Surface modification of poly(methyl-methacrylate) with farnesol to prevent Candida biofilm formation.

Candida albicans promotes biofilm formation on dentures, which compromises the use of poly(methyl-methacrylate) (PMMA) as a dental material. Farnesol (FAR), a natural compound that prevents C. albicans filamentation and biofilm formation, was incorporated into the PMMA matrix, to obtain antifungal PMMA_FAR materials. The tested concentrations (0·0125% and 0·4%) of FAR, 24 h after incubation on YPD agar, inhibited filamentation of C. albicans. PMMA was modified with different FAR concentrations (3-12%), and physicochemical properties, antifungal activity and cytotoxicity of these modified materials (PMMA_FAR) were tested. The presence of FAR in PMMA_FAR composites was verified by Fourier-transform infrared spectroscopy (FT-IR). Incorporation of FAR into the polymeric matrix significantly decreased hydrophilicity at all tested concentrations and significantly reduced biofilm and planktonic cells metabolic activity in the early stage of biofilm formation at ≥6% FAR in PMMA. PMMA_FAR composites with <9% FAR were non-toxic. Modification of PMMA with FAR is a good strategy for reducing C. albicans biofilm formation on dentures.

Neglected nano-effects of nanoparticles in the interpretation of their toxicity.

Nanoparticles with smaller diameters have larger surface areas. Unfortunately, this fact is often neglected in their biomedical characterization, e.g. in the evaluation of their toxicity with cell viability tests. We here point out the different scientific conclusions drawn in such tests when considering the traditional mass or concentration of nanoparticles, or their surface areas.

ATP and NADPH coated iron oxide nanoparticles for targeting of highly metabolic tumor cells.

The metabolic activity of tumor cells is known to be higher as compared to that of normal cells, which has been previously exploited to deliver nanomedicines to highly metabolic tumor cells. Unfortunately, current strategies, which are mostly based on complex energy sources, such as sugars, showed insufficient accumulation at the target sites. We here report the coating of IONPs with two essential units of cellular metabolism: adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). ATP and NADPH were directly bound to the IONPs' surface using a simple aqueous method. Both molecules were used as coatings, i.e. as stabilizing agents, but also simultaneously as targeting molecules to deliver IONPs to highly metabolic tumor cells. Indeed, we found that the uptake of ATP-IONPs and NADPH-IONPs is correlated with the metabolic activity of tumor cells, especially regarding their cellular ATP levels and NADPH consumption. We also measured one of the highest MRI r2 relaxivities for both ATP-IONPs and NADPH-IONPs. With the direct coating of IONPs with ATP and NADPH, we therefore provide an optimal platform to stabilize IONPs and at the same time promising properties for the targeting and detection of highly metabolic tumor cells.

Pituitary adenoma: a DNA flow cytometric study of 192 clinicopathologically characterized tumors.

A clinically, immunohistochemically and ultrastructurally characterized series of 192 pituitary adenomas was analyzed for DNA content by flow cytometry. Results were assessed not only relative to tumor immunotype, size, and invasiveness, but also with frequency of recurrence. Case selection was non-random; males predominated (1.8:1) and the ratio of macro-to-microadenomas was 4.2:1. Female patients were slightly younger and, in all adenoma categories, less often had invasive tumors: PRL (15%/30%), ACTH (17%/44%), LH/FSH (8%/27%) and null cell adenomas (0%/27%). With the exception of prolactin cell adenomas, similar proportions of macroadenomas and invasive tumors in all tumor subtypes were diploid and non-diploid. Prolactin adenomas differed in that tumors of males showed a high rate of non-diploidy (65%); such tumors were predominantly macroadenomas, but only 28% were invasive. Among GH-containing tumors 78% were macroadenomas, 40% were nondiploid, and the frequency of invasive macroadenomas was higher (49%) than in PRL tumors (21%). ACTH adenomas were mainly microadenomas (81%), their rate invasion (29%) and of non-diploidy being low (14%). Among "non-functioning" (LH/FSH, null cell adenomas), LH/FSH-producing tumors were all macroadenomas, but with low rates of invasion (23%) and non-diploidy (9%). Null cell adenomas, nearly all macroadenomas, had similar low invasion rate (21%), but were more often non-diploid (39%). In all adenoma subgroups S-phase fractions were higher in non-diploid adenomas by an overall ratio of 2.1:1. Prolactin adenomas showed the highest (15.2%) and LH/FSH adenomas the lowest (5.6%) mean S-phase fraction. When compared to long-term follow-up, neither this parameter nor ploidy correlated with tumor size or invasiveness. Lastly, long-term follow-up showed ploidy to be an unreliable predictor of tumor persistence or recurrence.

