bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation of precursor myogenic and chondrogenic cells in early limb bud mesenchyme by a monoclonal antibody.
Authors: Sasse J , Horwitz A , Pacifici M , Holtzer H
Published: May 2004

We have addressed the problem of the segregation of cell lineages during the development of cartilage and muscle in the chick limb bud. The following experiments demonstrate that early limb buds consist of at least two independent subpopulations of committed precursor cells--those in (a) the myogenic and (b) the chondrogenic lineage--which can be physically separated. Cells obtained from stage 20, 21, and 22 limb buds were cultured for 5 h in the presence of a monoclonal antibody that was originally isolated for its ability to detach preferentially myogenic cells from extracellular matrices. The detached limb bud cells were collected and replated in normal medium. Within 2 d nearly all of the replated cells had differentiated into myoblasts and myotubes; no chondroblasts differentiated in these cultures. In contrast, the original adherent population that remained after the antibody-induced detachment of the myogenic cells differentiated largely into cartilage and was devoid of muscle. Rearing the antibody-detached cells (i.e., replicating myogenic precursors and postmitotic myoblasts) in medium known to promote chondrogenesis did not induce these cells to chondrify. Conversely, rearing the attached precursor cells (i.e., chondrogenic precursors) in medium known to promote myogenesis did not induce these cells to undergo myogenesis. The definitive mononucleated myoblasts and multinucleated myotubes were identified by muscle-specific antibodies against light meromyosin or desmin, whereas the definitive chondroblasts were identified by a monoclonal antibody against the keratan sulfate chains of the cartilage-specific sulfated proteoglycan. These findings are interpreted as supporting the lineage hypothesis in which the differentiation program of a cell is determined by means of transit through compartments of a lineage.
Transient increase in intracellular pH during Dictyostelium differentiation.
Authors: Jamieson G A , Frazier W A , Schlesinger P H
Published: May 2004

The intracellular pH (pHi) of Dictyostelium discoideum amebae has been determined using the pH-dependent fluorescence of intracellularly trapped fluorescein (Thomas, J. A., R. N. Buschbaum, A. Zimiak, and E. Racker, Biochemistry, 18:2210-2218). The pHi of cells measured 45-60 min after initiation of differentiation was between 6.2 and 6.3. At approximately 2 h into differentiation cells underwent a transient intracellular alkalinization during which the pHi rose to 7.13 (+/- 0.3, n = 4), after which the pHi returned to approximately the original value (6.2-6.4). Cells that were removed from growth medium but were incubated in differentiation medium containing 3% dextrose did not exhibit this transient increase in pHi. The alkalinization event can also be prevented from occurring by differentiation in Na+-free solutions or by the addition of amiloride to sodium-containing buffer solutions, suggesting that the alkalinization is sodium dependent. When the alkalinization was prevented by amiloride treatment, cells did not progress normally into differentiation. This increase in pHi was initiated by the cells 2 h after removal from nutrient medium and it could be inhibited by several treatments that had been observed to delay the differentiation program, suggesting that it plays a major role in the initiation of the developmental program of this organism.
Osteoclast formation from mononuclear phagocytes: role of bone-forming cells.
Authors: Burger E H , van der Meer J W , Nijweide P J
Published: May 2004

In a previous study, using co-cultures of embryonic bone rudiments stripped of periosteum, and mononuclear phagocytes of various sources, we found that multinucleated mineral-resorbing osteoclasts developed in vitro from radiosensitive mouse bone marrow mononuclear phagocytes (BMMP). (Burger, E. H., J. W. M. van der Meer, J. S. van de Gevel, C. W. Thesingh, and R. van Furth, 1982, J. Exp. Med. 156:1604-1614). In the present study, this co-culture technique was used to analyze the influence of bone-forming cells on osteoclast formation and bone resorption by BMMP or peritoneal exudate cells (PEC). BMMP or PEC were co-cultured with liver or dead bone, i.e., in the presence or absence of liver bone-forming cells. Mineral resorption and osteoclast formation were monitored via 45Ca release from prelabeled live or dead bone followed by histology. Osteoclasts developed from precultured BMMP as indicated by [3H]thymidine labeling, but only in live and not in dead bone. They formed readily from BMMP but only erratically, and after a longer culture period, from PEC. Macrophages from BMMP and PEC invaded live and dead bone rudiments but did not resorb the intact mineralized matrix. In contrast, ground bone powder was resorbed avidly by both cell populations, without formation of osteoclasts. We conclude that live bone-forming cells are required for osteoclast formation from progenitors. Live bone is only resorbed by osteoclasts, and not by macrophages. Osteoclast progenitors are abundant in cultures of BMMP but scarce in PEC, which makes a direct descendance of osteoclasts from mature macrophages unlikely.
Programmed expression of beta-tubulin genes during development and differentiation of the chicken.
Authors: Havercroft J C , Cleveland D W
Published: May 2004

