Mechanisms of laser-induced damage in absorbing glasses with nanosecond pulses.

The propagation of 355-nm, nanosecond pulses in absorbing glasses is investigated for the specific case examples of the broadband absorbing glass SuperGrey and the Ce3+-doped silica glass. The study involves different laser irradiation conditions and material characterization methods to capture the transient material behaviors leading to laser-induced damage. Two damage-initiation mechanisms were identified: (1) melting of the surface as a result of increased temperature; and (2) self-focusing caused by a transient change in the index of refraction. Population of excited states greatly affects both mechanisms by increasing the transient absorption cross section via excited-state absorption and introducing a change of the refractive index to support the formation of graded-index lensing and self-focusing of the beam inside the material. The governing damage-initiation mechanism depends on the thermodynamic properties of the host glass, the electronic structure characteristics of the doped ion, and the laser-spot size.

Mechanisms of surface contamination in fused silica by means of laser-induced electrostatic effects.

We demonstrate that fused-silica samples exposed to nanosecond laser pulses at 355 nm and 1064 nm develop long-lived electrostatic charges on their surfaces. These charges extend well beyond the area exposed to the laser beam. The results suggest this effect is dependent on laser fluence and wavelength. In addition, ejected particles generated during laser-induced breakdown are electrostatically charged. Experiments indicate that such electrostatic charges can produce forces that can support the transport of dielectric and metallic microspheres between surfaces. This in turn can promote increased contamination of optical components during operation at relevant excitation conditions.

Identification of novel vascular targets in lung cancer.

BACKGROUND: Lung cancer remains the leading cause of cancer-related death, largely owing to the lack of effective treatments. A tumour vascular targeting strategy presents an attractive alternative; however, the molecular signature of the vasculature in lung cancer is poorly explored. This work aimed to identify novel tumour vascular targets in lung cancer. METHODS: Enzymatic digestion of fresh tissue followed by endothelial capture with Ulex lectin-coated magnetic beads was used to isolate the endothelium from fresh tumour specimens of lung cancer patients. Endothelial isolates from the healthy and tumour lung tissue were subjected to whole human genome expression profiling using microarray technology. RESULTS: Bioinformatics analysis identified tumour endothelial expression of angiogenic factors, matrix metalloproteases and cell-surface transmembrane proteins. Predicted novel tumour vascular targets were verified by RNA-seq, quantitative real-time PCR analysis and immunohistochemistry. Further detailed expression profiling of STEAP1 on 82 lung cancer patients confirmed STEAP1 as a novel target in the tumour vasculature. Functional analysis of STEAP1 using siRNA silencing implicates a role in endothelial cell migration and tube formation. CONCLUSIONS: The identification of cell-surface tumour endothelial markers in lung is of interest in therapeutic antibody and vaccine development.

The effect of laser pulse shape and duration on the size at which damage sites initiate and the implications to subsequent repair.

Growth of laser damage on SiO(2) optical components used in high power lasers can be reduced or eliminated by pre-exposure to pulses of a few hundred ps in duration. Such pre-exposure would cause weak locations on the optics surface to self-identify by initiating very small damage sites. The sites which initiate will be only a few microns in diameter and will have a very low probability of growing even without any further treatment. Repairing damage sites when small is important because both laser mitigation and acid etching are very successful in preventing such small sites from growing.

ATR is a caffeine-sensitive, DNA-activated protein kinase with a substrate specificity distinct from DNA-PK.

ATR is a large, > 300 kDa protein containing a carboxy-terminus kinase domain related to PI-3 kinase, and is homologous to the ATM gene product in human cells and the rad3/MEC1 proteins in yeast. These proteins, together with the DNA-PK, are part of a new family of PI-3 kinase related proteins. All members of this family play important roles in checkpoints which operate to permit cell survival following many forms of DNA damage. We have expressed ATR protein in HEK293 cells and purified the protein to near-homogeneity. We show that pure ATR is a protein kinase which is activated by circular single-stranded, double-stranded or linear DNA. Thus ATR is a new member of a sub-family of PIK related kinases, founded by the DNA-PK, which are activated in the presence of DNA. Unlike DNA-PK, ATR does not appear to require Ku proteins for its activation by DNA. We show directly that, like ATM and DNA-PK, ATR phosphorylates the genome surveillance protein p53 on serine 15, a site which is up-regulated in response to DNA damage. In addition, we find that ATR has a substrate specificity similar to, but unique from, the DNA-PK in vitro, suggesting that these proteins have overlapping but distinct functions in vivo. Finally, we find that the kinase activity of ATR in the presence and absence of DNA is suppressed by caffeine, a compound which is known to induce loss of checkpoint control. Our results are consistent with the notion that ATR plays a role in monitoring DNA structure and phosphorylation of proteins involved in the DNA damage response pathways.

