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I Hart

Publications and source records attributed to I Hart.

35 records · Page 2Linked to original sources
PubMed1993

Regional mapping of the gene encoding dihydroorotate dehydrogenase, an enzyme involved in UMP synthesis, electron transport, and superoxide generation, to human chromosome region 16q22.

De novo UMP synthesis is a critical metabolic pathway for nucleic acid synthesis and for a variety of metabolic pathways. The pathway is a target for many widely used cancer chemotherapy agents, several of which are pyrimidine analogs. Humans and cattle have been described with mutations in UMP synthesis that lead to serious inborn errors of metabolism. Dihydroorotate dehydrogenase (EC 1.3.3.1) (DHODH) carries out the fourth committed step in the pathway and may also be important for mitochondrial electron transport and oxygen radical metabolism. We report here that the gene encoding this enzyme in humans is located in the chromosomal region 16q22. With the mapping of DHODH, the mapping of all the steps of UMP synthesis is complete. All three genes involved map to different human chromosomes. This information is important in consideration of regulation of UMP synthesis in mammals, including humans.

Base Sequence↗
PubMed1993

Identification of class-mu glutathione transferase genes GSTM1-GSTM5 on human chromosome 1p13.

The GSTM1, GSTM2, GSTM3, GSTM4, and GSTM5 glutathione transferase genes have been mapped to human chromosome 1 by using locus-specific PCR primer pairs spanning exon 6, intron 6, and exon 7, as probes on DNA from human/hamster somatic cell hybrids. For GSTM1, the assignment was confirmed by Southern blot hybridization to a pair of 12.5/2.4-kb HindIII fragments. The GSTM1-specific primer pairs can be used to identify individuals carrying non-null GSTM1 alleles. The organization of these five genes was confirmed by the isolation of a yeast artificial chromosome clone (GSTM-YAC2) that contains all five genes. With this clone, the location of the GSTM1-GSTM5 gene cluster on chromosome 1 was confirmed by fluorescence in situ hybridization. Both regional assignment using the fractional length method and examination of probe signal with reference to R-banded chromosomes induced by BrdU places the gene cluster in or near the 1p13.3 region. The close physical proximity of the GSTM1 and GSTM2 loci, which share 99% nucleotide sequence identity over 460 nucleotides of 3'-untranslated mRNA, suggests that the GSTM1-null allele may result from unequal crossing-over.

Animals↗
PubMed1992

Effects of tumour cells on angiogenesis and vasoconstrictor responses in sponge implants in mice.

The effects of tumour cells (Colon 26) on the development and response of new blood vessels to different vasoconstrictors (platelet activating factor; PAF, endothelin-1, angiotensin II, adrenalin and 5-hydroxytryptamine) have been investigated. Sponge implants in mice were used to host tumour cells while washout of 133Xe was employed to assess local blood flow in the implanted sponges. By 14 days after implantation the response of vessels in tumour-bearing implants to the various vasoconstrictors generally was decreased compared to that obtained in control sponge implants or adjacent normal skin. Thus at this time point the t1/2 for 133Xe washout from control sponges treated with adrenalin (0.5 micrograms) was 30 +/- 4 min whereas in tumour-bearing sponges it was 5 +/- 1 min. This decreased sensitivity in tumour vessels was probably not due to a complete lack of contractile elements since actin was demonstrated by immunohistochemistry around blood vessels in both types of implant. The results of the present study have shown that the pharmacological responses of blood vessels in a growing tumour, Colon 26, differed from the responses of vessels of a similar age in non-neoplastic tissue. These results appear to suggest that the different angiogenic stimuli released from tumour tissue may markedly influence pharmacological reactivity of newly formed blood vessels.

Adenocarcinoma↗
PubMed1991

Therapy of human ovarian cancer xenografts with intraperitoneal liposome encapsulated muramyl-tripeptide phosphoethanolamine (MTP-PE) and recombinant GM-CSF.

