Randomized Trial of 2 Schedules of Meningococcal B Vaccine in Adolescents and Young Adults, Canada1

Emergency vaccination programs often are needed to control outbreaks of meningococcal disease caused by Neisseria meningitidis serogroup B (MenB) on college campuses. Such campaigns expend multiple campus and public health resources. We conducted a randomized, controlled, multicenter, observer-blinded trial comparing immunogenicity and tolerability of an accelerated vaccine schedule of 0 and 21 days to a longer interval of 0 and 60 days for 4-component MenB vaccine (MenB-4C) in students 17-25 years of age. At day 21 after the first MenB-4C dose, we observed protective human serum bactericidal titers >4 to MenB strains 5/99, H44/76, and NZ 98/254 in 98%-100% of participants. Geometric mean titers increased >22-fold over baseline. At day 180, >95% of participants sustained protective titers regardless of their vaccine schedule. The most common adverse event was injection site pain. An accelerated MenB-4C immunization schedule could be considered for rapid control of campus outbreaks.

PROKARYO: an illustrative and interactive computational model of the lactose operon in the bacterium Escherichia coli

Background

We are creating software for agent-based simulation and visualization of bio-molecular processes in bacterial and eukaryotic cells. As a first example, we have built a 3-dimensional, interactive computer model of an Escherichia coli bacterium and its associated biomolecular processes. Our illustrative model focuses on the gene regulatory processes that control the expression of genes involved in the lactose operon. Prokaryo, our agent-based cell simulator, incorporates cellular structures, such as plasma membranes and cytoplasm, as well as elements of the molecular machinery, including RNA polymerase, messenger RNA, lactose permease, and ribosomes.

Results

The dynamics of cellular ’agents’ are defined by their rules of interaction, implemented as finite state machines. The agents are embedded within a 3-dimensional virtual environment with simulated physical and electrochemical properties. The hybrid model is driven by a combination of (1) mathematical equations (DEQs) to capture higher-scale phenomena and (2) agent-based rules to implement localized interactions among a small number of molecular elements. Consequently, our model is able to capture phenomena across multiple spatial scales, from changing concentration gradients to one-on-one molecular interactions.

We use the classic gene regulatory mechanism of the lactose operon to demonstrate our model’s resolution, visual presentation, and real-time interactivity. Our agent-based model expands on a sophisticated mathematical E. coli metabolism model, through which we highlight our model’s scientific validity.

Conclusion

We believe that through illustration and interactive exploratory learning a model system like Prokaryo can enhance the general understanding and perception of biomolecular processes. Our agent-DEQ hybrid modeling approach can also be of value to conceptualize, illustrate, and—eventually—validate cell experiments in the wet lab.

Effectiveness of the standard and an alternative set of Streptococcus pneumoniae multi locus sequence typing primers

Background

Multi-locus sequence typing (MLST) is a portable, broadly applicable method for classifying bacterial isolates at an intra-species level. This methodology provides clinical and scientific investigators with a standardized means of monitoring evolution within bacterial populations. MLST uses the DNA sequences from a set of genes such that each unique combination of sequences defines an isolate’s sequence type. In order to reliably determine the sequence of a typing gene, matching sequence reads for both strands of the gene must be obtained. This study assesses the ability of both the standard, and an alternative set of, Streptococcus pneumoniae MLST primers to completely sequence, in both directions, the required typing alleles.

Results

The results demonstrated that for five (aroE, recP, spi, xpt, ddl) of the seven S. pneumoniae typing alleles, the standard primers were unable to obtain the complete forward and reverse sequences. This is due to the standard primers annealing too closely to the target regions, and current sequencing technology failing to sequence the bases that are too close to the primer. The alternative primer set described here, which includes a combination of primers proposed by the CDC and several designed as part of this study, addresses this limitation by annealing to highly conserved segments further from the target region. This primer set was subsequently employed to sequence type 105 S. pneumoniae isolates collected by the Canadian Immunization Monitoring Program ACTive (IMPACT) over a period of 18 years.

