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Biomedical subjects

D M Lang

Publications and source records attributed to D M Lang.

At least 19 recordsLinked to original sources
PubMed2004

Treatment of osteoporosis: missed opportunities in the hospital fracture clinic.

AIM: To identify what proportion of patients who, having sustained an initial distal radial fragility fracture and a subsequent femoral neck fracture, had had their osteoporosis addressed in the interval between the two events. PATIENTS AND METHODS: The hospital electronic information system was used to identify all patients aged over 50 years treated for a distal radial fracture, in our fracture clinic, between 1995-2000. In addition all patients admitted to our hospital, during the same time period, with a femoral neck fracture were identified. RESULTS: A study cohort of 74 patients were identified. The proportion of patients who received investigation of, or treatment for, osteoporosis between their wrist and femoral neck fracture was 8% whereas 84% did not. CONCLUSIONS: Current mechanisms for identifying patients with osteoporosis before they sustain a femoral neck fracture are inadequate.

Age Distribution↗
PubMed2001

Topographic restriction of TAG-1 expression in the developing retinotectal pathway and target dependent reexpression during axon regeneration.

TAG-1, a glycosylphosphatidyl inositol (GPI)-anchored protein of the immunoglobulin (Ig) superfamily, exhibits an unusual spatiotemporal expression pattern in the fish visual pathway. Using in situ hybridization and new antibodies (Abs) against fish TAG-1 we show that TAG-1 mRNA and anti-TAG-1 staining is restricted to nasal retinal ganglion cells (RGCs) in 24- to 72-h-old zebrafish embryos and in the adult, continuously growing goldfish retina. Anti-TAG-1 Abs selectively label nasal RGC axons in the nerve, optic tract, and tectum. Axotomized RGCs reexpress TAG-1, which occurs as late as 12 days after optic nerve lesion, when regenerating RGC axons arrive in the tectum, suggesting TAG-1 reexpression is target contact-dependent. Accordingly, TAG-1 reexpression ceases upon interruption of the regenerating projection by a second lesion. The topographic restriction of TAG-1 expression and its target dependency during regeneration suggests that TAG-1 might play a role in the retinotopic organization and restoration of the retinotectal pathway.

Animals↗
PubMed2001

Glycosylphosphatidyl inositol-anchored proteins and fyn kinase assemble in noncaveolar plasma membrane microdomains defined by reggie-1 and -2.

Using confocal laser scanning and double immunogold electron microscopy, we demonstrate that reggie-1 and -2 are colocalized in < or =0.1-microm plasma membrane microdomains of neurons and astrocytes. In astrocytes, reggie-1 and -2 do not occur in caveolae but clearly outside these structures. Microscopy and coimmunoprecipitation show that reggie-1 and -2 are associated with fyn kinase and with the glycosylphosphatidyl inositol-anchored proteins Thy-1 and F3 that, when activated by antibody cross-linking, selectively copatch with reggie. Jurkat cells, after cross-linking of Thy-1 or GM1 (with the use of cholera toxin), exhibit substantial colocalization of reggie-1 and -2 with Thy-1, GM1, the T-cell receptor complex and fyn. This, and the accumulation of reggie proteins in detergent-resistant membrane fractions containing F3, Thy-1, and fyn imparts to reggie-1 and -2 properties of raft-associated proteins. It also suggests that reggie-1 and -2 participate in the formation of signal transduction centers. In addition, we find reggie-1 and -2 in endolysosomes. In Jurkat cells, reggie-1 and -2 together with fyn and Thy-1 increase in endolysosomes concurrent with a decrease at the plasma membrane. Thus, reggie-1 and -2 define raft-related microdomain signaling centers in neurons and T cells, and the protein complex involved in signaling becomes subject to degradation.

Animals↗
PubMed2000

Survey of the extent and nature of care for adults and older adults by allergy/immunology practitioners.

