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PubMed1975

The cellular basis for the defect in haemopoiesis in flexed-tailed mice. III. Restriction of the defect to erythropoietic progenitors capable of transient colony formation in vivo.

Three assays for erythropoietic progenitor cells have been applied to mice of genotype f/f and to nearly congenic +/+ controls. When f/f mice were tested for their ability to generate transient endogenous erythroid spleen colonies 4-6 days after 800 rads and 10 units of erythropoietin, the numbers of such colonies detected were greatly reduced, although normal numbers of spleen colonies appeared at later times (9-12 days) postirradiation. In contrast, cells capable of erythropoietic colony formation in culture (CFU-E) were present within the normal range in both f/f spleen and marrow and their sensitivity to erythropoietin in culture was the same as that found previously for CFU-E in the marrow and spleen of +/+ mice. Transfusion-induced plethora reduced the number of CFU-E in marrow to a similar extent in both f/f and +/+ mice; likewise, subsequent administration of 10 units of erythropoietin induced a rapid return in the number of marrow CFU-E in both genotypes. In the spleen, CFU-E numbers were approximately three-fold lower in f/f mice in each group. These results support the view that the 5 day assay for transient endogenous spleen colonies detects cells (TE-CFU) that are different from both CFU-E and pluripotent stem cells (CFU-S), although possibly overlapping to some extent with the immediate progenitors of CFU-E. The results also indicate that the generation or maturation of TE-CFU represents a primary site of expression of the f/f defect.

Animals↗
PubMed2005

Recombinant CYP3A4*17 is defective in metabolizing the hypertensive drug nifedipine, and the CYP3A4*17 allele may occur on the same chromosome as CYP3A5*3, representing a new putative defective CYP3A haplotype.

Genetic variation in CYP3A activity may influence the rate of the metabolism and elimination of CYP3A substrates in humans. We previously reported four new CYP3A4 coding variants in three different racial groups. In the present study, we examined metabolism of nifedipine by the recombinant forms of these allelic variants. Metabolism of nifedipine by the L293P (CYP3A4*18), M445T (CYP3A4*3), and P467S (CYP3A4*19) allelic variants was not significantly different from wild-type CYP3A4*1. However, F189S (CYP3A4*17) exhibited a >99% decrease in both V(max) and CL(max) of nifedipine compared with CYP3A4*1. Of 72 racially diverse individuals, CYP3A4*17 was identified in 1 of 24 Caucasian samples [1:5 Eastern European (Adygei ethnic group)]. Genotyping of an extended set of 276 genomic DNAs of Caucasians (100 from the Coriell Repository and an additional 176 from the United States) for CYP3A4*17 detected no additional individuals containing the CYP3A4*17 allele. However, additional genotyping of four more Adygei samples available from Coriell detected an additional individual carrying the CYP3A4*17 allele. New specific polymerase chain reaction-restriction fragment length polymorphism genotyping procedures were developed for the major splice variant of CYP3A5 (CYP3A5*3) and CYP3A4*17. Genotyping revealed that the two individuals carrying CYP3A4*17 were either homozygous or heterozygous for the more frequent CYP3A5*3 allele, suggesting that the two alleles may exist on the same chromosome as a new putative CYP3A poor metabolizer haplotype. We predict that individuals who are homozygous for defective alleles of both of these genes would metabolize CYP3A substrates poorly. The new genetic tests will be useful in future clinical studies to investigate genotype/phenotype associations.

Algorithms↗
PubMed1994

DnaK mutants defective in ATPase activity are defective in negative regulation of the heat shock response: expression of mutant DnaK proteins results in filamentation.

