Dietary fat overcomes the protective activity of thrombospondin-1 signaling in the Apc(Min/+) model of colon cancer.

Thrombospondin 1 is a glycoprotein that regulates cellular phenotype through interactions with its cellular receptors and extracellular matrix-binding partners. Thrombospondin 1 locally regulates angiogenesis and inflammatory responses that contribute to colorectal carcinogenesis in Apc(Min/+) mice. The ability of thrombospondin 1 to regulate responses of cells and tissues to a variety of stresses suggested that loss of thrombospondin 1 may also have broader systemic effects on metabolism to modulate carcinogenesis. Apc(Min/+):Thbs1(-/-) mice exhibited decreased survival and higher tumor multiplicities in the small and large intestine relative to Apc(Min/+) mice when fed a low (5%) fat western diet. However, the protective effect of endogenous thrombospondin 1 was lost when the mice were fed a western diet containing 21% fat. Biochemical profiles of liver tissue identified systemic metabolic changes accompanying the effects of thrombospondin 1 and dietary lipid intake on tumorigenesis. A high-fat western diet differentially regulated elements of amino acid, energy and lipid metabolism in Apc(Min/+):Thbs1(-/-) mice relative to Apc(Min/+):Thbs1(+/+)mice. Metabolic changes in ketone body and tricarboxylic acid cycle intermediates indicate functional interactions between Apc and thrombospondin 1 signaling that control mitochondrial function. The cumulative diet-dependent differential changes observed in Apc(Min/+):Thbs1(-/-) versus Apc(Min/+) mice include altered amino acid and lipid metabolism, mitochondrial dysfunction, eicosanoids and ketone body formation. This metabolic profile suggests that the protective role of thrombospondin 1 to decrease adenoma formation in Apc(Min/+) mice results in part from improved mitochondrial function.

AT(1) antisense distinguishes receptors mediating angiotensin II actions in solitary tract nucleus.

Angiotensin (Ang) II receptors in the solitary tract nucleus (nTS) are located on vagal sensory-afferent fiber terminals as well as on neuronal cell bodies. Results from in vitro slice preparations indicate that approximately 50% of the neuronal excitatory actions of Ang II result from actions at presynaptic receptors. The differential contribution of actions on fiber terminals versus neuronal cell soma to the cardiovascular effects of Ang II in the nTS is not known. We used antisense oligonucleotides to the angiotensin type 1 (AT(1)) receptor, which should reduce receptors on neurons within the injection site but not those on fiber terminals projecting to the nTS. Ang II injections (250 fmol/30 nL) into the nTS reduced blood pressure by 14+/-1 mm Hg and heart rate by 13+/-1 bpm (n=8) in male Sprague-Dawley rats anesthetized with chloralose/urethane. Although there was still a significant fall in pressure that was induced by Ang II at 90 and 150 minutes after AT(1) antisense (164 pmol/120 nL) was injected into the nTS, the response was blunted 50% (P<0.01). Heart rate responses were completely blocked at the 150-minute time point. Scrambled sequence oligonucleotides did not alter Ang II responses at any time. There was a 40% reduction in (125)I[Sar(1)Thr8]-Ang II binding when antisense-injected and noninjected sides of the nTS were compared with receptor autoradiography. This finding is consistent with the continued presence of AT(1) receptors on afferent fibers. This unique strategy illustrates that both presynaptic fiber terminals and nTS neurons are involved in the blood pressure lowering actions of Ang II, whereas heart rate responses are largely due to actions directly on nTS neurons and activation of vagal efferent pathways.

Multi-presenter mental health patients in emergency departments--a review of models of care.

Only a small proportion of the treatment of mental illness occurs in an institution or hospital. By far the most significant treatment happens in the community and in the patient's own social and family environment. However, de-institutionalisation of mental health services has brought increasing numbers of patients to the emergency department in need of psychiatric assistance. The traditional service model of emergency departments, focusing on physical illness and injury, is being challenged. The literature review identified numerous psychiatric service models in place but dramatically highlighted the lack of a specific service model addressing psychiatric patients who present on multiple occasions [multi-presenters] in emergency departments. At present, accurate data on the effects of multi-presentation of psychiatric disorders are not available. Recent international and local research into models of service delivery management and best practice is examined.

The relationship of the -5, -8, and -24 variant alleles in African Americans to triosephosphate isomerase (TPI) enzyme activity and to TPI deficiency.

