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Biomedical subjects

E Ling

Publications and source records attributed to E Ling.

At least 19 recordsLinked to original sources
PubMed2006

Pneumococcal 6-phosphogluconate-dehydrogenase, a putative adhesin, induces protective immune response in mice.

For most bacteria, adherence to human cells is achieved by bacterial lectins binding to mammalian surface glyconjugates. 6-Phosphogluconate dehydrogenase (6PGD) was identified by us as one of Streptococcus pneumoniae cell wall lectin proteins, which elicits an age-dependent immune response in humans. This study assesses the role of 6PGD in S. pneumoniae pathogenesis as an adhesin and its ability to elicit a protective immune response in mice. Recombinant 6PGD (r6PGD) was cloned from S. pneumoniae serotype 3 (strain WU2). r6PGD interference in adhesion of three genetically unrelated unencapsulated pneumococcal strains (3.8, 14.8 and R6) and two genetically unrelated encapsulated pneumococcal strains (WU2 and D39) to A549 type II lung carcinoma cell was tested. BALB/c mice were immunized with r6PGD and boosted after 3 weeks. Immunized mice were challenged intranasally with a lethal dose of S. pneumoniae. r6PGD inhibited 90% and 80% of pneumococcal adhesion to the A549 cells of three unencapsulated S. pneumoniae strains and two encapsulated S. pneumoniae strains, respectively, in a concentration-dependent manner (P < 0.05). Antibodies to r6PGD produced in mice significantly inhibited bacterial adhesion to A549 cell (P < 0.05). Immunization of mice with r6PGD protected 60% (P < 0.001) of mice for 5 days and 40% (P < 0.05) of the mice for 21 days following intranasal lethal challenge. We have identified 6PGD as a surface-located immunogenic lectin protein capable of acting as an adhesin. 6PGD importance to bacterial pathogenesis was demonstrated by the ability of r6PGD to elicit a protective immune response in mice.

Adhesins, Bacterial↗
PubMed2006

Immulectin-4 from the tobacco hornworm Manduca sexta binds to lipopolysaccharide and lipoteichoic acid.

Insect C-type lectins function as pattern recognition receptors in innate immunity. In the tobacco hornworm Manduca sexta, we have previously isolated three C-type lectins named immulectins, which are involved in innate immune responses. Here, we report a new member of the immulectin family, immulectin-4 (IML-4). IML-4 mRNA was detected in the fat body of control larvae and was induced in the fat body when larvae were injected with bacteria. Recombinant IML-4 bound to bacterial lipopolysaccharide (LPS) and lipoteichoic acid (LTA), and the binding activity was not affected by addition of calcium or EGTA. IML-4 agglutinated bacteria and yeast, and agglutination of Escherichia coli by IML-4 was concentration- and calcium-dependent. IML-4 also enhanced haemocyte encapsulation and melanization.

Amino Acid Sequence↗
PubMed2005

Positive inductive effect of IL-2 on virus-specific cellular responses elicited by a PRRSV-ORF7 DNA vaccine in swine.

This study investigated the effect of swine interleukin 2 (IL-2) and swine interleukin 4 (IL-4) on the development of immune responses induced by a PRRSV-ORF7 DNA vaccine (phCMV-ORF7). The two cytokines were cloned separately in the eukaryotic expression vector phCMV, and delivered via gene gun as adjuvants for the DNA vaccine. Groups of 3-week-old certified PRRSV-free, castrated male, Yorkshire crossbred pigs, were vaccinated with or without the IL-2 or IL-4. The ensuing humoral and cellular immune responses were analyzed by a PRRSV-specific ELISA, and by an in vitro blastogenic response of peripheral blood mononuclear cells (PBMC) stimulated by viral antigen, respectively. The animals were boosted 21 days post-vaccination and challenged 28 days afterward. The virus loads post-challenge were measured by real time PCR. The group of swine receiving the vaccine plus IL-2 had significant virus-specific blastogenic responses 3 weeks after the vaccine-cytokine boost, when compared to those of the experimental pigs that received the vaccine plus IL-4, vaccine alone, unvaccinated controls or the pigs vaccinated with the DNA vaccine cloned in the reverse orientation (phCMV-ORF7(Rev)). None of the experimental swine had detectable specific antibodies against the virus during the vaccination phase. The virus load peak in vaccinated animals was delayed by about 72h as compared to that of the control pigs (unvaccinated and vaccinated with the phCMV-ORF7(Rev) construct). Interestingly, animals that received the phCMV-ORF7 vaccine alone consistently had low virus loads throughout the study. These results demonstrate that IL-2 has a positive inductive effect on the activation of vaccine-induced virus-specific cellular immunity, while IL-4 appeared to have a suppressive effect. Our data also suggest that ORF7 may play a role in reducing the virus load in PRRSV infected animals.