Three intraperitoneal human ovarian cancer xenografts (OS, HU, and LA) were used to assess the antitumour activity of intraperitoneal therapy with liposome encapsulated MTP-PE. MTP-PE led to significant prolongation of survival in all three xenograft models, but with varying efficacy. In one tumour model (OS), 80% of mice were cured of tumour by twice weekly therapy for 4 weeks, whereas in another xenograft model (LA), the median survival time was approximately doubled compared to PBS injected and placebo liposome injected controls (median survivals: 30 vs 62.5 days respectively). The antitumor efficacy of MTP-PE did not correlate with the extent of peritoneal neutrophil infiltration after intraperitoneal therapy. Combined therapy with liposome encapsulated MTP-PE and recombinant murine granulocyte-macrophage colony stimulating factor led to increased survival of mice bearing the LA and HU xenografts, compared to tumour bearing mice treated with either agent singly.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1991

Changes in intracranial CSF volume after lumbar puncture and their relationship to post-LP headache.

Post-lumbar puncture (LP) headache may be due to "low CSF pressure", leading to stretching of pain sensitive intracranial structures. The low intracranial pressure is secondary to net loss of intracranial CSF. It has, however, not been possible to measure intracranial CSF volume accurately during life until recently. Intracranial CSF volume can now be measured non-invasively by a MRI technique. The changes in intracranial CSF volume were studied in 20 patients who had LP. Total intracranial CSF volume was reduced in 19 of the 20 patients 24 hours after LP (range -1.8 mls to -158.6 mls). Most of the CSF was lost from the cortical sulci. Very large reductions in intracranial CSF volume were frequently related to post-LP headache but some patients developed headache with relatively little alteration in the intracranial CSF volume. There was not a measurable change in position of the intracranial structures following LP.

Adolescent↗
PubMed1990

Human chromosome 5 complements the DNA double-strand break-repair deficiency and gamma-ray sensitivity of the XR-1 hamster variant.

XR-1 is a Chinese hamster ovary (CHO) cell mutant which is unusually sensitive to killing by gamma rays in the G1 portion of the cell cycle but has nearly normal resistance to gamma-ray damage in late S phase. The cell-cycle sensitivity correlates with the mutant's inability to repair DNA double-strand breaks (DSBs) produced by ionizing radiation and restriction enzymes. We have previously shown in somatic cell hybrids of XR-1 cells and human fibroblasts that the XR-1 mutation is a recessive mutation. In this study, using somatic cell hybrids formed between XR-1 and human fibroblasts, we map the human complementing gene to chromosome 5 by chromosome-segregation analysis. This gene biochemically restores the hamster defect to wild-type levels of gamma-ray and bleomycin resistance as well as restoring its proficiency to repair DNA DSBs, suggesting that a single gene is responsible for the XR-1 phenotype. We have tentatively assigned the name XRCC4 (X-ray-complementing Chinese hamster gene 4) to this human gene until its biochemical function in repair is discovered.

Animals↗
PubMed1989

Regional and physical mapping studies characterizing the Greig polysyndactyly 3;7 chromosome translocation, t(3;7)(p21.1;p13).

The Greig polysyndactyly-craniofacial anomalies syndrome is an autosomal dominant disorder involving a gene(s) located in band 7p13. We have isolated and characterized a reciprocal 3;7 chromosome translocation that resulted in the syndrome. We have identified two closely linked (0 cM) conserved DNA sequences (P137/p944B) that flank the translocation breakpoint. A pulsed-filed analysis combined with available genetic linkage information demonstrates that the disorder is linked (2 cM) to the T-gamma receptor locus, lending considerable support to the hypothesis that the mouse mutant extra-toes is the counterpart of the Greig syndrome. We have found no evidence that physically links the EGF receptor to the P137/p944B region, again compatible with mouse linkage relationships. The isolation of the der(3) chromosome from the 3;7 translocation has allowed us to regionally localize probes within the 3p21.1 band. For three probes commonly used in heterozygosity experiments with human cancers involving chromosome 3, we have determined that the order from centromere to telomere is D3S3, D3S2, and DNF15S2. Our pulsed-field studies also demonstrate the utility of band density differences combined with partial digests in evaluating linkage relationships. The P137/p944B probes should be useful in examining other hereditary disorders with phenotypic similarities to the Greig syndrome.

Animals↗
PubMed1988

Localization of human ERBA2 to the 3p22----3p24.1 region of chromosome 3 and variable deletion in small cell lung cancer.

