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Chen H, Johnson RL. Dorsoventral patterning of the vertebrate limb: a process governed by multiple events. Cell Tissue Res 1999; 296:67-73. [PMID: 10199966 DOI: 10.1007/s004410051267] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this review, we detail recent studies which have led to the first molecular insights into dorsoventral vertebrate limb patterning. In keeping with classical experiments which defined ectodermal-mesodermal signaling as an important component of limb bud dorsoventral axis specification, the genes identified to date to be critically important for proper dorsoventral limb patterning include both ectodermally and mesodermally expressed cell:cell signaling molecules and transcription factors. A surprising complexity to dorsoventral vertebrate limb patterning has been revealed by gene targeting in the mouse and lineage tracing in the chick, with current models suggesting that the dorsoventral limb axis is specified by distinct mechanisms in the proximal versus distal limb.
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Aulehla A, Johnson RL. Dynamic expression of lunatic fringe suggests a link between notch signaling and an autonomous cellular oscillator driving somite segmentation. Dev Biol 1999; 207:49-61. [PMID: 10049564 DOI: 10.1006/dbio.1998.9164] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The metameric organization of the vertebrate trunk is a characteristic feature of all members of this phylum. The origin of this metamerism can be traced to the division of paraxial mesoderm into individual units, termed somites, during embryonic development. Despite the identification of somites as the first overt sign of segmentation in vertebrates well over 100 years ago, the mechanism(s) underlying somite formation remain poorly understood. Recently, however, several genes have been identified which play prominent roles in orchestrating segmentation, including the novel secreted factor lunatic fringe. To gain further insight into the mechanism by which lunatic fringe controls somite development, we have conducted a thorough analysis of lunatic fringe expression in the unsegmented paraxial mesoderm of chick embryos. Here we report that lunatic fringe is expressed predominantly in somite -II, where somite I corresponds to the most recently formed somite and somite -I corresponds to the group of cells which will form the next somite. In addition, we show that lunatic fringe is expressed in a highly dynamic manner in the chick segmental plate prior to somite formation and that lunatic fringe expression cycles autonomously with a periodicity of somite formation. Moreover, the murine ortholog of lunatic fringe undergoes a similar cycling expression pattern in the presomitic mesoderm of somite stage mouse embryos. The demonstration of a dynamic periodic expression pattern suggests that lunatic fringe may function to integrate notch signaling to a cellular oscillator controlling somite segmentation.
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Khalil EM, Ojala WH, Pradhan A, Nair VD, Gleason WB, Mishra RK, Johnson RL. Design, synthesis, and dopamine receptor modulating activity of spiro bicyclic peptidomimetics of L-prolyl-L-leucyl-glycinamide. J Med Chem 1999; 42:628-37. [PMID: 10052970 DOI: 10.1021/jm980525q] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the present study, the synthesis of the 5.5.6. and 5.6.5. spiro bicyclic lactam PLG peptidomimetics, compounds 3 and 4, respectively, was undertaken. These peptidomimetics were designed to examine the following: (1) the effect that changing the size of the thiazolidine and lactam ring systems would have on the ability of these systems to mimic the type-II beta-turn and (2) the effect that these structural perturbations would have on the ability of the peptidomimetics to modulate dopamine receptors. Through the use of the [3H]spiroperidol/N-propylnorapomorphine (NPA) dopamine D2 receptor competitive binding assay, 3 and 4, at a concentration of 100 nM, decreased the dissociation constant of the high-affinity state of the dopamine receptor for the agonist. These effects were observed when either Gpp(NH)p was absent or present and they were comparable to those produced by PLG at a concentration of 1 microM. Peptidomimetics 3 and 4 also increased the percentage of D2 receptors that existed in the high-affinity state. Even with Gpp(NH)p present, 3 and 4 were able to return the RH/RL ratios to values observed in the respective controls where Gpp(NH)p was absent. Furthermore, both peptidomimetics were able to attenuate the Gpp(NH)p-induced shift to the low-affinity state to a greater extent than PLG. Peptidomimetics 3 and 4 were evaluated in vivo as modulators of apomorphine-induced rotational behavior in the 6-hydroxydopamine-lesioned rat model of hemiparkinsonism, and each affected the rotational behavior in a bell-shaped dose-response relationship producing increases of 95 +/- 31% (0.01 mg/kg, ip) and 88 +/- 14% (0.001 mg/kg, ip), respectively. In comparison, the previously reported 5.5.5. spiro bicyclic lactam 2 increased rotational behavior by 25 +/- 11% (0.01 mg/kg, ip).
