Antibody-Mediated Endocytosis of Polysialic Acid Enables Intracellular Delivery and Cytotoxicity of a Glycan-Directed Antibody-Drug Conjugate

The specific targeting of differentially expressed glycans in malignant cells has emerged as an attractive anticancer strategy. One such target is the oncodevelopmental antigen polysialic acid (polySia), a polymer of α2,8-linked sialic acid residues that is largely absent during postnatal development but is re-expressed during progression of several malignant human tumors, including small-cell and non-small cell lung carcinomas, glioma, neuroblastoma, and pancreatic carcinoma. In these cancers, expression of polySia correlates with tumor progression and poor prognosis and appears to modulate cancer cell adhesion, invasiveness, and metastasis. To evaluate the potential of PolySia as a target for anticancer therapy, we developed a chimeric human polySia-specific mAb that retained low nanomolar (nmol/L) target affinity and exhibited exquisite selectivity for polySia structures. The engineered chimeric mAb recognized several polySia-positive tumor cell lines in vitro and induced rapid endocytosis of polySia antigens. To determine whether this internalization could be exploited for delivery of conjugated cytotoxic drugs, we generated an antibody-drug conjugate (ADC) by covalently linking the chimeric human mAb to the tubulin-binding maytansinoid DM1 using a bioorthogonal chemical reaction scheme. The resulting polySia-directed ADC demonstrated potent target-dependent cytotoxicity against polySia-positive tumor cells in vitro. Collectively, these results establish polySia as a valid cell-surface, cancer-specific target for glycan-directed ADC and contribute to a growing body of evidence that the tumor glycocalyx is a promising target for synthetic immunotherapies. SIGNIFICANCE: These findings describe a glycan-specific antibody-drug conjugate that establishes polySia as a viable cell surface target within the tumor glycocalyx.

A library of chemically defined human N-glycans synthesized from microbial oligosaccharide precursors

Synthesis of homogenous glycans in quantitative yields represents a major bottleneck to the production of molecular tools for glycoscience, such as glycan microarrays, affinity resins, and reference standards. Here, we describe a combined biological/enzymatic synthesis that is capable of efficiently converting microbially-derived precursor oligosaccharides into structurally uniform human-type N-glycans. Unlike starting material obtained by chemical synthesis or direct isolation from natural sources, which can be time consuming and costly to generate, our approach involves precursors derived from renewable sources including wild-type Saccharomyces cerevisiae glycoproteins and lipid-linked oligosaccharides from glycoengineered Escherichia coli. Following deglycosylation of these biosynthetic precursors, the resulting microbial oligosaccharides are subjected to a greatly simplified purification scheme followed by structural remodeling using commercially available and recombinantly produced glycosyltransferases including key N-acetylglucosaminyltransferases (e.g., GnTI, GnTII, and GnTIV) involved in early remodeling of glycans in the mammalian glycosylation pathway. Using this approach, preparative quantities of hybrid and complex-type N-glycans including asymmetric multi-antennary structures were generated and subsequently used to develop a glycan microarray for high-throughput, fluorescence-based screening of glycan-binding proteins. Taken together, these results confirm our combined synthesis strategy as a new, user-friendly route for supplying chemically defined human glycans simply by combining biosynthetically-derived precursors with enzymatic remodeling.

Immunization with Outer Membrane Vesicles Displaying Designer Glycotopes Yields Class-Switched, Glycan-Specific Antibodies

The development of antibodies against specific glycan epitopes poses a significant challenge due to difficulties obtaining desired glycans at sufficient quantity and purity, and the fact that glycans are usually weakly immunogenic. To address this challenge, we leveraged the potent immunostimulatory activity of bacterial outer membrane vesicles (OMVs) to deliver designer glycan epitopes to the immune system. This approach involved heterologous expression of two clinically important glycans, namely polysialic acid (PSA) and Thomsen-Friedenreich antigen (T antigen) in hypervesiculating strains of non-pathogenic Escherichia coli. The resulting glycOMVs displayed structural mimics of PSA or T antigen on their surfaces, and induced high titers of glycan-specific IgG antibodies following immunization in mice. In the case of PSA glycOMVs, serum antibodies potently killed Neisseria meningitidis serogroup B (MenB), whose outer capsule is PSA, in a serum bactericidal assay. These findings demonstrate the potential of glycOMVs for inducing class-switched, humoral immune responses against glycan antigens.