Conclusions

The inability of several of the standard S. pneumoniae MLST primers to fully sequence the required region was consistently observed and is the result of a shift in sequencing technology occurring after the original primers were designed. The results presented here introduce clear documentation describing this phenomenon into the literature, and provide additional guidance, through the introduction of a widely validated set of alternative primers, to research groups seeking to undertake S. pneumoniae MLST based studies.

Evaluation of meningococcal serogroup C conjugate vaccine programs in Canadian children: interim analysis

BACKGROUND

To assess antibody titers afforded by meningococcal C- (MenC) tetanus toxoid conjugate vaccine at 12 months of age in three different immunization schedules.

METHODS

This prospective study included three similar cohorts of healthy infants from 1-dose, 2-dose and 3-dose MenC infant immunization programs. Infants were enrolled at 12 months of age and given the final scheduled dose of MenC-tetanus toxoid conjugate vaccine with sera collected prior to and 1 month after the vaccination. Serum bactericidal activity (SBA) titers ≥ 1:8 were considered protective.

RESULTS

Before the 12 month dose, participants had significantly different protective titers according to the number of prior doses received: 100% (95% CI 97.6-100%) of infants who had 2 prior doses (at 2 and 4 months) were protected compared to 84.0% (76.7-89.3%) of participants with one dose (at 2 months) and 27.6% (21.0-35.4%) of unvaccinated infants. All subjects were protected after the 12 month MenC dose, but titers were higher with prior priming.

CONCLUSIONS

Two MenC doses given in infancy afford optimal protection during the first year of life; however, substantial protection was seen after one dose at 2 months.

The structural basis of transferrin sequestration by transferrin-binding protein B

Neisseria meningitidis, the causative agent of bacterial meningitis, acquires the essential element iron from the host glycoprotein transferrin (Tf) during infection via a surface Tf receptor system composed of proteins TbpA and TbpB. Here in we present the crystal structures of TbpB from N. meningitidis, in its apo form and in complex with human Tf (hTf). The structure reveals how TbpB sequesters hTf and initiates iron release from hTf.

Plant defense responses in opium poppy cell cultures revealed by liquid chromatography-tandem mass spectrometry proteomics

Opium poppy (Papaver somniferum) produces a diverse array of bioactive benzylisoquinoline alkaloids, including the narcotic analgesic morphine and the antimicrobial agent sanguinarine. In contrast to the plant, cell cultures of opium poppy do not accumulate alkaloids constitutively but produce sanguinarine in response to treatment with certain fungal-derived elicitors. The induction of sanguinarine biosynthesis provides a model platform to characterize the regulation of benzylisoquinoline alkaloid pathways and other defense responses. Proteome analysis of elicitor-treated opium poppy cell cultures by two-dimensional denaturing-polyacrylamide gel electrophoresis coupled with liquid chromatography-tandem mass spectrometry facilitated the identification of 219 of 340 protein spots based on peptide fragment fingerprint searches of a combination of databases. Of the 219 hits, 129 were identified through pre-existing plant proteome databases, 63 were identified by matching predicted translation products in opium poppy-expressed sequence tag databases, and the remainder shared evidence from both databases. Metabolic enzymes represented the largest category of proteins and included S-adenosylmethionine synthetase, several glycolytic, and a nearly complete set of tricarboxylic acid cycle enzymes, one alkaloid, and several other secondary metabolic enzymes. The abundance of chaperones, heat shock proteins, protein degradation factors, and pathogenesis-related proteins provided a comprehensive proteomics view on the coordination of plant defense responses. Qualitative comparison of protein abundance in control and elicitor-treated cell cultures allowed the separation of induced and constitutive or suppressed proteins. DNA microarrays were used to corroborate increases in protein abundance with a corresponding induction in cognate transcript levels.