Site-directed mutagenesis has previously been used to construct Escherichia coli dnaK mutants encoding proteins that are altered at the site of in vitro phosphorylation (J. S. McCarty and G. C. Walker, Proc. Natl. Acad. Sci. USA 88:9513-9517, 1991). These mutants are unable to autophosphorylate and are severely defective in ATP hydrolysis. These mutant dnaK genes were placed under the control of the lac promoter and were found not to complement the deficiencies of a delta dnaK mutant in negative regulation of the heat shock response. A decrease in the expression of DnaK and DnaJ below their normal levels at 30 degrees C was found to result in increased expression of GroEL. The implications of these results for DnaK's role in the negative regulation of the heat shock response are discussed. Evidence is also presented indicating the existence of a 70-kDa protein present in a delta dnaK52 mutant that cross-reacts with antibodies raised against DnaK. Derivatives of the dnaK+ E. coli strain MC4100 expressing the mutant DnaK proteins filamented severely at temperatures equal to or greater than 34 degrees C. In the dnaK+ E. coli strain W3110, expression of these mutant proteins caused extreme filamentation even at 30 degrees C. Together with other observations, these results suggest that DnaK may play a direct role in the septation pathway, perhaps via an interaction with FtsZ. Although delta dnaK52 derivatives of strain MC4100 filament extensively, a level of underexpression of DnaK and DnaJ that results in increased expression of the other heat shock proteins did not result in filamentation. The delta dnaK52 allele could be transduced successfully, at temperatures of up to 45 degrees C, into strains carrying a plasmid expressing dnaK+ dnaJ+, although the yield of transductants decreased above 37 degrees C. In contrast, with a strain that did not carry a plasmid expressing dnaK+ dnaJ+, the yield of delta dnaK52 transductants decreased extremely sharply between 39 and 40 degrees C, suggesting that DnaK and DnaJ play one or more roles critical for growth at temperatures of 40 degrees C or greater.

Adenosine Triphosphatases↗
PubMed1998

Mutants of the yeast Yarrowia lipolytica defective in protein exit from the endoplasmic reticulum are also defective in peroxisome biogenesis.

Mutations in the SEC238 and SRP54 genes of the yeast Yarrowia lipolytica not only cause temperature-sensitive defects in the exit of the precursor form of alkaline extracellular protease and of other secretory proteins from the endoplasmic reticulum and in protein secretion but also lead to temperature-sensitive growth in oleic acid-containing medium, the metabolism of which requires the assembly of functionally intact peroxisomes. The sec238A and srp54KO mutations at the restrictive temperature significantly reduce the size and number of peroxisomes, affect the import of peroxisomal matrix and membrane proteins into the organelle, and significantly delay, but do not prevent, the exit of two peroxisomal membrane proteins, Pex2p and Pex16p, from the endoplasmic reticulum en route to the peroxisomal membrane. Mutations in the PEX1 and PEX6 genes, which encode members of the AAA family of N-ethylmaleimide-sensitive fusion protein-like ATPases, not only affect the exit of precursor forms of secretory proteins from the endoplasmic reticulum but also prevent the exit of the peroxisomal membrane proteins Pex2p and Pex16p from the endoplasmic reticulum and cause the accumulation of an extensive network of endoplasmic reticulum membranes. None of the peroxisomal matrix proteins tested associated with the endoplasmic reticulum in sec238A, srp54KO, pex1-1, and pex6KO mutant cells. Our data provide evidence that the endoplasmic reticulum is required for peroxisome biogenesis and suggest that in Y. lipolytica, the trafficking of some membrane proteins, but not matrix proteins, to the peroxisome occurs via the endoplasmic reticulum, results in their glycosylation within the lumen of the endoplasmic reticulum, does not involve transport through the Golgi, and requires the products encoded by the SEC238, SRP54, PEX1, and PEX6 genes.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1990

Monozygotic twinning as a congenital defect and congenital defects in monozygotic twins.

The process of monozygotic twinning in animals and humans is presented. In addition, congenital defects in monozygotic twins versus dizygotic twins and singletons is discussed. Overall, the rates of congenital anomalies are higher among whites as compared to blacks, males as compared to females, and multiples as compared to singletons. The highest rates are among infants born to women in the oldest age category and infants with birth weights below 2,000 g. Among white infants, live births in plural deliveries had 22% more congenital anomalies as compared to single live births. Among black infants, the rate was only 4% higher among multiples. It has been suggested that the more frequent occurrence of low birth weight and preterm delivery among multiple births and by race are critical to the higher incidence of congenital anomalies in twins. Newer theories relating the twinning process to congenital anomalies in twins are also presented.

Adolescent↗
PubMed1980

Depressed primary in vitro antibody response in untreated systemic lupus erythematosus. T helper cell defect and lack of defective suppressor cell function.