We have previously demonstrated that the chicken genome contains at least four different, functional beta-tubulin genes. By using gene specific probes we have now analyzed the relative levels of expression of the four encoded messenger RNA (mRNA) transcripts as a function of chicken development and differentiation. We have found that the RNA transcript from the beta 2 gene is present in large amounts in embryonic chick brain and is also preferentially expressed in spinal cord neurons, indicating that this transcript encodes the dominant neuronal beta-tubulin polypeptide. The beta 3 mRNA is present in overwhelming amounts in RNA from chicken testis suggesting that this gene encodes a flagellar or meiotic spindle tubulin. However, both of these genes are transcribed to varying, but lesser, degrees in a number of additional cell and tissue types indicating that they are not neuronal or testis specific, respectively. Beta 4' transcripts are present at moderate levels in all cell and tissue types examined, suggesting that this mRNA encodes a constitutive beta-tubulin polypeptide that is involved in an essential or housekeeping microtubule function. Transcripts from the beta 1 gene are a minor component of the beta-tubulin mRNA populations in all cells and tissues tested. Overall, we conclude that specific beta-tubulin mRNA species are expressed in markedly different ratios in different tissues in the chicken. Such developmental regulation may reflect the function(s) of the individual beta-tubulin polypeptides or, alternatively, may be required for precise control of tubulin gene expression in cells that utilize microtubules for divergent purposes.
Synthesis of cartilage matrix by mammalian chondrocytes in vitro. III. Effects of ascorbate.
Authors: Daniel J C , Pauli B U , Kuettner K E
Published: May 2004

Chondrocytes isolated from bovine articular cartilage were plated at high density and grown in the presence or absence of ascorbate. Collagen and proteoglycans, the major matrix macromolecules synthesized by these cells, were isolated at times during the course of the culture period and characterized. In both control and ascorbate-treated cultures, type II collagen and cartilage proteoglycans accumulated in the cell-associated matrix. Control cells secreted proteoglycans and type II collagen into the medium, whereas with time in culture, ascorbate-treated cells secreted an increasing proportion of types I and III collagens into the medium. The ascorbate-treated cells did not incorporate type I collagen into the cell-associated matrix, but continued to accumulate type II collagen in this compartment. Upon removal of ascorbate, the cells ceased to synthesize type I collagen. Morphological examination of ascorbate-treated and control chondrocyte culture revealed that both collagen and proteoglycans were deposited into the extracellular matrix. The ascorbate-treated cells accumulated a more extensive matrix that was rich in collagen fibrils and ruthenium red-positive proteoglycans. This study demonstrated that although ascorbate facilitates the formation of an extracellular matrix in chondrocyte cultures, it can also cause a reversible alteration in the phenotypic expression of those cells in vitro.
Mutations of the Rous sarcoma virus env gene that affect the transport and subcellular location of the glycoprotein products.
Authors: Wills J W , Srinivas R V , Hunter E
Published: May 2004

The envelope glycoproteins of Rous sarcoma virus (RSV), gp85 and gp37, are anchored in the membrane by a 27-amino acid, hydrophobic domain that lies adjacent to a 22-amino acid, cytoplasmic domain at the carboxy terminus of gp37. We have altered these cytoplasmic and transmembrane domains by introducing deletion mutations into the molecularly cloned sequences of a proviral env gene. The effects of the mutations on the transport and subcellular localization of the Rous sarcoma virus glycoproteins were examined in monkey (CV-1) cells using an SV40 expression vector. We found, on the one hand, that replacement of the nonconserved region of the cytoplasmic domain with a longer, unrelated sequence of amino acids (mutant C1) did not alter the rate of transport to the Golgi apparatus nor the appearance of the glycoprotein on the cell surface. Larger deletions, extending into the conserved region of the cytoplasmic domain (mutant C2), resulted in a slower rate of transport to the Golgi apparatus, but did not prevent transport to the cell surface. On the other hand, removal of the entire cytoplasmic and transmembrane domains (mutant C3) did block transport and therefore did not result in secretion of the truncated protein. Our results demonstrate that the C3 polypeptide was not transported to the Golgi apparatus, although it apparently remained in a soluble, nonanchored form in the lumen of the rough endoplasmic reticulum; therefore, it appears that this mutant protein lacks a functional sorting signal. Surprisingly, subcellular localization by internal immunofluorescence revealed that the C3 protein (unlike the wild type) did not accumulate on the nuclear membrane but rather in vesicles distributed throughout the cytoplasm. This observation suggests that the wild-type glycoproteins (and perhaps other membrane-bound or secreted proteins) are specifically transported to the nuclear membrane after their biosynthesis elsewhere in the rough endoplasmic reticulum.
Identification and isolation of endothelial cells based on their increased uptake of acetylated-low density lipoprotein.
Authors: Voyta J C , Via D P , Butterfield C E , Zetter B R
Published: May 2004

Acetylated-low density lipoprotein (Ac-LDL) is taken up by macrophages and endothelial cells via the "scavenger cell pathway" of LDL metabolism. In this report, aortic and microvascular endothelial cells internalized and degraded 7-15 times more [125I]-Ac-LDL than did smooth muscle cells or pericytes. Bound [125I]-Ac-LDL was displaced by unlabeled Ac-LDL, but not unmodified LDL. The ability to identify endothelial cells based on their increased metabolism of Ac-LDL was examined using Ac-LDL labeled with the fluorescent probe 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate (Dil-Ac-LDL). When cells were incubated with 10 micrograms/ml Dil-Ac-LDL for 4 h at 37 degrees C and subsequently examined by fluorescence microscopy, capillary and aortic endothelial cells were brilliantly fluorescent whereas the fluorescent intensity of retinal pericytes and smooth muscle cells was only slightly above background levels. Dil-Ac-LDL at the concentration used for labeling cells had no effect on endothelial cell growth rate. When primary cultures of bovine adrenal capillary cells were labeled with 10 micrograms/ml of Dil-Ac-LDL for 4 h at 37 degrees C, then trypsinized and subjected to fluorescence-activated cell sorting, pure cultures of capillary endothelial cells could be obtained. Utilizing this method, large numbers of early passage microvascular endothelial cells can be obtained in significantly less time than with conventional methods.
Platelet-collagen adhesion: inhibition by a monoclonal antibody that binds glycoprotein IIb.
Authors: Shadle P J , Ginsberg M H , Plow E F , Barondes S H
Published: May 2004

