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Biomedical subjects

S McCormick

Publications and source records attributed to S McCormick.

At least 55 records · Page 3Linked to original sources
PubMed1997

Identification of the tobacco and Arabidopsis homologues of the pollen-expressed LAT59 gene of tomato.

We describe the complete genomic sequences for the tobacco and Arabidopsis homologues of tomato LAT59, a previously described member of a family of pectate lyase-like genes. Translation of the tobacco gene, Nt59, predicts a protein with 93.5% overall amino acid similarity to LAT59. Nt59 has two introns whose positions are exactly conserved with the two introns of LAT59. Both LAT59 and Nt59 are specifically expressed in pollen and their promoter and 5'-UTR sequences are highly similar. Furthermore, two promoter elements shown to be important for pollen expression of LAT59 are conserved in the Nt59 promoter. The Arabidopsis homologue, At59, was found by examination of four candidates. At59 has 72.6% amino acid similarity to LAT59 and the position of one of its two introns is conserved with one of the LAT59 introns. At59 is also pollen-expressed and although its promoter sequence is quite different from the Nt59 and LAT59 promoters, the two promoter elements are somewhat conserved.

Arabidopsis↗
PubMed1997

Vector of device placement and trajectory of mandibular distraction.

The role of preoperative planning, the geometric changes, and the long-term effects of mandibular distraction have not been previously reported. This study included 10 patients who underwent unilateral (5 patients) or bilateral (5 patients) mandibular distraction. Preoperative, postdistraction, and yearly radiographs (panoramic, posteroanterior, and lateral cephalograms) were reviewed. Postdistraction follow-up ranged from 12 to 70 months. Postdistraction, the mandibles showed evidence of anticipated growth without relapse. This growth rate was variable and dependent on the genetic program of the native bone. Previously reported improvement in temporomandibular joint morphology was maintained in the long term. The resulting shape of the neomandible was most influenced by the vector of placement of the distraction device. When placed vertically, ramal elongation was observed. When placed horizontally, anterior projection of the mandibular body occurred. When placed obliquely, ramal and body elongation occurred with preservation of the gonial angle. After 2 to 5 years of follow-up, continued growth of the neomandible was observed.

Cephalometry↗
PubMed1997

A strong inhibitor of gene expression in the 5' untranslated region of the pollen-specific LAT59 gene to tomato.

Promoter sequences that direct pollen-specific expression have been previously identified in the LAT59 (for late anther tomato) gene. Here, we show that the LAT59 sequences encoding the 5' untranslated region inhibit expression of reporter genes by > 20-fold in transient expression experiments and up to 300-fold after stable transformation. Inhibition occurred in somatic cells as well as in pollen. Our results indicate that the inhibitor still functions after pollen germination and therefore does not modulate the level of the LAT59 protein during pollen development. The presence of the leader sequence dramatically decreased mRNA accumulation but without affecting translation rate and mRNA stability. We believe that the leader inhibits transcription. We mapped the inhibitor to a region in the leader that coincides with a putative stem-loop and present evidence that this stem-loop participates in inhibition.

Gene Expression Regulation, Plant↗
PubMed1997

Alterations in parathyroid dynamics in lithium-treated subjects.

Chronic lithium (Li) therapy, used extensively in the treatment of bipolar affective disorders, is one of psychiatry's most effective treatments. The data on the effects of Li on baseline PTH and calcium (Ca) levels are conflicting. A clear resetting of the PTH set-point to the right was documented in vitro; however, the effect of Li on the Ca-PTH axis has not been rigorously studied in vivo. In this study, we used a Ca and citrate infusion protocol to fully characterize PTH dynamics in seven female patients, 40 +/- 11 yr old, on chronic Li therapy for 5.23 +/- 4.0 yr, compared with seven controls, 41 +/- 16 yr old (mean +/- SD). Baseline ionized Ca (Cai) and intact PTH levels were 5.2 +/- 0.06 mg/dL and 38.4 +/- 5.7 pg/mL in the Li group and 4.9 +/- 0.06 mg/dL and 21.2 +/- 5.0 pg/mL in the controls, (mean +/- SEM) P = 0.008 and 0.042, respectively. We defined an inverse sigmoidal curve between Cai and the intact biologically active PTH molecule (iPTH) for the two study groups and demonstrated a significant shift in the iPTH set-point to the right in the Li-treated patients, compared with controls. The set-point was 5.08 +/- 0.04 for the former group and 4.88 +/- 0.04 mg/dL for the latter, P = 0.004. Patients on Li had significantly higher Cai levels during citrate and Ca infusions, P = 0.0008 and 0.012, respectively; however, iPTH levels were not significantly different between the two study groups during either infusion. The shift in the iPTH set-point to the right in the Li-treated patients and the similar iPTH levels, despite higher serum Cai levels during both infusions, establish the presence of a clear alteration in PTH dynamics in patients on chronic Li therapy.