2-Heptyl-4-quinolone, a precursor of the Pseudomonas quinolone signal molecule, modulates swarming motility in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen capable of group behaviors, including biofilm formation and swarming motility. These group behaviors are regulated by both the intracellular signaling molecule c-di-GMP and acylhomoserine lactone quorum-sensing systems. Here, we show that the Pseudomonas quinolone signal (PQS) system also contributes to the regulation of swarming motility. Specifically, our data indicate that 2-heptyl-4-quinolone (HHQ), a precursor of PQS, likely induces the production of the phenazine-1-carboxylic acid (PCA), which in turn acts via an as-yet-unknown downstream mechanism to repress swarming motility. We show that this HHQ- and PCA-dependent swarming repression is apparently independent of changes in global levels of c-di-GMP, suggesting complex regulation of this group behavior.

Modulation of Pseudomonas aeruginosa surface-associated group behaviors by individual amino acids through c-di-GMP signaling

To colonize the cystic fibrosis lung, Pseudomonas aeruginosa establishes sessile communities referred to as biofilms. Although the signaling molecule c-di-GMP governs the transition from motile to sessile growth, the environmental signal(s) required to modulate biofilm formation remain unclear. Using relevant in vivo concentrations of the 19 amino acids previously identified in cystic fibrosis sputum, we demonstrated that arginine, ornithine, isoleucine, leucine, valine, phenylalanine and tyrosine robustly promoted biofilm formation in vitro. Among the seven biofilm-promoting amino acids, only arginine also completely repressed the ability of P. aeruginosa to swarm over semi-solid surfaces, suggesting that arginine may be an environmental cue favoring a sessile lifestyle. Mutating two documented diguanylate cyclases required for biofilm formation (SadC and RoeA) reduced biofilm formation and restored swarming motility on arginine-containing medium. Growth on arginine increased the intracellular levels of c-di-GMP, and this increase was dependent on the SadC and RoeA diguanylate cyclases. Strains mutated in sadC, roeA or both also showed a reduction in biofilm formation when grown with the other biofilm-promoting amino acids. Taken together, these results suggest that amino acids can modulate biofilm formation and swarming motility, at least in part, by controlling the intracellular levels of c-di-GMP.

Specific control of Pseudomonas aeruginosa surface-associated behaviors by two c-di-GMP diguanylate cyclases

The signaling nucleotide cyclic diguanylate (c-di-GMP) regulates the transition between motile and sessile growth in a wide range of bacteria. Understanding how microbes control c-di-GMP metabolism to activate specific pathways is complicated by the apparent multifold redundancy of enzymes that synthesize and degrade this dinucleotide, and several models have been proposed to explain how bacteria coordinate the actions of these many enzymes. Here we report the identification of a diguanylate cyclase (DGC), RoeA, of Pseudomonas aeruginosa that promotes the production of extracellular polysaccharide (EPS) and contributes to biofilm formation, that is, the transition from planktonic to surface-dwelling cells. Our studies reveal that RoeA and the previously described DGC SadC make distinct contributions to biofilm formation, controlling polysaccharide production and flagellar motility, respectively. Measurement of total cellular levels of c-di-GMP in ∆roeA and ∆sadC mutants in two different genetic backgrounds revealed no correlation between levels of c-di-GMP and the observed phenotypic output with regard to swarming motility and EPS production. Our data strongly argue against a model wherein changes in total levels of c-di-GMP can account for the specific surface-related phenotypes of P. aeruginosa.

Growing and analyzing static biofilms

Many bacteria can exist as surface-attached aggregations known as biofilms. Presented in this unit are several approaches for the study of these communities. The focus here is on static biofilm systems, which are particularly useful for examination of the early stages of biofilm formation, including initial adherence to the surface and microcolony formation. Furthermore, most of the techniques presented are easily adapted to the study of biofilms under a variety of conditions and are suitable for either small- or relatively large-scale studies. Unlike assays involving continuous-flow systems, the static biofilm assays described here require very little specialized equipment and are relatively simple to execute. In addition, these static biofilm systems allow analysis of biofilm formation with a variety of readouts, including microscopy of live cells, macroscopic visualization of stained bacteria, and viability counts. Used individually or in combination, these assays provide useful means for the study of biofilms.