Selective small molecule inhibitors of glycogen synthase kinase-3 modulate glycogen metabolism and gene transcription.

BACKGROUND: Glycogen synthase kinase-3 (GSK-3) is a serine/threonine protein kinase, the activity of which is inhibited by a variety of extracellular stimuli including insulin, growth factors, cell specification factors and cell adhesion. Consequently, inhibition of GSK-3 activity has been proposed to play a role in the regulation of numerous signalling pathways that elicit pleiotropic cellular responses. This report describes the identification and characterisation of potent and selective small molecule inhibitors of GSK-3. RESULTS: SB-216763 and SB-415286 are structurally distinct maleimides that inhibit GSK-3alpha in vitro, with K(i)s of 9 nM and 31 nM respectively, in an ATP competitive manner. These compounds inhibited GSK-3beta with similar potency. However, neither compound significantly inhibited any member of a panel of 24 other protein kinases. Furthermore, treatment of cells with either compound stimulated responses characteristic of extracellular stimuli that are known to inhibit GSK-3 activity. Thus, SB-216763 and SB-415286 stimulated glycogen synthesis in human liver cells and induced expression of a beta-catenin-LEF/TCF regulated reporter gene in HEK293 cells. In both cases, compound treatment was demonstrated to inhibit cellular GSK-3 activity as assessed by activation of glycogen synthase, which is a direct target of this kinase. CONCLUSIONS: SB-216763 and SB-415286 are novel, potent and selective cell permeable inhibitors of GSK-3. Therefore, these compounds represent valuable pharmacological tools with which the role of GSK-3 in cellular signalling can be further elucidated. Furthermore, development of similar compounds may be of use therapeutically in disease states associated with elevated GSK-3 activity such as non-insulin dependent diabetes mellitus and neurodegenerative disease.

PDK1, one of the missing links in insulin signal transduction?

The initial steps in insulin signal transduction occur at the plasma membrane and lead to the activation of phosphatidylinositide (PtdIns) 3-kinase and the formation of PtdIns(3,4,5,)P3 in the inner leaflet of the plasma membrane which is then converted to PtdIns(3,4)P2 by a specific phosphatase. Inhibitors of PtdIns 3-kinase suppress nearly all the metabolic actions of insulin indicating that PtdIns(3,4,5)P3 and/or PtdIns(3,4)P2 are key 'second messengers' for this hormone. A major effect of insulin is its ability to stimulate the synthesis of glycogen in skeletal muscle. By 'working backwards' from glycogen synthesis, we have dissected an insulin-stimulated protein kinase cascade which is triggered by the activation of PtdIns 3-kinase. The first enzyme in this cascade is termed 3-phosphoinositide-dependent protein kinase (PDK1), because it is only active in the presence of PtdIns(3,4,5)P3 or PtdIns(3,4)P2. PDK1 then activates protein kinase B (PKB) which, in turn, inactivates glycogen synthase kinase-3 (GSK3), leading to the dephosphorylation and activation of glycogen synthase and hence to an acceleration of glycogen synthesis. We review the evidence which indicates that the phosphorylation of other proteins by PKB and GSK3 is likely to mediate many of the intracellular actions of insulin.

Insulin activates protein kinase B, inhibits glycogen synthase kinase-3 and activates glycogen synthase by rapamycin-insensitive pathways in skeletal muscle and adipose tissue.

Insulin stimulated protein kinase B alpha (PKB alpha) more than 10-fold and decreased glycogen synthase kinase-3 (GSK3) activity by 50 +/- 10% in skeletal muscle and adipocytes. Rapamycin did not prevent the activation of PKB, inhibition of GSK3 or stimulation of glycogen synthase up to 5 min. Thus rapamycin-insensitive pathways mediate the acute effect of insulin on glycogen synthase in the major insulin-responsive tissues. The small and very transient effects of EGF on phosphatidylinositol (3,4,5)P3 PKB alpha and GSK3 in adipocytes, compared to the strong and sustained effects of insulin, explains why EGF does not stimulate glucose uptake or glycogen synthesis in adipocytes.

GSK-3 inhibition by adenoviral FRAT1 overexpression is neuroprotective and induces Tau dephosphorylation and beta-catenin stabilisation without elevation of glycogen synthase activity.

