Photochemical modification and patterning of polymer surfaces by surface adsorption of photoactive block copolymers

We report a simple photolithographic approach for the creation and micropatterning of chemical functionality on polymer surfaces by use of surface-active block copolymers that contain protected photoactive functional groups. The block copolymers self-assemble at the substrate-air interface to generate a surface that is initially hydrophobic with low surface tension but that can be rendered hydrophilic and functional by photodeprotection with UV radiation. The block copolymer employed, poly(styrene-b-tert butyl acrylate), segregates preferentially to the surface of a polystyrene substrate because of the low surface tension of the polyacrylate blocks. The strong adsorption of block copolymers causes a bilayer structure to form presenting a photoactive polyacrylate layer at the surface. In the example described, the tert-butyl ester groups on the polyacrylate blocks are deprotected by exposure to UV radiation in the presence of added photoacid generators to form surface carboxylic acid groups. Surface micropatterns of carboxylic acid groups are generated by UV exposure through a contact mask. The success of surface chemical modification and pattern formation is demonstrated by X-ray photoelectron spectroscopy and contact angle measurements along with imaging by optical and fluorescence microscopy methods. The resultant chemically patterned surfaces are then used to template patterns of various biomolecules by means of selective adsorption, covalent bonding and molecular recognition mechanisms. The surface modification/patterning concept can be applied to virtually any polymeric substrate because protected functional groups have intrinsically low surface tensions, rendering properly designed block copolymers surface active in almost all polymeric substrates.

Severe acute respiratory syndrome: report of treatment and outcome after a major outbreak

BACKGROUND

The outcome is reported of a prospective uncontrolled study based on a stepwise treatment protocol during an outbreak of severe acute respiratory syndrome (SARS) in Hong Kong.

METHOD

One hundred and thirty eight patients were treated with broad spectrum antibiotics, a combination of ribavirin and low dose corticosteroid, and then intravenous high dose methylprednisolone according to responses. Sustained response to treatment was defined as (1) defervescence for > or =4 consecutive days, (2) resolution of lung consolidation by >25%, and (3) oxygen independence by the fourth day without fever. Patients with defervescence who achieved either criterion 2 or 3 were classified as partial responders. Patients who fell short of criteria 2 and 3 were non-responders.

RESULTS

Laboratory confirmation of SARS coronavirus infection was established in 132 (95.7%). None responded to antibiotics but 25 (18.1%) responded to ribavirin + low dose corticosteroid. Methylprednisolone was used in 107 patients, of whom 95 (88.8%) responded favourably. Evidence of haemolytic anaemia was observed in 49 (36%). A high level of C-reactive protein at presentation was the only independent predictor for use of methylprednisolone (odds ratio 2.18 per 10 mg/dl increase, 95% confidence interval 1.12 to 4.25, p = 0.02). Thirty seven patients (26.8%) required admission to the intensive care unit and 21 (15.2%) required invasive mechanical ventilation. There were 15 deaths (mortality rate 10.9%), most with significant co-morbidities, whereas 122 (88.4%) had been discharged home 4 months after the outbreak onset.

CONCLUSION

The use of high dose pulse methylprednisolone during the clinical course of a SARS outbreak was associated with clinical improvement, but randomised controlled trials are needed to ascertain its efficacy in this condition.

Exercise reverses the harmful effects of consumption of a high-fat diet on synaptic and behavioral plasticity associated to the action of brain-derived neurotrophic factor

A diet high in total fat (HF) reduces hippocampal levels of brain-derived neurotrophic factor (BDNF), a crucial modulator of synaptic plasticity, and a predictor of learning efficacy. We have evaluated the capacity of voluntary exercise to interact with the effects of diet at the molecular level. Animal groups were exposed to the HF diet for 2 months with and without access to voluntary wheel running. Exercise reversed the decrease in BDNF and its downstream effectors on plasticity such as synapsin I, a molecule with a key role in the modulation of neurotransmitter release by BDNF, and the transcription factor cyclic AMP response element binding protein (CREB), important for learning and memory. Furthermore, we found that exercise influenced the activational state of synapsin as well as of CREB, by increasing the phosphorylation of these molecules. In addition, exercise prevented the deficit in spatial learning induced by the diet, tested in the Morris water maze. Furthermore, levels of reactive oxygen species increased by the effects of the diet were decreased by exercise. Results indicate that exercise interacts with the same molecular systems disrupted by the HF diet, reversing their effects on neural function. Reactive oxygen species, and BDNF in conjunction with its downstream effectors on synaptic and neuronal plasticity, are common molecular targets for the action of the diet and exercise. Results unveil a possible molecular mechanism by which lifestyle factors can interact at a molecular level, and provide information for potential therapeutic applications to decrease the risk imposed by certain lifestyles.

