The curious ability of polyethylene glycol fusion technologies to restore lost behaviors after nerve severance.

Traumatic injuries to PNS and CNS axons are not uncommon. Restoration of lost behaviors following severance of mammalian peripheral nerve axons (PNAs) relies on regeneration by slow outgrowths and is typically poor or nonexistent when after ablation or injuries close to the soma. Behavioral recovery after severing spinal tract axons (STAs) is poor because STAs do not naturally regenerate. Current techniques to enhance PNA and/or STA regeneration have had limited success and do not prevent the onset of Wallerian degeneration of severed distal segments. This Review describes the use of a recently developed polyethylene glycol (PEG) fusion technology combining concepts from biochemical engineering, cell biology, and clinical microsurgery. Within minutes after microsuturing carefully trimmed cut ends and applying a well-specified sequence of solutions, PEG-fused axons exhibit morphological continuity (assessed by intra-axonal dye diffusion) and electrophysiological continuity (assessed by conduction of action potentials) across the lesion site. Wallerian degeneration of PEG-fused PNAs is greatly reduced as measured by counts of sensory and/or motor axons and maintenance of axonal diameters and neuromuscular synapses. After PEG-fusion repair, cut-severed, crush-severed, or ablated PNAs or crush-severed STAs rapidly (within days to weeks), more completely, and permanently restore PNA- or STA-mediated behaviors compared with nontreated or conventionally treated animals. PEG-fusion success is enhanced or decreased by applying antioxidants or oxidants, trimming cut ends or stretching axons, and exposure to Ca(2+) -free or Ca(2+) -containing solutions, respectively. PEG-fusion technology employs surgical techniques and chemicals already used by clinicians and has the potential to produce a paradigm shift in the treatment of traumatic injuries to PNAs and STAs.

Polyethylene glycol-fused allografts produce rapid behavioral recovery after ablation of sciatic nerve segments.

Restoration of neuronal functions by outgrowths regenerating at ∼1 mm/day from the proximal stumps of severed peripheral nerves takes many weeks or months, if it occurs at all, especially after ablation of nerve segments. Distal segments of severed axons typically degenerate in 1-3 days. This study shows that Wallerian degeneration can be prevented or retarded, and lost behavioral function can be restored, following ablation of 0.5-1-cm segments of rat sciatic nerves in host animals. This is achieved by using 0.8-1.1-cm microsutured donor allografts treated with bioengineered solutions varying in ionic and polyethylene glycol (PEG) concentrations (modified PEG-fusion procedure), being careful not to stretch any portion of donor or host sciatic nerves. The data show that PEG fusion permanently restores axonal continuity within minutes, as initially assessed by action potential conduction and intracellular diffusion of dye. Behavioral functions mediated by the sciatic nerve are largely restored within 2-4 weeks, as measured by the sciatic functional index. Increased restoration of sciatic behavioral functions after ablating 0.5-1-cm segments is associated with greater numbers of viable myelinated axons within and distal to PEG-fused allografts. Many such viable myelinated axons are almost certainly spared from Wallerian degeneration by PEG fusion. PEG fusion of donor allografts may produce a paradigm shift in the treatment of peripheral nerve injuries.

Human genome-wide expression analysis reorients the study of inflammatory mediators and biomechanics in osteoarthritis.

A major objective of this article is to examine the research implications of recently available genome-wide expression profiles of cartilage from human osteoarthritis (OA) joints. We propose that, when viewed in the light of extensive earlier work, this novel data provides a unique opportunity to reorient the design of experimental systems toward clinical relevance. Specifically, in the area of cartilage explant biology, this will require a fresh evaluation of existing paradigms, so as to optimize the choices of tissue source, cytokine/growth factor/nutrient addition, and biomechanical environment for discovery. Within this context, we firstly discuss the literature on the nature and role of potential catabolic mediators in OA pathology, including data from human OA cartilage, animal models of OA, and ex vivo studies. Secondly, due to the number and breadth of studies on IL-1ß in this area, a major focus of the article is a critical analysis of the design and interpretation of cartilage studies where IL-1ß has been used as a model cytokine. Thirdly, the article provides a data-driven perspective (including genome-wide analysis of clinical samples, studies on mutant mice, and clinical trials), which concludes that IL-1ß should be replaced by soluble mediators such as IL-17 or TGF-ß1, which are much more likely to mimic the disease in OA model systems. We also discuss the evidence that changes in early OA can be attributed to the activity of such soluble mediators, whereas late-stage disease results more from a chronic biomechanical effect on the matrix and cells of the remaining cartilage and on other local mediator-secreting cells. Lastly, an updated protocol for in vitro studies with cartilage explants and chondrocytes (including the use of specific gene expression arrays) is provided to motivate more disease-relevant studies on the interplay of cytokines, growth factors, and biomechanics on cellular behavior.

