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Biomedical subjects

L Kline

Publications and source records attributed to L Kline.

At least 19 recordsLinked to original sources
PubMed2004

Differential gene expression in the T-helper lymphocytes of obstructive sleep apnea patients treated with nasal continuous positive airway pressure (nCPAP).

Obstructive sleep apnea (OSA) is a disease with significant morbidity, increased risk of accidents attributed to daytime somnolence, and has been associated with cardiovascular complications. The treatment of choice for OSA is nasal continuous positive airway pressure (nCPAP). Some OSA patients, however, are unable to benefit from this therapy as they find nCPAP intolerable due to the related nasal inflammation. It is hypothesized that nCPAP may cause nasal inflammation in these patients by inducing changes in the expression of genes that encode interleukins (IL-3, IL-4, IL-6, IL-8, IL-13) or adhesion molecules (i.e., ICAM-1) in T-helper lymphocytes. An understanding of the underlying inflammatory mechanism could lead to specific interventions that render nCPAP therapy tolerable for these individuals.

Clinical Trials as Topic↗
PubMed2001

Modulation of L-type Ca2+ channels in UMR 106 cells by parathyroid hormone-related protein.

The effects of rat parathyroid hormone-related protein (rPTHrP) and bovine and rat parathyroid hormone (bPTH and rPTH) on L-type Ca2+ channels in UMR 106 cells were investigated using the patch clamp technique. rPTHrP increased the whole cell L-type Ca2+ channel currents and the increase was concentration dependent. rPTHrP, at a concentration of 62.5 nM, increased the L-type Ca2+ channel current by 122+/-25%. bPTH was less potent. A concentration of 7.5 microM bPTH increased the current by 99+/-24%. Results obtained with rPTH were similar to those obtained using bPTH. Single channel measurements, using the cell-attached version of the patch clamp technique, showed an increase in both the number of channel openings and the mean open time when the cells were exposed to rPTHrP. This suggested that rPTHrP affected the gating of L-type Ca2+ channels in UMR 106 cells. This study demonstrates that the actions of bPTH and rPTHrP in UMR cells are mediated in part by extracellular Ca2+ entry. PTHrP, a paracrine agent important in development, is more potent in regulating Ca2+ entry than PTH.

Animals↗
PubMed2000

Coordinate activation of endogenous p38alpha, beta, gamma, and delta by inflammatory stimuli.

The p38 family of mitogen-activated protein kinases is believed to mediate a variety of leukocyte responses to pro-inflammatory stimuli. There are four members of the p38 family, and although activation of the different members has been studied in transiently transfected cells much less is known about activation of the endogenous p38s, particularly in myeloid lineage cells. To investigate activation of endogenous p38s, we have made monoclonal antibodies specific for each p38 and have used these antibodies to study p38 activation by pro-inflammatory stimuli in several human monocytic cell lines. Without stimulation endogenous p38alpha kinase activity was readily detectable, whereas that of p38beta, gamma, and delta was barely measurable. In response to inflammatory stimuli, we observed a time- and dose-dependent activation of all four p38s. The kinetics of activation of each of the p38s were similar for each stimulus used, suggesting a common upstream activation pathway. Simultaneous activation of the p38s suggests that all four may be important in inflammation.

Antibodies, Monoclonal↗
PubMed2000

Toll-like receptor 2-mediated NF-kappa B activation requires a Rac1-dependent pathway.

Mammalian Toll-like receptors (TLRs) are expressed on innate immune cells and respond to the membrane components of Gram-positive or Gram-negative bacteria. When activated, they convey signals to transcription factors that orchestrate the inflammatory response. However, the intracellular signaling events following TLR activation are largely unknown. Here we show that TLR2 stimulation by Staphylococcus aureus induces a fast and transient activation of the Rho GTPases Rac1 and Cdc42 in the human monocytic cell line THP-1 and in 293 cells expressing TLR2. Dominant-negative Rac1N17, but not dominant-negative Cdc42N17, block nuclear factor-kappa B (NF-kappa B) transactivation. S. aureus stimulation causes the recruitment of active Rac1 and phosphatidylinositol-3 kinase (PI3K) to the TLR2 cytosolic domain. Tyrosine phosphorylation of TLR2 is required for assembly of a multiprotein complex that is necessary for subsequent NF-kappa B transcriptional activity. A signaling cascade composed of Rac1, PI3K and Akt targets nuclear p65 transactivation independently of I kappa B alpha degradation. Thus Rac1 controls a second, I kappa B-independent, pathway to NF-kappa B activation and is essential in innate immune cell signaling via TLR2.