Pulmonary pathological features in coronavirus associated severe acute respiratory syndrome (SARS)

BACKGROUND

Severe acute respiratory syndrome (SARS) became a worldwide outbreak with a mortality of 9.2%. This new human emergent infectious disease is dominated by severe lower respiratory illness and is aetiologically linked to a new coronavirus (SARS-CoV).

METHODS

Pulmonary pathology and clinical correlates were investigated in seven patients who died of SARS in whom there was a strong epidemiological link. Investigations include a review of clinical features, morphological assessment, histochemical and immunohistochemical stainings, ultrastructural study, and virological investigations in postmortem tissue.

RESULTS

Positive viral culture for coronavirus was detected in most premortem nasopharyngeal aspirate specimens (five of six) and postmortem lung tissues (two of seven). Viral particles, consistent with coronavirus, could be detected in lung pneumocytes in most of the patients. These features suggested that pneumocytes are probably the primary target of infection. The pathological features were dominated by diffuse alveolar damage, with the presence of multinucleated pneumocytes. Fibrogranulation tissue proliferation in small airways and airspaces (bronchiolitis obliterans organising pneumonia-like lesions) in subpleural locations was also seen in some patients.

CONCLUSIONS

Viable SARS-CoV could be isolated from postmortem tissues. Postmortem examination allows tissue to be sampled for virological investigations and ultrastructural examination, and when coupled with the appropriate lung morphological changes, is valuable to confirm the diagnosis of SARS-CoV, particularly in clinically unapparent or suspicious but unconfirmed cases.

Multiple brain abscesses in a patient with bilateral pulmonary arteriovenous malformations and immunoglobulin deficiency

A 34 year old Chinese man presented with grand mal seizures complicating multiple brain abscesses caused by mixed oral flora. Because of persistent hypoxaemia contrast spiral thoracic computed tomography was done, which revealed bilateral pulmonary arteriovenous malformations (PAVMs). Concomitant IgA and IgG subclass deficiency was also found. The combination of these two conditions appears to have predisposed this patient to presumably paradoxical septic embolism. The patient's cerebral condition responded to postoperative antibiotic treatment and he eventually received selective coil embolisation of right lower lobe PAVMs, which relieved his hypoxaemia and dyspnoea.

Schwann cells and astrocytes induce synapse formation by spinal motor neurons in culture

Glia constitute 90% of cells in the human nervous system, but relatively little is known about their functions. We have been focusing on the potential synaptic roles of glia in the CNS. We recently found that astrocytes increase the number of mature, functional synapses on retinal ganglion cells (RGCs) by sevenfold and are required for synaptic maintenance in vitro. These observations raised the question of whether glia similarly enhance synapse formation by other neuron types. Here we have investigated whether highly purified motor neurons isolated from developing rat spinal cords are able to form synapses in the absence of glia or whether glia similarly enhance synapse number. We show that spinal motor neurons (SMNs) form few synapses unless Schwann cells or astrocytes are present. Schwann cells increase the number of functional synapses by ninefold as measured by immunostaining, and increase spontaneous synaptic activity by several hundredfold. Surprisingly, the synapses formed between spinal motor neurons were primarily glutamatergic, as they could be blocked by CNQX. This synapse-promoting activity is not mediated by direct glial-neuronal cell contact but rather is mediated by secreted molecule(s) from the Schwann cells, as we previously found for astrocytes. Interestingly, the synapse-promoting activity from astrocytes and Schwann cells was functionally similar: Schwann cells also promoted synapse formation between retinal ganglion cells, and astrocytes promoted synapse formation between spinal motor neurons. These studies show that both astrocytes and Schwann cells strongly promote synapse formation between spinal motor neurons and demonstrate that glial regulation of synaptogenesis extends to other neuron types.

