Therapeutic targeting of leukocyte trafficking across the blood-brain barrier

The central nervous system (CNS) has long been regarded as an immune privileged organ implying that the immune system avoids the CNS not to disturb its homeostasis, which is critical for proper function of neurons. Meanwhile, it is accepted that immune cells do in fact gain access to the CNS and that immune responses are mounted within this tissue. However, the unique CNS microenvironment strictly controls these immune reactions starting with tightly regulating immune cell entry into the tissue. The endothelial blood-brain barrier (BBB) and the epithelial blood-cerebrospinal fluid (CSF) barrier control immune cell entry into the CNS, which is rare under physiological conditions. During a variety of pathological conditions of the CNS such as viral or bacterial infections, or during inflammatory diseases such as multiple sclerosis (MS), immunocompetent cells readily traverse the BBB and subsequently enter the CNS parenchyma. Most of our current knowledge on the molecular mechanisms involved in immune cell entry into the CNS has been derived from studies performed in experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Thus, a large part of our current knowledge on immune cell entry across the BBBs is based on the results obtained in this animal model. Similarly, knowledge on the benefits and potential risks associated with therapeutic targeting of immune cell recruitment across the BBB in human diseases are mostly derived from such treatment regimen in MS. Other mechanisms of immune cell entry into the CNS might therefore apply under different pathological conditions such as bacterial meningitis or stroke and need to be considered.

Disseminated Tuberculosis Following Total Knee Arthroplasty in an HIV Patient

Skeletal tuberculosis is now uncommon in developed countries. In immunocompromised patients - particularly in the HIV-infected - who present with subacute or chronic joint pain refractory to conventional treatment, osteoarticular tuberculosis should still be included in the differential diagnosis. We report on a lethal case of disseminated tuberculosis in an HIV-infected subject. Dissemination may have resulted from the implantation of an articular prosthesis in a knee joint with unsuspected osteoarticular tuberculosis. The diagnosis was established months later when the patient presented with far-advanced tuberculous meningitis, miliary tuberculosis of the lungs, femoral osteomyelitis and extended cold abscesses along the femoral shaft. Failure to respond to a conventional four-drug regimen is explained by the resistance pattern of his multi-drug resistant strain of Mycobacterium tuberculosis, which was only reported after the patient's death. This case illustrates the diagnostic challenges of osteoarticular tuberculosis and the consequences of a diagnostic delay in an HIV-infected individual.

[Acute infectious emergencies in adults in medical practice]

Infectious diseases belong to the most frequent reasons to seek emergency care. Life-threatening infectious emergencies, which require rapid diagnosis and hospitalisation, are, however, rare. Leading signs and symptoms are high fever combined with rapidly deteriorating general conditions, hypotonia, tachycardia, tachypnea, dyspnea, confusion, headache, or petechia or information about asplenia, immunosuppression or recent travel to the tropics. Life threatening situations, such as suspicion of invasive meningococcal infection or bacterial infection in an asplenic patient, septic-toxic shock, and acute bacterial meningitis with delayed hospitalisation require rapid start of empiric antibiotic therapy in the outpatient practice. In addition, acute infectious emergencies comprise situation for which post exposure prophylaxis is indicated.

Vancomycin acts synergistically with gentamicin against penicillin-resistant pneumococci by increasing the intracellular penetration of gentamicin

Vancomycin and gentamicin act synergistically against penicillin-resistant pneumococci in vitro and in experimental rabbit meningitis. The aim of the present study was to investigate the underlying mechanism of this synergism. The intracellular concentration of gentamicin was measured by using the following experimental setting. Bacterial cultures were incubated with either gentamicin alone or gentamicin plus vancomycin for a short period (15 min). The gentamicin concentration was determined before and after grinding of the cultures by using the COBAS INTEGRA fluorescence polarization system (Roche). The grinding efficacies ranged between 44 and 54%, as determined by viable cell counts. In the combination regimen the intracellular concentration of gentamicin increased to 186% compared to that achieved with gentamicin monotherapy. These data suggest that the synergy observed in vivo and in vitro is based on an increased intracellular penetration of the aminoglycoside, probably due to the effect of vancomycin on the permeability of the cell wall.