The in vitro antibody response of peripheral blood lymphocytes (PBL) from 19 patients with untreated systemic lupus erythematosus (SLE) was compared with that of 20 control patients and 44 normal subjects. Trinitrophenyl polyacrylamide beads (TNP-PAA) were used to induce IgM anti-TNP plaque-forming cells. SLE patients displayed a markedly depressed, and in most instances virtually absent, response. This was not due to an unusual kinetics of the response; nor could it be induced by preincubation of SLE patients' PBL. In co-cultures of SLE patients and normal PBL, the former, with few exceptions, did not exert a suppressive effect. In four patients the anti-TNP response of either unfractionated or T-depleted SLE PBL could be restored by T cells from a normal individual. Conversely in three of these patients, SLE T cells could not support the response of normal B cells, suggesting a T helper cell defect in SLE PBL. Concanavalin A (Con A)-induced suppressor cells of the antibody response could be assayed by two approaches: (a) in responder SLE patients, by the direct addition of Con A to TNP-PAA-stimulated cultures; (b) in seven patients by transfer of Con A-activated cells to the responding culture of a normal allogeneic donor. In both cases SLE PBL were able to exert a suppressive effect to the same extent as normal PBL.

Adult↗
PubMed1983

Defective binding of macrophages to bone in rodent osteomalacia and vitamin D deficiency. In vitro evidence for a cellular defect and altered saccharides in the bone matrix.

In the osteomalacic as well as normal skeleton, few osteoclasts are associated with osteoid-covered bone surfaces. The reason for this particular cellular deficit is not clear, but may relate to the inability of osteoclasts and/or osteoclast precursors (monocyte-macrophages) to attach to immature, unmineralized bone matrix, a step apparently essential for normal resorptive activity and osteoclast differentiation. In this study, we have examined cell-bone binding using macrophages (M phi) and bone isolated from vitamin D-deficient rats and hypophosphatemic, osteomalacic mice and from their normal counterparts. The data show that M phi-bone attachment is greatly reduced (P less than 0.001) in both vitamin D deficiency and hypophosphatemia, but that the mechanisms responsible for this reduction are apparently different in the two disorders. In hypophosphatemia, the reduction in binding appears solely attributable to the absence or inaccessibility of bone matrix oligosaccharides or glycoproteins essential to the attachment process. In vitamin D deficiency, on the other hand, not only is the bone matrix defective as a binding substrate, but the M phi, per se, is limited in its capacity to attach to normal, vitamin D-deficient, and hypophosphatemic bone.

Animals↗
PubMed1999

Human leptin deficiency caused by a missense mutation: multiple endocrine defects, decreased sympathetic tone, and immune system dysfunction indicate new targets for leptin action, greater central than peripheral resistance to the effects of leptin, and spontaneous correction of leptin-mediated defects.

We have previously demonstrated that genetically based leptin deficiency due to a missense leptin gene mutation in a highly consanguineous extended Turkish pedigree is associated with morbid obesity and hypogonadism. We have now performed detailed assessments of endocrine, sympathetic, and immune function. We have also identified a new adult female homozygous patient in this extended family who is severely obese and amenorrheic. In this family all wild-type and heterozgous individuals have normal body weight. Seven obese members of this family, whom we presume to have been leptin deficient, died during childhood. There are several findings that indicate potentially novel targets for leptin action in humans. Four homozygous patients (1 adult male, 2 adult females, and 1 child) have sympathetic system dysfunction, whereas all heterozygous subjects have normal sympathetic system function. Despite sympathetic system dysfunction and postural hypotension, 1 of 3 homozygous adult patients has impaired renin-aldosterone function. The patients also exhibit alterations in GH and PTH-calcium function, and 1 of them has decreased bone mineral density. Despite their obesity, these patients do not have risk factors for cardiovascular disease, such as hypertension, impairments in lipid metabolism, or hyperleptinemia [corrected]. These data support the hypothesis that the obese may have central, but not peripheral, resistance to the effects of leptin and that hyperleptinemia [corrected] may mediate the cardiovascular morbidity of the obese who are not leptin deficient. Furthermore, these data indicate that there may be several new targets for leptin action in human physiology. Such new targets may lead to novel pharmacological strategies for the use of leptin agonists and antagonists in the treatment of human disease. All 19 normal weight individuals in this family are alive, whereas 7 of 11 obese individuals died in childhood after infections. The odds ratio for mortality in the context of this obesity phenotype is 25.4, indicating that this mutation severely impairs key biological functions during childhood, negatively impacting on survival. We found that only the obese child in this family had thyroid function abnormalities. The oldest homozygous female patient started to menstruate, albeit with a luteal phase defect, 7 months ago, after a delay of over 20 yr, whereas the younger adult subjects are still hypogonadic. Thus, we conclude that due to their long life span, humans who survive the negative effects of leptin deficiency during childhood can, in contrast to ob/ob mice, over decades compensate some of the effects of leptin deficiency on immunity and endocrine function through mechanisms that remain to be elucidated.