Voluntary exercise following traumatic brain injury: brain-derived neurotrophic factor upregulation and recovery of function

Voluntary exercise leads to an upregulation of brain-derived neurotrophic factor (BDNF) and associated proteins involved in synaptic function. Activity-induced enhancement of neuroplasticity may be considered for the treatment of traumatic brain injury (TBI). Given that during the first postinjury week the brain is undergoing dynamic restorative processes and energetic changes that may influence the outcome of exercise, we evaluated the effects of acute and delayed exercise following experimental TBI. Male Sprague-Dawley rats underwent either sham or lateral fluid-percussion injury (FPI) and were housed with or without access to a running wheel (RW) from postinjury days 0-6 (acute) or 14-20 (delayed). FPI alone resulted in significantly elevated levels of hippocampal phosphorylated synapsin I and phosphorylated cyclic AMP response element-binding-protein (CREB) at postinjury day 7, of which phosphorylated CREB remained elevated at postinjury day 21. Sham and delayed FPI-RW rats showed increased levels of BDNF, following exercise. Exercise also increased phosphorylated synapsin I and CREB in sham rats. In contrast to shams, the acutely exercised FPI rats failed to show activity-dependent BDNF upregulation and had significant decreases of phosphorylated synapsin I and total CREB. Additional rats were cognitively assessed (learning acquisition and memory) by utilizing the Morris water maze after acute or delayed RW exposure. Shams and delayed FPI-RW animals benefited from exercise, as indicated by a significant decrease in the number of trials to criterion (ability to locate the platform in 7 s or less for four consecutive trials), compared with the delayed FPI-sedentary rats. In contrast, cognitive performance in the acute FPI-RW rats was significantly impaired compared with all the other groups. These results suggest that voluntary exercise can endogenously upregulate BDNF and enhance recovery when it is delayed after TBI. However, when exercise is administered to soon after TBI, the molecular response to exercise is disrupted and recovery may be delayed.

Subcellular localization of IRS-1 in cell proliferation and differentiation

The type 1 insulin-like growth factor receptor (IGF-IR) and its docking protein, insulin receptor substrate-1 (IRS-1), play important roles in cell transformation, cell differentiation and aging. IRS-1 and other IRS proteins can, under certain conditions, localize to the nuclei of cells, where they undergo interactions with nuclear and nucleolar proteins. In this study, we confirm and extend these observations, demonstrating that IRS-1 is preferentially nuclear in growing cells. Differentiation and inhibition of ribosomal RNA synthesis cause subcellular redistribution of IRS-1 and other nuclear proteins to the cytoplasm.

Conventional 3D conformal versus intensity-modulated radiotherapy for the adjuvant treatment of gynecologic malignancies: a comparative dosimetric study of dose–volume histograms☆

OBJECTIVE

The goals of this study were to evaluate the feasibility of pelvic intensity-modulated radiotherapy (IMRT) in the adjuvant treatment of gynecologic malignancies and to compare the dose-volume histograms (DVHs) and determine the potential impact on acute and long-term toxicity based on the dose to target and nontarget tissues for both planning techniques.

METHODS

Ten consecutive patients referred for adjuvant radiotherapy for gynecologic malignancies at the University of Pittsburgh School of Medicine and Magee-Womens Hospital were selected for CT-based treatment planning using the ADAC 3D version 4.2g and the NOMOS Corvus IMRT version 4.0. Normal tissues and critical structures were contoured on axial CT slices by both systems in conjunction with a gynecologic radiologist. These regions included internal, external, and common iliac nodal groups, rectum, upper 4 cm of vagina, bladder, and small bowel. Conventional treatment planning included 3D four-field box using 18-MV photons designed to treat a volume from the L(5)/S(1) border superiorly to the bottom of the ischial tuberosity on the AP/PA field and shaped blocks on the lateral fields to minimize the dose to the rectum and small bowel. A seven-field technique using 6-MV photons was used for IMRT. Restraints on small bowel for IMRT were set at 23.0 Gy +/- 5% and 35.0 Gy+/- 5% for the rectum and 37.5 Gy +/- 5% for the bladder while simultaneously delivering full dose (45.0 Gy) to the intrapelvic nodal groups in 1.8-Gy daily fractions. The dose-volume histograms where then compared for both treatment delivery systems.

RESULTS

The volume of each organ of interest (small bowel, bladder, and rectum) receiving doses in excess of 30 Gy was compared in the 3D and IMRT treatment plans. The mean volume of small bowel receiving doses in excess of 30 Gy was reduced by 52% with IMRT compared with 3D. A similar advantage was noted for the rectum (66% reduction) and the bladder (36% reduction). The nodal regions at risk and the upper vagina all received the prescribed dose of 45.0 Gy.