Protein standard absolute quantification (PSAQ) method for the measurement of cellular ubiquitin pools.

The protein ubiquitin is an important post-translational modifier that regulates a wide variety of biological processes. In cells, ubiquitin is apportioned among distinct pools, which include a variety of free and conjugated species. Although maintenance of a dynamic and complex equilibrium among ubiquitin pools is crucial for cell survival, the tools necessary to quantify each cellular ubiquitin pool have been limited. We have developed a quantitative mass spectrometry approach to measure cellular concentrations of ubiquitin species using isotope-labeled protein standards and applied it to characterize ubiquitin pools in cells and tissues. Our method is convenient, adaptable and should be a valuable tool to facilitate our understanding of this important signaling molecule.

Fibrillar structure and charge determine the interaction of polyglutamine protein aggregates with the cell surface.

The pathogenesis of most neurodegenerative diseases, including transmissible diseases like prion encephalopathy, inherited disorders like Huntington disease, and sporadic diseases like Alzheimer and Parkinson diseases, is intimately linked to the formation of fibrillar protein aggregates. It is becoming increasingly appreciated that prion-like intercellular transmission of protein aggregates can contribute to the stereotypical spread of disease pathology within the brain, but the mechanisms underlying the binding and uptake of protein aggregates by mammalian cells are largely uninvestigated. We have investigated the properties of polyglutamine (polyQ) aggregates that endow them with the ability to bind to mammalian cells in culture and the properties of the cell surface that facilitate such uptake. Binding and internalization of polyQ aggregates are common features of mammalian cells and depend upon both trypsin-sensitive and trypsin-resistant saturable sites on the cell surface, suggesting the involvement of cell surface proteins in this process. polyQ aggregate binding depends upon the presence of a fibrillar amyloid-like structure and does not depend upon electrostatic interaction of fibrils with the cell surface. Sequences in the huntingtin protein that flank the amyloid-forming polyQ tract also influence the extent to which aggregates are able to bind to cell surfaces.

Aberrant Structural Brain Connectivity in Adolescents with Attentional Problems Who Were Born Prematurely.

BACKGROUND AND PURPOSE: Differences in structural brain connectivity that underlie inattention have been previously investigated in adolescents with attention deficit/hyperactivity disorder, but not in the context of premature birth, which is often associated with attentional problems. The purpose of this study was to identify the neural correlates of attentional problems in adolescents born prematurely and determine neonatal predictors of those neural correlates and attention problems. MATERIALS AND METHODS: The study included 24 adolescents (12.5 ± 1.8 years of age; 12 girls, 12 boys) who were born prematurely and underwent MR imaging of the brain and cognitive assessment, both shortly after birth and as adolescents. Structural connectivity was assessed at adolescence using diffusion tensor imaging and tractography. RESULTS: Of the 24 subjects, 12 had attention deficits. A set of axonal pathways connecting the frontal, parietal, temporal, and occipital lobes had significantly lower fractional anisotropy in subjects with attentional problems. The temporoparietal connection between the left precuneus and left middle temporal gyrus was the most significantly underconnected interlobar axonal pathway. Low birth weight and ventriculomegaly, but not white matter injury or intraventricular hemorrhage on neonatal MR imaging, predicted temporoparietal hypoconnectivity in adolescence. However, neither birth weight nor other neonatal characteristics were associated with attention deficits directly. CONCLUSIONS: We identified an aberrant structural brain connectivity pattern, involving temporoparietal hypoconnectivity, in prematurely born adolescents with attentional problems. We also identified birth weight as a potential neonatal predictor of the temporoparietal hypoconnectivity. These findings add to our understanding of the neural basis and etiology of inattention in adolescents after premature birth.

Diabetes risk factors in low-income Mexican-American children.