Benign paragangliomas: clinical presentation and treatment outcomes in 236 patients.

Paragangliomas are rare tumors that arise from extraadrenal chromaffin cells. We examined the clinical characteristics, location, treatment, and outcome of 236 patients (141 females, 60%) with 297 benign paragangliomas evaluated at the Mayo Clinic during 1978-1998. The mean age (+/-SD) at diagnosis was 47 +/- 16 yr. Of the 297 paragangliomas, 205 were in the head and neck region, and 92 were below the neck. Paragangliomas were discovered and diagnosed incidentally on imaging studies in 9% of patients. Biochemical screening was performed in 128 patients; 40 patients (17% of the total and 31% of those screened) had hyperfunctional tumors. Of the 40 patients with tumoral catecholamine excess, 38 had documented hypertension. In patients identified with catecholamine-secreting paragangliomas, the sensitivities achieved by measurements in the 24-h urine collection were 74% for total metanephrines, 84% for norepinephrine, 18% for dopamine, and 14% for epinephrine. Multiple imaging modalities were used for tumor localization. The false negative rates were 0% for magnetic resonance imaging, 5.8% for computed tomography, 3.4% for angiography, 10.7% for ultrasonography, and 39% for radioactive iodine-labeled metaiodobenzylguanidine scintigraphy. Of 192 patients (81.4%) with follow-up data (mean, 43.9 months; range, 0.5-240), operative cure was achieved in 133 (69%). Of the 59 patients without cure, 23 had persistent disease, 5 had recurrent disease, 16 had multiple persistent synchronous tumors, and 15 subsequently developed metachronous tumors. In conclusion, most paragangliomas are nonhypersecretory and located in the head and neck region. Magnetic resonance imaging was associated with the lowest false negative rate, and metaiodobenzylguanidine was the least sensitive imaging study. A significant proportion of patients (31%) has persistent or recurrent disease, and long-term follow-up is important.

Post-traumatic cerebrospinal fluid leakage.

Posttraumatic cerebrospinal fluid (CSF) leakage frequently complicates skull base fractures. While most CSF leaks will cease without treatment, patients with persistent CSF leaks may be at increased risk for meningitis, and many will require surgical intervention. We reviewed the medical records of 51 patients treated between 1984 and 1998, with CSF leaks that persisted for 24 hours or longer after head trauma. Twenty-eight patients (53%) had spontaneous resolution of the leakage at an average of 5 days. Twenty-three patients (47%) required surgery. Eight patients (16%) had occult leaks presenting with recurrent meningitis at an average of 6.5 years posttrauma. Forty-three (84%) patients with CSF leaks had an associated skull fracture, most commonly involving the frontal sinus, while only 18 patients (35%) had parenchymal brain injury or extra-axial hematoma. Eight patients (16%) had delayed leaks at an average of 13 days posttrauma. Among patients with clinically evident CSF leakage the frequency of meningitis was 10% with antibiotic prophylaxis, and 21% without antibiotic prophylaxis. Thus, prophylactic antibiotic administration halved risk of meningitis. A variety of surgical approaches was used, with minimal morbidity. Three of 23 surgically treated patients (13%) required additional surgery for continued leakage. Patients with CSF leaks that persist greater than 24 hours are at risk for meningitis, and many will require surgical intervention. Prophylactic antibiotics may be effective and should be considered in this group of patients. Patients with skull fractures involving the skull base or frontal sinus should be followed for delayed leakage. Surgical outcome is excellent.

