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L Quintana

Publications and source records attributed to L Quintana.

12 recordsLinked to original sources
PubMed1999

Cloning of a unique lipase from endothelial cells extends the lipase gene family.

A new lipoprotein lipase-like gene has been cloned from endothelial cells through a subtraction methodology aimed at characterizing genes that are expressed with in vitro differentiation of this cell type. The conceptual endothelial cell-derived lipase protein contains 500 amino acids, including an 18-amino acid hydrophobic signal sequence, and is 44% identical to lipoprotein lipase and 41% identical to hepatic lipase. Comparison of primary sequence to that of lipoprotein and hepatic lipase reveals conservation of the serine, aspartic acid, and histidine catalytic residues as well as the 10 cysteine residues involved in disulfide bond formation. Expression was identified in cultured human umbilical vein endothelial cells, human coronary artery endothelial cells, and murine endothelial-like yolk sac cells by Northern blot. In addition, Northern blot and in situ hybridization analysis revealed expression of the endothelial-derived lipase in placenta, liver, lung, ovary, thyroid gland, and testis. A c-Myc-tagged protein secreted from transfected COS7 cells had phospholipase A1 activity but no triglyceride lipase activity. Its tissue-restricted pattern of expression and its ability to be expressed by endothelial cells, suggests that endothelial cell-derived lipase may have unique functions in lipoprotein metabolism and in vascular disease.

Amino Acid Sequence↗
PubMed1998

Transferrin receptor mutation analysis in hereditary hemochromatosis patients.

The Cys282-->Tyr mutation in the HFE gene is carried by the majority of hereditary hemochromatosis patient chromosomes, yet some patients do not seem to harbor any mutation in this gene. This suggests a possibility that these patients may have a mutation in other genes in the same pathway as HFE. We analyzed the cDNA sequences of transferrin receptor (TFR), which was recently shown to interact with HFE, in twenty-one hereditary hemochromatosis patients including sixteen individuals who did not carry a Cys282-->Tyr mutation. A nucleotide substitution (424A-->G), which resulted in the Ser142-->Gly amino acid substitution, was the only amino acid polymorphism detected in the open reading frame of the TFR gene in these patients. This amino acid substitution was a rather common polymorphism in the general population (49%) and its frequency did not significantly differ in the hereditary hemochromatosis (HH) patients regardless of the HFE genotype. Thus, amino acid changes in the TFR gene do not appear to play a role in HH even when the patients do not have a HFE mutation. However, this study does not rule out the possibility of the involvement of mutations in non-coding regions.

Amino Acid Substitution↗
PubMed1997

HLA class II haplotype and sequence analysis support a role for DQ in narcolepsy.

A systematic haplotype and sequencing analysis of the HLA-DR and -DQ region in patients with narcolepsy was performed. Five new (CA)n microsatellite markers were generated and positioned on the physical map across the HLA-DQB1-DQA1-DRB1 interval. Haplotypes for these new markers and the three HLA loci were established using somatic cell hybrids generated from patients. A four-marker haplotype surrounding the DQB1(*)0602 gene was found in all narcolepsy patients, and was identical to haplotypes observed on random chromosomes harboring the DQB1(*)0602 allele. Eighty-six kilobases of contiguous genomic sequence across the region did not reveal new genes, and analysis of this sequence for single nucleotide polymorphisms did not reveal sequence variation among DQB1(*)0602 chromosomes. These results are consistent with other studies, suggesting that the HLA-DQ genes themselves are among the predisposing factors in narcolepsy.

Causality↗
PubMed1997

A 1.1-Mb transcript map of the hereditary hemochromatosis locus.

In the process of positionally cloning a candidate gene responsible for hereditary hemochromatosis (HH), we constructed a 1.1-Mb transcript map of the region of human chromosome 6p that lies 4.5 Mb telomeric to HLA-A. A combination of three gene-finding techniques, direct cDNA selection, exon trapping, and sample sequencing, were used initially for a saturation screening of the 1.1-Mb region for expressed sequence fragments. As genetic analysis further narrowed the HH candidate locus, we sequenced completely 0.25 Mb of genomic DNA as a final measure to identify all genes. Besides the novel MHC class 1-like HH candidate gene HLA-H, we identified a family of five butyrophilin-related sequences, two genes with structural similarity to a type 1 sodium phosphate transporter, 12 novel histone genes, and a gene we named RoRet based on its strong similarity to the 52-kD Ro/SSA lupus and Sjogren's syndrome auto-antigen and the RET finger protein. Several members of the butyrophilin family and the RoRet gene share an exon of common evolutionary origin called B30-2. The B30-2 exon was originally isolated from the HLA class 1 region, yet has apparently "shuffled" into several genes along the chromosome telomeric to the MHC. The conservation of the B30-2 exon in several novel genes and the previously described amino acid homology of HLA-H to MHC class 1 molecules provide further support that this gene-rich region of 6p21.3 is related to the MHC. Finally, we performed an analysis of the four approaches for gene finding and conclude that direct selection provides the most effective probes for cDNA screening, and that as much as 30% of ESTs in this 1.1-Mb region may be derived from noncoding genomic DNA.