To identify platelet surface structures involved in adhesion to collagen, the effect of 16 murine antiplatelet membrane hybridoma antibodies were tested in a defined, in vitro assay. Four of these antibodies inhibited platelet-collagen adhesion and reacted with a polypeptide with Mr approximately 125,000, as determined by immunoblots after gel electrophoresis under reducing conditions. Through detailed studies with one of these antibodies, the monoclonal antibody PMI-1, the relevant antigen was identified as platelet glycoprotein IIb alpha, based upon (a) co-migration with this glycoprotein in two-dimensional gel electrophoresis and (b) co-purification by immunoaffinity chromatography with a protein with apparent Mr identical to that of glycoprotein III, under conditions in which glycoproteins IIb and III form a complex. Univalent antibody fragments prepared from monoclonal antibody PMI-1 inhibited greater than 80% of platelet-collagen adhesion, and inhibition was completely blocked by the immunopurified antigen. These results indicate that glycoprotein IIb participates in some aspect of platelet-collagen adhesion. In contrast, the purified antigen only partially neutralized a polyclonal antiserum that blocked platelet-collagen adhesion, to a maximum of approximately 25%, at saturating antigen concentrations. Thus, by these immunological criteria, glycoprotein IIb is not the only molecule involved in this process.
Adhesion of platelets to laminin in the absence of activation.
Authors: Ill C R , Engvall E , Ruoslahti E
Published: May 2004

The binding of platelets to components in the subendothelial matrix is an initial event in hemostasis and thrombosis. The glycoprotein components of the matrix are considered important in this interaction. Of these, collagen binds and activates platelets and induces their aggregation. In this study we demonstrate that substrate-bound laminin causes time- and concentration-dependent adherence of human platelets to the substrate. The binding of platelets to laminin was found to be similar in some respects, but different in others, to their binding to surfaces coated with fibronectin or collagen. The binding of platelets to laminin or fibronectin was not associated with their activation under conditions in which type I collagen activates the platelets as measured by [14C]serotonin secretion. Platelets bound to laminin and fibronectin differed in their appearance; they remained rounded on laminin whereas they flattened completely on fibronectin. Binding of platelets to fibronectin, but not laminin, is inhibited by a recently described peptide (Pierschbacher, M., and E. Ruoslahti, 1984, Nature (Lond.), 309:30-33) containing the cell-attachment tetrapeptide sequence of fibronectin, which suggests that separate receptors exist for laminin and fibronectin. These studies establish laminin as a platelet-binding protein and suggest that laminin can contribute to the adhesiveness of exposed tissue matrices to platelets. Since laminin and fibronectin do not activate platelets, whereas collagen does, and laminin differs from fibronectin in that it does not induce spreading of the attached platelets, all three proteins appear to confer different signals to the platelets. Some of these may be related to platelet functions other than those necessary for the formation of a hemostatic plug.
Tubulin dynamics in cultured mammalian cells.
Authors: Saxton W M , Stemple D L , Leslie R J , Salmon E D , Zavortink M , McIntosh J R
Published: May 2004

Bovine neurotubulin has been labeled with dichlorotriazinyl-aminofluorescein (DTAF-tubulin) and microinjected into cultured mammalian cells strains PTK1 and BSC. The fibrous, fluorescence patterns that developed in the microinjected cells were almost indistinguishable from the pattern of microtubules seen in the same cells by indirect immunofluorescence. DTAF-tubulin participated in the formation of all visible, microtubule-related structures at all cell cycle stages for at least 48 h after injection. Treatments of injected cells with Nocodazole or Taxol showed that DTAF-tubulin closely mimicked the behavior of endogenous tubulin. The rate at which microtubules incorporated DTAF-tubulin depended on the cell-cycle stage of the injected cell. Mitotic microtubules became fluorescent within seconds while interphase microtubules required minutes. Studies using fluorescence redistribution after photobleaching confirmed this apparent difference in tubulin dynamics between mitotic and interphase cells. The temporal patterns of redistribution included a rapid phase (approximately 3 s) that we attribute to diffusion of free DTAF-tubulin and a second, slower phase that seems to represent the exchange of bleached DTAF-tubulin in microtubules with free, unbleached DTAF-tubulin. Mean half times of redistribution were 18-fold shorter in mitotic cells than they were in interphase cells.
Nonconverted, amino acid analog-modified proinsulin stays in a Golgi-derived clathrin-coated membrane compartment.
Authors: Orci L , Halban P , Amherdt M , Ravazzola M , Vassalli J D , Perrelet A
Published: May 2004