Adult↗
PubMed1996

The N gene of tobacco confers resistance to tobacco mosaic virus in transgenic tomato.

It has been proposed that cloned plant disease resistance genes could be transferred from resistant to susceptible plant species to control important crop plant diseases. The recently cloned N gene of tobacco confers resistance to the viral pathogen, tobacco mosaic virus. We generated transgenic tomato plants bearing the N gene and demonstrate that N confers a hypersensitive response and effectively localizes tobacco mosaic virus to sites of inoculation in transgenic tomato, as it does in tobacco. The ability to reconstruct the N-mediated resistance response to tobacco mosaic virus in tomato demonstrates the utility of using isolated resistance genes to protect crop plants from diseases, and it demonstrates that all the components necessary for N-mediated resistance are conserved in tomato.

Base Sequence↗
PubMed1996

A 610 kb YAC clone harbors 7 cM of tomato (Lycopersicon esculentum) DNA that includes the male sterile 14 gene and a hotspot for recombination.

Pollen development requires both sporophytic and gametophytic gene expression. We are using a map-based cloning technique to isolate sporophytic genes which, when mutant, cause pollen abortion and a male sterile (ms) phenotype in tomato (Lycopersicon esculentum). We have genetically characterized one ms locus (ms14) using RFLP analysis and identified flanking markers. High-resolution genomic physical mapping indicates that the ms14 locus is located in a approximately 300 kb region. We have identified a YAC clone with an insert size of approximately 610 kb that contains the ms14-linked markers, reflects the organization of the physical map and therefore most probably contains the ms14 gene. In addition, we present evidence that the relationship between physical and genetic distance in this chromosomal region changes abruptly from approximately 105-140 kb/cM to less than 24kb/cM, and suggest that the TG393-TG104 region is a hotspot for recombination.

Chromosome Mapping↗
PubMed1996

Effect of the R569W missense mutation on the biosynthesis of myeloperoxidase.

Human neutrophil microbicidal activity is largely mediated by reactive species generated by the oxygen-dependent myeloperoxidase (MPO) system. Peroxidase-negative neutrophils from many patients with hereditary MPO deficiency possess a 90-kDa MPO-related protein. We recently identified a missense mutation, R569W, in the MPO gene of many subjects with MPO deficiency. In these studies we examined the consequences of R569W on MPO biosynthesis and processing, using stably transfected K562 cells expressing normal MPO or the R569W mutation. K562 cells expressing normal MPO mimicked faithfully many features of MPO biosynthesis in myeloid cells. 1) apopro-MPO was synthesized; 2) a functional heme group was inserted into apopro-MPO, and enzymatically active pro-MPO was thereby generated; 3) pro-MPO underwent proteolytic processing to mature MPO; and 4) hemin augmented the processing of pro-MPO. pREP-R569W cells synthesized apopro-MPO, but heme was not inserted. Neither enzymatically active pro-MPO nor mature MPO was synthesized by transfectants expressing mutated cDNA, confirming our hypothesis that the R569W mutation results in a form of apopro-MPO which does not undergo post-translational processing to enzymatically active MPO species. In addition, these data support previous suggestions that heme insertion into apopro-MPO is necessary for its subsequent proteolytic processing into mature MPO subunits.

Amino Acid Sequence↗
PubMed1996

sidecar pollen, an Arabidopsis thaliana male gametophytic mutant with aberrant cell divisions during pollen development.

During pollen development each product of meiosis undergoes a stereotypical pattern of cell divisions to give rise to a three-celled gametophyte, the pollen grain. First an asymmetric mitosis generates a larger vegetative cell and a smaller generative cell, then the generative cell undergoes a second mitosis to give rise to two sperm cells. It is unknown how this pattern of cell divisions is controlled. We have identified an Arabidopsis gene, SIDECAR POLLEN, which is required for the normal cell division pattern during pollen development. In the genetic background of the NoO ecotype, sidecar pollen heterozygotes have about 45% wild-type pollen, 48% aborted pollen and 7% pollen with an extra cell. Homozygous sidecar pollen plants have about 20% wild-type pollen, 53% aborted pollen and 27% extra-celled pollen. Similar ratios of sidecar pollen phenotypes are seen in the Columbia ecotype but sidecar pollen is a gametophytic lethal in the Landsberg erecta ecotype. Thus this allele of sidecar pollen shows differential gametophytic penetrance and variable expressivity in different genetic backgrounds. The extra cell has the cell identity of a vegetative cell and is produced prior to any asymmetric microspore mitosis. Pollen tetrad analysis directly demonstrates that SIDECAR POLLEN is indeed expressed in male gametophytes. To our knowledge, scp is the first male gametophytic mutation to be described in Arabidopsis.