BACKGROUND: The proportion of older adults in the US population will increase dramatically in the near future, yet the frequency and nature of care furnished to older adults by Allergy/Immunology practitioners has not been described. OBJECTIVE: To determine the extent and nature of care being provided to adults and older adults by Allergy/Immunology practitioners. METHODS: ACAAI members and fellows were surveyed to obtain information regarding certification and training as well as their practice patterns. RESULTS: The distribution of diagnoses among patients aged 40 to 54 years were very similar to distributions found among adults age 55 to 69 years and > or = 70 years of age. Virtually all respondents indicated they provide inhalant allergen immunotherapy for patients age 40 to 54 years with asthma and/or allergic rhinitis; administration of inhalant allergen immunotherapy for asthma and allergic rhinitis was also frequently reported for adults > or = 55 years. The proportions of respondents providing venom immunotherapy for adults aged 40 to 54, 55 to 69, and > or = 70 years were 82%, 70%, and 39%, respectively. CONCLUSION: ACAAI members and fellows commonly provide care to older adults. Our survey findings highlight the need to develop strategies for successful management of Allergy/Immunology conditions specifically pertaining to older adults, including studies to determine the therapeutic utility of inhalant allergen and venom immunotherapy in this age group.

Adult↗
PubMed2000

Net nearest neighbor analysis (NNNA) summarizes non-compensated dinucleotides within gene sequences.

MOTIVATION: Net Nearest Neighbor Analysis (NNNA) measures a previously unexamined aspect of dinucleotide frequency-the non-compensated, non-repetitive dinucleotides in a sequence. Non-compensated dinucleotides are those in excess of their corresponding reverse dinucleotides. RESULTS: NNNA regards dinucleotides as vector quantities, making it possible to summarize any sequence as a group of circuits and tags. The results of NNNA are found to be consistent with traditional analytic methods, yet reveal additional characteristics of the sequences. The NNNA circuits and tags uniquely identify each tRNA in Escherichia coli K-12 and certain structural components of each tRNA, extract function-specific characteristics for each of the sequences involved in the formation of insulin from preinsulin, and exhibit species-specific phylogenetic characterization (demonstrated with MONILINIA:). AVAILABILITY: Nearest neighbor analysis software has been available for many years and is a component of most gene analysis software packages, including the Staden Package which is available at no charge to academic users (http://www.mrc-1mb.cam.ac. uk/pubseq/).

Dinucleotide Repeats↗
PubMed2000

Osteoid osteoma of the lunate--a case report.

We report a rare case of an osteoid osteoma of the lunate bone in a young lady who presented to us with chronic wrist pain. She was treated by excision and cancellous bone grafting of the lesion with complete resolution of symptoms.

Adult↗
PubMed1998

Modulation of secreted beta-amyloid precursor protein and amyloid beta-peptide in brain by cholesterol.

The effects of dietary cholesterol on brain amyloid precursor protein (APP) processing were examined using an APP gene-targeted mouse, genetically humanized in the amyloid beta-peptide (Abeta) domain and expressing the Swedish familial Alzheimer's disease mutations. These mice express endogenous levels of APP holoprotein and abundant human Abeta. Increased dietary cholesterol led to significant reductions in brain levels of secreted APP derivatives, including sAPPalpha, sAPPbeta, Abeta1-40, and Abeta1-42, while having little to no effect on cell-associated species, including full-length APP and the COOH-terminal APP processing derivatives. The changes in levels of sAPP and Abeta in brain all were negatively correlated with serum cholesterol levels and levels of serum and brain apoE. These results demonstrate that secreted APP processing derivatives and Abeta can be modulated in the brain of an animal by diet and provide evidence that cholesterol plays a role in the modulation of APP processing in vivo. APP gene-targeted mice lacking apoE, also have high serum cholesterol levels but do not show alterations in APP processing, suggesting that effects of cholesterol on APP processing require the presence of apoE.

Alzheimer Disease↗
PubMed1998

Identification of reggie-1 and reggie-2 as plasmamembrane-associated proteins which cocluster with activated GPI-anchored cell adhesion molecules in non-caveolar micropatches in neurons.

Neurons are believed to possess plasmalemmal microdomains and proteins analogous to the caveolae and caveolin of nonneuronal cells. Caveolae are plasmalemmal invaginations where activated glycosyl-phosphatidylinositol (GPI)-anchored proteins preferentially assemble and where transmembrane signaling may occur. Molecular cloning of rat reggie-1 and -2 (80% identical to goldfish reggie proteins) shows that reggie-2 is practically identical to mouse flotillin-1. Flotillin-1 and epidermal surface antigen (ESA) (flotillin-2) are suggested to represent possible membrane proteins in caveolae. Rat reggie-1 is 99% homologous to ESA in overlapping sequences but has a 49-amino-acid N-terminus not present in ESA. Antibodies (ABs) which recognize reggie-1 or -2 reveal that both proteins cluster at the plasmamembrane and occur in micropatches in neurons [dorsal root ganglia (DRGs), retinal ganglion, and PC-12 cells] and in nonneuronal cells. In neurons, reggie micropatches occur along the axon and in lamellipodia and filopodia of growth cones, but they do not occur in caveolae. By quantitative electronmicroscopic analysis we demonstrate the absence of caveolae in (anti-caveolin negative) neurons and show anti-reggie-1 immunogold-labeled clusters at the plasmamembrane of DRGs. When ABs against the GPI-anchored cell adhesion molecules (CAMs) F3 and Thy-1 are applied to live DRGs, the GPI-linked CAMs sequester into micropatches. Double immunofluorescence shows a colocalization of the CAMs with micropatches of anti-reggie antibodies. Thus, reggie-1 and reggie-2 identify sites where activated GPI-linked CAMs preferentially accumulate and which may represent noncaveolar micropatches (domains).