The secretion of insulin by the pancreatic B-cell involves a passage of the newly synthetized (pro)insulin polypeptides across the Golgi apparatus, at the trans pole of which secretory proteins are released as a population of secretory granules characterized by a clathrinlike coat on segments of their limiting membrane. When the conversion of radiolabeled proinsulin to insulin was inhibited by replacing arginine and lysine with the aminoacid analogs, canavanine and thialysine, the nonconverted radioactive material remained associated with Golgi-derived, coated secretory granules. The coat was characterized as clathrin-containing by immunocytochemistry. Under analog treatment, the noncoated, storage secretory granules did not become markedly labeled during the pulse-chase experiment. These data are compatible with the hypothesis that in normal conditions, the maturation of the coated compartment into noncoated granules is linked to the effective conversion of the prohormone.
Paramecium secretory granule content: quantitative studies on in vitro expansion and its regulation by calcium and pH.
Authors: Garofalo R S , Satir B H
Published: May 2004

Ca2+-dependent secretion in Paramecium involves the exocytic release of a paracrystalline secretory product, the trichocyst matrix, which undergoes a characteristic structural change from a highly condensed storage form (Stage I) to an extended needle-like structure (Stage III) during release. We studied trichocyst matrix expansion in vitro to examine factors regulating the state of secretory organelle content. A new method for the isolation of membrane-free, condensed (Stage I) trichocyst matrices is described. These highly purified, condensed matrices were used to develop a rapid quantitative, spectrophotometric assay for matrix expansion to examine factors regulating the Stage I and Stage III transition. Expansion from Stages I to III was elicited in vitro by addition of Ca2+ and we found that at neutral pH, expansion required a Ca2+ concentration slightly above 10(-6)M. Previous studies indicate that calmodulin (CaM) antagonists inhibit matrix expansion in vivo. However, in vitro matrix expansion is normal even when trichocyst matrices are preincubated in CaM antagonists before stimulation. Thus, matrix components themselves are unlikely to be the site of CaM antagonist action in vivo. In vitro matrix expansion is also modulated by pH. Decreasing pH to 6.0 inhibits expansion, i.e., expansion requires higher Ca2+ concentration. Conversely, increasing pH to greater than 7.0 promotes expansion, allowing it to occur at a lower Ca2+ concentration. The pH sensitivity of the Ca2+ binding sites of the matrix suggests that, in vivo, the interior of the trichocyst vesicle may be maintained at an acidic pH. Exposure of cells to acridine orange, a fluorescent amine that accumulates in acidic intracellular compartments, leads to its uptake and concentration within trichocysts. Thus intratrichocyst pH appears to be acidic in vivo and may serve as a regulatory or "safety" mechanism to inhibit premature expansion.
Characterization of cytoplasmically oriented Golgi proteins with a monoclonal antibody.
Authors: Chicheportiche Y , Vassalli P , Tartakoff A M
Published: May 2004

BALB/c mice were repeatedly immunized with a galactosyl transferase-rich microsomal fraction of rat myeloma cells. Spleen cells were subsequently fused with Sp2/0 mouse myeloma cells, the resulting hybridomas were cloned, and their secreted Ig was screened for reactivity with antigens belonging to the Golgi complex. One such monoclonal antibody, 6F4C5, gave especially intense immunofluorescent staining of the Golgi area of myeloma cells and fibroblasts. It recognized two proteins bands on immunoblots of gel-fractionated cell lysates: a major one with an estimated Mr of 54,000 and a minor one at 86,000. Both proteins were concentrated in microsomal fractions isolated at low ionic strength. They were hydrophilic judging from partitioning of a Triton X-114 cell lysate. Both were cytoplasmically oriented as demonstrated by protease and high KCl treatments of postmitochondrial supernatants and microsomal fractions. Neither was retained by columns of insolubilized wheat germ agglutinin or concanavalin A, which suggests that they are not glycoproteins. Their more detailed location in the Golgi complex was studied by immunoelectron microscopy, using a saponin permeabilization procedure and peroxidase-conjugated reagents. The observed staining was restricted to two or three cisternae in the medial part of the stack. Nevertheless, differential centrifugation experiments indicated that the two antigens may be recovered in distinct subcellular fractions: this may be related to the unexpected observation that rather low salt concentrations strip the antigens from microsomal fraction.
Segregation of the polypeptide translocation apparatus to regions of the endoplasmic reticulum containing ribophorins and ribosomes. I. Functional tests on rat liver microsomal subfractions.
Authors: Amar-Costesec A , Todd J A , Kreibich G
Published: May 2004

A preparation of rat liver microsomes containing 70% of the total cellular endoplasmic reticulum (ER) membranes was subfractionated by isopycnic density centrifugation. Twelve subfractions of different ribosome content ranging in density from 1.06 to 1.29 were obtained and analyzed with respect to marker enzymes, RNA, and protein content, as well as the capacity of these membranes to bind 80S ribosomes in vitro. After removal of native polysomes from these microsomal subfractions by puromycin in a buffer of high ionic strength their capacity to rebind 80S ribosomes approached levels found in the corresponding native membranes before ribosome stripping. This indicates that in vitro rebinding of ribosomes occurs to the same sites occupied in the cell by membrane-bound polysomes. Microsomes in the microsomal subfractions were also tested for their capacity to effect the translocation of nascent secretory proteins into the microsomal lumen utilizing a rabbit reticulocyte translation system programmed with mRNA coding for the precursor of human placental lactogen. Membranes from microsomes with the higher isopycnic density and a high ribosome content showed the highest translocation activity, whereas membranes derived from smooth microsomes had only a very low translocation activity. These results indicate the membranes of the rough and smooth portions of the endoplasmic reticulum are functionally differentiated so that sites for ribosome binding and the translocation of nascent polypeptides are segregated to the rough domain of the organelle.
Shape changes in human erythrocytes induced by replacement of the native phosphatidylcholine with species containing various fatty acids.
Authors: Kuypers F A , Roelofsen B , Berendsen W , Op den Kamp J A , van Deenen L L
Published: May 2004