Comparative efficacies of antibiotics in a rat model of meningoencephalitis due to Listeria monocytogenes

The antibacterial activities of amoxicillin-gentamicin, trovafloxacin, trimethoprim-sulfamethoxazole (TMP-SMX) and the combination of trovafloxacin with TMP-SMX were compared in a model of meningoencephalitis due to Listeria monocytogenes in infant rats. At 22 h after intracisternal infection, the cerebrospinal fluid was cultured to document meningitis, and the treatment was started. Treatment was instituted for 48 h, and efficacy was evaluated 24 h after administration of the last dose. All tested treatment regimens exhibited significant activities in brain, liver, and blood compared to infected rats receiving saline (P < 0.001). In the brain, amoxicillin plus gentamicin was more active than all of the other regimens, and trovafloxacin was more active than TMP-SMX (bacterial titers of 4.1 +/- 0.5 log10 CFU/ml for amoxicillin-gentamicin, 5.0 +/- 0.4 log10 CFU/ml for trovafloxacin, and 5.8 +/- 0.5 log10 CFU/ml for TMP-SMX; P < 0.05). In liver, amoxicillin-gentamicin and trovafloxacin were similarly active (2.8 +/- 0.8 and 2.7 +/- 0.8 log10 CFU/ml, respectively) but more active than TMP-SMX (4.4 +/- 0. 6 log10 CFU/ml; P < 0.05). The combination of trovafloxacin with TMP-SMX did not alter the antibacterial effect in the brain, but it did reduce the effect of trovafloxacin in the liver. Amoxicillin-gentamicin was the most active therapy in this study, but the activity of trovafloxacin suggests that further studies with this drug for the treatment of Listeria infections may be warranted.

Toxicity of Streptococcus pneumoniae in neurons, astrocytes, and microglia in vitro

The toxicity of pneumococci and endotoxin in primary cultures of rat neurons, astrocytes, and microglia and in a human astrocyte and two human glial cell lines was determined. Heat-inactivated, rough pneumococci (up to 10(8) cfu/mL) or their cell wall (up to 50 micrograms/mL) produced dose-dependent toxicity after 48 h in microglial cells and to a lesser extent in astrocytes but not in neurons. Toxicity was similar for equivalent doses of heat-inactivated organisms and pneumococcal cell wall, but time-course experiments showed significant differences between the two stimuli. Endotoxin at concentrations of up to 5 micrograms/mL did not induce significant toxicity in any of the cells. Thus, pneumococci can induce toxicity in two brain cell types, microglia and astrocytes, and the pneumococcal cell wall appears to mediate toxicity. Direct toxic effects of bacteria on brain cells may in part be responsible for brain injury during meningitis.

Effect of a recombinant N-terminal fragment of bactericidal/permeability-increasing protein (rBPI23) on cerebrospinal fluid inflammation induced by endotoxin

Endotoxin triggers the subarachnoid inflammation of gram-negative meningitis. This study examined the ability of a recombinant N-terminal fragment of bactericidal/permeability-increasing protein (rBPI23) to block endotoxin-induced meningitis in rabbits. Intracisternal (ic) injection of 10-20 ng of meningococcal endotoxin induced high cerebrospinal fluid (CSF) concentrations of tumor necrosis factor (TNF) and CSF pleocytosis and increased CSF lactate concentrations. ic administration of rBPI23 significantly reduced meningococcal endotoxin-induced TNF release into CSF (P < .005), lactate concentrations (P < .001), and CSF white blood cell counts (P < .01). No such effect was observed in animals receiving intravenous rBPI23. Concentrations of rBPI23 in CSF were high after ic administration but low or undetectable after systemic administration. Thus, high concentrations of rBPI23 can effectively neutralize meningococcal endotoxin in CSF, but low CSF concentrations after systemic administration currently limit its potential usefulness as adjunctive drug treatment in gram-negative meningitis.

Experimental models of CNS infections. Contributions to concepts of disease and treatment

Lessons learned from studies of experimental meningitis and brain abscess in animal models of infection represent major, highly significant contributions to our understanding of the pathogenesis and antimicrobial chemotherapy of these infections. For example, studies of experimental meningitis in rabbits demonstrated that the subarachnoid space is deficient in local host defenses, a finding that explains why only bactericidal antibiotic regimens are effective in treating this disease; studies of the efficacy of corticosteroids as adjunctive therapy for meningitis yielded data indicating that both beneficial and detrimental effects on the host are imparted by these compounds. These and a number of other key investigations of experimental meningitis and brain abscess, the results of these investigations, and the clinical significance of these results are presented in this article.

Langerhans cell histiocytosis as differential diagnosis of a mediastinal tumor

We describe the case of a 55-year-old man who presented with parasternal swelling. The chest CT scan showed a large tumor of the chest wall infiltrating the subcutaneous tissue. To assume histologic diagnosis an open biopsy was performed. Between the myofibrils a coarse, white tumor with infiltrative growth was noted. Histopathologic examination revealed expanded atrophic skeletal muscle that was infiltrated by histiocytic cells. Numerous eosinophilic granulocytes and lymphocytes CD20 and CD3 positive could be detected and immunohistochemical staining was also positive for S-100 proteins and CD1a. Histologic findings were characteristic of Langerhans cell histiocytosis (LCH). To the best of our knowledge a LCH originating from the mediastinum in an adult as presented has not been previously described.