Amino Acid Sequence↗
PubMed1998

Retinal axon regeneration in the lizard Gallotia galloti in the presence of CNS myelin and oligodendrocytes.

Retinal ganglion cell (RGC) axons in lizards (reptiles) were found to regenerate after optic nerve injury. To determine whether regeneration occurs because the visual pathway has growth-supporting glia cells or whether RGC axons regrow despite the presence of neurite growth-inhibitory components, the substrate properties of lizard optic nerve myelin and of oligodendrocytes were analyzed in vitro, using rat dorsal root ganglion (DRG) neurons. In addition, the response of lizard RGC axons upon contact with rat and reptilian oligodendrocytes or with myelin proteins from the mammalian central nervous system (CNS) was monitored. Lizard optic nerve myelin inhibited extension of rat DRG neurites, and lizard oligodendrocytes elicited DRG growth cone collapse. Both effects were partially reversed by antibody IN-1 against mammalian 35/250 kD neurite growth inhibitors, and IN-1 stained myelinated fiber tracts in the lizard CNS. However, lizard RGC growth cones grew freely across oligodendrocytes from the rat and the reptilian CNS. Mammalian CNS myelin proteins reconstituted into liposomes and added to elongating lizard RGC axons caused at most a transient collapse reaction. Growth cones always recovered within an hour and regrew. Thus, lizard CNS myelin and oligodendrocytes possess nonpermissive substrate properties for DRG neurons--like corresponding structures and cells in the mammalian CNS, including mammalian-like neurite growth inhibitors. Lizard RGC axons, however, appear to be far less sensitive to these inhibitory substrate components and therefore may be able to regenerate through the visual pathway despite the presence of myelin and oligodendrocytes that block growth of DRG neurites.

Animals↗
PubMed1998

Exercise-induced bronchospasm in high school athletes via a free running test: incidence and epidemiology.

BACKGROUND: Exercise-induced bronchospasm (EIB) affects up to 35% of athletes and up to 90% of asthmatics. Asthma morbidity and mortality have increased over the past several decades among residents of Philadelphia, PA. It is possible that a simple free running test for EIB may serve as a tool to study the factors contributing to recent trends in asthma, and to screen for asthma in athletes in the urban setting. OBJECTIVES: The purposes of this study were to (1) assess a free running test to screen for EIB, and (2) examine prevalence of and epidemiologic factors associated with EIB in high school athletes. DESIGN: Cross-sectional observational study on the incidence and risk factors for EIB. To validate our method and criteria for the diagnosis of EIB, a repeat test was performed on a portion of the athletes. In a randomized single-blinded fashion, 15 athletes who had demonstrated EIB initially received albuterol or placebo prior to a repeat exercise test. SETTING: Community high school athletic facilities. PARTICIPANTS: We studied 238 male high school varsity football players. INTERVENTION: All athletes underwent an acquaintance session with a questionnaire, followed by a 1-mile outdoor run (6 to 8 mins). MEASUREMENTS: Peak expiratory flow (PEF) measurements were determined prior to and 5, 15, and 30 min after exercise. Heart rates (HRs) and dyspnea scores were measured. EIB was defined as a decrease of 15% in PEF at any time point after exercise. Associations of EIB with demographic factors were assessed by univariate and multivariate analyses. RESULTS: Two hundred thirty-eight athletes participated: 92 European-Americans (EA), 140 African-Americans (AA), 5 Hispanics, and 1 Native American. Mean age was 16+/-1 years. Average HR postexercise was 156+/-24 beats/min. Twenty-four (10%) reported a history of treated asthma. The prevalence of EIB among the remaining 214 athletes was 19 of 214 (9%). The rate of EIB among AA athletes was higher than among EA athletes: (17/126 [13%] AA vs 2/82 [2%] EA, p = 0.01). During the validation portion of the study, the placebo-treated group (n = 7) demonstrated a consistent drop in PEF after exercise on repeat testing, with a 16+/-5% fall in PEF on initial testing and a 14+/-13 drop with placebo. In contrast, the fall in airflow in the albuterol-treated athletes (n = 8) following exercise reversed with albuterol treatment, from a 15+/-6% fall in PEF at initial testing to an increase in PEF of 6+/-9% from baseline following albuterol administration. A history of wheezing (p < 0.001), residence in a poverty area (p < 0.0001), race (p = 0.01), remote history of asthma (p < 0.001), and absolute water content of the air on the day tested (p = 0.04) were significantly associated with EIB. By stepwise regression, EIB was most closely associated with a history of wheezing (p = 0.001) and poverty area residence (p = 0.003). CONCLUSIONS: Our findings indicate a substantial rate of unrecognized EIB exists among urban varsity athletes, and suggest that active screening for EIB, especially for students residing in poverty areas, may be indicated to identify individuals at risk for EIB and asthma.