SadC reciprocally influences biofilm formation and swarming motility via modulation of exopolysaccharide production and flagellar function

Pseudomonas aeruginosa has served as an important organism in the study of biofilm formation; however, we still lack an understanding of the mechanisms by which this microbe transitions to a surface lifestyle. A recent study of the early stages of biofilm formation implicated the control of flagellar reversals and production of an exopolysaccharide (EPS) as factors in the establishment of a stable association with the substratum and swarming motility. Here we present evidence that SadC (PA4332), an inner membrane-localized diguanylate cyclase, plays a role in controlling these cellular functions. Deletion of the sadC gene results in a strain that is defective in biofilm formation and a hyperswarmer, while multicopy expression of this gene promotes sessility. A DeltasadC mutant was additionally found to be deficient in EPS production and display altered reversal behavior while swimming in high-viscosity medium, two behaviors proposed to influence biofilm formation and swarming motility. Epistasis analysis suggests that the sadC gene is part of a genetic pathway that allows for the concomitant regulation of these aspects of P. aeruginosa surface behavior. We propose that SadC and the phosphodiesterase BifA (S. L. Kuchma et al., J. Bacteriol. 189:8165-8178, 2007), via modulating levels of the signaling molecule cyclic-di-GMP, coregulate swarming motility and biofilm formation as P. aeruginosa transitions from a planktonic to a surface-associated lifestyle.

BifA, a cyclic-Di-GMP phosphodiesterase, inversely regulates biofilm formation and swarming motility by Pseudomonas aeruginosa PA14

The intracellular signaling molecule, cyclic-di-GMP (c-di-GMP), has been shown to influence bacterial behaviors, including motility and biofilm formation. We report the identification and characterization of PA4367, a gene involved in regulating surface-associated behaviors in Pseudomonas aeruginosa. The PA4367 gene encodes a protein with an EAL domain, associated with c-di-GMP phosphodiesterase activity, as well as a GGDEF domain, which is associated with a c-di-GMP-synthesizing diguanylate cyclase activity. Deletion of the PA4367 gene results in a severe defect in swarming motility and a hyperbiofilm phenotype; thus, we designate this gene bifA, for biofilm formation. We show that BifA localizes to the inner membrane and, in biochemical studies, that purified BifA protein exhibits phosphodiesterase activity in vitro but no detectable diguanylate cyclase activity. Furthermore, mutational analyses of the conserved EAL and GGDEF residues of BifA suggest that both domains are important for the observed phosphodiesterase activity. Consistent with these data, the DeltabifA mutant exhibits increased cellular pools of c-di-GMP relative to the wild type and increased synthesis of a polysaccharide produced by the pel locus. This increased polysaccharide production is required for the enhanced biofilm formed by the DeltabifA mutant but does not contribute to the observed swarming defect. The DeltabifA mutation also results in decreased flagellar reversals. Based on epistasis studies with the previously described sadB gene, we propose that BifA functions upstream of SadB in the control of biofilm formation and swarming.

Inverse regulation of biofilm formation and swarming motility by Pseudomonas aeruginosa PA14

We previously reported that SadB, a protein of unknown function, is required for an early step in biofilm formation by the opportunistic pathogen Pseudomonas aeruginosa. Here we report that a mutation in sadB also results in increased swarming compared to the wild-type strain. Our data are consistent with a model in which SadB inversely regulates biofilm formation and swarming motility via its ability both to modulate flagellar reversals in a viscosity-dependent fashion and to influence the production of the Pel exopolysaccharide. We also show that SadB is required to properly modulate flagellar reversal rates via chemotaxis cluster IV (CheIV cluster). Mutational analyses of two components of the CheIV cluster, the methyl-accepting chemotaxis protein PilJ and the PilJ demethylase ChpB, support a model wherein this chemotaxis cluster participates in the inverse regulation of biofilm formation and swarming motility. Epistasis analysis indicates that SadB functions upstream of the CheIV cluster. We propose that P. aeruginosa utilizes a SadB-dependent, chemotaxis-like regulatory pathway to inversely regulate two key surface behaviors, biofilm formation and swarming motility.

Lack of effect of 94 GHz radio frequency radiation exposure in an animal model of skin carcinogenesis

Although there is no evidence that electromagnetic energy in the radio frequency radiation (RFR) band is mutagenic, there have been suggestions that RFR energy might serve as either a promoter or co-promoter in some animal models of carcinogenesis. Recent developments in electromagnetic technology have resulted in the manufacture of RFR sources capable of generating frequencies in the millimeter wavelength (MMW) range (30-300 GHz). Because absorption of MMW energy occurs in the skin, it is to be expected that long-term detrimental health effects, if any, would most likely be manifest in the skin. In this study we investigated whether a single (1.0 W/cm(2) for 10 s) or repeated (2 exposures/week for 12 weeks, 333 mW/cm(2) for 10 s) exposure to 94 GHz RFR serves as a promoter or co-promoter in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced SENCAR mouse model of skin carcinogenesis. Neither paradigm of MMW exposure significantly affected papilloma development, as evidenced by a lack of effect on tumor incidence and multiplicity. There was also no evidence that MMW exposure served as a co-promoter in DMBA-induced animals repeatedly treated with 12-O-tetradecanoylphorbol 13-acetate. Therefore, we conclude that exposure to 94 GHz RFR under these conditions does not promote or co-promote papilloma development in this animal model of skin carcinogenesis.