Symptomatic C1-2 fusion failure due to a fracture of the lateral C-1 posterior arch in a patient with rheumatoid arthritis. Case report and review of the literature.

The authors report a case in which the lateral C-1 arch fractured in a patient with rheumatoid arthritis and an intact fusion mass; this patient had previously undergone a C1-2 Brooks-type fusion. This unique complication occurred secondary to continued resorption of the C1-2 rheumatoid pannus. Two years after occipitocervical fusion the patient has made a complete neurological recovery.

Developmental control of endocytosis in dendritic cells by Cdc42.

Dendritic cells (DCs) developmentally regulate antigen uptake by controlling their endocytic capacity. Immature DCs actively internalize antigen. However, mature DCs are poorly endocytic, functioning instead to present antigens to T cells. We have found that endocytic downregulation reflects a decrease in endocytic activity controlled by Rho family GTPases, especially Cdc42. Blocking Cdc42 function by Toxin B treatment or injection of dominant-negative inhibitors of Cdc42 abrogates endocytosis in immature DCs. In mature DCs, injection of constitutively active Cdc42 or microbial delivery of a Cdc42 nucleotide exchange factor reactivates endocytosis. DCs regulate endogenous levels of Cdc42-GTP with activated Cdc42 detectable only in immature cells. We conclude that DCs developmentally regulate endocytosis at least in part by controlling levels of activated Cdc42.

Herpes simplex virus type 1 entry into host cells: reconstitution of capsid binding and uncoating at the nuclear pore complex in vitro.

During entry, herpes simplex virus type 1 (HSV-1) releases its capsid and the tegument proteins into the cytosol of a host cell by fusing with the plasma membrane. The capsid is then transported to the nucleus, where it docks at the nuclear pore complexes (NPCs), and the viral genome is rapidly released into the nucleoplasm. In this study, capsid association with NPCs and uncoating of the viral DNA were reconstituted in vitro. Isolated capsids prepared from virus were incubated with cytosol and purified nuclei. They were found to bind to the nuclear pores. Binding could be inhibited by pretreating the nuclei with wheat germ agglutinin, anti-NPC antibodies, or antibodies against importin beta. Furthermore, in the absence of cytosol, purified importin beta was both sufficient and necessary to support efficient capsid binding to nuclei. Up to 60 to 70% of capsids interacting with rat liver nuclei in vitro released their DNA if cytosol and metabolic energy were supplied. Interaction of the capsid with the nuclear pore thus seemed to trigger the release of the viral genome, implying that components of the NPC play an active role in the nuclear events during HSV-1 entry into host cells.

Transport of peptide-MHC class II complexes in developing dendritic cells.

Major histocompatibility complex class II (MHC II) molecules capture peptides within the endocytic pathway to generate T cell receptor (TCR) ligands. Immature dendritic cells (DCs) sequester intact antigens in lysosomes, processing and converting antigens into peptide-MHC II complexes upon induction of DC maturation. The complexes then accumulate in distinctive, nonlysosomal MHC II+ vesicles that appear to migrate to the cell surface. Although the vesicles exclude soluble lysosomal contents and antigen-processing machinery, many contain MHC I and B7 costimulatory molecules. After arrival at the cell surface, the MHC and costimulatory molecules remain clustered. Thus, transport of peptide-MHC II complexes by DCs not only accomplishes transfer from late endocytic compartments to the plasma membrane, but does so in a manner that selectively concentrates TCR ligands and costimulatory molecules for T cell contact.