Animals↗
PubMed2005

Reexamination of phenoloxidase in larval circulating hemocytes of the silkworm, Bombyx mori.

We have developed a modified method to detect phenoloxidase activity on hemocytes by using freshly prepared l-DOPA (1 mg/ml in 35% ethanol) to fix and incubate larval hemocytes. This method is more sensitive than the common method, in which hemocytes were fixed in 4% formaldehyde and then incubated with 2 mg/ml l-DOPA in water separately. Phenoloxidase assayed using this modified method can be inhibited by phenyltiourea (phenoloxidase inhibitor). After incubation with l-DOPA solution in ethanol, most prohemocytes, all plasmatocytes and young granulocytes are stained brown due to oxidation of l-DOPA into pigments, indicating that they have phenoloxidase. Oenocytoids are dimly stained because many of their cell inclusions have been released during the treatment. Large propidium-iodide-negative prohemocytes have strong phenoloxidase activity and are easily misunderstood as propidium-iodide-positive oenocytoids if the fluorescent method is not used for identification. Thus, in addition to oenocytoids and plasmatocytes, some prohemocytes and granulocytes in the silkworm also have phenoloxidase.

Animals↗
PubMed2004

Virulence of Streptococcus pneumoniae may be determined independently of capsular polysaccharide.

Mice were inoculated intranasally with Streptococcus pneumoniae isolates of serotype 14 with different genetic backgrounds (14R, 14DW) and a capsular switch of 14R, strain 9VR (serotype 9V). Inoculation of the mice with 14R and 9VR resulted in 60% mortality. All the mice survived 14DW inoculation. No differences in lungs' bacterial loads were found 3 h following inoculation. Bacterial clearance of 5 logs was observed 48 h after inoculation with 14DW versus within 1 log 48 h after inoculation with 14R and 9VR. No significant differences in bacterial size or the capsular amount could be found between 14R and 14DW. We conclude that factor(s) in addition to the capsule, contribute to disease outcome.

Animals↗
PubMed2004

Spermine reduces infarction and neurological deficit following a rat model of middle cerebral artery occlusion: a magnetic resonance imaging study.

The role of nitric oxide (NO) in post-ischemic cerebral infarction has been extensively examined, but few studies have investigated its role on the neurological deficit. In the present study, we investigated the effect of spermine on the temporal evolution of infarct volume, NO production and neurological deficit using magnetic resonance imaging in a model of permanent focal cerebral ischemia in rats. Spermine given at 10 mg/kg 2 h after ischemia reduced the infarct volume by 40% and abolished brain NO production and improved the neurological score 24 h, 48 h and 72 h after ischemia. Spermine also reduced the neurological deficit as evaluated by rotamex, grip strength and neurological severity score tests.

Analysis of Variance↗
PubMed2004

Glycolytic enzymes associated with the cell surface of Streptococcus pneumoniae are antigenic in humans and elicit protective immune responses in the mouse.

Streptococcus pneumoniae is a leading cause of otitis media, sinusitis, pneumonia, bacteraemia and meningitis worldwide. The drawbacks associated with the limited number of various capsular polysaccharides that can be included in the polysaccharide-based vaccines focuses much attention on pneumococcal proteins as vaccine candidates. We extracted an enriched cell wall fraction from S. pneumoniae WU2. Approximately 150 soluble proteins could be identified by 2D gel electrophoresis. The proteins were screened by 2D-Western blotting using sera that were obtained longitudinally from children attending day-care centres at 18, 30 and 42 months of age and sera from healthy adult volunteers. The proteins were further identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry. Seventeen proteins were antigenic in children and adults, of which 13 showed an increasing antibody response with age in all eight children analysed. Two immunogenic proteins, fructose-bisphosphate aldolase (FBA) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and a control protein with known low immunogenicity, heat shock protein 70 (DnaK), were expressed in Escherichia coli, purified and used to immunize mice. Mouse antibodies elicited to the recombinant (r) FBA and rGAPDH were cross-reactive with several genetically unrelated strains of different serotypes and conferred protection to respiratory challenge with virulent pneumococci. In addition, the FBA used in this study (NP_345117) does not have a human ortholog and warrants further investigation as a candidate for a pneumococcal vaccine. In conclusion, the immunoproteomics based approach utilized in the present study appears to be a suitable tool for identification of novel S. pneumoniae vaccine candidates.