OBJECTIVE: To learn if Mexican-American children from low income neighborhoods have excess diabetes risk factors. RESEARCH DESIGN AND METHODS: The study involved 173 Mexican-American children aged 9 years. This is the age before type 2 diabetes usually develops in youths and where the disparity in body fat between Mexican-American and non-Hispanic white children is evident. The study also targets poor children because diabetes and being overweight are more common in Mexican-American adults from a lower than from a higher socioeconomic status. The diabetes risk factors measured were percent body fat, dietary fat intake, daily fruit and vegetable intake, and physical fitness. Body fat was measured by bioelectric impedance, dietary intake was measured by three 24-h dietary recalls, and physical fitness was measured by a modified Harvard step test. RESULTS: According to self-reported dietary recalls, Mexican-American children ate higher than recommended fat servings and had higher percent energy from fat and saturated fat. On the other hand, their reported daily fruit and vegetable intake was half of that recommended by national dietary guidelines. A large percentage of these children were at unacceptable physical fitness levels. Percent body fat was higher in these Mexican-American children than that reported for non-Hispanic white children. Finally, 60% of the children had a first- or second-degree relative with diabetes. CONCLUSIONS: Because diabetes is highly prevalent in Mexican-American adults, type 2 diabetes in increasing in Mexican-American youths, and diabetes risk factors are more common in Mexican-American children, a prudent measure would be to explore early-age diabetes risk factor prevention programs in this population.

Needs assessment to improve neonatal intensive care in Mexico.

BACKGROUND: At the time of the research, Dr Weiss was a clinical fellow in neonatal-perinatal medicine at Baylor College of Medicine, Texas Children's Hospital. Dr Profit was on faculty at Baylor College of Medicine, Texas Children's Hospital, Department of Pediatrics, Section of Neonatology. He held a secondary appointment in the Department of Medicine, Section of Health Services Research and conducted his research at the VA Health Services Research and Development Center of Excellence where he collaborated with Dr Kowalkowski.: Improving the quality of neonatal intensive care is an important health policy priority in Mexico. A formal assessment of barriers and priorities for quality improvement has not been undertaken. AIM: To provide guidance to providers and policy makers with regard to addressing opportunities for better care delivery in Mexican neonatal intensive care units. OBJECTIVE: To conduct a needs assessment regarding improvement of quality of neonatal intensive care delivery in Mexico. METHODS: Spanish-language survey administered to a volunteer sample of Mexican neonatal care providers attending a large paediatric conference in Mexico in June 2011. Survey domains included institutional context of quality improvement, barriers, priorities, safety culture, and respondents' characteristics. Results were analysed using descriptive analyses of frequencies, proportions and percentage positive response (PPR) rates. RESULTS: Of 91 respondents, the majority identified neonatology as their primary specialty (n = 48, 65%) and were physicians (n = 55, 73%). Generally, providers expressed a desire to improve quality of care (PPR 69%) but reported notable deterrents. Respondents (n, %) identified family inability to pay (38, 48%), overcrowded work areas (38, 44%), insufficient financial reimbursement (25, 36%), lack of availability of nurses (26, 30%), ancillary staff (25, 29%), and subspecialists (22, 25%) as the principal barriers. Respiratory care (27, 39%)--reduction of mechanical ventilation and initiation of nasal continuous positive airway pressure--and reduction in frequency of late-onset infections (19, 28%) were selected as top clinical priorities. There were substantial opportunities for improving safety (PPR 48%) and teamwork climate (PPR 58%). CONCLUSION: These findings may guide efforts to improving quality of care delivery in Mexican neonatal intensive care units.

Mechanism of blood flow generated by precordial compression during CPR. I. Studies on closed chest precordial compression.

The mechanism of forward flow produced by precordial compression during CPR was investigated with the aid of echocardiographic and hemodynamic measurements in anesthetized, mechanically ventilated domestic pigs. Both mitral and tricuspid valves opened during compression diastole and closed during compression systole. Valve motion persisted throughout resuscitation in 17 of 22 animals which were hemodynamically resuscitated. There was a 25 percent reduction in left ventricular area during compression systole. Maximum pressure generated during compression systole in the aorta exceeded that of the right atrium throughout the 12-min interval of precordial compression in successfully resuscitated animals. These observations provide evidence of direct cardiac compression as the mechanism accounting for effective forward blood flow during CPR. The persistence of valve function, chamber compression, and pressure gradients during precordial compression was predictive of successful resuscitation. The absence of these factors prognosticates failure of resuscitation and explains, in part, the inconsistency of prior reports.

Immunologic mechanisms in the production of food sensitivities.