Large-scale culture and selective maturation of human Langerhans cells from granulocyte colony-stimulating factor-mobilized CD34+ progenitors.

Dendritic cells (DCs) play a critical role as APCs in the induction of the primary immune response. Their capacity for Ag processing and presentation is tightly regulated, controlled by a terminal developmental sequence accompanied by striking changes in morphology, organization, and function. The maturation process, which converts DCs from cells adapted for Ag accumulation to cells adapted for T cell stimulation, remains poorly understood due in part to difficulties in the culture and manipulation of DCs of defined lineages. To address these issues, we have devised conditions for the culture of a single DC type, Langerhans cells (LCs), using CD34+ cells from G-CSF-mobilized patients. Homogenous populations of LCs, replete with abundant immunocytochemically demonstrable Birbeck granules, could be stably maintained as immature DCs for long periods in culture. Unlike other human DC preparations, the LCs remained fully differentiated after cytokine removal. Following exposure to TNF-alpha, LPS, or CD40 ligand, the LCs could be synchronously induced to mature. Depending on the agent used, distinct types of LCs emerged differing in their capacity for T cell stimulation, IL-12 production, intracellular localization of MHC products, and overall morphology. Most interestingly, the expression of different sets of Toll family receptors is induced or down-regulated according to the maturation stimulus provided. These results strongly suggest that different proinflammatory stimuli might drive distinct developmental events.

Persistent posttraumatic cerebrospinal fluid leakage.

OBJECT: Persistent posttraumatic cerebrospinal fluid (CSF) leakage frequently complicates skull base fractures. Although many CSF leaks will cease without treatment, patients with CSF leaks that persist greater than 24 hours may be at increased risk for meningitis, and many will require surgical intervention. The authors reviewed their 15-year experience with posttraumatic CSF leaks that persisted longer than 24 hours. METHODS: The authors reviewed the medical records of 51 patients treated between 1984 and 1998 with CSF leaks that persisted for 24 hours or longer after traumatic head injury. In 27 patients (55%) spontaneous resolution of CSF leakage occurred at an average of 5 days posttrauma. In 23 patients (45%) surgery was required to resolve the leakage. Eight patients (16%) with occult CSF leaks presented with recurrent meningitis at an average of 6.5 years posttrauma. Forty-three (84%) patients with CSF leaks sustained a skull fracture, most commonly involving the frontal sinus, whereas parenchymal brain injury or extraaxial hematoma was demonstrated in only 18 patients (35%). Delayed CSF leaks, with an average onset of 13 days posttrauma, were observed in eight patients (16%). Among patients with clinically evident CSF leakage, the frequency of meningitis was 10% with antibiotic prophylaxis, and 21% without antibiotic prophylaxis. Thus, prophylactic antibiotic administration halved the risk of meningitis. A variety of surgical approaches was used, and no significant neurological morbidity occurred. Three (13%) of 23 surgically treated patients required additional surgery to treat continued CSF leakage. CONCLUSIONS: A significant proportion of patients with CSF leaks that persist greater than 24 hours will require surgical intervention. Prophylactic antibiotic therapy may be effective in this group of patients. Patients with skull base or frontal sinus fractures should be followed to detect the occurrence of delayed leakage. Surgery-related outcome is excellent.

Tension pneumocranium, a rare complication of transsphenoidal pituitary surgery: Mayo Clinic experience 1976-1998.

We describe four cases of symptomatic pneumocranium, a rare, potentially life-threatening complication of transsphenoidal pituitary surgery. Symptomatic pneumocranium manifested as impaired mental status, headaches, and grand mal seizures, early in the postoperative course after transsphenoidal pituitary surgery. Furthermore, a Cushing response, including systemic hypertension and bradycardia (secondary to intracranial hypertension) was seen, which has not been previously described in association with symptomatic pneumocranium. We describe a previously unreported risk factor for tension pneumocranium, untreated obstructive sleep apnea. Other factors predisposing to tension pneumocranium in our patients included: cerebrospinal fluid leaks, postoperative positive-pressure mask ventilation, large pituitary tumors, and intraoperative lumbar drainage catheters. Surgical drainage of the pneumocranium and repair of any coexistent cerebrospinal fluid leak markedly improved neurologic status. Symptomatic pneumocranium occurring early in the postoperative course after transsphenoidal pituitary surgery is rare, but prompt recognition and treatment of this condition can be life-saving.