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Johnson RL. Analyte specific reagents: FDA final rule and implications for your clinical flow cytometry laboratory. CYTOMETRY 1999; 38:40-1. [PMID: 10088975 DOI: 10.1002/(sici)1097-0320(19990215)38:1<40::aid-cyto6>3.3.co;2-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In summary, the FDA Final Rule on Analyte Specific Reagents has provided clarity and simplification for manufactures to develop and market products. The burden of establishing performance characteristics is now the responsibility of the clinical flow cytometry laboratory. The FDA now requires a disclaimer to be included in every lab report utilizing these products.
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Keys DN, Lewis DL, Selegue JE, Pearson BJ, Goodrich LV, Johnson RL, Gates J, Scott MP, Carroll SB. Recruitment of a hedgehog regulatory circuit in butterfly eyespot evolution. Science 1999; 283:532-4. [PMID: 9915699 DOI: 10.1126/science.283.5401.532] [Citation(s) in RCA: 295] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The origin of new morphological characters is a long-standing problem in evolutionary biology. Novelties arise through changes in development, but the nature of these changes is largely unknown. In butterflies, eyespots have evolved as new pattern elements that develop from special organizers called foci. Formation of these foci is associated with novel expression patterns of the Hedgehog signaling protein, its receptor Patched, the transcription factor Cubitus interruptus, and the engrailed target gene that break the conserved compartmental restrictions on this regulatory circuit in insect wings. Redeployment of preexisting regulatory circuits may be a general mechanism underlying the evolution of novelties.
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Costain WJ, Buckley AT, Evans MC, Mishra RK, Johnson RL. Modulatory effects of PLG and its peptidomimetics on haloperidol-induced catalepsy in rats. Peptides 1999; 20:761-7. [PMID: 10477133 DOI: 10.1016/s0196-9781(99)00060-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A behavioral model of dopaminergic function in the rat was used to examine the anticataleptic effects of L-prolyl-L-leucyl-glycinamide (PLG) and peptidomimetic analogs of PLG. Administration of 1 mg/kg PLG intraperitoneally significantly attenuated haloperidol (1 mg/kg)-induced catalepsy (as measured by the standard horizontal bar test), whereas doses of 0.1 and 10 mg/kg PLG did not. Eight synthetic PLG peptidomimetics (Calpha, alpha-dialkylated glycyl residues with lactam bridge constraint [1-4] and without [5-8]) were tested in the same manner (at a dose of 1 microg/kg) and categorized according to their activity, i.e. very active (5), moderately active (2, 3, 4, and 6), and inactive (1, 7, and 8). The catalepsy-reversal action of the diethylglycine-substituted peptidomimetic 5 was examined further and found to exhibit a U-shaped dose-response effect with an optimal dose of 1 microg/kg. The similarity between the effects of PLG and the synthetic peptidomimetics suggests a common mechanism of action. Finally, the synthetic peptidomimetics examined here, particularly peptidomimetic 5, were more effective than PLG in attenuating haloperidol-induced catalepsy.
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Lange JH, Bruce KM, Johnson RL, Phillips MJ, Smith DM, Weidenboemer KM. A survey of lead-based paint abatement projects performed in public buildings in Erie and Crawford Counties, Pennsylvania, during the time period 1995-1997. Regul Toxicol Pharmacol 1998; 28:73-8. [PMID: 9927556 DOI: 10.1006/rtph.1998.1231] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A survey of lead-based paint abatement projects in public buildings of Crawford and Erie Counties, Pennsylvania, was conducted during the time period January 1995 to March 1997. These survey results suggest that few lead abatement projects were performed during this time period. Projects that were performed commonly did not employ proper lead abatement practices as described by the U.S. Occupational Safety and Health Administration, U.S. Environmental Protection Agency, and U.S. Department of Housing and Urban Development. These data suggest that most contractors and public officials have misunderstandings of both environmental regulations and required procedures for safe and effective lead-based paint abatement.