Adult↗
PubMed2003

Differential activation of the immune system by virulent Streptococcus pneumoniae strains determines recovery or death of the host.

Streptococcus pneumoniae infection may result in asymptomatic carriage, mucosal or invasive disease. We hypothesize that self-limiting or fatal disease outcome follows infection with S. pneumoniae differential activation of the host immune response. BALB/c and C57BL/6 mice were inoculated intranasally with S. pneumoniae serotype 3 strain WU2 and serotype 14 strain DW14 and mortality, bacterial load, pathological changes in the lungs and cytokines mRNA levels in the spleen were analysed. No differences between the C57BL/6 and the BALB/c inbred mice were observed except for the severity of their lung pathology and IL-4 expression. Infection of the two mouse strains with S. pneumoniae WU2 resulted in sepsis and death that occurred within 4 days post-inoculation. This death was preceded, in both mouse strains, in an increase over time of the lung bacterial load and bacteraemia. The lung pathology was characterized by diffuse pneumonia with marked congestion of the lungs. Analysis of mRNA expression of cytokines in the spleen revealed no alterations in tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, interleukin (IL)-12 and interferon (IFN)-gamma and induction of IL-10 and IL-4. The two strains of mice survived infection with S. pneumoniae DW14. This was accompanied by a reduction over time of lung bacterial load and bacteraemia. The lung pathology was characterized by focal lymphocyte infiltration and preserved architecture of the organ. Analysis of mRNA expression of cytokines in the spleen revealed a significant decrease in the levels of TNF-alpha, TGF-beta, IL-12 and IFN-gamma mRNA expression, which usually precedes cytokine protein expression. Interestingly, a significant increase in the levels of IL-4 mRNA expression was found in BALB/c mice only. This study suggests that differential activation or evasion of cytokine expression by S. pneumoniae virulent strains determines disease outcome regardless of the host's immunogenetic background.

Administration, Intranasal↗
PubMed2001

Airway difficulties caused by improperly applied cricoid pressure.

Cricoid pressure, when properly applied, may prevent gastric regurgitation and may improve the view of laryngoscopy. When improperly applied, however, it can impede laryngoscopy and mask-ventilation. When faced with a "cannot intubate" or "cannot mask-ventilate" situation, clinicians should reevaluate the manner with which the assistant is applying cricoid pressure and must be prepared to adjust or even to release it.

Adult↗
PubMed2000

Changes in apoptosis-related protein (p53, Bax, Bcl-2 and Fos) expression with DNA fragmentation in the central nervous system in rats after closed head injury.

This study aimed to examine the temporal profile of neuronal apoptosis in the central nervous system (CNS) following closed head injury in rat. Fos immunoreactivity was detected in neuronal nuclei in the cerebral cortex at 2 h after head injury. At 4 h, Bax protein expression was elevated with a concomitant down-regulation of Bcl-2 expression. Along with this, a marked immunoexpression of p53 was also observed in these cells. Double immunolabelling study has shown the colocalization of Bax immunoreactivity with Bcl-2 and p53. In rats killed 1 day after injury, a variable number of transferase d-UTP nick-end labelling positive cells were observed. Present findings suggest that the upregulation of p53 and a shift in the ratio of Bcl-2 to Bax may contribute to neuronal apoptosis in the CNS after closed head injury.

Animals↗
PubMed2000

Elastomeric pumps for ambulatory patient controlled regional analgesia.