Cell Line↗
PubMed1998

Acoustic startle, prepulse inhibition, locomotion, and latent inhibition in the neuroleptic-responsive (NR) and neuroleptic-nonresponsive (NNR) lines of mice.

The acoustic startle reflex (ASR) is inhibited by low intensity acoustic stimuli (prepulse inhibition; PPI) delivered prior to the startle stimulus. PPI may reflect underlying sensorimotor processes involved in the filtering of exteroceptive stimuli for their cognitive or physiological relevance. Latent inhibition (LI) is a cognitive process in which pre-exposure to the conditioned stimulus (CS) produces pro-active interference with the acquisition of an associative learning task. LI is thought to reflect a selective attention mechanism that contributes to an organism's ability to adjust its behavior to changing contingencies of reinforcement. In the present series of experiments, the ASR, PPI at three prepulse intensities (56, 68, and 80 dB), locomotor activity, and LI using an active avoidance paradigm were assessed in mice bidirectionally selected from a heterogeneous stock for response (NR line) or nonresponse (NNR line) to neuroleptic-induced catalepsy. A randomly selected line was used as the control. Mice from the NNR line displayed weak startle responses and a complete absence of PPI. In contrast, the NR line displayed the largest ASR and the greatest PPI. The control line displayed ASRs and PPI values intermediate to the selected lines. Locomotor activity which is known to affect LI was lowest in the NR line but was similar in the NNR and control lines. In the LI paradigm, acquisition of the avoidance response was impaired in mice from the NR and control lines that were pre-exposed to the auditory CS (normal response). In contrast, the acquisition of the avoidance response in the NNR line was similar in CS pre-exposed and CS non-pre-exposed animals. Overall, the results demonstrate that some of the same genetic factors which regulate neuroleptic response also play a significant role in PPI and LI.

Acoustic Stimulation↗
PubMed1998

Cell activation mediated by glycosylphosphatidylinositol-anchored or transmembrane forms of CD14.

CD14 is a glycosylphosphatidylinositol (GPI)-anchored membrane glycoprotein which functions as a receptor on myeloid cells for ligands derived from microbial pathogens such as lipopolysaccharide (LPS). We have studied the importance of the GPI tail of CD14 in signalling with the promonocytic cell line THP-1 expressing recombinant CD14 in a GPI-anchored form (THP1-wtCD14 cells) or in a transmembrane form (THP1-tmCD14). We found that, like other GPI-anchored molecules, GPI-anchored CD14 was recovered mainly from a Triton X-100-insoluble fraction, whereas transmembrane CD14 was fully soluble in Triton X-100. LPS induced cell activation of THP1-wtCD14 and of THP1-tmCD14 (protein tyrosine kinase phosphorylation, NF-kappaB activation, and cytokine production) in a very similar manner. However, anti-CD14 antibody-induced cross-linking caused a rapid calcium mobilization signal only in GPI-anchored CD14 cells. Studies with pharmacologic inhibitors of intracellular signalling events implicate phospholipase C and protein tyrosine kinases in the genesis of this antibody-induced calcium signal. Our results suggest that GPI anchoring and CD14 targeting to glycolipid-rich membrane microdomains are not required for LPS-mediated myeloid cell activation. GPI anchoring may however be important for other signalling functions, such as those events reflected by antibody cross-linking.

Cell Line↗
PubMed1997

Phagocytosis of gram-negative bacteria by a unique CD14-dependent mechanism.