Phosphatidylcholine-specific transfer protein from beef liver has been used to replace native phosphatidylcholine (PC) molecules from intact human erythrocytes by a variety of PC species differing in fatty acid composition. These replacements changed neither the total phospholipid content of the membrane, nor the composition of this fraction in terms of the various phospholipid classes. The morphology of the erythrocyte was not modified when native PC was replaced by 1-palmitoyl,2-oleoyl PC, 1-palmitoyl,2-linoleoyl PC, egg PC, or PC isolated from rat liver microsomes. Replacement with the disaturated species 1,2-dimyristoyl PC, 1,2-dipalmitoyl PC, and 1,2-distearoyl PC resulted in the formation of echinocytes and, at higher levels of replacement, in spheroechinocytes. Echinocyte-like erythrocytes were also observed after replacement with 1-palmitoyl,2-arachidonoyl PC, whereas stomatocytes were formed upon replacement with PC species containing two unsaturated fatty acids, e.g., 1,2-dioleoyl PC and 1,2-dilinoleoyl PC. The observations show that the erythrocyte membrane structure and the overall discoid cell shape of the human erythrocyte are optimally stabilized by PC species that contain one saturated and one mono- or diunsaturated fatty acid, and that the cell tolerates only limited variations in the species composition of its PC.
Expression of specific keratin markers by rabbit corneal, conjunctival, and esophageal epithelia during vitamin A deficiency.
Authors: Tseng S C , Hatchell D , Tierney N , Huang A J , Sun T T
Published: May 2004

Using an in vivo rabbit model system, we have studied the morphological and biochemical changes in corneal, conjunctival, and esophageal epithelia during vitamin A deficiency. Light and electron microscopy showed that the three epithelia undergo different degrees of morphological keratinization. Corneal and conjunctival epithelia became heavily keratinized, forming multiple layers of superficial, anucleated cornified cells. In contrast, esophageal epithelium underwent only minor morphological changes. To correlate morphological alterations with the expression of specific keratin molecules, we have analyzed the keratins from these epithelia by the immunoblot technique using the subfamily-specific AE1 and AE3 monoclonal antikeratin antibodies. The results indicate that during vitamin A deficiency, all three epithelia express an AE1-reactive, acidic 56.5-kd keratin and an AE3-reactive, basic 65-67-kd keratin. Furthermore, the expression of these two keratins correlated roughly with the degree of morphological keratinization. AE2 antibody (specific for the 56.5- and 65-67-kd keratins) stained keratinized corneal epithelial sections suprabasally, as in the epidermis, suggesting that these two keratins are expressed mainly during advanced stages of keratinization. These two keratins have previously been suggested to represent markers for epidermal keratinization. Our present data indicate that they can also be expressed by other stratified epithelia during vitamin A deficiency-induced keratinization, and suggest the possibility that they may play a role in the formation of the densely packed tonofilament bundles in cornified cells of keratinized tissues.
MAP 4: a microtubule-associated protein specific for a subset of tissue microtubules.
Authors: Parysek L M , Wolosewick J J , Olmsted J B
Published: May 2004

The cytological distribution of microtubule-associated protein 4 (MAP 4) (L. M. Parysek, C. F. Asnes, J. B. Olmsted, 1984, J. Cell Biol., 99:1309-1315) in mouse tissues has been examined. Adjacent 0.5-0.9-micron sections of polyethylene glycol-embedded tissues were incubated with affinity-purified MAP 4 or tubulin antibodies, and the immunofluorescent images were compared. Tubulin antibody labeling showed distinct microtubules in all tissues examined. MAP 4 antibody also labeled microtubule-like patterns, but the extent of MAP 4 reactivity was cell type-specific within each tissue. MAP 4 antibody labeled microtubules in vascular elements of all tissues and in other cells considered to have supportive functions, including Sertoli cells in the testis and glial elements in the nervous system. Microtubule patterns were also observed in cardiac, smooth, and skeletal (eye) muscle, podocytes in kidney, Kuppfer cells in liver, and spermatid manchettes. The only MAP 4-positive cells in which the pattern was not microtubule-like were the principal cells of the collecting ducts in kidney cortex, in which diffuse fluorescence was seen. MAP 4 antibody did not react with microtubule-rich neuronal elements of the central and peripheral nervous system, skeletal muscle from anterior thigh, liver parenchymal cells, columnar epithelial cells of the small intestine, and absorptive cells of the tubular component of the nephron. These observations indicate that MAP 4 may be associated with only certain kinds of cell functions as demonstrated by the preferential distribution with microtubules of defined cell types.
Qualitative analysis of skeletal myosin as substrate of Ca2+-activated neutral protease: comparison of filamentous and soluble, native, and L2-deficient myosin.
Authors: Pemrick S M , Grebenau R C
Published: May 2004