Headache after resection of acoustic neuroma.

Long-lasting severe headaches are reported to occur in up to 83% of patients who have undergone resection of acoustic neuroma, especially through a suboccipital approach. These headaches, however, are not well defined. The objective of this study was to assess the frequency and character of new-onset headaches after resection of acoustic neuroma by a suboccipital approach with cranioplasty. Review of the medical record was followed by a telephone interview with 48 patients (67% female; mean age, 52 years) who had undergone resection of an acoustic neuroma through a suboccipital craniotomy during the 2 years before the study. Of the 48 patients, 58% had post-operative head pain that lasted more than 7 days and could be categorized into two types. A moderate to severe, short-term head pain with gradual resolution occurred in 35% of the patients, and a mild, unremitting pain was reported by 23%. Both types of pain had a dull ache or pressure quality and were adjacent to or confined to the incisional area. Overall, 77% of the patients were pain-free within 4 months after operation. Age, sex, tumor size, or preoperative history of headache did not influence development of the postoperative pain. We found that new-onset headache after resection of acoustic neuroma by a suboccipital approach with cranioplasty is much less common than previously reported and is best described as mild incisional pain rather than a severe headache. The literature regarding headaches after different surgical approaches for acoustic neuroma resection is reviewed, and possible explanations for development of the pain are discussed.

Venous air embolism in sitting and supine patients undergoing vestibular schwannoma resection.

OBJECTIVE: This study retrospectively compares the incidence of venous air embolism (VAE) detection and morbidity in the sitting and supine positions. All patients underwent vestibular schwannoma resection via the retrosigmoid approach by a single surgical team. METHODS: A total of 432 consecutive operations were reviewed, 222 of which were performed with the patients in the sitting position and 210 of which were performed with the patients in the supine position. Charts were reviewed for evidence of intraoperative VAE, intraoperative hypotension secondary to VAE, postoperative morbidity related to VAE, and other variables to compare the groups. RESULTS: This study demonstrated a 28% incidence of VAE detection when patients were in the sitting position compared to a 5% incidence of VAE detection when patients were in the supine position (P < 0.0001). Intraoperative hypotension secondary to VAE was noted in 1.8% of the sitting patients and 1.4% of the supine patients (P=0.72, no significant difference). Postoperative morbidity caused by VAE was noted in one sitting patient (0.5%) (pulmonary edema) and in no supine patients (P=0.48, no significant difference). Blood loss was slightly greater in the supine group, and operative times were similar in both groups, despite that the average tumor size of patients operated on in the sitting position was 2.8 cm versus 2.2 cm in the supine group (P < 0.0001). CONCLUSION: Our results indicate that although there is a higher incidence of VAE detection in sitting patients, the morbidity is not statistically greater. We conclude that because morbidity from VAE is similar in either position, patient positioning should be based on surgical team preference.

Long-term outcome of lumbar discectomy in children and adolescents sixteen years of age or younger.