THP-1-derived cell lines were stably transfected with constructs encoding glycophosphatidylinositol (GPI)-anchored or transmembrane forms of human CD14. CD14 expression was associated with enhanced phagocytosis of serum (heat-inactivated)-opsonized Escherichia coli (opEc). Both the GPI-anchored and transmembrane forms of CD14 supported phagocytosis of opEc equally well. Lipopolysaccharide-binding protein (LBP) played a role in CD14-dependent phagocytosis as evidenced by inhibition of CD14-dependent phagocytosis of opEc with anti-LBP monoclonal antibody (mAb) and by enhanced phagocytosis of E. coli opsonized with purified LBP. CD14-dependent phagocytosis was inhibited by a phosphatidylinositol (PI) 3-kinase inhibitor (wortmannin) and a protein tyrosine kinase inhibitor (tyrphostin 23) but not a protein kinase C inhibitor (bisindolyl-maleimide) or a divalent cation chelator (ethylenediaminetetraacetate). Anti-LBP mAb 18G4 and anti-CD14 mAb 18E12 were used to differentiate between the pathways involved in CD14-dependent phagocytosis and CD14-dependent cell activation. F(ab')2 fragments of 18G4, a mAb to LBP that does not block cell activation, inhibited ingestion of opEc by THP1-wtCD14 cells. 18E12 (an anti-CD14 mAb that does not block LPS binding to CD14 but does inhibit CD14-dependent cell activation) did not inhibit phagocytosis of LBP-opEc by THP1-wtCD14 cells. Furthermore, CD14-dependent phagocytosis was not inhibited by anti-CD18 (CR3 and CR4 beta-chain) or anti-Fcgamma receptor mAb.

Cell Line↗
PubMed1997

Activation of phospholipase D in FRTL-5 thyroid cells by forskolin and dibutyryl-cyclic adenosine monophosphate.

We demonstrated previously that TSH activates phospholipase D (PLD) via stimulation of protein kinase C (PKC) in Fischer rat thyroid line (FRTL)-5 thyroid cells. To examine the role of the cAMP pathway in the regulation of PLD, we studied the effects of forskolin (0-100 microM; 30 min) and dibutyryl cAMP (dbcAMP; 0-1 mM; 30 min) on PLD activation. FRTL-5 thyroid cells were labeled mainly in phosphatidylcholine with [3H]myristate followed by incubation with 200 mM ethanol before the addition of agonist. PLD was assessed by the measurement of [3H]phosphatidylethanol. Forskolin (100 nM to 100 microM) and dbcAMP (100 pM to 100 microM) increased PLD activity significantly. Maximal responses to forskolin and dbcAMP exceed the PLD responses produced by 100 microU/ml of TSH. To determine whether the effects of forskolin and dbcAMP on PLD occurred as a consequence of PKC activation, FRTL-5 thyroid cells were preincubated for 10 min with the PKC inhibitors, chelerythrine (1 microM) or calphostin C (1 microM), or they were pretreated for 24 h with phorbol myristate acetate (100 nM) to down-regulate PKC. Unlike TSH-mediated PLD activation, these treatments had no effect on PLD activation by cAMP agonists. Forskolin (10 microM; 30 min) had no effect on the subcellular distribution of PKC alpha-, epsilon-, or zeta-isoforms, confirming the lack of involvement of PKC. The protein kinase A (PKA) inhibitors, H-89 (10 microM; 30 min) and dideoxyadenosine (5 nM; 10 min) significantly decreased the forskolin- and dbcAMP-mediated PLD activation without any effect on the phorbol ester-mediated PLD response. Following pretreatment with H-89 or dideoxyadenosine, the TSH-mediated PLD response was also significantly reduced. These studies indicate that forskolin and dbcAMP stimulate PLD in FRTL-5 thyroid cells directly via PKA without involvement of PKC. Studies of cells in the presence and absence of ethanol revealed approximately 60% of the phosphatidate plus diacylglycerol produced via TSH occurs via PLD activation. Although TSH-mediated inositol phosphate generation occurred with similar concentrations of TSH that led to PLD activation, 10-fold higher TSH concentrations were required to increase intracellular Ca2+. These results and the lack of a rapid Ca2+ transient following physiological TSH concentrations suggest that alternatives to conventional hydrolysis of phosphatidylinositol 4,5-bisphosphate may initiate PKC activation. Thus, the two major signal transduction systems in the FRTL-5 thyroid cell (PKA and PKC) appear to converge on PLD activation. Stimulation of both of these pathways by TSH may be required for optimal physiological activation of PLD.

