC2 gene: analysis of the complete coding sequence using the protein truncation test (PTT) 总被引:4,自引:0,他引:4
Mutations in the TSC2 gene on chromosome 16p13.3 are responsible for
approximately 50% of familial tuberous sclerosis (TSC). The gene has 41
small exons spanning 45 kb of genomic DNA and encoding a 5.5 kb mRNA. Large
germline deletions of TSC2 occur in <5% of cases, and a number of small
intragenic mutations have been described. We analysed mRNA from 18
unrelated cases of TSC for TSC2 mutations using the protein truncation test
(PTT). Three cases were predicted to be TSC2 mutations on the basis of
linkage analysis or because a hamartoma from the patient showed loss of
heterozygosity for 16p13.3 markers. Three overlapping PCR products,
covering the complete coding sequence of mRNA, were generated from
lymphoblastoid cell lines, translated into 35S-methionine labelled protein,
and analysed by SDS-PAGE. PCR products showing PTT shifts were directly
sequenced, and mutations confirmed by restriction enzyme digestion where
possible. Six PTT shifts were identified. Five of these were caused by
mutations predicted to produce a truncated protein: (i) a sporadic case
showed a 32 bp deletion in exon 11, and a mutant mRNA without exon 11 was
produced; the normal exon 10 was also spliced out; (ii) a sporadic case had
a 1 bp deletion in exon 12 (1634delT); (iii) a TSC2-linked mother and
daughter pair had a G-->T transversion in exon 23 (G2715T) introducing a
cryptic splice site causing a 29 bp truncation of mRNA from exon 23; (iv) a
sporadic case showed a 2 bp deletion in exon 36; (v) a sporadic case showed
a 1 bp insertion disrupting the donor splice site of exon 37 (5007+2insA),
resulting in the use of an upstream exonic cryptic splice site to cause a
29 bp truncation of mRNA from exon 37. In one case, the PTT shift was
explained by in-frame splicing out of exon 10, in the presence of a normal
exon 10 genomic sequence. Alternative splicing of exon 10 of the TSC2 gene
may be a normal variant. Three 3rd base substitution polymorphisms were
also detected during direct sequencing of PCR products. Confirmed mutations
were identified in 28% of the families studied and on the assumption that
half of the sporadic cases should have TSC2 mutations, a crude estimate of
the detection rate would be 60%. This compares favourably with other
screening methods used for TSC2, notably SSCP, and since PTT involves much
less work it may be the method of choice.
相似文献
43.
H H Parving J M Hansen S L Nielsen N Rossing O Munck N A Lassen 《The New England journal of medicine》1979,301(9):460-465
We assessed extravascular accumulation of albumin and fluid in primary myxedema by measuring metabolic turnover and transcapillary escape of 131I-labeled human albumin in seven patients. In the hypothyroid state, we found a low plasma volume (P less than 0.05), a reduced rate of albumin synthesis and catabolism (P less than 0.01), an increased transcapillary escape rate of albumin (P less than 0.01), a remarkable increase in the extravascular mass of albumin (1500 micronmol; P less than 0.01) and a longer mean transit time through the extravascular spaces in primary myxedema than in other states of generalized edema (P less than 0.05). All variables returned to normal during l-thyroxine treatment. The extravascular accumulation of albumin, and presumably of all other plasma proteins, is important in the generalized edema typically found in myxedema. Inadequate lymphatic drainage may also explain the formation of exudates in the serous cavities that are well known in myxedema. 相似文献
44.
Detecting pre-ovulatory luteinizing hormone surges in urine 总被引:2,自引:1,他引:2
Kesner JS; Knecht EA; Krieg EF Jr; Wilcox AJ; O'Connor JF 《Human reproduction (Oxford, England)》1998,13(1):15-21
The study objectives were to determine (i) if pre-ovulatory luteinizing
hormone (LH) surges, undetected in urine by two immunoradiometric assays
(IRMA), were detectable by an ultrasensitive immunofluorometric assay
(IFMA) and (ii) the influence of creatinine adjustment on the detection and
timing of the urinary LH surges. Daily urine specimens were contributed by
healthy 25-36 year old volunteers during 14 ovulatory menstrual cycles for
an epidemiological study conducted in 1983-1985. Specimens were selected as
having been previously assayed by two IRMA without consistently detecting
LH surges. These urine specimens were remeasured using an IFMA and adjusted
for creatinine concentration. IFMA measurements revealed unambiguous LH
surges in all cycles. Adjusting IRMA urinary LH values for creatinine
concentrations revealed previously undetected LH surges in four of eight
cycles. Creatinine adjustment also altered the timing of IRMA and IFMA LH
surges by 1-5 days. These results demonstrate an IFMA that detects pre-
ovulatory LH surges in unpreserved, frozen urine from cycles where such
surges were previously undetectable. Further, creatinine adjustment can
markedly affect detection and timing of the onset and peak of the urinary
LH surge. While our analysis suggests that this adjustment improves the
validity of the LH measure, this requires further investigation.