Adult↗
PubMed1994

Multiple developmental defects in Engrailed-1 mutant mice: an early mid-hindbrain deletion and patterning defects in forelimbs and sternum.

During mouse development, the homeobox-containing gene En-1 is specifically expressed across the mid-hindbrain junction, the ventral ectoderm of the limb buds, and in regions of the hindbrain, spinal cord, somites and somite-derived tissues. To address the function of En-1 during embryogenesis, we have generated mice homozygous for a targeted deletion of the En-1 homeobox. En-1 mutant mice died shortly after birth and exhibited multiple developmental defects. In the brains of newborn mutants, most of the colliculi and cerebellum were missing and the third and fourth cranial nerves were absent. A deletion of midhindbrain tissue was observed as early as 9.5 days of embryonic development and the phenotype resembles that previously reported for Wnt-1 mutant mice. In addition, patterning of the forelimb paws and sternum was disrupted, and the 13th ribs were truncated. The results of these studies suggest a cell autonomous role for En-1 in generation and/or survival of mid-hindbrain precursor cells and also a non-cell autonomous role in signalling normal development of the limbs and possibly sternum.

Animals↗
PubMed2000

Two genetic defects in alphaIIb are associated with type I Glanzmann's thrombasthenia in a Great Pyrenees dog: a 14-base insertion in exon 13 and a splicing defect of intron 13.

Glannzmann's thrombasthenia (GT) is an autosomal recessive bleeding disorder caused by qualitative or quantitative deficiencies of the platelet membrane glycoprotein alphaIIbbeta3. This is the first report of a molecular genetic basis for type I GT in dogs. As previously reported, a thrombasthenic Great Pyrenees dog (dog No. 1) experienced uncontrolled epistaxis despite results of coagulation screening tests, platelet quantitation, and von Willebrand factor quantitation that were within reference ranges. Platelet aggregation was minimal in response to agonists. Flow cytometry, autoradiography, and immunoblot experiments demonstrated either marked reduction or absence of glycoproteins alphaIIb and beta3. In this study, we report the presence of a 14-base insertion in exon 13 and defective splicing of intron 13 in the alphaIIb gene of two thrombasthenic dogs (Nos. 1 and 8). The insertion disrupted the fourth alphaIIb calcium-binding domain, caused a shift in the reading frame and resulted in a premature termination codon. Possible consequences of this mutation include decreased alphaIIb mRNA stability and production of truncated alphaIIb protein that lacks the transmembrane and cytoplasmic domains and a large portion of the extracellular domain. We identified the dam, sire, and three littermates of dog No. 8 as carriers of the alphaIIb mutation. Canine alphaIIb and beta3 genes share significant homology with the genes in human beings, making canine GT an excellent translational model for human GT. A defined molecular basis for canine GT will enhance ongoing gene therapy research and increase the understanding of structure-function relationships of this integrin.

Alternative Splicing↗
PubMed2005

Knee cartilage defect documentation: computer assistance in quantification of cartilage defects.

In order to determine the potential for a computer-assisted program to allow accurate and reproducible measurements of joint surface defects, area measurements were repeated 10 times by three observers for two complex lesions of predetermined size. The results indicate that this system offers a significant improvement over the surgeon's freehand method of assessment and that further development is indeed warranted.

Cartilage Diseases↗
PubMed2003

[Formation of congenital defects during ocular development. II. Genetic background of oculogenesis and developmental birth defects].