Alkaloids↗
PubMed1996

Development and evaluation of a shipping system for platelet components.

BACKGROUND: Platelet concentrates and apheresis platelets must be maintained at a temperature as close as possible to 20 to 24 degrees C during transport. To improve temperature control, ensure component quality, and meet handling and freight carrier needs, a new insulated shipping container system was developed and evaluated. STUDY DESIGN AND METHODS: Molded polyurethane-insulated shipping containers were loaded with different payloads of simulated platelet components, with or without gel-based temperature stabilizing packs (TSPs). The containers were subjected to constant ambient temperature of 37, 4 or -10 degrees C. Payload temperatures were continuously monitored, in situ, for 24 hours. RESULTS: Temperature data are reported as the mean number of hours needed for components to warm or cool by 1 degree C. The temperature of payloads exposed to a constant 37 degrees C ambient temperature increased by 1 degree C in 2.5 to 3.8 hours when no TSPs were included in the shipment and in 6.1 to 6.9 hours when TSPs were used. Exposure to a constant 4 degrees C ambient temperature resulted in a 1 degree C temperature decrease in 1.8 to 3.4 hours without TSPs and in 4.6 to 5.6 hours with TSPs. At a -10 degrees C ambient temperature, there was a 1 degree C drop within 1.0 to 1.6 hours without TSPs and within 2.7 to 2.9 hours with TSPs. CONCLUSION: The container and packing methods described moderate the rate of change in the temperature of platelet components during their exposure to challenging ambient conditions. The use of TSPs substantially improves the performance of the system. In addition, the system meets freight carrier requirements and is easy to use, environmentally friendly, and durable.

Blood Preservation↗
PubMed1996

Assessment of blood donor privacy during health history interviews.

BACKGROUND: Given the personal nature of health history interviews, it is important to provide donors with both visual and auditory privacy. Privacy is affected by variables such as background noise, the use of visual screens, and the loudness of the donor's voice. STUDY DESIGN AND METHODS: In Phase I of this study, an interview station and waiting area were simulated. To measure auditory privacy, a speech intelligibility test was given to subjects with and without the use of a free-standing privacy screen and masking noise device. Phase II was a field trial designed to evaluate screens and masking noise. Background noise was measured during each blood collection operation, and donors completed a survey. RESULTS: In Phase I, speech intelligibility test scores ranged from 78 to 5.1 percent, depending on the type of visual screen and the number of masking noise devices used. In Phase II, with the use of screens, 94 percent of donors rated visual privacy as "good to excellent," compared with 74 percent who did so when no screens were used. At many blood drives, the background noise level exceeded the level of the masking noise. CONCLUSION: The use of visual screens increases donors' perception of visual privacy. The use of masking noise is effective only when the health history interview is conducted under conditions of low background noise levels.

Blood Donors↗
PubMed1996

Endotoxin tolerance is induced in Chinese hamster ovary cell lines expressing human CD14.

Changes in patterns of gene induction by myeloid lineage cells following multiple exposures to endotoxin (lipopolysaccharide; LPS) is a feature of LPS tolerance. To further understand the mechanism of this phenomenon we describe studies using stably transfected Chinese hamster ovary cell lines that express human CD14 (CHO-hCD14). Using NF-kappa B activation as a measure of LPS-induced cell activation we show that a single treatment with LPS renders CHO-hCD14 cells tolerant to subsequent challenge with LPS, but not with other stimuli such as tumor necrosis factor. Tolerance may result from the induction of gene(s) that control LPS-induced signaling pathways and here we suggest that such genes may be found in the group of immediate, early response genes characterized by the protein phosphatase 3CH134. The CHO-hCD14 cell lines provide a novel model system to further explore the mechanism of endotoxin tolerance.