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Latkovich P, Johnson RL. Carcinosarcoma of the parotid gland: report of a case with cytohistologic and immunohistochemical findings. Arch Pathol Lab Med 1998; 122:743-6. [PMID: 9701339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
True malignant mixed tumors (carcinosarcomas) of salivary gland origin are exceedingly rare and demonstrate malignant epithelial and stromal components. We report a case of parotid gland carcinosarcoma that showed squamous cell carcinoma and malignant fibrous hystiocytoma without clinical or histologic evidence of a preexisting pleomorphic adenoma. This tumor consisted of 2 histologically different populations of cells without evidence of a common origin from the myoepithelial cell, which is the putative precursor cell of pleomorphic adenoma and its derived carcinosarcoma. In addition to supplementing the literature, this case report includes cytohistologic and immunohistochemical analyses that provide further insights into the variable histogenesis of this neoplasm and the distinction between de novo carcinosarcoma and carcinosarcoma originating from pleomorphic adenoma.
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Abstract
Members of the Hedgehog (Hh) family of signaling proteins control cell fates and proliferation during animal development in part by regulating the transcription of specific genes. Depending on the tissue, Hh can act over long or short distances, to signal directly or by inducing secondary signals. Recent discoveries include new components of the pathway as well as novel regulatory mechanisms involving cholesterol, proteolysis, and the cytoskeleton. The role of Hh in carcinogenesis is underscored by the identification of mutations in several pathway components in skin and brain tumors.
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Evrard YA, Lun Y, Aulehla A, Gan L, Johnson RL. lunatic fringe is an essential mediator of somite segmentation and patterning. Nature 1998; 394:377-81. [PMID: 9690473 DOI: 10.1038/28632] [Citation(s) in RCA: 294] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The gene lunatic fringe encodes a secreted factor with significant sequence similarity to the Drosophila gene fringe. fringe has been proposed to function as a boundary-specific signalling molecule in the wing imaginal disc, where it is required to localize signalling activity by the protein Notch to the presumptive wing margin. By targeted disruption in mouse embryos, we show here that lunatic fringe is likewise required for boundary formation. lunatic fringe mutants fail to form boundaries between individual somites, the initial segmental unit of the vertebrate trunk. In addition, the normal alternating rostral-caudal pattern of the somitic mesoderm is disrupted, suggesting that intersomitic boundary formation and rostral-caudal patterning of somites are mechanistically linked by a process that requires lunatic fringe activity. As a result, the derivatives of the somitic mesoderm, especially the axial skeleton, are severely disorganized in lunatic fringe mutants. Taken together, our results demonstrate an essential function for a vertebrate fringe homologue and suggest a model in which lunatic fringe modulates Notch signalling in the segmental plate to regulate somitogenesis and rostral-caudal patterning of somites simultaneously.
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DiBernardo LR, Kirshbom PM, Skaryak LA, Quarterman RL, Johnson RL, Davies MJ, Gaynor JW, Ungerleider RM. Acute functional consequences of left ventriculotomy. Ann Thorac Surg 1998; 66:159-65. [PMID: 9692457 DOI: 10.1016/s0003-4975(98)00376-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Left ventriculotomies are sometimes used during intracardiac congenital defect repair. Acute changes in left ventricular function after longitudinal or apical ventriculotomy were assessed using dynamic pressure-dimensional data. METHODS Ultrasonic dimension transducers along the major, minor, and septal free wall axes and micromanometers were placed in 24 piglets. Pressure-volume data were collected during caval occlusions at baseline and 60 minutes after warm cardiopulmonary bypass alone or with longitudinal ventriculotomy or apical left ventriculotomy. Hemodynamics, contractility, and contraction geometry were analyzed. RESULTS Cardipulmonary bypass caused decreased compliance in all groups, with equally decreased preload and cardiac output. Heart rate increased, but ventriculotomy led to a significantly greater increase. Longitudinal ventriculotomy produced a greater loss of stroke volume and ejection fraction than apical ventriculotomy. Contractility assessed by the preload recruitable stroke work relationship showed no difference between groups; however, all groups showed a slight increase in unit myocardial power at 60 minutes. Axis fractional shortening revealed that the septal freewall is responsible for 50% of stroke volume and that this axis is significantly impaired after longitudinal ventriculotomy. CONCLUSION Apical left ventriculotomy impairs the less important major axis only and is predicted to be better tolerated.