Development of a 1+/N+ setup for the production of multicharged radioactive alkali ions in SPIRAL

In the framework of the production of radioactive ion beams by the isotope separator online method, a new system has been developed at GANIL/SPIRAL I to produce multicharged alkali ions. The principle, referred to as the "direct 1+/N+ method," consists of a surface ionization source associated with a multicharged electron-cyclotron-resonance ion source without an intermediate mass separator. This new system has been tested online using a (48)Ca primary beam at 60.3 A MeV. The experimental evidence of the direct 1+/N+ process has been obtained for a potential difference between the two sources of 11 V and with a 1+/N+ charge breeding efficiency of 0.04% for (47)K(5+). This value is significantly lower than the value of 6% obtained for stable K ions with the standard 1+/N+ method. A possible explanation is given in the text.

The role of phloem sieve elements and laticifers in the biosynthesis and accumulation of alkaloids in opium poppy

The benzylisoquinoline alkaloids of opium poppy, including the narcotic analgesics morphine and codeine, accumulate in the multinucleate cytoplasm of specialized laticifers that accompany vascular tissues throughout the plant. In mature opium poppy plants, immunofluorescence labeling using specific antibodies showed that four alkaloid biosynthetic enzymes, (S)-norcoclaurine 6-O-methyltransferase (6OMT), (S)-coclaurine N-methyltransferase (CNMT), (S)-3'-hydroxy-N-methylcoclaurine-4'-O-methyltransferase (4'OMT) and salutaridinol-7-O-acetyltransferase (SAT) were restricted to sieve elements of the phloem adjacent or proximal to laticifers. The identity of sieve elements was confirmed by (i) the specific immunogold labeling of the characteristic cytoplasm of this cell type, (ii) the co-localization of a sieve element-specific H(+)-ATPase with all biosynthetic enzymes and (iii) the strict association of sieve plates with immunofluorescent cells. The localization of laticifers was demonstrated antibodies specific to major latex protein (MLP), which is characteristic of this cell type. In situ hybridization using antisense RNA probes for 6OMT, CNMT, 4'OMT and SAT showed that the corresponding gene transcripts were found in the companion cell paired with each sieve element. Seven benzylisoquinoline alkaloid biosynthetic enzymes, (S)-N-methylcoclaurine 3'-hydroxylase (CYP80B1), berberine bridge enzyme, codeinone reductase, 6OMT, CNMT, 4'OMT and SAT were localized by immunofluorescence labeling to the sieve elements in the root and hypocotyl of opium poppy seedlings. The abundance of these enzymes increased rapidly between 1 and 3 days after seed germination. The localization of seven biosynthetic enzymes to the sieve elements provides strong support for the unique, cell type-specific biosynthesis of benzylisoquinoline alkaloids in the opium poppy.

Sanguinarine biosynthesis is associated with the endoplasmic reticulum in cultured opium poppy cells after elicitor treatment

Three key benzylisoquinoline alkaloid biosynthetic enzymes, (S)-N-methylcoclaurine-3'-hydroxylase (CYP80B1), berberine bridge enzyme (BBE), and codeinone reductase (COR), were localized in cultured opium poppy (Papaver somniferum) cells by sucrose density gradient fractionation and immunogold labeling. CYP80B1 catalyzes the second to last step in the formation of (S)-reticuline, the last common intermediate in sanguinarine and morphine biosynthesis. BBE converts (S)-reticuline to (S)-scoulerine as the first committed step in sanguinarine biosynthesis, and COR catalyzes the penultimate step in the branch pathway leading to morphine. Sanguinarine is an antimicrobial alkaloid that accumulates in the vacuoles of cultured opium poppy cells in response to elicitor treatment, whereas the narcotic analgesic morphine, which is abundant in opium poppy plants, is not produced in cultured cells. CYP80B1 and BBE were rapidly induced to high levels in response to elicitor treatment. By contrast, COR levels were constitutive in the cell cultures, but remained low and were not induced by addition of the elicitor. Western blots performed on protein homogenates from elicitor-treated cells fractionated on a sucrose density gradient showed the cosedimentation of CYP80B1, BBE, and sanguinarine with calreticulin, and COR with glutathione S-transferase. Calreticulin and glutathione S-transferase are markers for the endoplasmic reticulum (ER) and the cytosol, respectively. In response to elicitor treatment, large dilated vesicles rapidly developed from the lamellar ER of control cells and fused with the central vacuole. Immunogold localization supported the association of CYP80B1 and BBE with ER vesicles, and COR with the cytosol in elicitor-treated cells. Our results show that benzylisoquinoline biosynthesis and transport to the vacuole are associated with the ER, which undergoes major ultrastructural modification in response to the elicitor treatment of cultured opium poppy cells.