CONCLUSIONS

Intensity-modulated radiotherapy appears to offer several advantages over conventional 3D radiotherapy (3D CRT) planning for adjuvant radiotherapy for gynecologic malignancies. These include a significant reduction in treatment volume for bladder, rectum, and small bowel. It is anticipated that this reduction in volume of normal tissue irradiated would translate into overall reduction in acute and potentially late treatment-related toxicity. Prospective trials are necessary to better evaluate the advantages in a larger group of patients.

Neuroprotective effects of nitrone radical scavenger S-PBN on reperfusion nerve injury in rats

The nitrone-based free radical scavengers have potent neuroprotective activities in models of stroke in which oxidative stress plays a key role in its development. We examined the effects of S-PBN (sodium 4-[(tert-butylimino) methyl]benzene-3-sulfonate N-oxide), a spin trap nitrone, on reperfusion injury in rat peripheral nerves. Immediately after the onset of 4-h ischaemia in rat right hindlimb, S-PBN was administered via mini-osmotic pumps, containing 2 ml of S-PBN (1.2 M), inserted subcutaneously. S-PBN, in addition, was given by a single injection (50 mg/kg BW, i.p.). Mean plasma concentrations of S-PBN were significantly greater in S-PBN-treated rats than in controls after 24, 48 and 72 h of reperfusion. Pump and dosing solution analysis indicated that the rats received between 82 and 99% of the target S-PBN concentration. Morphology in sciatic, tibial and peroneal nerves was assessed after 4 h of ischaemia followed by 72 h and 7 days of reperfusion. After 72 h of reperfusion, saline-treated control rats showed endoneurial oedema at the thigh level and diffuse axonal degeneration of myelinated nerve fibres distally. S-PBN-treated nerves were normal or revealed less severe abnormalities in myelinated fibres after 72 h and 7 days of reperfusion, when compared with those in saline-treated control nerves. Morphometrically, the frequency of abnormal myelinated fibres at calf levels was significantly less in S-PBN-treated nerves than in controls. In conclusion, post-ischaemic administration of S-PBN exhibits substantial neuroprotective properties in ischemia/reperfusion nerve injury.

A saturated-fat diet aggravates the outcome of traumatic brain injury on hippocampal plasticity and cognitive function by reducing brain-derived neurotrophic factor

We have conducted studies to determine the potential of dietary factors to affect the capacity of the brain to compensate for insult. Rats were fed with a high-fat sucrose (HFS) diet, a popularly consumed diet in industrialized western societies, for 4 weeks before a mild fluid percussion injury (FPI) or sham surgery was performed. FPI impaired spatial learning capacity in the Morris water maze, and these effects were aggravated by previous exposure of the rats to the action of the HFS diet. Learning performance decreased according to levels of brain-derived neurotrophic factor (BDNF) in individual rats, such that rats with the worst learning efficacy showed the lowest levels of BDNF in the hippocampus. BDNF immunohistochemistry localized the decreases in BDNF to the CA3 and dentate gyrus of the hippocampal formation. BDNF has a strong effect on synaptic plasticity via the action of synapsin I and cAMP-response element-binding protein (CREB), therefore, we assessed changes in synapsin I and CREB in conjunction with BDNF. Levels of synapsin I and CREB decreased in relation to decreases in BDNF levels. The combination of FPI and the HFS diet had more dramatic effects on the active state (phosphorylated) of synapsin I and CREB. There were no signs of neurodegeneration in the hippocampus of any rat group assessed with Fluoro-Jade B staining. The results suggest that FPI and diet impose a risk factor to the molecular machinery in charge of maintaining neuronal function under homeostatic and challenging situations.