Animals↗
PubMed1994

Effects of new brochures on blood donor recruitment and retention.

BACKGROUND: Currently, donors may arrive at blood collection sites without prior knowledge of eligibility and deferral criteria. STUDY DESIGN AND METHODS: The effects of distributing newly developed recruitment brochures 2 weeks in advance of blood drives and the provision of brochures on temporary deferral at the taking of health history were examined in four southeastern regional blood collection centers. Twenty-four similar pairs of worksites, with employee-only recruitment, were randomly assigned to a control (C) or experimental (E) group. Information about sponsor recruitment strategies, worksite factors, and first-time, repeat, and temporarily deferred donors was obtained at three collection drives per site over a 1-year period. Drive 1 was used as a baseline. Two weeks before Drives 2 and 3, the recruitment brochures were distributed to all Group E employees, with temporary deferral brochures provided as needed when the health history was taken. RESULTS: No significant differences between groups or drives were found in the total percentage of employees recruited or returning as a result of recruitment or deferral brochure distribution (Wilcoxon's signed rank test and t test). Substantiating previous observations by donor recruiters, the study results showed decreased donations during vacation periods and busier times at the workplace. Loudspeaker announcements led to decreased donations; increased donations followed special appeals in relation to a specific patient, an accident, or a natural disaster. CONCLUSION: The brochures may have encouraged previous donors to return, but their use did not significantly increase the recruitment of new donors or the return of temporarily deferred donors.

Blood Donors↗
PubMed1993

Cross-linking of lipopolysaccharide (LPS) to CD14 on THP-1 cells mediated by LPS-binding protein.

Recent work has established that bacterial endotoxin (LPS) binds to the plasma protein LPS-binding protein (LBP) forming high affinity complexes (LPS-LBP), that LBP is an opsonin for LPS-bearing particles, and that LPS-LBP complexes are potent agonists for monocytic cells (MO). mAb to the MO plasma membrane protein, CD14, inhibit LBP-dependent binding of LPS to MO, and LPS-LBP-dependent stimulation of cytokine release from MO. These data suggest that CD14 functions as a membrane receptor for LPS but do not demonstrate a direct association of LPS with CD14. Calcitriol was used to induce a high level of CD14 expression in the human monocyte-like cell line THP-1, resulting in enhanced responses of these cells to LPS-LBP complexes manifested by enhanced binding of LPS and a decrease in the amount of LPS needed to induce IL-8 release. An Re595 LPS derivative containing a radioiodinated, photoreactive, phenyl azide (125I-ASD-LPS) was used in cross-linking experiments to identify membrane proteins in calcitriol-treated THP-1 cells that interact with LPS. 125I-ASD-LPS was added to calcitriol-induced THP-1 cells in the presence or absence of LBP, the mixture photolyzed, and the resultant radioiodinated proteins analyzed by SDS-PAGE and autoradiography. We observed strong cross-linking of 125I-ASD-LPS to a 55-kDa membrane protein when LBP was present, but failed to observe radiolabeling of any other proteins with apparent molecular masses distinct from CD14. The cross-linked product was identified as CD14 by immunoprecipitation with anti-human CD14 mAb. Studies with human CD14 expressing transfectants of the murine B cell line 70Z/3 also revealed LBP-dependent cross-linking of 125I-ASD-LPS to CD14. These data document binding of LPS to a specific membrane protein that serves as an LPS receptor.

Acute-Phase Proteins↗
PubMed1991

Hyperexpression of interferon-gamma-induced MHC class II genes associated with reorganization of the cytoskeleton.