Mumps

Mumps is a common childhood infection caused by the mumps virus. The hallmark of infection is swelling of the parotid gland. Aseptic meningitis and encephalitis are common complications of mumps together with orchitis and oophoritis, which can arise in adult men and women, respectively; other complications include deafness and pancreatitis. Clinical diagnosis can be based on the classic parotid swelling; however, this feature is not present in all cases of mumps and can also occur in various other disorders. Laboratory diagnosis is based on isolation of virus, detection of viral nucleic acid, or serological confirmation (generally presence of IgM mumps antibodies). Mumps is vaccine-preventable, and one dose of mumps vaccine is about 80% effective against the disease. Routine vaccination has proven highly effective in reducing the incidence of mumps, and is presently used by most developed countries; however, there have been outbreaks of disease in vaccinated populations. In 2005, a large epidemic peaked in the UK, and in 2006 the American midwest had several outbreaks. In both countries, the largest proportion of cases was in young adults. In the UK, susceptible cohorts too old to have been vaccinated and too young to have been exposed to natural infections were the primary cause of the mumps epidemic. In the USA, effectiveness and uptake in combination appear not to have been sufficient to obtain herd immunity for mumps in populations such as college students.

Correlation of intravascular ultrasound findings with histopathological analysis of thrombus aspirates in patients with very late drug-eluting stent thrombosis

BACKGROUND: Intravascular ultrasound of drug-eluting stent (DES) thrombosis (ST) reveals a high incidence of incomplete stent apposition (ISA) and vessel remodeling. Autopsy specimens of DES ST show delayed healing and hypersensitivity reactions. The present study sought to correlate histopathology of thrombus aspirates with intravascular ultrasound findings in patients with very late DES ST. METHODS AND RESULTS: The study population consisted of 54 patients (28 patients with very late DES ST and 26 controls). Of 28 patients with very late DES ST, 10 patients (1020+/-283 days after implantation) with 11 ST segments (5 sirolimus-eluting stents, 5 paclitaxel-eluting stents, 1 zotarolimus-eluting stent) underwent both thrombus aspiration and intravascular ultrasound investigation. ISA was present in 73% of cases with an ISA cross-sectional area of 6.2+/-2.4 mm(2) and evidence of vessel remodeling (index, 1.6+/-0.3). Histopathological analysis showed pieces of fresh thrombus with inflammatory cell infiltrates (DES, 263+/-149 white blood cells per high-power field) and eosinophils (DES, 20+/-24 eosinophils per high-power field; sirolimus-eluting stents, 34+/-28; paclitaxel-eluting stents, 6+/-6; P for sirolimus-eluting stents versus paclitaxel-eluting stents=0.09). The mean number of eosinophils per high-power field was higher in specimens from very late DES ST (20+/-24) than in those from spontaneous acute myocardial infarction (7+/-10), early bare-metal stent ST (1+/-1), early DES ST (1+/-2), and late bare-metal stent ST (2+/-3; P from ANOVA=0.038). Eosinophil count correlated with ISA cross-sectional area, with an average increase of 5.4 eosinophils per high-power field per 1-mm(2) increase in ISA cross-sectional area. CONCLUSIONS: Very late DES thrombosis is associated with histopathological signs of inflammation and intravascular ultrasound evidence of vessel remodeling. Compared with other causes of myocardial infarction, eosinophilic infiltrates are more common in thrombi harvested from very late DES thrombosis, particularly in sirolimus-eluting stents, and correlate with the extent of stent malapposition.

Expression and Function of Siglec-8 in Human Eosinophils, Basophils, and Mast Cells

Siglec-8, the eighth member of the sialic acid-binding, immunoglobulin [Ig]-like lectin family, was initially discovered as a cell surface protein selectively expressed on human eosinophils. It is now know to also be expressed by mast cells and basophils. Siglec-8 engagement with specific antibodies causes apoptosis via caspase and mitochondrial-dependent pathways. For mast cells, inhibition of mediator release, but no apoptosis, is observed. Siglec-F is the closest mouse paralog to Siglec-8, and both selectively bind the sulfated glycan 6’-sulfo-sialyl Lewis X. Antibodies to Siglec-F reduce blood and tissue eosinophil numbers in vivo. This suggests that Siglec-8 may be a useful future therapeutic target for allergic and other eosinophilic disorders.