Precise and efficient cleavage of recombinant fusion proteins using mammalian aspartic proteases

Expression of recombinant proteins as translational fusions is commonly employed to enhance stability, increase solubility and facilitate purification of the desired protein. In general, such fusion proteins must be cleaved to release the mature protein in its native form. The usefulness of the procedure depends on the efficiency and precision of cleavage and its cost per unit activity. We report here the development of a general procedure for precise and highly efficient cleavage of recombinant fusion proteins using the protease chymosin. DNA encoding a modified pro-peptide from bovine chymosin was fused upstream of hirudin, carp growth hormone, thioredoxin and cystatin coding sequences and expressed in a bacterial Escherichia coli host. Each of the resulting fusion proteins was efficiently cleaved at the junction between the pro-peptide and the desired protein by the addition of chymosin, as determined by activity, N-terminal sequencing and mass spectrometry of the recovered protein. The system was tested further by cleavage of two fusion proteins, cystatin and thioredoxin, sequestered on oilbody particles obtained from transgenic Arabidopsis seeds. Even when the fusion protein was sequestered and immobilized on oilbodies, precise and efficient cleavage was obtained. The precision, efficiency and low cost of this procedure suggest that it could be used in larger scale manufacturing of recombinant proteins which benefit from expression as fusions in their host organism.

Chiropractic care of a patient with vertebral subluxations and unsuccessful surgery of the cervical spine

OBJECTIVE

The chiropractic care of a patient with vertebral subluxations, neck pain, and cervical radiculopathy after a cervical diskectomy is described.

CLINICAL FEATURES

A 55-year-old man had neck pain and left upper extremity radiculopathy after unsuccessful cervical spine surgery.

INTERVENTION AND OUTCOME

Contact-specific, high-velocity, low-amplitude adjustments (i.e., Gonstead technique) were applied to sites of vertebral subluxations. Rehabilitation exercises were also used as adjunct to care. The patient reported a decrease in neck pain and left arm pain after chiropractic intervention. The patient also demonstrated a marked increase in range of motion (ROM) of the left glenohumeral articulation.

CONCLUSION

The chiropractic care of a patient with neck pain and left upper extremity radiculopathy after cervical diskectomy is presented. Marked resolution of the patient's symptoms was obtained concomitant with a reduction in subluxation findings at multiple levels despite the complicating history of an unsuccessful cervical spine surgery. This is the first report in the indexed literature of chiropractic care after an unsuccessful cervical spine surgery.

Chiropractic management of a patient with myasthenia gravis and vertebral subluxations

OBJECTIVE

The chiropractic management of a patient with myasthenia gravis and vertebral subluxation is described. We discuss the pathophysiology, clinical features, and treatment of patients with these diseases.

CLINICAL FEATURES

The 63-year-old male patient suffered from complaints associated with the disease myasthenia gravis along with signs of vertebral subluxation. The patient had an initial complaint of dysphagia. In addition, the patient experienced swelling of the tongue, nausea, digestive problems, weakness in the eye muscles, difficulty breathing, myopia, diplopia, and headaches. Balance and coordination problems resulted in walking difficulties.

INTERVENTION AND OUTCOME

Contact specific, high-velocity, low-amplitude adjustments were applied to sites of patient subluxation. Myasthenia gravis is no longer debilitating to the patient; he is medication free and has resumed a "normal life."