Human genes homologous to the v-erbA oncogene of avian erythroblastosis virus have been mapped to at least two human chromosomes. Recently, the ERBA2 gene was shown to encode a thyroid hormone receptor and localized to chromosome 3 by using flow-sorted chromosomes. We now demonstrate that this gene is located at 3p22----3p24.1, using both somatic cell hybrids and in situ hybridization studies. Since this localization is close to the distal border of the small cell lung cancer (SCLC) 3p14----3p23 deletion, we undertook additional studies to examine the ERBA2 gene in SCLC. Using somatic cell hybrids constructed from the SCLC line NCI-H182 as well as matched patient tumor and control tissue samples, we found that ERBA2 is variably deleted. Therefore, ERBA2 defines at the molecular level the distal border of the SCLC deletion and further implies that the putative suppressor gene is located centromeric of this locus. We also determined that, at least in NCI-H182, the 3p14 breakpoint is proximal to the constitutive 3p14.2 fragile site. These studies would indicate that the mechanism or initiation site of chromosomal rearrangement in SCLC is different from that which occurs during induction of the 3p14 fragile site by aphidicolin.

Carcinoma, Small Cell↗
PubMed1986

Regional assignment of human liver-type 6-phosphofructokinase to chromosome 21q22.3 by using somatic cell hybrids and a monoclonal anti-L antibody.

The three structural loci encoding human phosphofructokinase, a key regulatory enzyme of glycolysis, are located on separate chromosomes. The gene coding for the liver-type subunit PFKL has previously been assigned to chromosome 21. We have used a subunit- and human-specific monoclonal antibody to liver PFK to detect the expression of human PFKL in hamster X human hybrid cell lines. A cell line carrying an 8;21 translocation which contains all of chromosome 21 except the band 21q22.3 was negative for the expression of PFKL whereas cell lines carrying the reciprocal 8;21 translocation were positive. In addition, a cell line with a ring chromosome 21 containing a breakpoint which excluded the distal part of the q22.3 band was negative for expression of PFKL. These results indicate that human PFKL is located on chromosome 21q22.3.

Animals↗
PubMed1985

Translocation of c-myc in the hereditary renal cell carcinoma associated with a t(3;8)(p14.2;q24.13) chromosomal translocation.

A translocation between chromosomes 3 and 8, t(3;8)(p14.2;q24.13), has been reported in a family with hereditary renal cell carcinoma. Using somatic cell hybrids, we have isolated, separately, both derivative chromosomes. We find that the c-myc oncogene (8q24.1) has been translocated to the derivative 3 [der(3)]. We have not detected a rearrangement within an approximately equal to 21-kilobase region around the c-myc gene using restriction enzyme digestion and Southern blot hybridization analysis. The translocated c-myc gene should provide a probe to the chromosome 3p14 region, which appears to be important not only in renal cell carcinoma but also in small cell carcinoma of the lung. These hybrids have also been useful for the regional mapping of the Chinese hamster ovary cell Gly-B defect to 8q22.1----q24.13 and support the regional assignment of acylase I to 3p21.

Animals↗
PubMed1978

Prostaglandins in the sheep fetus: implications for fetal function.

1. In chronically catheterized sheep fetuses, during normal pregnancy, the concentration of PGE in the fetal femoral arterial plasma is invariably greater than that of PGF, and increases during the 12 to 24 hr preceding delivery. The concentration of both PGE and PGF decreases repidly after birth. 2. These changes in fetal prostaglandin levels contrast with the marked increase in PGF, but negligible increase in PGE, in the maternal uteroovarian vein before parturition. 3. The changes in prostaglandin concentrations in fetal plasma at term are associated with only small changes in the concentrations of PGE and PGF in tracheal fluid. In amniotic fluid the concentrations of PGE and PGF increase during the last 4 days in utero. At birth the concentrations of PGE and PGF in fetal urine are similar to the concentrations in amniotic fluid. 4. The concentration of PGE in fetal plasma and in tracheal fluid is significantly elevated for up to 3 days after surgery. The concentration of PGF is significantly elevated in fetal plasma nad tracheal fluid for at least 24 hr after surgery. 5. Three fetuses which were chronically hypoxemic had elevated plasma PGE concentrations in utero. However, acute (1 hr) hypoxia or hypercapnia induced in the fetal lamb by making the ewe breathe appropriate gas mixtures did not produce consistent changes in fetal plasma prostaglandin concentrations. 6. During late pregnancy (day 128) exogenous PGE2 infused at about 1.6 microgram/min for 60 min into the fetal carotid artery achieved concentrations in the fetal femoral artery which were within the physiological range seen at term. At this infusion rate, there was no effect on fetal arterial Po2, Pco2, pH, or hematocrit, and no consistent effect on fetal blood pressure or heart rate. PGE2 infusion had no significant effect on the concentration of growth hormone or prolactin in fetal plasma. Within 30 min after beginning the infusion, however, there was a significant increase in the cortisol concentration in fetal plasma. This effect was seen even at times in pregnancy when the fetal adrenal gland responds only poorly to exogenous or endogenous ACTH.

