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Biomedical subjects

S Lindsay

Publications and source records attributed to S Lindsay.

At least 73 records · Page 4Linked to original sources
PubMed1992

The gene for Aarskog syndrome is located between DXS255 and DXS566 (Xp11.2-Xq13).

Aarskog syndrome has been mapped to Xq13 on the basis of a patient carrying an Xq13:8p21.2 translocation. We have identified a new microsatellite marker in a clone mapping to this region (HX60;DXS566). Using primers flanking this microsatellite along with primers detecting a microsatellite at PGK1P1 and DXS255, and DXS72, we have performed a multipoint analysis in a large kindred with Aarskog syndrome. Our results suggest that the Aarskog locus lies proximal to Xq13. This is supported by the recent redefining of the breakpoint of the original translocation as between DXS14 (Xp11.21-p11.1) and DXS146 (Xp11.23-p11.22).

Abnormalities, Multiple↗
PubMed1992

Molecular genetics of inherited retinal degenerations.

There has recently been substantial progress in categorizing the vast range of human retinal degeneration phenotypes. A molecular approach has assigned chromosomal locations for approximately a dozen such diseases and has identified four of the genes involved.

Albinism, Ocular↗
PubMed1991

The test-retest reliability of the hyperventilation provocation test.

The hyperventilation provocation test (HPT) has been widely used for reproducing symptoms of panics. It is assumed that subjects experience similar symptoms on consecutive occasions of hyperventilation. Fourteen subjects with a history of panics and fourteen without such a history underwent the HPT on two occasions one week apart. In the group of 28 subjects as a whole, there were moderate similarities between the HPTs in both the choice and severity of symptoms reported, even when pre-existing symptoms were controlled statistically. Nevertheless, in the subject-by-subject analysis, many subjects showed no resemblance between the two HPTs in the choice of symptoms. This suggests that many subjects would not show any resemblance between the symptoms experienced in an HPT and those of their latest panic even if hyperventilation occurred in that panic.

Adult↗
PubMed1991

Genetic and physical mapping around the properdin P gene.

A CA repeat has been found on the human X chromosome within 16 kb of the gene encoding properdin P factor (PFC) and has been shown to be a highly informative marker. Two more polymorphic CA repeats were found in a cosmid containing DXS228. The CA repeats, and other markers from proximal Xp, were mapped genetically in CEPH families and the likely order of markers was established as Xpter-(DXS7, MAO-A, DXS228)-(PFC, DXS426)-(TIMP, OATL1)-DXS255-Xcen. This places PFC in the region Xp11.3-Xp11.23, thus refining previous in situ hybridization data. Two yeast artificial chromosomes (YACs) (440 and 390 kb) contain both PFC and DXS426, and one of them (440 kb) also contains TIMP. This confirms the genetic order TIMP-(PFC, DXS426). PFC and TIMP are located on the same 100-kb SalI/PvuI fragment of the 440-kb YAC. Given the genetic orientation of TIMP and (PFC, DXS426), this YAC can now serve as a starting point for directional walking toward disease genes located in Xp11.3-Xp11.2 such as retinitis pigmentosa (RP2) and Wiskott-Aldrich syndrome.

Base Sequence↗
PubMed1991

Role of xanthine dehydrogenase and oxidase in focal cerebral ischemic injury to rat.

The role of xanthine dehydrogenase and oxidase as a source of free radicals contributing to focal cerebral ischemic injury was evaluated in Long-Evans rats after the middle cerebral artery was permanently occluded and both carotid arteries were clamped for 90 min. The fraction of xanthine dehydrogenase present as the free radical producing oxidase increased slightly from 22% in control cortex to 30% in the ischemic right cortex during the first 3 h of reperfusion and then remained relatively unchanged over the next 24 h. This increase may in part be due to entrapped plasma, which contained 4.5 +/- 0.8 nmol.min-1.ml-1 xanthine oxidase entirely in the free radical-producing form. Infarct volume was unaffected by pretreatment with 50 mg allopurinol/kg per day over 3 days before surgery but was decreased by 8% with 100 mg/kg and 24% with 150 mg/kg of allopurinol (P less than 0.05). However, inhibition of xanthine oxidase by dietary depletion of the essential molybdenum cofactor increased infarct volume by 19%, suggesting that protection by allopurinol at higher dosages was independent of xanthine oxidase inhibition. Neither xanthine oxidase present in rat brain nor circulating in plasma appears to be the primary source of oxygen radicals that contributes to infarction in focal cerebral ischemia.

Allopurinol↗
PubMed1990

Optimal therapy for patients with biliary atresia: portoenterostomy ("Kasai" procedures) versus primary transplantation.