CONCLUSION

The clinical aspects of the disease, including the possible role of chiropractic intervention in the treatment of patients suffering from myasthenia gravis, are also discussed. This case study encourages further investigation into the holistic approach to patient management by chiropractors vis-a-vis specific adjustments of vertebral subluxation.

Chiropractic management of a patient with subluxations, low back pain and epileptic seizures

OBJECTIVE

To describe the chiropractic management of a patient presenting with complaints of low back pain and epileptic seizures. The discussion also addresses epilepsy and the current concepts of this disorder; possible mechanisms for the neurological effects of the chiropractic adjustment at sites of subluxation and its therapeutic implications are proposed.

CLINICAL FEATURES

A 21-year-old woman with low back pain reported that she had fainted during the night and hit her head. She had been diagnosed since childhood with grand mal (tonicclonic) seizures as well as petit mal seizures. She had a seizure approximately every 3 hr, with a duration between 10 sec and 30 min for each episode. Examination indicated signs of subluxation/dysfunction at the L5-S1, C6-C7 and C3-C4 spinal levels. There was no evidence of cranial nerve involvement or any upper motor neuron lesion. Radiographic analysis revealed retrolisthesis of L5, hypolordosis of the cervical spine and hyperextension of the C6-C7 motion segment.

INTERVENTION AND OUTCOME

Chiropractic adjustments using a specific-contact, short-lever arm, high-velocity, low-amplitude maneuver (i.e., Gonstead) were applied to the subluxations at the cervical, thoracic and lumbopelvic region. The patient's reported low back pain and neck complaints improved and her seizure frequency decreased. At 1.5-yr follow-up, the patient reported her low back complaints had resolved and her seizures had decreased (period between seizures as great as 2 months).

CONCLUSION

Results encourage further investigation of possible neurological sequalae, such as epileptic seizures, from spinal dysfunction identified as vertebral subluxation complexes by chiropractors and treated by specific spinal adjustments.

Management of a patient with calcium pyrophosphate deposition disease and meniscal tear of the knee: a case report

OBJECTIVE

To describe the chiropractic management of a patient suffering from a right lateral meniscus tear concurrent with calcium pyrophosphate dihydrate (CPPD) deposition disease.

CLINICAL FEATURES

A 51-yr-old bus driver suffered from right knee pain (7 on a 1-10 pain scale). The onset of the pain was gradual and increased during braking and accelerating. Palpatory tenderness was noted at the right lateral knee joint line and the inferior lateral margin of the patella. Active resistive range of motion (ROM) in the knee during extension was painful throughout the full ROM, whereas passive ROM was restricted in flexion at 110 degrees. A positive McMurray's test reproduced pain at the knee. Radiographic analysis revealed CPPD deposition disease, and magnetic resonance imaging revealed a probable "parrot's beak" tear in the posterior horn of the right lateral meniscus.

INTERVENTION AND OUTCOME

The patient was treated conservatively. He was instructed not to put weight on the knee and not to return to work for 5 days. Initial treatments involved the use of ice and interferential electrical stimulation along with glucosamine sulfate supplements. Bicycling, weight lifting for general fitness and general knee strengthening exercises were prescribed. Approximately 5 months after initial treatment, the patient was lost to follow-up; 12 months later, he returned for treatment because of a recurrence. Physical examination at that time revealed knee pain rated at 3/10 but there was no pain upon palpation, McMurray's test was negative and right knee ROM was full without pain.

CONCLUSION

A patient suffering from CPPD can be managed by conservative means. The pathophysiology, clinical features and management considerations in the treatment of the patient's condition(s) are also discussed.

Management of a patient with a lamina fracture of the sixth cervical vertebra and concomitant subluxation

OBJECTIVE

To discuss the chiropractic management of a patient who sustained a unilateral lamina fracture of the sixth cervical vertebra.

CLINICAL FEATURES

The patient had suffered cervical trauma from a motor vehicle accident. Clinical evaluation revealed acute global neck pain with associated left arm radiculitis and approximately 75% loss of useful left-arm motor function. The patient also complained of headache and low back pain. Computerized tomography and radiographic findings indicated a left lamina fracture of the sixth cervical vertebra.