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Aszterbaum M, Rothman A, Johnson RL, Fisher M, Xie J, Bonifas JM, Zhang X, Scott MP, Epstein EH. Identification of mutations in the human PATCHED gene in sporadic basal cell carcinomas and in patients with the basal cell nevus syndrome. J Invest Dermatol 1998; 110:885-8. [PMID: 9620294 DOI: 10.1046/j.1523-1747.1998.00222.x] [Citation(s) in RCA: 479] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mutations in PATCHED (PTC), the human homolog of the Drosophila patched gene, have been identified in most exons of the gene in patients with the basal cell nevus syndrome and in sporadic basal cell carcinomas. We have screened the 23 PTC exons for mutations using single strand conformation polymorphism analysis of DNA from 86 basal cell nevus syndrome probands, 26 sporadic basal cell carcinomas, and seven basal cell nevus syndrome-associated basal cell carcinomas. This screen identified mutations located in eight exons in 13 of the basal cell nevus syndrome patients and in three of the tumors. The most common mutations were frameshifts resulting in premature chain termination. These results provide further evidence for the crucial role of PTC as a tumor suppressor in human keratinocytes.
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Johnson RL, Scott MP. Control of cell growth and fate by patched genes. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 1998; 62:205-15. [PMID: 9598353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Kengaku M, Capdevila J, Rodriguez-Esteban C, De La Peña J, Johnson RL, Izpisúa Belmonte JC, Tabin CJ. Distinct WNT pathways regulating AER formation and dorsoventral polarity in the chick limb bud. Science 1998; 280:1274-7. [PMID: 9596583 DOI: 10.1126/science.280.5367.1274] [Citation(s) in RCA: 339] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The apical ectodermal ridge (AER) is an essential structure for vertebrate limb development. Wnt3a is expressed during the induction of the chick AER, and misexpression of Wnt3a induces ectopic expression of AER-specific genes in the limb ectoderm. The genes beta-catenin and Lef1 can mimic the effect of Wnt3a, and blocking the intrinsic Lef1 activity disrupts AER formation. Hence, Wnt3a functions in AER formation through the beta-catenin/LEF1 pathway. In contrast, neither beta-catenin nor Lef1 affects the Wnt7a-regulated dorsoventral polarity of the limb. Thus, two related Wnt genes elicit distinct responses in the same tissues by using different intracellular pathways.
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Capdevila J, Johnson RL. Endogenous and ectopic expression of noggin suggests a conserved mechanism for regulation of BMP function during limb and somite patterning. Dev Biol 1998; 197:205-17. [PMID: 9630747 DOI: 10.1006/dbio.1997.8824] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The gene noggin, originally cloned in Xenopus, encodes a secreted factor expressed in the Spemann organizer, where it functions to oppose the ventralizing influence of bone morphogenetic proteins (BMPs). Noggin protein acts by binding directly to BMPs, thereby preventing them from interacting with their receptors. Here we describe the pattern of expression of the chicken noggin gene during somite and limb development, two tissues in which BMPs have been postulated to play essential patterning roles. We find that noggin is expressed in dynamic restricted patterns consistent with an important role in the modulation of BMP signaling. Using a replication competent retrovirus we have ectopically expressed noggin in developing somitic and limb bud mesoderm and observed phenotypes consistent with complete block of BMP activity. This includes suppression of lateral somite differentiation and, in the limb, complete inhibition of chondrogenesis and local suppression of programmed cell death. In addition, we find that ectopic noggin expression in the limb has no effect on anteroposterior limb pattern, suggesting that BMPs are unlikely to play a significant role in this process. Taken together,, our results indicate that noggin is a key regulator of vertebrate limb and somite patterning and suggest that the antagonistic Noggin-BMP interaction is a widely used mechanism to modulate BMP signaling during multiple inductive events in vertebrate embryogenesis.