Class I and class II major histocompatibility complex (MHC) gene products are key recognition units in the induction and regulation of the immune response. Expression of class I and class II may be constitutive or inducible by cytokines such as interferon-gamma (IFN-gamma). A key step in the induction of MHC genes is recognition of IFN-gamma by its membrane receptor. The work described here examines the regulation of the occupied IFN-gamma receptor by the cytoskeleton. To do this the authors have used the fungal metabolites dihydrocytochalasin B (DHCB) and cytochalasin D (CD), substances that bind to actin filaments and thereby disrupt the cytoskeleton. The authors have studied the effect of DHCB and CD on IFN-gamma-induced MHC gene expression in 143 B cells, a human osteosarcoma-derived cell line. Herein the authors demonstrate that alterations in the cytoskeleton induced by DHCB and CD can lead to increases in IFN-gamma-induced MHC gene expression. Dihydrocytochalasin B added up to 3 hours after IFN-gamma results in a threefold to sixfold increase in levels of class II mRNA while producing minimal enhancement of class I gene expression. In contrast, glyceraldehyde-3-phosphate dehydrogenase mRNA expression was unaltered by IFN-gamma or by the cytochalasins. The increased amount of class II mRNA can be accounted for by a concomitant increase in transcription rate of this gene. Studies using 125I-IFN-gamma demonstrate that the occupied IFN-gamma receptor associates with a Triton X-100 insoluble fraction of 143 B cells and that DHCB and CD markedly inhibit this association. The results described here provide evidence that is consistent with the hypothesis that the activity of the occupied IFN-gamma receptor may be modulated by interactions with the cytoskeleton of the cell. This receptor may be one of a group of plasma membrane receptors that are sensitive to the action of cytochalasins after ligand binding.

B-Lymphocytes↗
PubMed1990

MR of uncommon congenital and vascular lesions of the intracranial visual pathways.

The MR findings of two patients with rare congenital abnormalities of the optic pathways are reported and illustrated, including one case of unilateral aplasia of the optic chiasm, tract, and visual radiations and another patient with anophthalmos. In three other patients with unusual vascular causes of visual disturbance, MR was important in early establishment of an accurate diagnosis and had consequent implications for decisions regarding further patient management.

Adult↗
PubMed1989

Evaluation of technical and behavioral issues in predonation alanine aminotransferase testing.

To evaluate the technical and behavioral impact of predonation alanine aminotransferase (ALT) testing, one group of 2914 donors (Reflotron group) were tested with the Boehringer Mannheim Reflotron instrument; 3042 control group donors had no predonation test. Mobile blood collection sites in three regional blood centers were studied. More Reflotron group donors than control group donors thought that predonation testing did not add time and was a good idea. Both groups were equally satisfied with the donation process and indicated they would donate again even if testing added time. Comparison of the Reflotron and standard laboratory tests showed excellent correlation with low variability. The mean r value was 0.934, with a mean sensitivity of 94.4 percent and a specificity of 99.8 percent. The staff working with the Reflotron group found predonation testing easy to incorporate into donor screening. They observed that donors were pleased with testing and accepting of deferral counseling for elevated ALT. The control group staff was concerned that predonation testing would require more time and would have a negative effect on the donor return rate. This did not appear to be the case as judged by donor response and the 6-month return rates of 50 percent for Reflotron group and 54 percent for control group donors.

Alanine Transaminase↗
PubMed1988

Calcitonin gene-related peptide relaxed rat tail artery helical strips in vitro in an intracellular calcium-dependent manner.

The vasoactive properties of calcitonin gene-related peptide (CGRP) were examined using the helical strip of the rat tail artery as a model. CGRP was found to inhibit norepinephrine-induced contraction but not KCl- or vasopressin-induced contraction. No significant inhibition occurred in either KCl- or norepinephrine-stimulated strips when Ca2+ was added incrementally to otherwise Ca2+-free bathing solution. However, a dose-related inhibition to norepinephrine-stimulated contraction in Ca2+-free bathing solution was observed. This strongly suggests that CGRP exerts its effect by inhibiting the mobilization of intracellular Ca2+.

Animals↗