Fifty-five test patients and ten control patients were selected for provocation of symptoms using the oral challenge test. The provoking food was selected with the use of the leukocyte cytotoxic test. The test patients developed adverse symptomatology clinically while the control patients did not. During the phase of symptomatology it was shown that IgE did not change in the blood and, therefore, the Type I, anaphylactic type of reaction, which is IgE dependent, did not participate in symptom production. It was shown that 2 components of the classical pathway of complement C3 and C4 were utilized in the test group and not in the control group. Complement is 1 of the 2 components of the humoral system of the human immune system. C4 is one of the components that is triggered by the classic complement pathway, whose stimulus is IgG and IgM, and not by the other complement pathways. It can therefore be hypothesized that all the components of the circulatory humoral system are participating in this reaction and that Type II, the cytotoxic, and Type III, th immune-complex type of immunologic reaction, are the major contributors in the production of symptoms.

Rectal-scalp temperature difference predicts brain death in children.

When brain death in children occurs, commonly the scalp feels cold despite a normal core temperature. This phenomenon might reflect absent cerebral blood flow and metabolic activity. The authors, therefore, measured rectal-scalp temperature differences in critically ill comatose children to test the hypothesis that a particular temperature difference may correlate with clinical brain death. In a prospective cohort study set in a pediatric intensive care unit, rectal-scalp, rectal-abdomen, and rectal-mastoid temperatures in critically ill comatose children older than 18 months of age were measured before and during brain death evaluations. Twelve children were enrolled. Clinical criteria for brain death were met by seven patients, and five patients survived. All of the seven children who died had rectal-scalp temperature differences greater than 4 degrees C (mean = 6.7, range = 6.0-7.4) at the time of clinical brain death. No survivor had a rectal-scalp temperature difference of 4 degrees C at any time (mean = 3.4, range = 2.9-3.9). Rectal-scalp temperature differences of those who died and those who survived were significantly different at the P < 0.005 level. Rectal-abdomen and rectal-mastoid temperature differences did not correlate with clinical brain death or rectal-scalp temperature difference. In this preliminary study a rectal-scalp temperature difference of greater than 4 degrees C correlates with clinical criteria for brain death in children.

Nosocomial infections in the pediatric intensive care unit.

Pediatric intensive care units have contributed considerably to the management of children with severe diseases and life-threatening conditions. The use of mechanical ventilation, invasive monitoring, and indwelling catheters increase the risk for nosocomial infection. Improving infection control practices and surveillance can significantly reduce the incidence of nosocomial infections.

Comparison of results of immunotherapy based on skin end-point titration, prick testing, and scratch testing.

Presented is a clinical study comparing the result of immunotherapy based on allergy testing with three different test modalities: skin end-point titration, prick testing, and scratch testing. Thirty patients with allergic rhinitis were randomly assigned to one of the three test groups. Treatment vials were made on test results according to the instructions for each test. For skin end-point titration, each antigen was included at a concentration based on the patient's sensitivity, found with the fivefold dilution testing procedure. For the prick test, treatment vials were based on a two-level test response scale of stronger or lesser positive results. The scratch test yields vials used in one concentration based simply on a positive vs. negative test result. Patients in all three groups were treated at weekly intervals with immunotherapy, progressing in volume until the maximum tolerated dose was achieved. Relief of symptoms was evaluated after 6 months of treatment. Nine of the 10 patients receiving skin end-point titration based immunotherapy had complete relief of symptoms, and one had partial relief. None of the patients in the prick or scratch test groups achieved relief of symptoms after 6 months of treatment. Results dramatically demonstrate the need to base allergy immunotherapy treatment on a test that quantifies the patient's level of sensitivity to each antigen.

The biochemistry of neutralization.

It has been shown that injections of low doses of common environmental antigens or irritants cause a reduced sensitivity during a subsequent exposure to the same antigen and irritant. On the basis of these findings, the following study was performed: 20 allergic patients who manifested allergic symptoms were observed during skin end-point titration testing, which is described in the manuscript. During the testing procedure, 60% of the patients reported a complete relief of symptoms. It is postulated that a cytoprotective dose was given during the testing procedure that caused the symptoms to be relieved. The second part of the study was a double-blind placebo control study in which 40 patients received the end-point dose and 10 patients received placebo. All patients entered the study with allergic symptoms. None of the placebo patients reported any relief of symptoms when given their injection. Of patients who received the active ingredient, 67.5% reported relief of symptoms within 5 to 10 minutes after the subcutaneous administration of the active ingredient. With these findings, it is postulated that this low dose of active ingredient caused the production of prostaglandin E intracellularly, which causes an increase in cyclic AMP and a decrease in cyclic GMP, which results in the resolution of symptoms.