In 424 African-American and 75 white subjects, we found that the -5 (TPI 592 A-->G), -8 (TPI 589 G-->A), and -24 (TPI 573 T-->G) variants in the triosephosphate isomerase (TPI) gene occurred frequently (41.0%) in the African-American subjects but did not occur in the whites. These data suggest that this set of polymorphisms may turn out to be one of the higher-incidence molecular markers of African lineage, a surprising finding because others had reported that these nucleotide substitutions were restricted to a small subset of African Americans who had been characterized as TPI-deficiency heterozygotes. Additionally, we investigated the relationship of these variants to TPI-enzyme activity. Although the variant substitutions (occurring in three haplotypes: -5 alone, -5 -8, and -5 -8 -24) were associated with moderate reduction in enzyme activity, severe-deficiency heterozygotes could not be identified with certainty, and none of the haplotypes were restricted to subjects with marked reduction of enzyme activity. Three subjects were homozygous for the -5 -8 haplotype, a finding inconsistent with the putative role of this haplotype as the cause of a null variant incompatible with life in homozygotes. Despite these findings, the possibility remains that the -5 -8 or -5 -8 -24 haplotypes may in some instances contribute to compound heterozygosity and clinical TPI deficiency.

G6PD variants in three South American ethnic groups: population distribution and description of two new mutations.

A review is made of G6PD population surveys conducted in 4,558 European-derived, 2,484 admixed Black/Indian/White or Black/White, and 10,298 Indian subjects living in South America. Despite the fact that twice more Amerindians than Whites had been examined, no autochtonous variant was found among them, while seven different types (besides the most common Gd*B, Gd*A, Gd*A- and Gd*Med) were observed among the Whites. We also describe two new mutations in the G6PD molecule (Farroupilha, 977 C-->A and Lages, 40 G-->A), bringing the number of mutants characterized to 98. G6PD Lages is the most 5' mutation detected thus far. G6PD Seattle, previously found in the United States and Italy, seems to occur in other European countries and was observed by us in five independent Brazilian families.

NK1 receptor antagonist blocks angiotensin II responses in renin transgenic rat medulla oblongata.

Angiotensin (Ang) II increases substance P (SP) efflux from perfused slices of medulla oblongata, and a peptide antagonist of SP, [Leu11,psiCH2NH10-11]SP, blocks the acute hypotension and bradycardia caused by Ang II injected into the nucleus tractus solitarii (nTS) of Harlan Sprague-Dawley (SD) rats. We investigated whether the same relationships exist in (mRen2)27 renin transgenic (TG) rats, which have chronic elevations of medullary tissue Ang II levels. Ang II increased SP efflux (48% above control; P<0.01) from slices of medulla prepared from 8- to 12-week old male TG rats. Injections of Ang II (250 fmol in 30 nL) into the nTS of chloralose-urethane anesthetized TG rats produced a significant increase in pressure of 7+/-2 mm Hg before a 13+/-3 mm Hg fall in pressure. Ang II induced similar depressor responses in Hannover SD rats but no increase in pressure. After nTS injection of the NK1-selective SP antagonist CP-96,345 (30 pmol in 60 nL), Ang II-induced hypotension was blocked in both groups, as was the pressor component in hypertensive rats. Hypotensive and bradycardic effects of glutamate (0.6 nmol in 30 nL) injected into the nTS were not altered by CP-96,345. In vitro receptor autoradiography showed that the SP antagonist (10 or 100 microM) did not compete for 125I-Ang II binding in the dorsal medulla, a result suggesting that it did not interact directly with Ang II receptors. Thus, the nTS cardiovascular effects of Ang II are mediated by SP in both normotensive rats and a model of hypertension with altered endogenous levels of Ang II. These findings link Ang II-induced effects on SP release from brain slices of the medulla oblongata to acute cardiovascular actions of the peptide through an NK1 receptor.

Glucose-6-phosphate dehydrogenase Durham: a de novo mutation associated with chronic hemolytic anemia.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common X-linked enzyme defect. We report a new variant, G6PD Durham713G, that is associated with chronic nonspherocytic hemolytic anemia. The G6PD Durham713G variant has a unique biochemical and enzymatic profile and a novel A-->G substitution mutation at nucleotide 713, changing lysine to arginine at amino acid 238. This mutation was not found in the mother of our patient, indicating that G6PD Durham713G resulted from a de novo mutation.