Glycogen synthase kinase 3 (GSK-3) has previously been shown to play an important role in the regulation of apoptosis. However, the nature of GSK-3 effector pathways that are relevant to neuroprotection remains poorly defined. Here, we have compared neuroprotection resulting from modulation of GSK-3 activity in PC12 cells using either selective small molecule ATP-competitive GSK-3 inhibitors (SB-216763 and SB-415286), or adenovirus overexpressing frequently rearranged in advanced T-cell lymphomas 1 (FRAT1), a protein proposed as a negative regulator of GSK-3 activity towards Axin and beta-catenin. Our data demonstrate that cellular overexpression of FRAT1 is sufficient to confer neuroprotection and correlates with inhibition of GSK-3 activity towards Tau and beta-catenin, but not modulation of glycogen synthase (GS) activity. By comparison, treatment with SB-216763 and SB-415286 proved more potent in terms of neuroprotection, and correlated with inhibition of GSK-3 activity towards GS in addition to Tau and beta-catenin.

Soluble extracts from larval Ostertagia ostertagi modulating immune function.

BALB/c mice were immunized with Ostertagia ostertagi antigens and keyhole limpet hemocyanin (KLH) or sheep erythrocytes (SR) for evaluation of antibody production by enzyme linked immunosorbent assay (ELISA) or modified Jerne plaque assay. One semi-purified larval antigen caused both decreased anti-KLH serum antibody levels and fewer anti-SR IgM-secreting B cells. This antigen was shown to depress lymphocyte blastogenesis to Concanavalin A when added to cultured BALB/c splenic lymphocytes.

Decreased basal tear production associated with general anesthesia.

Basal tear production was measured by means of standardized Schirmer strips and 0.5% proparacaine hydrochloride topical anesthesia in 20 patients. Premedication with systemic diazepam (Valium) and atropine sulfate had no effect on basal tear production. General surgical anesthesia resulted in a noticeable depression of basal tear production at 10, 30, and 60 minutes following induction of the anesthesia. It is suggested that prophylactic eye care include both replacement of tears and prevention of mechanical exposure of the cornea during general anesthesia.

Lymphocyte blastogenic responses of calves experimentally infected with Ostertagia ostertagi.

Twelve 9-week-old calves were divided into four groups; two groups were maintained helminth-free as controls and the other groups were given Ostertagia ostertagi infective-stage larvae (L3) orally. One group received 100,000 L3 as a single inoculum and the other group received L3 in increasing dosages at weekly intervals for 8 consecutive weeks. The blastogenic responses to concanavalin A (Con A), phytohemagglutinin (PHA), and a soluble larval antigen from O. ostertagi (SLA) of peripheral blood lymphocytes were evaluated using tritiated thymidine incorporation into DNA as a measure of blastogenesis. The responses to Con A of all infected calves were significantly depressed while the responses to PHA were not. SLA, at concentrations of 4 micrograms ml-1 and above, caused blastogenic activity in lymphocytes from uninfected calves. Using SLA at 1 microgram ml-1 in lymphocyte cultures supplemented with autologous serum, an antigen-induced blastogenic response was detected in calves receiving serial inoculations of L3.

Preliminary report: immunodiagnosis of pre-type II ostertagiasis.

Ostertagia ostertagi soluble antigens were prepared by gel electrophoresis and electrophoretic transfer onto nitrocellulose for enzyme-linked immunosorbent assays with serum probes. Serologic responses to L3-derived antigen of approximately 32 kDa may be unique and diagnostic for cattle harboring inhibited larvae, or pre-Type II ostertagiasis. Specificity was evaluated by comparing sera from pre-Type II cattle to sera from Type I, uninfected, Fascioloides magna infected, Fasciola hepatica infected or Cooperia oncophora infected cattle.

Dermal cellular responses of helminth-free and Ostertagia ostertagi-infected calves to intradermal injections of soluble extracts from O. ostertagi L3 larvae.

Twelve calves were raised helminth-free until 9 weeks of age when six were orally inoculated with 100,000 Ostertagia ostertagi infective stage larvae (L3). Three uninfected and three experimentally infected calves received intradermal injections of sterile saline and soluble larval extract (SLE) from O. ostertagi L3 with a protein concentration ranging from 1 to 200 micrograms ml-1. Biopsies were performed 48 h post-injection. A kinetic study was performed on the remaining six calves, three infected and three uninfected, using a 100 micrograms ml-1 concentration of SLE and taking biopsies 1, 4, 8, 12, 24, and 72 h post-injection at both the saline and SLE-injected sites. All calves had an immediate wheal and increase in skin thickness at the SLE-injected sites. The numbers of eosinophils infiltrating SLE-injected sites as compared to saline-injected sites were significant in both uninfected and infected calves, but the infected calves had significant numbers to a wider range of SLE concentrations and had significantly higher numbers than uninfected calves in the kinetic study. Infected calves also had significant numbers of basophils in the dose response study at concentrations of 5 and 100 micrograms ml-1 SLE. Neutrophil infiltration was similar in both groups and was significant at SLE-injected sites early in the kinetic study. Detectable mast cells were decreased in SLE-injected sites of infected animals and perivascular accumulation of mononuclear and some polymorphonuclear cells was observed in the deep dermis of infected animals.