Albuterol↗
PubMed1997

Guidelines and realities of asthma management. The Philadelphia story.

BACKGROUND: Guidelines from the National Heart, Lung, and Blood Institute, Bethesda, Md, have encouraged more frequent use of inhaled steroids in asthma management. OBJECTIVES: To determine (1) whether prescription rates for inhaled steroids have increased compared with prescriptions for bronchodilators and (2) significant associations of demographic factors with bronchodilator-inhaled steroid prescription ratios and with rates of inhaled steroid prescriptions. DESIGN: Cross-sectional analysis of monthly bronchodilator and inhaled steroid prescription rates, numbers and types of asthma care providers, and demographic factors. SETTING: Philadelphia, Pa. MEASUREMENTS: Using univariate and multivariate analyses, bronchodilator and inhaled steroid prescription rates were determined for 45 ZIP codes and studied for associations with race and ethnicity, poverty, educational attainment, marital status, gender, total numbers of asthma drug prescriptions, and numbers and types of asthma care providers. RESULTS: Monthly bronchodilator-inhaled steroid prescription ratios increased from July 1991 to June 1993 (P < .001). Prescription rates for inhaled steroids and inhaled bronchodilators declined, but rates for oral bronchodilators (beta-agonists and theophylline) increased. By stepwise multiple regression, higher bronchodilator-inhaled steroid prescription ratios and lower inhaled steroid prescription rates were each significantly associated with ZIP codes in which greater proportions of residents lacked a high school diploma (P < .001); associations that approached statistical significance were found for higher bronchodilator-inhaled steroid ratios and fewer asthma care providers (P = .05) and for lower inhaled steroid prescription rates and lower proportions of asthma specialists (P = .04). CONCLUSIONS: In Philadelphia, a gap exists between optimal asthma drug prescribing and actual prescribing patterns that has widened from July 1991 to June 1993. Underuse of inhaled steroids is most closely associated with lower educational attainment, suggesting that interventions that include addressing the special asthma care needs of a low-literacy population will be required to achieve the goals of the National Asthma Education Program.

Administration, Inhalation↗
PubMed1996

Enhanced amyloidogenic processing of the beta-amyloid precursor protein in gene-targeted mice bearing the Swedish familial Alzheimer's disease mutations and a "humanized" Abeta sequence.

The processing of the beta-amyloid precursor protein (APP) in vivo has been characterized in a novel animal model that recapitulates, in part, the APP genotype of a familial form of Alzheimer's disease (AD). A gene-targeting strategy was used to introduce the Swedish familial AD mutations and convert mouse Abeta to the human sequence. The mutant APP is expressed at normal levels in brain, and cleavage at the mutant beta-secretase site is both accurate and enhanced. Furthermore, human Abeta production is significantly increased to levels 9-fold greater than those in normal human brain while nonamyloidogenic processing is depressed. The results on Abeta production extend similar findings obtained in cell culture to the brain of an animal and substantiate Abeta as a etiological factor in Swedish familial AD. These animals provide several distinguishing features over others created by conventional transgenic methodologies. The spatial and temporal expression patterns of human Abeta are expected to be faithfully reproduced because the gene encoding the mutant APP remains in its normal chromosomal context. Thus, the neuropathological consequences of human Abeta overproduction can be evaluated longitudinally in the absence of potential mitigating effects of APP overexpression or presence of the mouse Abeta peptide.