We retrospectively reviewed the cases of seventy-two consecutive patients who had a lumbar discectomy, between 1950 and 1983, when they were sixteen years of age or younger. There were forty boys and thirty-two girls. At the time of the lumbar discectomy, twelve patients (17 per cent) also had a spinal arthrodesis. The mean duration of follow-up was 27.8 years (range, twelve to forty-five years). Twenty patients (28 per cent) had one reoperation or more, with the first reoperation performed at a mean of 9.7 years after the initial discectomy. Fourteen patients had one reoperation, four had two reoperations, one had three, and one had five. Fifty-two patients (72 per cent) did not need a reoperation. At the time of the latest follow-up, forty-eight (92 per cent) of the fifty-two patients either had no pain or had occasional pain related to strenuous activity and fifty-one (98 per cent) could participate in daily activities with no or mild limitations. Survivorship analysis showed that the overall probability that a patient would not need a reoperation was 80 per cent at ten years and 74 per cent at twenty years after the initial operation. With the numbers available for study, we could not show that age, gender, or an arthrodesis performed at the time of the initial operation were risk factors for a reoperation. We could not detect a difference, with respect to pain or the level of activity, between the patients who had had an arthrodesis at the initial operation and those who had not or between those who had a coexisting structural abnormality of the lumbar spine and those who did not.

Surgical treatment of spontaneous spinal cerebrospinal fluid leaks.

OBJECT: Spontaneous spinal cerebrospinal fluid (CSF) leaks are an increasingly recognized cause of intracranial hypotension and may require neurosurgical intervention. In the present report the authors review their experience with the surgical management of spontaneous spinal CSF leaks. METHODS: Between 1992 and 1997, 10 patients with spontaneous spinal CSF leaks and intracranial hypotension were treated surgically. The mean age of the seven women and three men was 42.3 years (range 22-61 years). Preoperative imaging showed a single meningeal diverticulum in two patients, a complex of diverticula in one patient, and a focal CSF leak alone in seven patients. Surgical exploration in these seven patients demonstrated meningeal diverticula in one patient; no clear source of CSF leakage could be identified in the remaining six patients. Treatment consisted of ligation of the diverticula or packing of the epidural space with muscle or Gelfoam. Multiple simultaneous spinal CSF leaks were identified in three patients. CONCLUSIONS: All patients experienced complete relief of their headaches postoperatively. There has been no recurrence of symptoms in any of the patients during a mean follow-up period of 19 months (range 3-58 months; 16 person-years of cumulative follow up). Complications consisted of transient intracranial hypertension in one patient and leg numbness in another patient. Although the disease is often self-limiting, surgical treatment has an important role in the management of spontaneous spinal CSF leaks. Surgery is effective in eliminating the headaches and the morbidity is generally low. Surgical exploration for a focal CSF leak, as demonstrated on radiographic studies, usually does not reveal a clear source of the leak. Some patients may have multiple simultaneous CSF leaks.

Cell wall 1,6-beta-glucan synthesis in Saccharomyces cerevisiae depends on ER glucosidases I and II, and the molecular chaperone BiP/Kar2p.

The role of glucose trimming in the endoplasmic reticulum of Saccharomyces cerevisiae was investigated using glucosidase inhibitors and mutant strains devoid of glucosidases I and II. These glucosidases are responsible for removing glucose residues from the N-linked core oligosaccharides attached to newly synthesized polypeptide chains. In mammalian cells they participate together with calnexin, calreticulin and UDP-glucose:glycoprotein glucosyltransferase in the folding and quality control of newly synthesized glycoproteins. In S.cerevisiae, glucosidase II is encoded by the GLS2 gene, and glucosidase I, as suggested here, by the CWH41 gene. Using castanospermine (an alpha-glucosidase inhibitor) and yeast strains defective in glucosidase I, glucosidase II and BiP/Kar2p, it was demonstrated that cell wall synthesis depends on the two glucosidases and BiP/Kar2p. In double mutants with defects in both BiP/Kar2p and either of the glucosidases the phenotype was particularly clear: synthesis of 1,6-beta-glucan_a cell wall component_was reduced; the cell wall displayed abnormal morphology; the cells aggregated; and their growth was severely inhibited. No defects in protein folding or secretion could be detected. We concluded that glucose trimming in S.cerevisiae is necessary for proper cell wall synthesis, and that the glucosidases function synergistically with BiP/Kar2p in this process.