Arabidopsis↗
PubMed1996

Inflammatory pseudotumor (plasma cell granuloma) of the heart. Report of two cases and literature review.

We report pathologic findings in two patients with inflammatory pseudotumor of the heart. The first patient was a 15-year-old-boy who died suddenly and unexpectedly of myocardial ischemia caused by an angiocentric inflammatory pseudotumor affecting all of the major coronary arteries and some of their branches. Inflammatory pseudotumor was also centered around some intrasplenic arteries. The second patient was a 5-month-old girl who had subtotal resection of a mass in the right atrial free wall. Her inflammatory pseudotumor was confined to the myocardium and showed no angiocentricity. The patient is doing well 22 months after surgery. Inflammatory pseudotumor is a benign inflammatory response evoked by an unknown agent(s). In both patients, the inflammatory cells comprised a mixture of B and T lymphocytes. Among B cells, a mixture of kappa and lambda plasma cells was evident. A moderate number of tissue macrophages was also observed. The process is usually self-limited but may cause death if vital structures are involved.

Adolescent↗
PubMed1996

Choroid plexus papilloma of the cerebellopontine angle.

Choroid plexus papillomas are rare tumors, representing less than 1% of all intracranial neoplasms in our review of the English literature. Derived from the neuroepithelial cells of the choroid plexus, these tumors recapitulate the structure of the normal choroid plexus, often demonstrating a well-developed papillary architecture. This tumor most commonly affects children and typically arises in the lateral ventricles. Before 1992, 26 cases have been reported arising in the cerebellopontine angle. We describe an example of choroid plexus papilloma of the cerebellopontine angle that was initially diagnosed as metastatic papillary carcinoma. A metastatic disease workup revealed a right thyroid lobe nodule. Fine needle aspiration biopsy of this nodule yielded a few atypical cells, but no evidence of papillary carcinoma. We performed additional laboratory investigations to rule out the possibility of a primary papillary carcinoma of the thyroid gland and to make a definitive diagnosis of a choroid plexus papilloma. This article reviews choroid plexus papilloma of the cerebellopontine angle and demonstrates the use of immunohistochemistry to differentiate this benign primary neoplasm from well-differentiated metastatic papillary carcinoma.

Adult↗
PubMed1995

Pollen specificity elements reside in 30 bp of the proximal promoters of two pollen-expressed genes.

Functional analyses previously identified minimal promoter regions required for maintaining high-level expression of the late anther tomato LAT52 and LAT59 genes in tomato pollen. Here, we now define elements that direct pollen specificity. We used a transient assay system consisting of two cell types that differentially express the LAT genes and both "loss-of-function" and "gain-of-function" approaches. Linker substitution mutants analyzed in the transient assay and in transgenic plants identified 30-bp proximal promoter regions of LAT52 and LAT59 that are essential for their expression in pollen and that confer pollen specificity when fused to the heterologous cauliflower mosaic virus 35S core promoter. In vivo competition experiments demonstrated that a common trans-acting factor interacts with the pollen specificity region of both LAT gene promoters and suggested that a common mechanism regulates their coordinate expression. Adjacent upstream elements, the 52/56 box in LAT52 and the 56/59 box in LAT59, are involved in modulating the level of expression in pollen. The 52/56 box may be a target for the binding of a member of the GT-1 transcription factor family.

Base Sequence↗
PubMed1994

LAT52 protein is essential for tomato pollen development: pollen expressing antisense LAT52 RNA hydrates and germinates abnormally and cannot achieve fertilization.