Alzheimer Disease↗
PubMed1996

Modulation of the inhibitory substrate properties of oligodendrocytes by platelet-derived growth factor.

Although growth cones typically collapse after encountering O1/galactocerebroside (GalC)-positive oligodendrocytes, the majority of growth cones traversed oligodendrocytes, which were raised for 8-10 d in medium containing 10 ng/ml platelet-derived growth factor (PDGF). Oligodendrocytes raised 8-10 d in control medium caused growth cone collapse as they normally do, but failed to elicit this response after being transferred to PDGF-containing medium for an additional 8-10 d. The opposite was observed when PDGF-treated oligodendrocytes were brought to control medium. Growth cones collapsed when contacting these cells. Oligodendrocytes also lost their collapse-inducing activity when raised in medium conditioned by astrocytes, known to produce PDGF. Antibody IN-1 is directed against against neurite growth inhibitors (NI), proteins of 35 and 250 kDa on the surface of O1/GalC-positive oligodendrocytes, which are known to elicit growth cone collapse. IN-1 immunoreactivity was markedly reduced in PDGF-treated oligodendrocytes. However, both PDGF-treated and control oligodendrocytes exhibited myelin-associated glycoprotein, proteolipid protein, and myelin basic protein immunoreactivity. This suggests that PDGF-treatment affects NI expression but does not interfere with the expression of advanced myelin marker proteins. Because NI cause growth cone collapse, the loss of collapse-inducing activity by PDGF-treated oligodendrocytes suggests that PDGF regulates, directly or indirectly, the expression of these proteins.

Animals↗
PubMed1996

Biologically active monomeric and heterodimeric recombinant human calpain I produced using the baculovirus expression system.

Calpain I is a heterodimeric protein that is part of a family of calcium-activated intracellular cysteine proteases presumed to play a role in mediating signals transduced by calcium. Expression of bioactive recombinant human calpain I has been achieved using the baculovirus expression system, by either co-infection with two viruses, each expressing one of the subunits, or infection with a single virus containing both subunits. The approximately 80 kDa catalytic subunit exhibited calcium-dependent proteolytic activity when expressed alone or with the approximately 30 kDa regulatory subunit. Baculoviral recombinant calpain I appeared fully active in that the catalytic subunit in unpurified cell extracts exhibited calcium-dependent autocatalytic cleavage at the correct locus. The amount of approximately 80 kDa subunit accumulated at steady state was greatly increased by co-expression of the approximately 30 kDa subunit, suggesting a possible role for enzyme stabilization by the latter subunit. The recombinant human calpain I was purified to near homogeneity and compared with purified native human erythrocyte calpain I. The recombinant and native enzymes had equivalent inhibition constants for structurally diverse calpain inhibitors, identical calcium activation profiles, and similar specific activities, demonstrating the suitability of using the recombinant protein for studies of the native enzyme.

Amino Acid Sequence↗
PubMed1996

Adaptive plasticity of Xenopus glial cells in vitro and after CNS fiber tract lesions in vivo.

Xenopus oligodendrocytes and aspects of their differentiation were analyzed in vitro and in vivo using cell- and stage-specific antibodies. Undifferentiated oligodendrocytes were derived from optic nerves or spinal cords. They divided in vitro, were of elongated shape, were glial fibrillary acidic protein and O4 positive, transiently exhibited several antigens including HNK-1 and L1, and promoted axon growth as do Schwann cells. With forskolin they differentiated and, much like myelin-forming oligodendrocytes in the intact optic nerve and spinal cord, they expressed sets of advanced myelin markers. These advanced myelin markers disappeared from the regenerating optic nerve 4 weeks after lesion. The optic nerve instead was populated by cells with radial processes and somata in the center of the nerve; among them were cells and processes that were O4 positive and that are suspected to represent undifferentiated oligodendrocytes. Where processes of these cells reached to the retinal axons in the nerve's periphery, advanced myelin markers typical of differentiated oligodendrocytes reappeared 8 weeks after lesion. These glial changes did not occur in the absence of retinal axons. Thus, the apparent capability of Xenopus oligodendrocytes to adapt to the transient absence, reappearance, and regenerative state of the axons enables them to contribute to central nervous system fiber tract repair. This occurs in the lesioned optic nerve but not in the spinal cord, where no such glial changes were observed and where axons fail to regenerate.

Adaptation, Physiological↗