Ca2+ -activated neutral protease (CAF) was capable of degrading myosin over a 200-fold range of protease concentrations. CAF selected the heavy chain of myosin, although either prolonged exposure to or high concentrations of the protease degraded the L1, but not the L2 or L3, light chains of myosin. The following results indicated that during the first hour of digestion, under conditions where native myosin was the substrate, CAF selected for the "head" region of the myosin heavy chain: (a) large heavy chain fragments of identical molecular weight were produced from filamentous and from soluble myosin; (b) light meromyosin was not a substrate; (c) agents known to bind to the head of myosin (actin, MgATP, and L2) had both a qualitative and quantitative effect on degradation; and (d) similar cleavage sites could be demonstrated for myosin and for heavy meromyosin (HMM) despite the fact that HMM was a much poorer substrate than myosin. This observation is interpreted as an indication that the conformation of myosin heavy chain is altered in the preparation of HMM. The principal cleavage sites on the heavy chain of myosin were 20,000, 35,000 and 50,000 D from the N-terminus, producing large fragments with molecular weights of 180,000, 165,000, and 150,000 which comprised a "nicked" species of myosin. This nicked species retained both normal solubility properties and normal hydrolytic activities. For this reason, it is concluded that "nicked myosin" is an important pathophysiological species.
The Role of State Fiscal Policy in State Economic Growth
Authors: Tomljanovich Marc
Published: May 2004

Do state policy makers have the ability to affect a state's rate of economic growth? This article examines one possible source of growth and per capita output level disparities by studying the role that state taxation and public expenditure decisions play in fostering economic development. Using pooled annual U.S. state‐level data from 1972 to 1998, a fixed‐effects model is employed to examine the effects of changing tax rates on both state per capita output levels and growth rates. The results indicate that higher tax rates negatively influence short‐run state economic growth, which lowers state output levels. However, long‐run growth is unaffected by changes in state tax rates, even after adjusting for the effects of initial per capita output levels, state expenditures, and aid from the federal government. Nor do changes in state public spending rates and federal aid permanently alter state growth rates, implying that state fiscal policies have only transitory effects on state growth. (JEL H71, O40, R11)
Employer‐provided Health Insurance and Job Change
Authors: Adams Scott J.
Published: May 2004

The author uses data from the 1988–2000 Annual Demographic Files of the Current Population Survey to revisit the question of whether job lock exists. Limiting the sample to males with employer‐provided health insurance, it is tested whether the lack of a potential source of alternative coverage through the individual's spouse affects his or her job mobility. The author controls for both characteristics of the respondent and spouse, as well as the attributes of their jobs. Although evidence produced by other researchers using similar methodology has been mixed, this article presents significant evidence that employer‐provided health insurance lowers mobility. (JEL J320, J620)
The young Arthur Cayley
Authors: Crilly T.
Published: May 2004

Arthur Cayley, F.R.S. (1821–1895) is widely regarded as Britain's leading pure mathematician of the 19th century. From his start as a Cambridge prodigy, he built up a formidable record of publication, from incidental notes to extensive memoirs, on a wide range of mathematics. His emergence as a mathematician, before he became the sober–minded eminence of the 1860s and 1870s, is largely unknown. The primary guide to his whole life remains, more than a century later, the obituary written by his student and successor at Cambridge, A.R. Forsyth. The folklore surrounding Cayley's life is dominated by his collaboration with James Joseph Sylvester, F.R.S. (1814–1897). This partnership, tempered by Sylvester's obsession with the apportionment of credit, began in earnest in the 1850s. In this paper, I attempt to signpost Cayley's formative years, when he was at the beginning of his long mathematical journey, the period which ends on 3 June 1852, the date of his election to the Royal Society, when he formally came of age as a Victorian man of science.
Illustrating a revolution: an unrecognized contribution to the ‘golden era’ of cerebral localization
Authors: Millett D.
Published: May 2004

The late 19th century witnessed a remarkable growth of knowledge concerning the functions of the brain. The excitability of the cerebral cortex was first reported by Gustav Fritsch (1838–1927) and Eduard Hitzig (1838–1907) in 1870, followed by the classical investigation of cerebral localization by David Ferrier (1843–1928). Ferrier's identification of cerebral motor 'centres' based on a series of cortical stimulations and ablations was central to the physiological and clinical achievements of cerebral localization in the late 19th century. Cerebral illustrations were an important component of Ferrier's physiological research, synthesizing a great deal of experimental data and suggesting precise locations and boundaries of sensory and motor areas. Surprisingly, little attention has been paid to the construction of cerebral maps and their role in establishing the utility and veracity of the doctrine of cerebral localization. Two illustrations of the macaque brain based on Ferrier's experimental work were particularly influential. These and other important illustrations accompanied Ferrier's manuscript, 'The localisation of functions in the brain', submitted to the Royal Society in early 1874, but were not produced by Ferrier himself. Rather, they were sketched by E. A. Waterlow (1850–1919), a young painter and acquaintance of Ferrier's who—undoubtedly under Ferrier's guidance—synthesized the experimental data of more than a dozen experiments in these diagrams. Unfortunately, during the contentious review, abstraction and fragmentation of Ferrier's manuscript, Waterlow's monogrammed insignia was omitted from reproductions of his sketches and Ferrier's acknowledgement to him was not published in subsequent works. While circumstantial evidence suggests that Waterlow may have requested that these identifiers be withheld, and while Waterlow has never been recognized for his illustrations of cerebral localization, both the artist and his sketches soon achieved prominence. Waterlow's diagrams were reproduced in Ferrier's widely influential monograph,
The Functions of the Brain
(1876), where the cerebral centres of Waterlow's macaque brain were directly transposed onto Ecker's diagram of the human brain. These diagrams were reprinted during the late 1870s and 1880s in many textbooks and reviews of cerebral physiology, and provided an important guide to the localization of brain lesions during the early years of neurosurgery. This paper recounts Waterlow's contribution to the history of clinical neurology and physiology, and his independent success as a landscape painter.
Lionel Penrose, F.R.S. (1898–1972) and eugenics. Part two
Authors: Watt D.C.
Published: May 2004