The course of oculogenesis is genetically controlled by genes, that are selectively expressed in the developing eye. Many of them, first recognized in studies on model animals, such as fruit fly (Drosophila melanogaster) proved, that they play similar roles in humans. The crucial role in cascade of genetic control of oculogenesis plays a system of genes PAX6-EYA1/SIX3-DACH1. In this work there are described also other genes, that form a network of interactions and regulations, such as: BMP4, BMP7, OPTX2, SOX1, PAX2, PITX2, PAX3, CHX10 and other genes. Describing function of each gene, author presented simultaneously all known congenital defects and syndromes, that are caused by mutations of above mentioned genes, such as: aniridia, anophthalmia, Peters anomaly and others.

Animals↗
PubMed1990

Defective expression of p70/75 interleukin 2 receptor in T cells from patients with systemic lupus erythematosus: a possible defect in the process of increased intracellular calcium leading to p70/75 expression.

Phytohemagglutinin (PHA) stimulated T cells from patients with systemic lupus erythematosus (SLE) showed hyporesponsiveness to interleukin 2 (IL-2) and expressed less p70/75 IL-2R than healthy controls. Ionomycine (IM, calcium ionophore) which selectively upregulated p70/75 expression, induced less p70/75 in patients with SLE than in healthy controls. However, intracellular calcium levels of T cells from patients with SLE increased as much as those from healthy controls, when T cells were stimulated by IM or PHA. Our results suggest that an impaired expression of p70/75 IL-2R in T cells from patients with SLE is not due to a defective calcium influx but to the events after the rise of calcium levels.

Adult↗
PubMed1975

Mutants of Escherichia coli defective in membrane phospholipid synthesis. Properties of wild type and Km defective sn-glycerol-3-phosphate acyltransferase activities.

The sn-glycerol-3-phosphate (glycerol-P) acyltransferase, the first enzyme of membrane phospholipid synthesis in Escherichia coli, was investigated in a wild type and a mutant strain defective in this activity. The mutant strain, selected as a glycerol-P auxotroph, was previously shown to contain a glycerol-P acyltransferase activity with an apparent Km for glycerol-P 10 times higher than that of its parent or revertants. The membranous mutant glycerol-P acyltransferase but did not appear to be thermolabile in vivo. Revertants no longer requiring glycerol-P for growth, showed glycerol-P acyltransferase activity with thermolability properties similar to the wild type. The second phospholipid biosynthetic enzyme, 1-acylglycerol-P acyltransferase, was not thermolabile in membranes containing a thermolabile glycerol-P acyltransferase activity. The pH optimum for the mutant acyltransferase was over 1 pH unit higher than that of the parental activity. Further, the mutant and wild type glycerol-P acyltransferase differed in their response to magnesium chloride and potassium chloride. The palmitoyl-CoA dependence of the wild type and mutant glycerol-P acyltransferase activities were different. The mutant glycerol-P acyltransferase activity was inhibited greater than 90% by Triton X-100 under conditions where the wild type activity was not affected. These experiments provide novel information about the wild type glycerol-P acyltransferase activity of E. coli and provide six additional lines of evidence for the mutant character of the glycerol-P acyltransferase in the mutant strains.

Acyltransferases↗
PubMed1986

Immunoperoxidase localization of prolactin in endometrium during normal menstrual, luteal phase defect, and corrected luteal phase defect cycles.

An avidin-biotin immunoperoxidase staining technique for human prolactin (hPRL) was developed for determination of the location of PRL-producing cells in the endometrium of women with normal menstrual cycles (NMC), luteal phase defects (LPD), and corrected LPD cycles (CLPD). One hundred eight biopsy specimens were studied. Fifty-six patients had NMC, 29 had LPD, and 23 had CLPD. Only decidualized stromal cells stained specifically for hPRL. There was no specific staining in specimens dated earlier than day 25. All specimens dated later than day 25 exhibited decidual cell staining. In specimens dated day 25, 15 of 20 NMC, 5 of 11 CLPD, and 6 of 10 LPD demonstrated decidual staining (P greater than 0.1). These findings suggest that decidual cells are responsible for hPRL production in late secretory endometrium and that the ability of decidual cells to stain for hPRL is dependent on the histologic date of the endometrium and not on the diagnosis of LPD or CLPD.