Solving physician-hospital administration conflicts: a physician strategy for the '90s.

Today's health care climate creates increased potential for conflict between hospital administrators and hospital-based physicians. Voluminous regulations, increasing operating costs, professional liability exposure, changing methods of reimbursement, constraints on capital expenditures, and similar constraints on bed expansion have caused hospitals to explore new and innovative sources of revenue. Hospitals have become more eager to provide "bundled" services and health care "packages" in order to compete for discounted reimbursement contracts demanded by large-volume purchasers. While the impact of these changes is clearly felt in the private sector, similar fiscal constraints also may require university hospitals to modify their traditional role as leaders in education, research, and community service. In short, all hospitals are under intense pressure to increase revenues, reduce operating costs, and maintain the scope and quality of services provided.

Quality versus variance: a plea for a different focus and terminology.

Much has been written about quality assurance in medical practice over the past 15 years. Medicine suddenly found itself trying to design systems that ensured that medicine was being practiced according to standards of quality when it had neither a definition of its product nor defined standards of practice. Consequently, early quality assurance programs focused primarily on documentation of patient care. As the process matured, it evolved to generic screens, with tolerances and outliers. The theory was that the quality of medical care was enhanced by physicians who practiced within often artificially established norms and was diminished by physicians who practiced outside those same norms. It was much like saying that the quality of manufacturing a new car could be improved by reducing all systems down to one of closely standardizing, observing, and documenting how each individual assembly worker put on a lock nut and then holding each worker independently accountable for the final quality of the care. Physicians felt they were being held responsible for conforming to a rigid set of poorly designed and retrospectively applied standards. Moreover, they were held accountable for applying those standards to all practice situations. Understandably, physicians felt at the mercy of nonphysician quality assurance "detectives" in hospitals and became increasingly suspicious of nurses and administrators, who were perceived as abusing the system at the expense of the physicians. Because of these inadequacies of the earlier quality assurance programs, paranoia among physicians about the quality assurance process remains rampant today. The use of blind outcome scores and practice patterns in credentialing and the reporting of these data to databanks have reinforced the paranoia.(ABSTRACT TRUNCATED AT 250 WORDS)

Guidelines for Regional Anesthesia in Obstetrics: potential impact on obstetric anesthesia services in rural Alabama.

When the American Society of Anesthesiologists published its Guidelines for Regional Anesthesia in Obstetrics, I did a survey to determine what impact a broadly implemented strict interpretation of those guidelines might have on obstetric anesthesia care in small rural Alabama hospitals. Thirty-six rural Alabama hospitals with fewer than 200 beds were included in the survey, with a response rate of 50%. Data included total deliveries, cesarean section rates, utilization rates of anesthesia services, personnel providing anesthesia care, and identification of physician personnel available during labor and cesarean section. Results showed that anesthesia care is provided for approximately 52% of births in the responding hospitals. Of these, approximately 60% of cesarean sections and 90% of vaginal deliveries are not routinely attended by anesthesiologists. If these data also reflect the nonrespondent hospitals, statewide access could be limited for approximately 6000 parturients annually. The Guidelines should be interpreted with caution. Rather than conform to related policies, interpretation should allow implementation consistent with the capabilities of the individual institutions, while ensuring quality anesthesia care for the parturients.

Postoperative deaths due to unsuspected pheochromocytoma.

Two cases of postoperative death due to unsuspected pheochromocytoma are presented. Both patients exhibited signs and symptoms preoperatively which might have been attributable to a pheochromocytoma. These reports serve as a reminder of the potentially fatal consequences of inadequate evaluation of hypertensive patients before surgery.

Hypertension and anesthesia: cause for concern.

Our clinical experience and the literature regarding anesthetic management of the hypertensive patient are reviewed. Preoperative evaluation and treatment of all hypertensive patients, regardless of their degree of lability, is recommended. For emergency surgery on an untreated hypertensive patient, control of blood pressure with nitroprusside should be attempted before an awake or rapid sequence intubation. The evaluation of hypertension, the physiology of idiopathic hypertension, and the effects of treatment are discussed.