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Chen H, Lun Y, Ovchinnikov D, Kokubo H, Oberg KC, Pepicelli CV, Gan L, Lee B, Johnson RL. Limb and kidney defects in Lmx1b mutant mice suggest an involvement of LMX1B in human nail patella syndrome. Nat Genet 1998; 19:51-5. [PMID: 9590288 DOI: 10.1038/ng0598-51] [Citation(s) in RCA: 336] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Dorsal-ventral limb patterning in vertebrates is thought to be controlled by the LIM-homeodomain protein Lmx1b which is expressed in a spatially and temporally restricted manner along the dorsal-ventral limb axis. Here we describe the phenotype resulting from targeted disruption of Lmx1b. Our results demonstrate that Lmx1b is essential for the specification of dorsal limb fates at both the zeugopodal and autopodal level with prominent phenotypes including an absence of nails and patellae. These features are similar to those present in a dominantly inherited human condition called nail patella syndrome (NPS), which also has renal involvement. Mouse Lmx1b maps to a region syntenic to that of the NPS gene, and kidneys of Lmx1b mutant mice exhibit pathological changes similar to that observed in NPS (refs 5,6). Our results demonstrate an essential function for Lmx1b in mouse limb and kidney development and suggest that NPS might result from mutations in the human LMX1B gene.
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Dreyer SD, Zhou G, Baldini A, Winterpacht A, Zabel B, Cole W, Johnson RL, Lee B. Mutations in LMX1B cause abnormal skeletal patterning and renal dysplasia in nail patella syndrome. Nat Genet 1998; 19:47-50. [PMID: 9590287 DOI: 10.1038/ng0598-47] [Citation(s) in RCA: 300] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The LIM-homeodomain protein Lmx1b plays a central role in dorso-ventral patterning of the vertebrate limb. Targeted disruption of Lmx1b results in skeletal defects including hypoplastic nails, absent patellae and a unique form of renal dysplasia (see accompanying manuscript by H. Chen et al.; ref. 2). These features are reminiscent of the dominantly inherited skeletal malformation nail patella syndrome (NPS). We show that LMX1B maps to the NPS locus and that three independent NPS patients carry de novo heterozygous mutations in this gene. Functional studies show that one of these mutations disrupts sequence-specific DNA binding, while the other two mutations result in premature termination of translation. These data demonstrate a unique role for LMX1B in renal development and in patterning of the skeletal system, and suggest that alteration of Lmx1b/LMX1B function in mice and humans results in similar phenotypes. Furthermore, we provide evidence for the first described mutations in a LIM-homeodomain protein which account for an inherited form of abnormal skeletal patterning and renal failure.
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Abstract
Among the reasons that cancer pain is not controlled adequately are patient-related barriers. Patient beliefs that may contribute to poor outcome have been measured in previous research with the Barriers Questionnaire (BQ). The purpose of this study was to examine the internal consistency of a shortened version of the BQ. A sample of 217 outpatients with cancer completed a 17-item version of the scale. Factor analysis suggested two subscales, one reflecting beliefs about communication about pain and the other reflecting beliefs about the use of analgesics. Both subscales demonstrated adequate internal consistency. Beliefs did not differ between patients who had and those who had not experienced pain within the previous two weeks. Findings suggest the shortened BQ provides an internally consistent measure of two broad patient barriers to pain management.