The LAT52 gene of tomato is expressed in a pollen-specific manner. It is shown that LAT52 encodes a heat-stable, glycosylated protein that traverses the secretory pathway when expressed in a baculovirus expression system. The LAT52 protein shows some similarity with Kunitz trypsin inhibitors and with pollen proteins from maize, rice and olive, but the biological function of these pollen proteins is unknown. To test whether the LAT52 protein plays an important role during pollen development, tomato plants were transformed with an antisense LAT52 gene driven by the LAT52 promoter. Because the LAT52 gene is expressed gametophytically, only 50% of the pollen of the primary transformants would be expected to express the antisense construct. Selfprogeny of 19 of the primary transformants showed the predicted 3:1 segregation for a single locus insertion of the linked kanamycin-resistance gene. However, the self-progeny of the other 32 primary transformants showed a 1:1 segregation pattern and could not transmit the linked kanamycin-resistance gene through the male. A subset of these 1:1 segregation class plants was examined in detail. The pollen showed lower levels of LAT52 mRNA and LAT52 protein when compared with wild-type. In vitro, approximately 50% of the pollen grains appear to hydrate abnormally; this anomaly is not present when the same pollen grains are incubated in a medium with higher water potential. In vivo pollination experiments showed that the growth of around 50% of the pollen tubes is arrested in the style. The 3:1 segregation class plants showed no significant differences from untransformed control plants. Taken together, the results show a direct correlation between the reduced expression of LAT52 protein and abnormal pollen function, and suggest that the LAT52 protein plays a role in pollen hydration and/or pollen germination.

Amino Acid Sequence↗
PubMed1993

Functional domain in an arginine-rich carboxyl-terminal region of p47phox.

Activation of the neutrophil respiratory burst oxidase involves phosphorylation-dependent translocation of the cytosolic proteins p47phox and p67phox to the plasma membrane, a process in intact cells that is inhibited by staurosporine. We now report that in a cell-free oxidase system, staurosporine and protein kinase C pseudosubstrate PKC(19-36) both inhibited p47phox phosphorylation but had no effect on superoxide generation. In contrast, p47phox phosphorylation, translocation, and superoxide generation were inhibited by a peptide, p47phox(323-332) (AYRRNSVRFL), based on a putative serine phosphorylation domain. This effect was specific for the 323-332 peptide, as it was not observed with two peptides based on other p47phox phosphorylation domains. All three peptides served as substrates for phosphorylation, but the extent of peptide phosphorylation did not correlate with inhibition of oxidase function. p47phox(325-330), which represents the serine phosphorylation motif of p47phox(323-332), did not inhibit translocation or superoxide production despite its ability to block phosphorylation of p47phox. These data indicate the presence of functionally important sites within the p47phox(323-332) peptide. Although serine 328 is in a consensus phosphorylation motif, the lack of correlation in the cell-free system between p47phox phosphorylation and either protein translocation or superoxide formation suggests that a phosphorylation-independent function resides in the 323-332 segment of p47phox.

Amino Acid Sequence↗
PubMed1993

Non-enzymic glycation of collagen inhibits binding of oxidized low-density lipoprotein.

We have examined the effect of non-enzymic glycation of native soluble collagen, in solution or in gels, on binding of oxidized low-density lipoprotein (LDL). We found the following. (1) Glycation markedly inhibited binding of LDL. This is contrary to results previously reported; the difference may be attributable to the use of detergent- and heat-denatured collagen, covalently bound to agarose beads, in the earlier study. (2) With increased duration of glycation, collagen solution would not gel, and preformed gels dissolved. (3) [14C]Glucose bound to collagen gels dissociated slowly, even at pH 5, suggesting that it was not present as a Schiff's base; in addition, ketoamines, pentosidine and fluorescent advanced glycation products were not detectable in glycated collagen gels, although they accumulated in tendon collagen glycated under the same conditions. It is hypothesized that the difference in glycation effects between gel and tendon may be due to the strength of cross-linking before glycation: the increase in intermolecular distance in collagen fibrils which results from glycation disrupts the fibrils in gels, preventing binding of LDL and formation of glycation-dependent cross-links, whereas the extensive cross-linking in tendon maintains the intermolecular distances within a range which permits formation of glycation cross-links.

Animals↗
PubMed1993

Histopathology of argon laser peripheral iridoplasty.

We report the light and electron microscopic findings from two eyes treated with argon laser peripheral iridoplasty (ALPI) for bilateral angle-closure glaucoma. The patient, a 45-year-old man, died from complications of acquired immunodeficiency syndrome 16 days following ALPI. Ocular pathologic findings included contraction furrow formation and proliferation of fibroblast-like cells, accompanied by collagen deposition on the iris surface, denaturation of stromal collagen, and coagulative necrosis of blood vessels within the anterior two thirds of the iris stroma. These findings suggest that heat shrinkage of collagen may be responsible for the short-term response to ALPI, and that contraction of the fibroblastic membrane may be responsible for its long-term effects. Additionally, the presence of coagulative necrosis of iris blood vessels suggests that overt treatment may result in iris necrosis. To our knowledge this is the first report of the histopathology of ALPI.

Acquired Immunodeficiency Syndrome↗