Molecular genetics of glucose-6-phosphate dehydrogenase deficiency in Mexico.

Several studies carried out between 1965 and 1985 showed that G-6-PD deficiency in Mexico is heterogeneous at the biochemical level and that the G-6-PD A- phenotype is relatively common. We have now investigated the molecular basis of G-6-PD deficiency in Mexico. Up-to-date 60 chromosomes with G6PD mutations have been studied, 16 in previous studies and 44 in the present work. Molecular analysis of DNA from G-6-PD deficient Mexican mestizos and their relatives show that G-6-PD A- genotypes are relatively common but also that in Mexico G-6-PD deficiency is heterogeneous at the DNA level. Thus, five different genotypes have been observed: G-6-PD A-(202A/376G) (41 chromosomes), G-6-PD A-(376G/968C) (14 chromosomes), G-6-PD Seattle844C (3 chromosomes), G-6-PD "Mexico City"680A (1 chromosome) and G-6-PD Guadalajara1159T (1 chromosome). The G-6-PD A-(202A/376G), G-6-PD A-(376G/968C) and G-6-PD Seattle844C mutations in Mexico are on the same Pvu II/ Pst I/ 1311 / Nla III haplotypes as found in individuals from Africa, Spain and the Canary Islands. Consequently, these mutations were probably imported to Mexico through African slaves and/or the Spanish immigrants during and after the colonization.

Hypothalamic substance P release. Attenuated angiotensin responses in mRen2(27) transgenic rats.

Increases in arterial pressure and paraventricular nucleus vasopressin release in response to intracerebroventricular injections of angiotensin peptides are blunted in mRen2(27) renin transgenic [TG(+)] rats. Intraventricular injections of tachykinin peptides mimic several of the actions of angiotensin peptides, and angiotensin peptides evoke substance P release from hypothalamic brain slices. The present study assessed whether diminished substance P release occurs in response to angiotensin peptides in TG(+) rats. Systolic blood pressure at 8 to 12 weeks of age averaged 197 +/- 4 mm Hg (n = 20; P < .05) in TG(+) rats compared with 123 +/- 4 mm Hg in normotensive control [TG(-)] rats (n = 18). Body weight was lower in hypertensive than in normotensive rats (305 +/- 14 versus 344 +/- 13 g, respectively; P < .05). Brain slices from hypothalamus were perfused at 37 degrees C with oxygenated Krebs' bicarbonate buffer. Substance P was measured before (basal) and during perfusion with either Krebs' buffer (control) or 2 mumol/L angiotensin-(1-7) or angiotensin II. Basal substance P release was 92 +/- 10 pg/g wet tissue in TG(+) and 98 +/- 12 pg/g in TG(-) rats (P > .05). Angiotensin-(1-7) and angiotensin II significantly increased substance P release from hypothalamus of TG(-) rats (82% and 70% above control: P < .05) but not TG(+) rats. These studies further support the hypothesis that the cardiovascular effects of angiotensin peptides are mediated in part by substance P and that this relationship is blunted in a hypertensive model that results from excess tissue production of angiotensins.

Neonatal jaundice in Saudi newborns with G6PD Aures.

Sixty-five of 3261 (2%) Saudi neonates were found to be severely G6PD-deficient during a cord blood screening programme conducted from April to December, 1992. However, at the time of molecular studies, the blood samples were available from only 20 randomly selected children, aged from 1 to 6 years. DNA analyses showed that seven (three boys, four girls) of these 20 (35%) had G6PD Aures (nt 143 T - > C), a variant associated with favism which was recently reported in an Algerian. Twelve carried the G6PD Mediterranean (563 T) mutation, and in one child the mutation remained unidentified. The medical records of these children showed that all who had G6PD Aures, including a premature baby, were jaundiced during the 1st week of life, but only six full-term infants had moderate-to-severe hyperbilirubinaemia. Two of seven babies had seizures and one of these two developed kernicterus, in spite of timely blood transfusion.

The 1591C mutation in triosephosphate isomerase (TPI) deficiency. Tightly linked polymorphisms and a common haplotype in all known families.