INTERVENTION AND OUTCOME

A rigid cervical collar was prescribed for the patient and specific-contact, short lever-arm, high-velocity, low-amplitude adjustments were applied at the levels of C2, C7 and L5, on different treatment visits, 11 days after trauma. The patient continued to wear the orthosis after each adjustment. The patient recovered from his injury and had no late biomechanical or neurological instability as a result of this management approach.

CONCLUSION

The chiropractic management of a patient who sustained a unilateral lamina fracture of C6 with concomitant subluxations at C2 and C7 is discussed. This case study is the second reported in the scientific literature in which conservative chiropractic methods were applied to a patient with a lamina fracture.

Management of the patient with a Chance fracture of the lumbar spine and concomitant subluxation

OBJECTIVE

To document the chiropractic management of a patient who sustained a Chance fracture of the third lumbar vertebra. This case study represents the first report in the scientific literature of such an injury managed through chiropractic methods.

CLINICAL FEATURES

An 18-yr-old man complained of low back pain and paresthesia in the lower extremities 10 days after suffering an automobile accident. Examination revealed a large circular edematous area from L1 to L4, tenderness to palpation at the L3 spinous process, reduction in global range of motion at the thoracolumbar region, and positive Lasègue and Kemp tests (bilaterally). Radiographic and computed tomographic scans revealed a Chance fracture of the L3 vertebra.

INTERVENTION AND OUTCOME

The patient received specific-contact, short-lever arm spinal adjustments delivered primarily at L3 and L5, as well as bracing. Four months after initial treatment, the patient's complaint of paresthesia had resolved and he suffered only occasional minor low back pain. The comparative radiographs demonstrate a reduction in the separation of the fracture fragments.

CONCLUSION

A case report is presented of a patient who suffered a Chance fracture of L3. The patient was eventually managed by chiropractic methods including a specific contact high-velocity thrust procedure administered at the level of the fractured vertebra. The case represents the first known reporting of this type of chiropractic procedure applied to a patient with a Chance fracture.

Missed sacral fracture before chiropractic adjustment

OBJECTIVE

Reports of complications after chiropractic adjustments were administered to the lumbar spine and/or pelvis are rare. This case report provides the events associated with a sacral fracture that was not identified before a side-posture sacroiliac adjustment.

CLINICAL FEATURES

The patient suffered from blunt, low back trauma as a result of a fall. Clinical evaluation indicated fixation dysfunction at the left sacroiliac articulation, with minimal edema/tenderness at the inferior portion of the left sacroiliac joint. Initial radiological evaluation failed to disclose the zone 2 sacral fracture because of an underexposed radiograph; thus, the patient was given a diagnosis of a sacroiliac sprain subluxation.

INTERVENTION AND OUTCOME

A specific contact sacroiliac adjustment that uses the innominate as the short lever arm was administered to the patient in the side-posture position. Two adjustments were administered over 2 days. The patient developed sciatic pain after the second adjustment and subsequently referred herself to a medical orthopedist. Additional plain films were obtained, and a diagnosis of a zone 2 sacral fracture was made. The patient was prescribed bed rest; at 6 wk, her symptoms resolved and she returned to normal activity levels.

CONCLUSION

Fractures of the spine and pelvis need to be considered in a patient who suffers blunt trauma. An adequate radiographic examination is necessary to make the appropriate diagnosis. Failure to diagnose the fracture may lead to complications, because the adjustment is not administered with regard to the biomechanics of the trauma or the actual clinical entity under scrutiny. This case study represents the first report of a complication after a sacroiliac adjustment in a patient who had a zone 2 sacral fracture that was missed in the diagnosis.