PURPOSE: To report our experience with the use of the (Eclipse) elastomeric pump for ambulatory Patient Controlled Regional Analgesia (PCRA) METHOD: After a pilot study using this device in patients admitted to the hospital, seven patients received PCRA at home using the elastomeric pump. Patients with a variety of continuous regional anesthetic blocks were sent home with written and verbal instructions regarding the use of this device, boluses, side effects of local anesthetics and removal of block catheters. Patients were contacted daily to collect data with regards to the efficacy of the block, problems associated with the use of this device and their satisfaction with the method of analgesia. RESULTS: During the pilot study there were two catheter disconnections requiring rescue analgesics. Two patients had the entire contents of the bulb delivered over several minutes. Among the seven patients receiving PCRA at home, one patient had to be admitted to the hospital. One patient had block catheter slip out during transit. The volume delivered could not be measured. Patients found it difficult to know if the drug had been delivered. Three patients noted that the pumps were empty earlier than expected. One patient found it difficult to change the bulb. No patient had difficulty with catheter removal or with bolusing. CONCLUSIONS: PCRA offers excellent postoperative analgesia at home. Elastomeric pumps facilitate PCRA but are imprecise with drug delivery and may not be safe for epidural infusions. The safety of this device for peripheral nerve blocks should be evaluated further.

Adult↗
PubMed2000

Are twitches, startles, and body movements pain indicators in extremely low birth weight infants?

OBJECTIVE: The goal of this study was to examine whether body activity such as postural, trunk, and limb movements may be potential pain cues in preterm infants. DESIGN: Convenience sample. SETTING: Level III neonatal intensive care unit (NICU). PATIENTS: Extremely low birth weight (< or = 1,000 g) preterm infants (n = 64) undergoing routine NICU medical care. OUTCOME MEASURES: Procedures likely to differ in evoking distress (i.e., endotracheal suctioning, chest physical therapy, diaper change, or nasogastric feed) were observed. Behaviors were recorded at bedside using the Neonatal Individualized Developmental Care and Assessment Program system. RESULTS: Changes in heart rate and sleep/waking state were related to the procedures, supporting the assumption of differing relative disruption to the infant. Arching, squirming, startles, and twitching were not observed significantly more during procedures than at baseline. After controlling for background variables, finger splay and leg extension were significantly related to ongoing procedures. Facial brow raising was a function of the number of invasive procedures in the past 24 hours; thus, it may be a useful cue of sensitization. CONCLUSIONS: Some extensor movements seemed to be distress signals, whereas tremors, startles, and twitches were not related to discomfort during the observation period. These behaviors may differ qualitatively during longer lasting tissue invasive events. The results of this study indicate the need for more in-depth study of patterns of motor activity in preterm infants over longer observation periods to evaluate potential signs of stress and pain in babies undergoing NICU medical care.

Cues↗
PubMed1999

Contamination susceptibility of three needleless and one standard needle injection systems.

PURPOSE: To compare in vitro the contamination susceptibility of three needleless and one standard needle injection systems. METHODS: The Baxter InterLink, St. Paul Medical Key-Lok, Braun SafSite, and Becton Dickinson heparin lock, were compared. Fifty of each were studied. Each system was connected to a culture bottle and injected 30 times over 72 hr. The manufacturers' directions were followed except for Braun's, which recommend that a new sterile cap be used after each injection. Instead, the same cap was used after each injection to reflect day-to-day clinical practice. Culture bottles were subsequently analyzed for bacterial growth. RESULTS: The contamination rates for the heparin lock, InterLink, Key-Lok, and SafSite were 3/50 (6%), 6/50 (12%), 4/50 (8%), and 36/50 (72%), respectively. All positive cultures grew coagulase-negative staphylococcus species. There was no difference in contamination rates between the InterLink, Key-Lok, and heparin lock designs. The contamination rate of the SafSite was higher (P < 0.001) than the other three systems. CONCLUSIONS: The InterLink and Key-Lok systems had a similarly low contamination susceptibility as a standard needle injection system. It was not clear if the high contamination rate found with the SafSite system was due to non-adherence to the manufacturer's directions for handling.

Bacteria↗
PubMed1999

Systemic air embolism after lung trauma.