In order to investigate the basis of the repeated occurrence of the 1591C mutation (TPI 1591C, 105 Glu-Asp) in multiple unrelated families throughout the world, we studied five microsatellite and short tandem repeat markers that lie within a 1.77 megabase region which includes the TPI gene. We also studied an intragenic polymorphic marker that lies within intron 5 of the TPI gene. This polymorphism, recently described by others, is characterized by either an A or a G at position 2262 (the A in the initiation ATG is designated as +1 for both genomic and cDNA nucleotides). With very minor exceptions, all of the known families in the world with the 1591C mutation were available for study. These included five families from the U.S., three from France, one from Greece, one (of Turkish origin) from Germany, and two from Australia. Although we did not have the opportunity to directly study five families from the U.K., key data concerning the 2262 intragenic polymorphism in these subjects were made available to us. Four of the microsatellite and short tandem repeat markers were linked, but in apparent equilibrium. In contrast, a polymorphic repeat pentamer in the CD4 gene, thought to lie telomeric to TPI, was in apparent complete linkage disequilibrium with the TPI 1591C mutation. The intragenic polymorphism was also in apparent complete linkage disequilibrium with the mutation. In unrelated persons of known phase (1591C homozygotes or normal controls), the comparative allele frequencies for the CD4 pentameric repeat were 1.0 (14/14 alleles) in homozygous TPI 1591C subjects and 0.412 (28/68 alleles) in normal subjects (p < 0.0001). Again, in persons of known phase, the comparative allele frequencies for the A form of the intragenic 2262 A or G polymorphism were 1.0 (14/14 alleles) in 1591C homozygotes and 0.130 (7/54 alleles) in normals (p < 0.0001). Haplotypes were discernible in all of the 1591C homozygotes and in several of the heterozygotes and normals. The CD4 162, TPI 2262A haplotype was found on only two of thirty-eight normal chromosomes, but was universally associated with 1591C. The data indicate that all TPI 1591C subjects are descendants of a common ancestor who probably lived in what is now England or France. The original mutation probably occurred well in excess of 1000 years ago.

Triosephosphate isomerase deficiency: repetitive occurrence of point mutation in amino acid 104 in multiple apparently unrelated families.

The molecular basis of triosephosphate isomerase (TPI) deficiency was studied in 3 patients from three separate families. In all 3 patients, genomic DNA directly sequenced after amplification by the polymerase chain reaction exhibited the point mutation TPI315C amino acid 104 Glu-->Asp. Although other mutations known to cause TPI deficiency have been restricted to single families, the amino acid 104 defect has now been described in nine apparently unrelated families throughout the world and is clearly the most frequently occurring form of the disorder. The basis of the repetitive occurrence of this mutation remains unexplained.

Study of the molecular defects in pyruvate kinase deficient patients affected by nonspherocytic hemolytic anemia.

We have examined DNA from fifteen unrelated pyruvate kinase deficient patients with hereditary nonspherocytic hemolytic anemia (HNSHA) for the molecular alterations responsible for the enzyme deficiency. All but 3 of the 30 putative mutations were identified. Fourteen different mutations were found. Nine were missense mutations: 320 T-->C, 823 G-->C, 1276 C-->T, 1378 G-->A, 1484 C-->T, 1529 G-->A, 1654 G-->A, 1675 C-->G; three were nonsense mutations: 603 G-->A, 721 G-->T, 1501 C-->T; one was an insertion at 1574 GGG-->GGGG and the other a three nucleotide in-frame deletion 391-392-393 ATC. Eight of these mutations have not been previously described. We also investigated all of the patients for the C/A polymorphism at nt 1705 and the microsatellite ATT repeat in intron 11. All of the mutations that had previously been reported by us (391-393del, 721T, 1484T, 1529A) were found in the context of the same haplotype as the earlier cases, supporting the concept that each may have a single origin.

Three new exon 10 glucose-6-phosphate dehydrogenase mutations.

Three previously undescribed mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene have been documented in patients with hereditary non-spherocytic hemolytic anemia (HNSHA). In none of the cases have we been able to obtain a sufficient volume of blood to characterize the residual enzyme biochemically. "G6PD Calvo Mackenna" was due to an A-->G transition in cDNA nucleotide 1138 creating an Aat II site and resulting in a substitution of valine for isoleucine at amino acid 380. "G6PD Riley" was due to a T-->C transition at cDNA nucleotide 1139 also changing the 380 isoleucine, in this case to a threonine. "G6PD Wisconsin" was due to an C-->G transversion in cDNA nucleotide 1177, destroying a Aci I site and resulting in a substitution of glycine for arginine at amino acid 393. All of these mutations were in exon 10, where mutations that cause HNSHA appear to be clustered. We present a list of the 83 mutations of G6PD that have been documented to the end of April, 1995.