[Severe acute respiratory syndrome (SARS)]

The severe acute respiratory syndrome (SARS) is a highly infectious respiratory disease, to the best of our knowledge caused by a hitherto unknown corona virus. The virus has spread from South East Asia to many countries of the world. Three case reports of patients from the Prince of Wales Hospital of The Chinese University of Hong Kong demonstrate typical clinical courses. Fever, cough, in most cases non-productive, myalgia, chills, and rigor are the leading symptoms. Leucopenia and thrombocytopenia are the most prominent laboratory parameters, increased values for lactatedehydrogenase (LDH) reflect a more severe clinical course. Advanced age and coexisting conditions seem to influence the prognosis unfavourably. The chest roentgenogram may be normal initially but at a later stage progressive consolidations in the majority of peripheral parts of the lung are observed, which cannot be differentiated from pneumonias of other origin. Even young patients can enter a stage of respiratory compromise rather fast. A therapy against the cause of the disease is not known. Empirical therapy with ribavirin in combination with high dose corticosteroids have proved successful. The disease may progress into respiratory failure comparable with an acute respiratory distress syndrome (ARDS). Mortality is around five to ten per cent. Stringent hygiene and quarantine measures are mandatory to prevent the further spread of this threatening disease.

Sinonasal (angiocentric) T/NK cell lymphoma: report of a case with a -12-year history free of recurrent/residual disease and a sudden deterioration

This report describes a case involving a 78-year-old Caucasian male, whose medical history was significant for sinonasal (angiocentric) T/NK lymphoma, who was treated by surgery and radiation in 1988. After the treatment, the patient was apparently free of residual/recurrent disease for a period of 12 years. There was periodical clinical follow up including repeated biopsies. After this period, the patient suffered from sudden deterioration of the health status with multiorgan involvement by the disease and he died. The diagnosis was confirmed by an autopsy. To our knowledge, this is the fifth reported case with extended survival (more than 12 years) free of recurrent/residual disease after the initial treatment, in which the patients ultimately died because of the disease. These findings suggest the importance of prolonged clinical follow-up in patients with this diagnosis.

Appican, the proteoglycan form of the amyloid precursor protein, contains chondroitin sulfate E in the repeating disaccharide region and 4-O-sulfated galactose in the linkage region

Chondroitin sulfate (CS)-D and CS-E, which are characterized by oversulfated disaccharide units, have been shown to regulate neuronal adhesion, cell migration, and neurite outgrowth. CS proteoglycans (CSPGs) consist of a core protein to which one or more CS chains are attached via a serine residue. Although several brain CSPGs, including mouse DSD-1-PG/phosphacan, have been found to contain the oversulfated D disaccharide motif, no brain CSPG has been reported to contain the oversulfated E motif. Here we analyzed the CS chain of appican, the CSPG form of the Alzheimer's amyloid precursor protein. Appican is expressed almost exclusively by astrocytes and has been reported to have brain- and astrocyte-specific functions including stimulation of both neural cell adhesion and neurite outgrowth. The present findings show that the CS chain of appican has a molecular mass of 25-50 kDa. This chain contains a significant fraction (14.3%) of the oversulfated E motif GlcUA beta 1-3GalNAc(4,6-O-disulfate). The rest of the chain consists of GlcUA beta 1-3GalNAc(4-O-sulfate) (81.2%) and minor fractions of GlcUA beta 1-3GalNAc and GlcUA beta 1-3GalNAc(6-O-sulfate). We also show that the CS chain of appican contains in its linkage region the 4-O-sulfated Gal structure. Thus, appican is the first example of a specific brain CSPG that contains the E disaccharide unit in its sugar backbone and the 4-O-sulfated Gal residue in its linkage region. The presence of the E unit is consistent with and may explain the neurotrophic activities of appican.

Stepwise deletions of polyA sequences in mismatch repair-deficient colorectal cancers

PolyA simple repeat sequence deletions are common in tumors with microsatellite instability (MSI+). Such deletions occur one base at a time in DNA mismatch repair (MMR)-deficient yeast suggesting larger deletions in human MSI+ tumors represent multiple sequential stepwise losses. Sum total deletions in four polyA repeats were variable (between -17 to -45 bp) in 20 sporadic MSI+ colorectal cancers. Progressive but less extensive total deletions (maximum of -12 bp) occurred in similar polyA sequences in MMR-deficient mice (mlh1-/-) up to 478 days old. PolyA repeat lengths were relatively stable but already shortened in the MMR-deficient cell line HCT116. A transgene with 26 A's transfected into HCT116 shortened an average of 3.8 bases pairs after 469 days in culture, less than average deletions of BAT25 (-5.3) or BAT26 (-9.0) in MSI+ cancers. These findings further suggest that extensive polyA deletions common in MSI+ tumors likely reflect multiple stepwise smaller deletions that accumulate more than hundreds of divisions after loss of MMR.