相似文献
45.
We performed a randomized doubled-blind study to evaluate whether there was a benefit in delay in tourniquet deflation with intra-articular administration of morphine and bupivacaine following operative arthroscopic surgery. In 34 patients the tourniquet was deflated immediately and in 38 patients the tourniquet remained inflated for 10 min following injection. The analgesic efficacy was assessed using pain scores and the amount of supplementary analgesia required. The results demonstrate no benefit in delay in tourniquet deflation. 相似文献
46.
47.
48.
Storlazzi CT Fioretos T Paulsson K Strömbeck B Lassen C Ahlgren T Juliusson G Mitelman F Rocchi M Johansson B 《Human molecular genetics》2004,13(14):1479-1485
Double minutes (dmin), the cytogenetic hallmark of genomic amplification, are found in approximately 1% of karyotypically abnormal acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS). The MYC gene at 8q24 has been reported to be amplified in the majority of the cases, and generally it has been assumed that MYC is the target gene. However, only a few studies have focused on the extent of the amplicon or on the expression patterns of the amplified genes. We have studied six cases (five AML and one MDS) with MYC-containing dmin. Detailed fluorescence in situ hybridization analyses identified a common 4.3 Mb amplicon, with clustered proximal and distal breakpoints, harboring eight known genes (C8FW, NSE2, POU5FLC20, MYC, PVT1, AK093424, MGC27434 and MLZE). The corresponding region was deleted in one of the chromosome 8 homologues in five of the six cases, suggesting that the dmin originated through extra replication (or loop-formation)--excision--amplification. Northern blot analysis revealed that MYC was not overexpressed. Instead, the C8FW gene, encoding a phosphoprotein regulated by mitogenic pathways, displayed increased expression. These results exclude MYC as the target gene and indicate that overexpression of C8FW may be the functionally important consequence of 8q24 amplicons in AML and MDS. 相似文献
49.
Cord blood IgE. III. Prediction of IgE high-response and allergy 总被引:1,自引:1,他引:1
L. G. Hansen A. Høst S. Halken A. Holmskov S. Husby L. B. Lassen K. Storm O. Østerballe 《Allergy》1992,47(4):404-410
Screening of total IgE in 2814 cord blood samples was analysed by Phadebas IgE PRIST in 2 1-year birth cohorts (1983–1984 and 1985–1986) in Denmark (n= 1189 + 1625). For follow-up we chose all infants with cord blood IgE≥0.5 kU/1 and a randomly chosen group of the same size with cord blood IgE < 0.5 kU/1. A total group of 762 infants were clinically evaluated at 18 months of age, and in 688 of these we evaluated total and specific IgE. A diagnosis of definite atopy, probable atopy or no atopy was established. In the present study we defined allergic disease as atopic disease combined with elevated total IgE. We found a statistically significant correlation between cord blood IgE and IgE at 18 months of age. Significantly more infants with elevated cord blood IgE had developed allergic disease at 18 months. A cut-off value of 0.3 kU/1 for cord blood IgE was superior to the originally suggested 0.5 kU/1. Significantly more infants with elevated cord blood IgE had developed specific IgE antibodies at 18 months. The most frequent specific IgE antibody was towards cow's milk. Specific IgE antibodies were very rarely found when total IgE was not elevated. A total IgE at the age of 18 months > 26 kU/1 could be regarded as elevated. With regard to allergic disease the positive predictive values of cord blood lgE≥0.3 kU/1 in the 2 series were 21 % and the corresponding sensitivities 67% and 46%, respectively. The risk of developing allergic disease was elevated with a factor 3 to 4 when cord blood IgE ≥ 0.3 kU/1. In a high-risk group based on atopic predisposition and elevated eord blood IgE ≥0.5 kU/1 the relative risk of allergic disease was 5, the predictive value of positive test 38%, the sensitivity 24% and the specificity 96%. Clinical aspects Cord blood IgE was a good predictor of allergic disease at the age of 18 months. A cord blood cut-off IgE value of 0.3 kU/l was superior to other cord blood IgE values with the Phadebas IgE PRIST method. 相似文献
50.
Poethko-Müller Christina Kuhnert Ronny Gillesberg Lassen Sofie Siedler Anette 《Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz》2021,64(1):104-104
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - Ein Erratum zu dieser Publikation wurde veröffentlicht: https://doi.org/10.1007/s00103-019-02901-5 相似文献