The method of improving the human genetic constitution divides into positive and negative eugenics. Positive eugenics is the policy of encouraging and promoting the procreation of those with socially desirable faculties and abilities. Negative eugenics on the other hand is designed to limit the procreation of those with a poor, disadvantageous genetic constitution which may be transmitted to their offspring. Policy proposals to achieve the aims of positive eugenics included family allowances, grants towards the education of children of able families, counselling, physical and psychological testing, medical examination to facilitate ssortative marriage of desirable parents and banking sperm of outstanding men for insemination of comparable women. These were all vigorously advocated. Fisher stated in a review of an article by Leonard Darwin that

Galton's work in fact left no room for doubt that if the methods of the stockyard were applicable to mankind the human race could be improved in any desired direction, within a short historical period, to an extent exceeding existing differences between widely different races.

Despite continued vigorous approbation the practical outcome of positive eugenics proposals seems very little in terms, for instance, of government enquiries, formal scientific trials or earnest attempts at practical application.
The origins of the unit of nitrogen fixation at the University of Sussex
Authors: Postgate J.
Published: May 2004

During the ‘golden age’ of British scientific research funding, that is, the two decades following the end of the Second World War, the two biologically orientated research councils, medical (MRC) and agricultural (ARC), would sometimes establish personal research units. Although staffed by career scientists, units differed from institutes in being small and personal, i.e. a small team of researchers, employees of the Council, would be attached to a distinguished research leader. The leader would usually be an academic, on the staff of a university, and would thus become an honorary director, but sometimes the director would be employed by the Council, and might then have an honorary academic position as well. Most units were located on a university campus, or more rarely within one of the Council's research institutes. Units were very effective scientifically, being both productive and economical; the ARC set up 24 during its history and in 1960, its peak period for units, it was supporting 15. However, the problems of redeploying staff, which arose when the unit's leader retired, emigrated or died, made them unpopular with administrators. When a unit was sited at a university the understanding had often been that the university would absorb the staff, but as university expansion came to a standstill this became impracticable. In later decades the ARC's units were gradually closed.
Book reviews
Authors: Russell Colin A.
Published: May 2004

Eleven book reviews in the July 1998 edition of
Notes and Records
:
Robert Boyle. A free enquiry into the vulgarly received notion of nature
, Edward B. Davis and Michael Hunter (eds.). P. Mancosu,
Philosophy of mathematics and mathematical practice in the seventeenth century
. Patricia Fara,
Sympathetic attractions: magnetic practices, beliefs, and symbolism in eighteenth–century England
. Alan Cook,
Edmond Halley: charting the heavens and the seas
. Jan Bondeson,
A cabinet of medical curiosities
. J.M.H. Moll,
Presidents of The Royal Society of Medicine
. W.H. Brock,
Justus von Liebig: the chemical gatekeeper
.
Charles Lyell's Principles of Geology (1830–33)
, J. Secord (ed.).
X–rays––the first hundred years
, Alan Michette and Slawka Pfauntsch (eds.). Jack Morrell,
Science at Oxford 1914–1939
. John Polkinghorne,
Beyond science. The wider human context
.
Bioethics—Eleven Approaches
Authors: Lebacqz Karen
Published: May 2004

Abstract:  Using a case study, the author reviews 11 different approaches to bioethics, examining both their implications in clinical practice and their importance for clergy. In addition to the popular stress on patients’ rights and principles in bioethics, the approaches include perspectives drawn from feminist ethics, phenomenology, ethnography, covenant views, virtue ethics, postmodernism, and casuistry. Lebacqz shows that each perspective may be important for stressing something different in the clinical setting, and suggests that clergy should be prepared to extend the range of views that may be operating in a given case.
Assisted Suicide: Do We Own Our Bodies?
Authors: Tarkki Jarmo
Published: May 2004

Abstract:  The ethics of physician‐assisted suicide is explored here in light of classic philosophical discussions of the ownership of one's body plus biblical discussions of the relationship of body and soul. Motives for individual and group suicide are brought to bear on bioethical principles such as that of autonomy. Ethical analysis is here challenged by the case of a 91 year‐old woman, Ragnhild, who lived after professional judgments that her life should be ended.
Efficacy and Tolerability of the New Antiepileptic Drugs, II: Treatment of Refractory Epilepsy: Report of the TTA and QSS Subcommittees of the American Academy of Neurology and the American Epilepsy Society
Authors: French Jacqueline A. , Kanner Andres M. , Bautista Jocelyn , Abou‐Khalil Bassel , Browne Thomas , Harden Cynthia L. , Theodore William H. , Bazil Carl , Stern John , Schachter Steven C. , Bergen Donna , Hirtz Deborah , Montouris Georgia D. , Nespeca Mark , Gidal Barry , Marks William J. , Turk William R. , Fischer James H. , Bourgeois Blaise , Wilner Andrew , Faught R. Edward , Sachdeo Rajesh C. , Beydoun Ahmad , Glauser Tracy A.
Published: May 2004

Summary:  Purpose: To assess the evidence demonstrating efficacy, tolerability, and safety of seven new antiepileptic drugs (AEDs) [gabapentin (GBP), lamotrigine (LTG), topiramate (TPM), tiagabine (TGB), oxcarbazepine (OXC), levetiracetam (LEV), and zonisamide (ZNS)] in the treatment of children and adults with refractory partial and generalized epilepsies.