Effect of natural seasonal pollen exposure and repeated nasal allergen provocations on elevation of exhaled nitric oxide

BACKGROUND: Exhaled nitric oxide (FENO) is a marker for allergic airway inflammation. We wondered whether in patients with intermittent allergic rhinitis only (i) natural pollen exposure and (ii) artificial pollen exposure by repeated nasal allergen provocations may lead to an elevation of FENO. METHODS: In two prospective studies, we compared the FENO of nonatopic controls with the FENO of nonasthmatic individuals with mild intermittent rhinitis to tree and/or grass pollen. Study I: 13 atopic individuals and seven controls had measurements of FENO, blood eosinophils and eosinophilic cationic protein (ECP) before, during and after pollen season. Study II: 16 atopic individuals and 12 controls had nasal allergen provocations on four following days out of pollen season, with daily measurements of FENO before, 2 and 6 h after provocation, and determination of blood eosinophils, ECP and FEV1 at baseline, on days 5 and 10-12. RESULTS: Natural pollen exposure (study I) caused a significant elevation of FENO in allergic individuals. Nasal allergen provocations (study II) did not elicit a statistically significant rise neither of FENO nor of blood eosinophils between baseline and day 5. However, a subgroup of four individuals with a rise of blood eosinophils during nasal allergen provocations showed also a rise of FENO. CONCLUSIONS: We suppose that in allergic rhinitis a concomitant reaction of the bronchial system is dependent on a strong local inflammation leading to a generalized immune stimulation.

[The comatose child]

The child who presents with acute coma runs a high risk of cardiopulmonary insufficiency, direct brain injury or even cerebral herniation. The case-management of such child requires a coma-specific emergent evaluation, immediate treatment of any hypoxicischemic insults and of the underlying cause. The coma-specific examination includes performance of child-adapted Glasgow Coma Score, the evaluation of brain stem functions such as pupillary response to light, cough- and gag reflex, and determination of all vital signs including body temperature. Treatment of hypoxicischemic insults includes control of airways and ventilation in patient with coma defined as GCS <8; liberal treatment of impaired cardiovascular states with isotonic fluids such as 0.9% sodium chloride; and treatment of cerebral herniation with head elevation, mannitol, hypertonic sodium chlorid fluids, steroids and hyperventilation. Immediately treatable causes are hypoglycemia, meningitis/encephalitis, opioid overdose and status epilepticus. Exclusion of rapidly progressive intracranial lesions almost always requires referral to the tertiary centre with head CT-scan facilities. Finally, an extensive etiology search of the stable coma is performed by looking for disease or trauma of the brain, for metabolic causes, for intoxications and for cardiopulmonary problems.

Microvascular decompression for trigeminal neuralgia in the elderly: long-term treatment outcome and comparison with younger patients

OBJECTIVE: Multiple studies have proved that microvascular decompression (MVD) is the treatment of choice in cases of medically refractory trigeminal neuralgia (TN). In the elderly, however, the surgical risks related to MVD are assumed to be unacceptably high and various alternative therapies have been proposed. We evaluated the outcomes of MVD in patients aged older than 65 years of age and compared them with the outcomes in a matched group of younger patients. The focus was on procedure-related morbidity rate and long-term outcome. METHODS: This was a retrospective study of 112 patients with TN operated on consecutively over 22 years. The main outcome measures were immediate and long-term postoperative pain relief and neurological status, especially function of trigeminal, facial, and cochlear nerves, as well as surgical complications. A questionnaire was used to assess long-term outcome: pain relief, duration of a pain-free period, need for pain medications, time to recurrence, pain severity, and need for additional treatment. RESULTS: The mean age was 70.35 years. The second and third branches of the trigeminal nerve were most frequently affected (37.3%). The mean follow-up period was 90 months (range, 48-295 months). Seventy-five percent of the patients were completely pain free, 11% were never pain free, and 14% experienced recurrences. No statistically significant differences existed in the outcome between the younger and older patient groups. Postoperative morbidity included trigeminal hypesthesia in 6.25%, hypacusis in 5.4%, and complete hearing loss, vertigo, and partial facial nerve palsy in 0.89% each. Cerebrospinal fluid leak and meningitis occurred in 1 patient each. There were no mortalities in both groups. CONCLUSION: MVD for TN is a safe procedure even in the elderly. The risk of serious morbidity or mortality is similar to that in younger patients. Furthermore, no significant differences in short- and long-term outcome were found. Thus, MVD is the treatment of choice in patients with medically refractory TN, unless their general condition prohibits it.