Bromocriptine↗
PubMed1987

Defective lymphopoiesis in the bone marrow of motheaten (me/me) and viable motheaten (mev/mev) mutant mice. II. Description of a microenvironmental defect for the generation of terminal deoxynucleotidyltransferase-positive bone marrow cells in vitro.

We have presented evidence in a previous paper that the development of prothymocytes, pre-B cells, and TdT+ lymphoid precursor cells in the bone marrow of motheaten (me/me) and viable motheaten (mev/mev) mice is defective. In the present study, we have used a selective culture system that supports the generation of rat- and mouse-origin TdT+ bone marrow lymphoid cells in vitro to further investigate the early stages of lymphopoiesis in me/me and mev/mev mice. The results demonstrate that bone marrow stromal cell feeder layers derived from me/me and mev/mev mice do not support the growth of rat TdT+ cells in vitro, whereas stromal cell feeder layers from heterozygous (+/-) littermates and wild type (+/+) control mice do. Moreover, composite feeder layers formed by mixing as few as one part me/me and mev/mev bone marrow cells with 7 to 9 parts +/- littermate bone marrow cells also fail to effectively support the generation of TdT+ cells in vitro. In contrast to me/me and mev/mev mice, other mutant mouse models of autoimmune (NZB, NZB/W), immunodeficient (nu/nu), and hemopoietic (W/Wv, Sl/Sld) disorders form feeder layers that support normal to elevated levels of TdT+ cell growth in vitro. Thus, to date, only the me/me and mev/mev mutant mice have been found to lack the appropriate microenvironment for the generation of TdT+ bone marrow cells. Histologic analysis of the stromal cell feeder layers that are formed in our culture system shows that multilayered cellular patches, which normally are the most active sites of TdT+ cell development in vitro, are absent in feeder layers of me/me and mev/mev cells. Moreover, feeder layers from mev/mev mice contain a population of MAC 1+, basophilic, nonvacuolated, macrophage-like cells; whereas feeder layers from control mice contain MAC 1+, eosinophilic, vacuolated macrophage-like cells. Stromal cell feeder layers formed by mixtures of me/me or mev/mev and control mouse bone marrow cells contain numerous multilayered cellular patches and vacuolated mononuclear cells, but also contain large numbers of basophilic mononuclear cells. These composite feeder layers have a disproportionately reduced capacity to support the generation of TdT+ cells in vitro. Although the stromal microenvironment of me/me and mev/mev bone marrow does not support the growth of TdT+ cells in vivo or in vitro, the bone marrow from these mutant mice contains detectable numbers of pre-TdT+ cells. Thus, when cultured on normal mouse feeder layers, mutant mouse bone marrow rapidly generates TdT+ cells in vitro, albeit at significantly reduced levels as compared to +/- littermate controls.(ABSTRACT TRUNCATED AT 400 WORDS)

Acid Phosphatase↗
PubMed1979

Defective tumoricidal capacity of macrophages from A/J mice. I. Characterization of the macrophage cytotoxic defect after in vivo and in vitro activation stimuli.

Macrophages from A/J mice fail to develop tumoricidal activity after any of several in vivo or in vitro treatments that activate cells from C3H/HeN mice. Peritoneal macrophages from A/J mice treated i.p. with viable Mycobacterium bovis, strain BCG, killed Corynebacterium parvum, or pyran copolymer fail to develop in vitro tumoricidal activity; varying the numbers of macrophages from treated mice added to target cells, or the dose and time of treatment, or the treatment schedule of these in vivo activation stimuli did not evoke cytotoxic activity. Moreover, cytotoxic activity by macrophages from A/J mice was not observed with any of four target cell lines derived from three different mouse strains. In vitro treatment of peritoneal exudate macrophages from A/J mice with lymphokine-rich supernatants, bacterial endotoxins, or T cell mitogens was also ineffective; varying the numbers of treated macrophages added to target cells, the dose of in vitro activation stimuli, or the time of treatment did not evoke cytotoxic activity. Thus, A/J mice exhibit a profound defect in macrophage tumoricidal capacity to both in vivo and in vitro activation stimuli over a wide range of experimental conditions.

Animals↗