Methods: A 23‐member committee, including general neurologists, pediatric neurologists, epileptologists, and doctors in pharmacy, evaluated the available evidence based on a structured literature review including MEDLINE, Current Contents, and Cochrane Library for relevant articles from 1987 to March 2003.

Results: All of the new AEDs were found to be appropriate for adjunctive treatment of refractory partial seizures in adults. GBP can be effective for the treatment of mixed seizure disorders, and GBP, LTG, OXC, and TPM for the treatment of refractory partial seizures in children. Limited evidence suggests that LTG and TPM also are effective for adjunctive treatment of idiopathic generalized epilepsy in adults and children, as well as treatment of the Lennox–Gastaut syndrome.

Conclusions: The choice of AED depends on seizure and/or syndrome type, patient age, concomitant medications, and AED tolerability, safety, and efficacy. The results of this evidence‐based assessment provide guidelines for the prescription of AEDs for patients with refractory epilepsy and identify those seizure types and syndromes for which more evidence is necessary.
Parietal Lobe Epilepsy: The Semiology, Yield of Diagnostic Workup, and Surgical Outcome
Authors: Kim Dong Wook , Lee Sang Kun , Yun Chang‐Ho , Kim Kwang‐Ki , Lee Dong Soo , Chung Chun‐Kee , Chang Kee‐Hyun
Published: May 2004

Summary:  Purpose: To characterize the clinical features, the prognostic value, and diagnostic sensitivities of various presurgical evaluations and the surgical outcomes in parietal lobe epilepsy (PLE), we describe 40 patients who were diagnosed as having PLE, including 27 surgically treated patients.

Methods: The diagnosis was established by means of a standard presurgical evaluation, including magnetic resonance imaging (MRI), fluorodeoxyglucose–positron emission tomography (FDG‐PET), ictal single‐photon emission tomography (SPECT), and scalp video‐electroencephalography (EEG) monitoring, with additional intracranial EEG monitoring in selected cases.

Results: Among the 40 patients, 27 experienced at least one type of aura. The most common auras were somatosensory (13 patients), followed by affective, vertiginous, and visual auras. The patients had diverse manifestations. Eighteen patients showed simple motor seizure, followed by automotor seizure, and dialeptic seizure. Two patients manifested generalized tonic–clonic seizures only, and 19 patients experienced more than one type of seizure. The surgical outcome was favorable in 22 of 26 patients including 14 who were seizure free. Patients with localized MRI abnormality had a higher probability to be seizure free, with marginal significance (p = 0.062), whereas other diagnostic modalities failed to predict the surgical outcome. In the seizure‐free group, localization sensitivity was 64.3% by MRI, 50% by PET, 45.5% by ictal SPECT, and 35.7% by ictal EEG. The concordance rate of the various diagnostic modalities was higher in the seizure‐free group than in the non–seizure‐free group, although it did not reach statistical significance.

Conclusions: Seizures, in the case of PLE, can manifest themselves in a wider variety of ways than was previously thought. Surgical outcome was favorable in most of the patients. MRI abnormality and concordance of different diagnostic modalities were associated with high seizure‐free rate.
Accidents in Patients with Epilepsy: Types, Circumstances, and Complications: A European Cohort Study
Authors: Van Den Broek Mariska , Beghi Ettore ,   RESt‐1 Group
Published: May 2004

Summary: Purpose:To investigate the risk of accidents in a cohort of patients with epilepsy and in matched nonepilepsy controls, by type, circumstances, and complications.

Methods:A total of 951 children and adults with idiopathic, cryptogenic, or remote symptomatic epilepsy and 904 matched controls seen in secondary and tertiary centers in eight European countries (England, Estonia, Germany, Italy, the Netherlands, Portugal, Russia, and Slovenia) were followed up prospectively for 17,484 and 17,206 person‐months and asked to report any accident requiring medical attention, its site, and complications. Risk assessment was done by using actuarial methods, relative risks (RRs), and 95% confidence intervals (CIs).

Results:During the study period, 199 (21%) patients and 123 (14%) controls reported an accident (p < 0.0001); 24% were seizure related. The cumulative probability of accidents at 12 and 24 months was 17 and 27% in the cases and 12 and 17% in the controls. The risk was highest for concussions (RR, 2.6; 95% CI, 1.2–5.8), abrasions (RR, 2.1; 95% CI, 1.1–4.0), and wounds (RR, 1.9; CI, 1.2–3.1). Domestic accidents prevailed in both groups, followed by street and work accidents, and were more common among cases. Compared with controls, patients with epilepsy reported more hospitalization, complications, and medical action. Disease characteristics associated with an increased risk of accidents included generalized epilepsy (concussions), active epilepsy, and at least monthly seizures (abrasions). Most risks decreased, becoming nonsignificant after excluding seizure‐related events.

Conclusions:Patients with epilepsy are at higher risk of accidents and their complications. However, the risk was substantially lower after exclusion of seizure‐related events.