Amniotic Fluid↗
PubMedDate not supplied

Adenovirus type 5 uptake by lung adenocarcinoma cells in culture correlates with Ad5 fibre binding is mediated by alpha(v)beta1 integrin and can be modulated by changes in beta1 integrin function.

BACKGROUND: Recombinant adenoviruses (Ad) have been employed as vectors for a wide variety of gene therapy applications, but their use has been hindered by problems relating to efficacy and safety. The efficiency of Ad-mediated gene transfer depends on the interaction of the fibre and penton base proteins with their corresponding cell receptors. Ad infection is initiated by the formation of a high affinity complex between the fibre protein and a host cell protein that for most Ad serotypes is CAR (the coxsackie B virus and Ad receptor). A second molecule, the MHC class I, may also be involved in Ad type 2 and Ad type 5 uptake. Ad internalization results from the interaction of the penton base protein with cell surface integrins alpha(v)beta3 and alpha(v)beta5. In this study, we addressed the interaction between Ad type 5 (Ad5) and its receptors on lung derived adenocarcinoma cells in culture. METHODS: Using flow cytometry, we determined the level of expression of attachment and internalization receptors that are expressed on the cell surface of A549, H322 and H441 lung-derived adenocarcinoma cells in culture. The level of alpha(v)beta1 cell surface integrin was assessed by immunoprecipitation. Measuring the level of luciferase gene expression at different viral titres quantitated Ad5 uptake by these cells. The kinetics of binding of Ad5 fibre knobs to A549, H322 and H441 cells was assessed in direct binding studies using 125I labelling of purified recombinant Ad5 fibre-knob domains. In order to assess the functionality of integrins, adhesion assays were performed in the presence or absence of activators of integrin function. In competition experiments, prior to exposure to the virus, the cells were pre-incubated with purified recombinant Ad5 fibre-knob domains, function blocking anti-integrin antibodies, or integrin activating agents, prior to the introduction of luciferase expressing Ad5. RESULTS: We found that Ad5-mediated gene transfer in A549, H322 and H441 adenocarcinoma cells in culture is highly variable and that this variation correlates with specific binding of Ad5 fibre-knob domain binding to the cell surface. We also found, for the first time, that Ad5 infection is mediated by integrin alpha(v)beta1 and that functional activation of beta1 integrin by means of the specific anti-beta1 monoclonal antibody, TS2/16, induced increased A549 cell adhesion to fibronectin and vitronectin and also enhanced Ad5 uptake by these cells. CONCLUSIONS: Our studies demonstrate that the Ad5 fibre-knob domain interaction with CAR represents a major determinant of Ad5-mediated gene transfer to lung-derived adenocarcinoma cells in culture. The finding that integrin alpha(v)beta1 is involved in Ad5 infection has implications for the use of recombinant Ad5 vectors for cancer gene therapy, since alpha(v)beta1 is expressed at high levels and acts as an alternative vitronectin receptor in many epithelial and some melanoma tumours which express no alpha(v)beta3 and constant low levels of alpha(v)beta5. The fact that the beta1 integrin-activating antibody TS2/16 can enhance alpha(v)beta1-mediated Ad5 infection suggests that the efficacy of Ad5-mediated gene transfer might be influenced not only by the level of cell surface expression of integrins but also by their state of activation.

Adenocarcinoma↗