Amino Acid Sequence↗
PubMed1997

[Validity of routine serum calcium measurements].

BACKGROUND: The frequency of diagnosis of primary hyperparathyroidism increased dramatically with the advent of routine serum calcium measurements. The reliability of colorimetric serum calcium measurements is not well known. AIM: To know the frequency of hyper and hypocalcemia in a population of healthy people and the reliability of serum calcium measurements. SUBJECTS AND METHODS: Serum calcium was measured in 731 subjects participating in a preventive medical examination, using an automated colorimetric method. Serum albumin was also measured. In 31 randomly chosen serum samples, calcium was also measured by atomic absorption spectrometry. Normal serum calcium ranges were established as the mean +/- 1.34 SD of the sample. RESULTS: Mean serum calcium was 9 +/- 0.7 mg/dl, serum albumin was 4.3 +/- 0.5 g/dl and albumin corrected calcium levels were 8.7 +/- 0.7 mg/dl. Excluding lipemic sera, colorimetric calcium measurement had a correlation of 0.6 with atomic absorption spectrometry and a reliability of 17.9%. Using the proposed normal ranges (7.3-10.6 mg/dl), the frequency of hypercalcemia and hypocalcemia was 0.14 and 0.4% respectively. CONCLUSIONS: Most subjects found to have hyper or hypocalcemia in this study were asymptomatic.

Adolescent↗
PubMed1996

A novel MHC class I-like gene is mutated in patients with hereditary haemochromatosis.

Hereditary haemochromatosis (HH), which affects some 1 in 400 and has an estimated carrier frequency of 1 in 10 individuals of Northern European descent, results in multi-organ dysfunction caused by increased iron deposition, and is treatable if detected early. Using linkage-disequilibrium and full haplotype analysis, we have identified a 250-kilobase region more than 3 megabases telomeric of the major histocompatibility complex (MHC) that is identical-by-descent in 85% of patient chromosomes. Within this region, we have identified a gene related to the MHC class I family, termed HLA-H, containing two missense alterations. One of these is predicted to inactivate this class of proteins and was found homozygous in 83% of 178 patients. A role of this gene in haemochromatosis is supported by the frequency and nature of the major mutation and prior studies implicating MHC class I-like proteins in iron metabolism.

Alleles↗
PubMed1985

Electromyography results of exercise overflow in hemiplegic patients.

The purpose of this study was to determine the effects of exercise overflow in hemiplegic patients. Eleven subjects with a diagnosis of cerebrovascular accident (CVA) performed active exercises with their uninvolved extremities while their involved extremities were monitored with EMG. The muscles monitored were the biceps brachii, triceps brachii, and quadriceps femoris. Active exercise of the comparable uninvolved muscles was performed under three different weight lifting conditions: 1) maximal weight, 2) 50% of the maximal weight, and 3) no weight. Significant (p less than .05) overflow to the involved nonexercised extremities was found in all of the exercise conditions. Overflow was frequently found in all three muscle groups when only one muscle group was being exercised. Overflow always occurred in the contralateral homologous muscle. Exercise overflow appears to be an effective therapeutic technique to facilitate muscle activity in paretic muscles. This muscle activity may cause desired or undesired muscular effects during therapy in the rehabilitation of patients with CVAs.

Adult↗
PubMed1982

The effect of prostacyclin on cerebral vasospasm. An experimental study.

Prostacyclin (PGI2), a strong vasodilator of cerebral vessels and potent inhibitor of platelet aggregation, was infused intravenously into seven cats after induction of prolonged vasospasm by hourly application of oxyhaemoglobin solution into the subarachnoid space round the basilar artery. PGI2, at a concentration of 50 ng/kg/min, was effective in releasing the vasospasm in the seven cats. It did not produce significant hypotension. This report gives our results and the probable mechanism of action of PGI2 in cerebral vasospasm.

Animals↗
PubMed1982

[Effect of prostacyclin on cerebral vasospasm--an experimental study].

Prostacyclin(PGI2), a strong vasodilator of cerebral vessels and a potent inhibitor of platelet aggregation, was infused intravenously in 7 cats after induction of prolonged vasospasm by hourly application of oxyhemoglobin solution into the subarachnoid space around the basilar artery. PGI2, at a concentration of 50 ng/kg/min, was effective in releasing the vasospasm in the 7 cats. On the other hand, PGI2 did not produce significant hypotension. This report will discuss our results and the probable mechanism of action of PGI2 in cerebral vasospasm.

Animals↗
PubMed1974

[Lichen aureus].

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Child↗