Systemic air or gas embolism has been increasingly recognized as a complication of serious chest trauma and often presents with catastrophic circulatory and cerebral events. The classic findings are hemoptysis, sudden cardiac or cerebral dysfunction after initiation of PPV, air in retinal vessels, and air in arterial aspirations. The clinician must be wary of more subtle presentations. Several diagnostic tools (TEE, Doppler, CT) can detect intracardiac and cerebral air, but they may not be necessary to confirm the diagnosis of SAE. Cessation of SAE is essential for successful resuscitation. In those with unilateral lung injury, this can theoretically be achieved by isolating and ventilating the noninjured lung. Sole reliance on immediate thoracotomy for hilar clamping to stem the flow of gas emboli is a concept that needs to be challenged. Whether airway and ventilation interventions will eliminate, delay, or decrease the need for thoracotomy and improve the prognosis of SAE remains to be seen. There is little reported in the literature regarding such interventions. Airway management of a patient at risk for SAE should include a technique that can selectively ventilate each lung. Patients with bilateral sources of SAE may benefit from the avoidance of high airway pressures. Regional anesthesia should be considered when appropriate. HBOT is useful in managing cerebral air embolism and should be incorporated as soon as possible. Clinicians involved in trauma care must be familiar with SAE. By adopting a problem-based solution through innovative airway and ventilation management, anesthesiologists may significantly alter and improve the morbidity and mortality rate of SAE resulting from chest trauma.

Animals↗
PubMed1995

Effect of group B streptococcal meningitis on retinal and choroidal blood flow in newborn pigs.

PURPOSE: To assess the effect of group B streptococcal (GBS) meningitis on retinal blood flow (RetBF) and choroidal blood flow (ChBF) autoregulation in sedated newborn piglets (1 to 5 days of age). METHODS: Fourteen study animals injected with 0.5 ml heat-killed GBS (10(9)) were compared to 10 control animals injected with 0.5 ml saline. The site of injection for both groups was the cerebral lateral ventricles. RetBF and ChBF were measured by radioactive microspheres (141Ce, 51Cr, 113Sn, 85Sr, 95Nb, 46Sc) over a mean arterial blood pressure (MABP) range of 20 to 150 mm Hg. Hypertension and hypotension were induced 2 hours apart in random sequence on each animal by inflating balloon-tipped catheters placed at the descending aorta and the aortic root, respectively. RetBF and ChBF were measured 15 minutes before and after injection of GBS or saline (baseline) and during hypotension or hypertension. RESULTS: Fifth-order polynomial regression analyses of RetBF and ChBF (ml/100 g per minute) versus MABP showed that in control animals, blood flows were constant at MABP of 60 to 110 mm Hg for RetBF and was pressure passive above and below these ranges. However, no autoregulation was observed for ChBF throughout the MABP range. In contrast, RetBF of GBS-treated animals increased with increasing blood pressure throughout range of MABP studied, and absence of autoregulation was maintained in the choroid. Vascular resistance (mm Hg/ml per minute/100 g) increased as MABP was raised to maintain constant flow and was correlated linearly with MABP at 60 to 110 mm Hg (r = 0.6682, P = 0.0003) in RetBF of control animals but not in GBS-treated animals (r = -0.291, P = NS). Vascular resistance did not change with MABP for ChBF of control animals (r = -0.264, P = NS) but decreased as MABP was raised in GBS-treated animals (r = -0.548, P < 0.0001). GBS did not alter oxygen delivery, which varied directly with MABP in control animals (RetBF: r = 0.74, P < 0.001; ChBF: r = 0.68, P < 0.001) and in GBS-treated animals (RetBF: r = 0.55, P < 0.001; ChBF: r = 0.68, P < 0.001). CONCLUSION: Group B streptococcal meningitis significantly impairs eye blood flow autoregulation and may contribute to increased risk of retinal damage in infants with meningitis.

Animals↗
PubMed1994

Platelet function in patients with hypercholesterolaemia.

Platelets and plasma lipoproteins, particularly low density lipoprotein, have important roles in atherogenesis. Evidence from several sources suggests that important interactions occur between these individual components of the atherogeneic process. Here we review work from our own laboratory on platelet function in normal individuals and patients heterozygous for familial hypercholesterolaemia (FH). Data is presented on the role of platelet noradrenaline and also on altered cellular signalling in platelets from FH individuals who have plasma low density lipoprotein concentrations which are approximately double those seen in normal subjects.

Blood Platelets↗