As the results with liver transplantation have improved, a controversy has arisen regarding the precise role of a portoenterostomy in the treatment of infants with biliary atresia. The controversy centers around three issues: (1) the short- and long-term survival rates achieved with both procedures, (2) the influence of a portoenterostomy on a subsequent transplant, and (3) the shortage of suitable liver donors for very small infants. To address these questions, we retrospectively reviewed the charts of 48 children with biliary atresia who underwent liver transplantation and compared these results with 35 children transplanted for other liver diseases. As a group, the biliary atresia patients had significantly lower mean body weights and ages and spent a significantly longer time on the waiting list. In addition, significantly more of the biliary atresia patients had undergone prior abdominal surgery when compared with the non-biliary atresia group. There was no difference in the intraoperative variables of mean anesthesia time, mean operative time, mean anesthesia preparation time, nor the mean amount of blood transfused intraoperatively between the two groups. However, when the biliary atresia patients who had undergone a portoenterostomy with a stoma were compared with either the biliary atresia patients who did not have a stoma created as part of their portoenterostomy or the non-biliary atresia patients, significant differences were noted in mean total anesthesia time, mean operative time, and the mean amount of blood transfused intraoperatively. The survival rate of the biliary atresia patients was significantly greater than the non-biliary atresia patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1990

Localization of the microsatellite probe DXS426 between DXS7 and DXS255 on Xp and linkage to X-linked retinitis pigmentosa.

The microsatellite marker DXS426 maps to the interval Xp21.1-Xp11.21, the chromosomal region which contains two loci for X-linked retinitis pigmentosa (XLRP; RP2 and RP3). We have refined the localization of DXS426 both physically, by mapping it to a deletion which spans the interval Xp21.3-Xp11.23, and genetically, by studying multiply informative crossovers which indicate that DXS426 lies between DXS7 and DXS255 (i.e., Xp11.4-Xp11.22). As this is the region which contains the RP2 gene, RP2 families could be identified on the basis of linkage of XLRP to DXS426. Multiply informative crossovers in two RP2 families indicate that the most likely location of the RP2 gene is between DXS426 and DXS7. DXS426 is therefore an important highly informative marker for the purposes of carrier detection and early diagnosis of RP2 and for the localization of the disease gene.

Base Sequence↗
PubMed1989

Til 1--a human lymphoblastoid cell line with minimal DNA methylation.

Methylation has been shown to be correlated with several fundamental cellular processes, including changes in gene expression, alterations in chromatin structure and inactivation of the mammalian X chromosome. It is possible, therefore, that the methylation status of a particular sequence may reflect involvement in a number of processes. Given this potentially confused situation, it is clear that many studies would be facilitated if unmethylated or minimally methylated DNA from a mammalian source were available. A major use of such DNA would be in the construction of long-range physical maps. In many cases, long-range physical maps are a prerequisite for the eventual isolation of disease genes that have been localised to a particular chromosomal region by other means (e.g. genetic linkage studies). Many of the enzymes used in such long-range mapping experiments are methylation sensitive, which makes it difficult to determine how many sites for a particular enzyme are present in any DNA sequence. Here we report the finding of a minimally methylated DNA in the human lymphoblastoid cell line, Til 1. The methylation level of Til 1 DNA was analysed in several ways and compared with that in human lymphocytes, placental tissue and other lymphoblastoid cell lines. The results showed clear and reproducible differences in methylation among the cell types, both at a global level and in the vicinities of specific DNA sequences. Lymphocyte DNA had the highest level of methylation while placental DNA and cell line DNA had lower but similar levels. Til 1 had abnormally low levels of 5-methylcytosine when measured directly, and no detectable methylation at any of the restriction sites examined.

5-Methylcytosine↗
PubMed1985

Differences in methylation on the active and inactive human X chromosomes.

Methylation of CCGG sites was examined in four regions of the X chromosome with four X-chromosome clones, three obtained by cloning random segments and one encoding a structural gene. In DNA from human peripheral blood cells unmethylated sites correlating with the inactive X chromosome were detected in the vicinity of two of the random clones and also in the vicinity of a cloned sequence of the X-linked phosphoglycerate kinase gene (PGK). The third random clone covered a region whose methylation pattern was unchanged between the active and inactive X chromosomes. Differential methylation at the sites detected appears to have no functional role in the maintenance of the inactive X chromosome since both active and inactive X chromosomes were found to be undermethylated in DNA from human lymphoblastoid cells.

Base Sequence↗
PubMed1984

Sequence of the promoter region of the gene for human X-linked 3-phosphoglycerate kinase.

We have determined the sequence of an 812-bp BamHI-EcoRI restriction fragment containing the 5' region of the human gene for PGK (3-phosphoglycerate kinase or ATP:3-phospho-D-glycerate 1-phosphotransferase; EC 2.7.2.3). The fragment contains 450 bp 5' to three start points for transcription (located by primer extension and S1 nuclease mapping), a leader sequence 85-94 bp long, the first exon of gene (65 bp), and part of the first intron. The promoter region is extremely G + C-rich, lacks a TATA box, and has an 8-bp direct repeat. A comparison of the promoter region for PGK with other promoters on the X-chromosome reveals homology with the promoter for HPRT, but not with the operator for factor IX.

Base Sequence↗
PubMed1977

Neonatal barbiturate withdrawal.

An infant with neonatal barbiturate withdrawal syndrome is reported. The clinical features, diagnosis and treatment of this condition are discussed. A retrospective review of fifty-three infants of barbiturate-treated epileptic mothers indicated a high incidence of "jitteriness" (17%) and feeding problems (36%) in the immediate neonatal period.

Adult↗