Transferrin binding protein two interacts with both the N-lobe and C-lobe of ovotransferrin

The present study was initiated to identify the region(s) of ovotransferrin involved in binding to the bacterial transferrin receptors from Haemophilus paragallinarum and Haemophilus avium. Ovotransferrin was digested with either trypsin or thermolysin to obtain its N-lobe and C-lobe fragments. The individual fragments were then purified by a combination of gel exclusion and ion-exchange chromatography. Solid phase binding experiments with the individual fragments demonstrated that the C-lobe fragments blocked the binding of horse radish peroxidase-conjugated ovotransferrin to the transferrin receptors and that much higher concentrations of the N-lobe fragment were required for any detectable blocking. Affinity isolation of the bacterial transferrin receptor from the two Haemophilus species revealed that both native ovotransferrin and its C-lobe fragment were capable of isolating two iron repressible outer membrane proteins. These 95 and 60 kDa outer membrane proteins correspond to Tbp1 and Tpb2, respectively. In contrast, the N-lobe fragment was capable of isolating Tbp2 of H. paragallinarum but not that of H. avium. The inability of the N-lobe and C-lobe fragments from ovotransferrin and human transferrin to support the growth of iron-limited cultures of H. paragallinarum and Neisseria meningitidis, respectively, suggested that interaction with both lobes is necessary for efficient iron acquisition.

The region of human transferrin involved in binding to bacterial transferrin receptors is localized in the C-lobe

Iron-saturated human transferrin was digested with either chymotrypsin or trypsin to produce C-lobe and N-lobe protein fragments. Individual protein fragments were purified by a combination of gel filtration and Concanavalin A affinity chromatographic procedures. The C-lobe and N-lobe fragments of human transferrin were then used in binding assays to assess their ability in binding to the bacterial transferrin receptors. Competitive binding assays demonstrated that the C-lobe fragment of human transferrin binds as well as intact human transferrin to bacterial transferrin receptors from Neisseria meningitidis, Neisseria gonorrhoeae and Haemophilus influenzae. Using isogenic mutants of N. meningitidis deficient in either of the transferrin-binding proteins (Tbps), we demonstrated that both transferrin-binding proteins were able to bind to the C-lobe fragment of human transferrin.

The N-linked oligosaccharides of human lactoferrin are not required for binding to bacterial lactoferrin receptors

The oligosaccharides of human lactoferrin were enzymatically removed with glycopeptidase F, resulting in a preparation containing partial and fully deglycosylated human lactoferrin. The derivatives were separated by Concanavalin A affinity chromatography and compared with native human lactoferrin with respect to their ability to bind to bacterial receptors. Competitive binding experiments demonstrated that the lactoferrin derivatives were equally capable as native lactoferrin in binding to receptors of Neisseria meningitidis, Neisseria gonorrhoeae, and Moraxella catarrhalis. This result indicates that the oligosaccharides on human lactoferrin are not essential for binding to the bacterial receptors.

Pseudomonas aeruginosa biofilm as a diffusion barrier to piperacillin

Pseudomonas aeruginosa 579 biofilms formed on dialysis membranes retarded piperacillin diffusion. Treatment of biofilms with 5.0 mM CaCl2.2H2O prevented diffusion. Biofilms permitted equilibration of [14C]glucose. Thin-layer chromatography of fluids distal to untreated (viable and nonviable) and viable Ca(2+)-treated P. aeruginosa 579 biofilms and fluids distal to a viable P. aeruginosa mutant noninducible for the expression of beta-lactamase did not detect piperacillinoic acid.

Evidence for non-siderophore-mediated acquisition of transferrin-bound iron by Pasteurella multocida

Two clinical isolates of Pasteurella multocida associated with bovine pneumonia were examined for iron acquisition. Both isolates were capable of obtaining iron for growth from bovine but not from human, avian, equine or porcine transferrin. This correlated with specific binding of bovine transferrin by iron-limited cells or isolated membranes. No siderophore was detected in the strains by a general screening assay. In response to iron-limited conditions, a number of high molecular mass iron-regulated outer membrane proteins were produced including an 82 kDa receptor protein which was affinity isolated with biotinylated transferrin. In contrast, avian strains of P. multocida could not use transferrin-bound for growth and did not express either transferrin binding activity or the 82 kDa receptor protein.