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Capdevila J, Tabin C, Johnson RL. Control of dorsoventral somite patterning by Wnt-1 and beta-catenin. Dev Biol 1998; 193:182-94. [PMID: 9473323 DOI: 10.1006/dbio.1997.8806] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In vertebrates, the dorsoventral patterning of somitic mesoderm is controlled by factors expressed in adjacent tissues. The ventral neural tube and the notochord function to promote the formation of the sclerotome, a ventral somite derivative, while the dorsal neural tube and the surface ectoderm have been shown to direct somite cells to a dorsal dermomyotomal fate. A number of signaling molecules are expressed in these inducing tissues during times of active cell fate specification, including members of the Hedgehog, Wnt, and BMP families. However, with the exception of the ventral determinant Sonic hedgehog (Shh), the functions of these signaling molecules with respect to dorsoventral somite patterning have not been determined. Here we investigate the role of Wnt-1, a candidate dorsalizing factor, in the regulation of sclerotome and dermomyotome formation. When ectopically expressed in the presomitic mesoderm of chick embryos in ovo, Wnt-1 differentially affects the expression of dorsal and ventral markers. Specifically, ectopic Wnt-1 is able to completely repress ventral (sclerotomal) markers and to enhance and expand the expression of dorsal (dermomyotomal) markers. However, Wnt-1 appears to be unable to convert all somitic mesoderm to a dermomyotomal fate. Delivery of an activated form of beta-catenin to somitic mesoderm mimics the effects of Wnt-1, demonstrating that Wnt-1 likely acts directly on somitic mesoderm, and not through adjacent tissues via an indirect signal relay mechanism. Taken together, our results support a model for somite patterning where sclerotome formation is controlled by the antagonistic activities of Shh and Wnt signaling pathways.
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Johnson RL. Physicians as executives: barriers to success. Front Health Serv Manage 1998; 13:28-32. [PMID: 10164862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Johnson RL, Gerhart KA, McCray J, Menconi JC, Whiteneck GG. Secondary conditions following spinal cord injury in a population-based sample. Spinal Cord 1998; 36:45-50. [PMID: 9471138 DOI: 10.1038/sj.sc.3100494] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
This prospective study investigates the frequency of both medical and non-medical complications reported by the population based cohort of SCI survivors reported to the Colorado Spinal Cord Injury Early Notification System (ENS). Persons reported to the ENS between January 1 1986 and December 31 1993, representing the broad spectrum of all severities of spinal cord injury and potential complications, were solicited to participate in comprehensive follow-up interviews at their first, third and fifth year post injury. Hospitalizations of a week or longer were experienced by more than 10% of the participants at each of the three interview years. Similarly, the medical complications of spasticity or pain were reported by more than 25% of the participants, and pressure sores were reported by more than 10% at all three time periods. The chief non-medical complications (conditions) were financial concerns and transportation problems. Although these reported medical and non-medical complications present significant obstacles to be overcome, less than three percent of those surveyed at any of the time periods reported experiencing depression; and only 14% rated their quality of life as being poor.
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Marcotte ER, Chugh A, Mishra RK, Johnson RL. Protection against MPTP treatment by an analog of Pro-Leu-Gly-NH2 (PLG, MIF-1). Peptides 1998; 19:403-6. [PMID: 9493876 DOI: 10.1016/s0196-9781(97)00321-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
3(R)-[(2(S)-Pyrrolidinyl-carbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA) is a peptidomimetic analog of Pro-Leu-Gly-NH2 (PLG or MIF-1) that has previously been demonstrated to be more potent and efficacious that MIF-1 in enhancing dopamine receptor activity. Given the ability of MIF-1 to protect against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) lesioning in C57 BL/6 mice, the present study was undertaken to evaluate the neuroprotective effect of PAOPA in this model. PAOPA was found to be more potent and efficacious that MIF-1 in sparing dopamine and its metabolite levels following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration. Whether the enhanced neuroprotective effect of PAOPA is due to dopamine receptor stimulation, or a result of reduced oxidative stress through normalization of dopamine turnover, remains to be determined.
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Abstract
The inhibitory effect that suckling has on the reproductive function of primate mothers varies as a function of the intensity with which they are suckled. Here we present an easily computed index of one parameter of suckling intensity, namely the temporal patterning of suckling bouts. High intensity suckling is characterized by frequent nursing bouts demarcated by short interbout intervals. Therefore, our suckling index is based on the brevity of observed interbout intervals, more specifically the proportion of such intervals that fail to exceed a criterion length. The index is an appropriate means of making interspecific comparisons of the development of infant suckling and is well suited for application to field data that include interbout intervals that were not observed in their entirety. To demonstrate its utility, we apply the index to field data collected on the suckling behavior of free-ranging rhesus monkey (Macaca mulatta) infants in India. In this context, we demonstrate that, in rhesus, between-infant differences in suckling intensity manifest themselves early in the postpartum period and contribute to between-female differences in the timing of first mating postpartum.
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