Molecular heterogeneity of G-6-PD deficiency in Mexico.

DNA samples from seven G-6-PD deficient Mexican mestizo patients were analyzed. Three different G-6-PD genotypes were observed: G-6-PD A-202A/376G (three patients), G-6-PD A-376G/968C (three patients) and G-6-PD Seattle844C. The present results, along with previous reports, suggest not only G-6-PD A-genotypes are relatively common but also G-6-PD deficiency seems to be heterogeneous at DNA level in Mexico.

Glucose-6 phosphate dehydrogenase mutations and haplotypes in various ethnic groups.

Mutations that produce glucose-6-phosphate dehydrogenase (G6PD) deficiency have been identified in samples from patients with hemolytic disease in the United States, and in G6PD-deficient samples from Greece, the Canary Islands, the Czech and Slovak Republics, South China, and in samples from the Coriell Cell Repository. Eight new mutations are described. Particularly unusual were a nonsense mutation ("G6PD Georgia"1284A), a deletion of six bases ("G6PD Stony Brook" 724-729 del) coding for two amino acids, and a deletion of the invariant dinucleotide ApG at the 3' acceptor splice site in the highly conserved sequence between intron 10 and exon 11 ("G6PD Varnsdorf"). In addition, five new missense point mutations were identified: "G6PD Cleveland"820A creates a deduced AA 274 Glu-->Lys; "G6PD West Virginia"910T AA 303 Val-->Phe; "G6PD Fushan"1004A, AA 335 Ala-->Asp; "G6PD Olomouc"1141C AA 381 Leu-->Phe; and "G6PD Praha"1166G AA 389 Glu-->Gly. All of the new mutations except for "G6PD Fushan"1004A were found in patients with hereditary nonspherocytic hemolytic anemia. A coincidental finding in the case of G6PD "West Virginia" was a C-->T transition at nucleotide 1,191. This silent mutation, Asn-->Asn, appears to be rare. Haplotype analysis of mutations in samples from the Canary Islands and South China agreed with previous findings.

Frequency of glucose-6-phosphate dehydrogenase (G6PD) mutations in Chinese, Filipinos, and Laotians from Hawaii.

In a Hawaii Hereditary Anemia Screening Project, 4,984 participants were tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency by a filter paper blood spot fluorescence test. Abnormal samples and suspected heterozygotes were checked by quantitative G6PD assay (normal 4.5 to 14 units/g Hb). G6PD was deficient (< 1.5 units/g Hb) in 188 of 2,155 males; 7 other males had low activity (1.5 to 2.8 units/g Hb). The gene frequency, estimated from males after excluding referred and related cases, was 0.037 for Chinese, 0.134 for Filipinos, and 0.203 for Laotians. Among 2,829 females tested, family data showed 111 females were obliged to be at least heterozygous, regardless of G6PD activity, and 43 others had low G6PD activity. Most heterozygotes probably remained undetected by G6PD screening. In 28 females, activity was under 10%; in another 9 females, activity was < 1.5 units/g Hb. Since only 25 homozygotes would be predicted, this apparent excess of females with deficient activity could be due to unequal X-inactivation in some heterozygotes. DNA analysis by polymerase chain reaction amplification and special analytic procedures revealed 10 different missense mutations in 75 males. The nucleotide 835 A-->T and 1360 C-->T transitions were first detected in this Hawaiian Project; we found that the nucleotide 1360 mutation was the most common cause of G6PD deficiency in Filipinos. This is the first report of G6PD screening and analysis of molecular G6PD mutations in Filipino and Laotian populations.

Molecular characterization of glucose-6-phosphate dehydrogenase variants from Brazil.

Electrophoretic surveys of 7794 individuals from different regions of Brazil and a study of subjects with hemolytic anemia have disclosed 9 putative G6PD variants in addition to the B, A, A-, and Mediterranean types. No variants were found among the 3739 Brazilian Indians tested. Four variants underwent DNA analysis. Three were identified with the Mediterranean, Seattle, and Anaheim types, but the fourth variant was previously undescribed and we propose to designate it G6PD São Borja.