Food pollution.

Food can influence the human body in many ways, both positively and negatively. Several key elements of contemporary food cultivation and production are presented, along with their potential consequences to our health. The history of food cultivation and consumption is contrasted between early hunter-gatherer societies and modern day societies. Natural nutrient-rich foods produced from the soil in early societies have been replaced with artificial supplements and treated with pesticides and herbicides to control plant disease. The evolution of pesticides is chronicled from the synthesis of DDT in 1870 to present day. Several commonly used chemicals are described along with their documented side effects. A number of methods of pest control from ancient to modern day are offered as alternatives to polluting chemicals. Integrated pest management is proposed as a promising, economically feasible method of pest management, reducing pollution and risk to wildlife and human health.

Air pollution and its effect on the upper respiratory tract and on allergic rhinosinusitis.

The nose is the first organ system encountered by inhaled air and its associated pollutants. Pollutants are deposited during inspiration through the nose. They accumulate on mucus and are absorbed in the nasal mucosa, resulting in a number of deleterious effects on the body. Irritation of the nose and sinus from these pollutants, resulting from direct contact with the nasal mucosa, leads to inflammation, edema, swelling, and blocked sinuses. The result is acute and chronic sinusitis. Absorption of these chemicals into the body produces systemic effects. Their effect on the immune system, although subtle, leads to dramatic changes in the allergic diathesis. The T suppressor cell is the most sensitive cell of the immune system and the first to be affected by exposure to chemical pollutants. Diminution of the suppressor activity and the relative increase in helper activity in turn lead to increased immunoglobulin production and the manifestation of allergy symptoms. The underlying biochemical reaction is caused by the effects of pollutants on the T suppressor cell. Patients with existing allergies become brittle and difficult to treat with the exacerbation of the allergic diathesis. Removal of these chemical pollutants from the body as quickly as possible is essential for effective treatment of this problem. Dietary antioxidants help reduce the oxidizing effect of the pollutants and act as conjugators to remove the pollutants from the body.

Immunology of foods.

Investigation of food sensitivity is difficult and often confusing. However, there are multiple articles in the literature which illustrate that food is absorbed from the gastro-intestinal tract in an antigenic fashion and that the entire immune system is stimulated by these antigenic food particles. All four Gell and Coombs varieties of immunologic reactions have been demonstrated as causes of symptoms in patients. Test techniques are available for each of these immunologic reactions, as is treatment for their noxious effects.

IgG levels after treatment with antigen vials based on the scratch testing, intradermal testing, modified RAST testing.

In this study, there were three groups of patients--each group consisting of four patients. The first group had been skin tested by the scratch method, the second group was skin tested by the end point titration intradermal method, and the third group had been tested for inhalant allergy by the modified RAST technique. All of them had multiple treatment vials made, dependent on the type of testing they had, and the vials all included the ten inhalants that were tested for. All patients had been treated for a year with weekly immunotherapy injections. Specific IgG levels, blocking antibody levels to the ten inhalant allergens, were determined. The results were that the patients who had been scratch tested had the lowest levels of specific IgG blocking antibody--while both intradermal end point titration and modified RAST testing had much higher elevations of blocking IgG antibody, with the RAST having the highest. It is concluded that, since the treatment vials prepared after scratch testing of all the antigens are at the same concentration, there are many antigens that are not given in adequate amounts to cause a good IgG response whereas, by calibrating the concentrations of antigens in the intradermal titration and the modified RAST testing, all the antigens are being injected in sufficient quantities to get a good blocking antibody response.

Efficacy of alternative tests for delayed-cyclic food hypersensitivity.

With the oral challenge food test (OCFT) used as the standard for delayed-cyclic food hypersensitivity diagnosis, blinded comparison studies were accomplished with 175 in vitro food specific IgE and 180 IgG radioallergosorbent tests, 180 food enzyme-linked immune complex assays, and 155 in vivo Multi-Test prick tests. The study was multi-centered, eight physicians and 37 patients participating. All of the compared tests were shown to be approximately 50% efficient when compared with the OCFT results, and, thus, nonefficacious.