Effects of high peak power microwaves on the retina of the rhesus monkey

We studied the retinal effects of 1.25 GHz high peak power microwaves in Rhesus monkeys. Preexposure fundus photographs, retinal angiograms, and electroretinograms (ERG) were obtained to screen for normal ocular structure and function and, after exposure, as endpoints of the study. Histopathology of the retina was an additional endpoint. Seventeen monkeys were randomly assigned to receive sham exposure or pulsed microwave exposures. Microwaves were delivered anteriorly to the face at 0, 4.3, 8.4, or 20.2 W/kg spatially and temporally averaged retinal specific absorption rates (R-SAR). The pulse characteristics were 1.04 MW ( approximately 1.30 MW/kg temporal peak R-SAR), 5.59 micros pulse length at 0, 0.59, 1. 18, and 2.79 Hz pulse repetition rates. Exposure was 4 h per day and 3 days per week for 3 weeks, for a total of nine exposures. The preexposure and postexposure fundus pictures and angiograms were all within normal limits. The response of cone photoreceptors to light flash was enhanced in monkeys exposed at 8.4 or 20.2 W/kg R-SAR, but not in monkeys exposed at 4.3 W/kg R-SAR. Scotopic (rod) response, maximum (combined cone and rod) response, and Naka-Rushton R(max) and log K of scotopic b-waves were all within normal range. Retinal histopathology revealed the presence of enhanced glycogen storage in photoreceptors among sham (2/5), 8.4 W/kg (3/3), and 20.2 W/kg (2/5) exposed monkeys, while enhanced glycogen storage was not observed in the 4.3 W/kg (0/4) exposed group. Supranormal cone photoreceptor b-wave was R-SAR dependent and may be an early indicator of mild injury. However no evidence of degenerative changes and ERG depression was seen. We concluded that retinal injury is very unlikely at 4 W/kg. Functional changes that occur at higher R-SAR are probably reversible since we saw no evidence of histopathologic correlation with ERG changes. Bioelectromagnetics 21:439-454, 2000. Published 2000 Wiley-Liss, Inc.

Thresholds of microwave-evoked warmth sensations in human skin

We measured thresholds for microwave-evoked skin sensations of warmth at frequencies of 2.45, 7.5, 10, 35, and 94 GHz. In the same subjects, thresholds of warmth evoked by infrared radiation (IR) were also measured for comparison. Detection thresholds were measured on the skin in the middle of the back in 15 adult male human subjects at all microwave (MW) frequencies and with IR. Long duration (10-s), large area (327-cm2) stimuli were used to minimize any differential effects of temporal or spatial summation. Sensitivity increased monotonically with frequency throughout the range of microwave frequencies tested. The threshold at 94 GHz (4.5 +/- 0.6 mW/cm2) was more than an order of magnitude less than at 2.45 GHz (63.1 +/- 6.7 mW/cm2), and it was comparable to the threshold for IR (5.34 +/- 1.07 mW/cm2).

Chronic exposure of cancer-prone mice to low-level 2450 MHz radiofrequency radiation

The purpose of this study was to determine whether chronic, low-level exposure of mammary-tumor-prone mice to 2450 MHz radiofrequency radiation (RFR) promotes an earlier onset (decreased latency), a greater total incidence, or a faster growth rate of mammary tumors. One hundred C3H/ HeJ mice were exposed in circularly polarized waveguides (CWG) for 18 months (20 h/day, 7 days/wk) to continuous-wave, 2450 MHz RFR at a whole body average specific absorption rate (SAR) of 0.3 W/kg; 100 mice were sham exposed. Before exposure, SARs were determined calorimetrically; during experimentation, SARs were monitored by differential power measurement. All animals were visually inspected twice daily and were removed from the CWG cages for a weekly inspection, palpation, and weighing. From the time of detection, tumor size was measured weekly. Animals that died spontaneously, became moribund, or were killed after 18 months of exposure were completely necropsied; tissues were fixed and subjected to histopathological evaluations. Results showed no significant difference in weight profiles between sham-irradiated and irradiated mice. Concerning mammary carcinomas, there was no significant difference between groups with respect to palpated tumor incidence (sham = 52%; irradiated = 44%), latency to tumor onset (sham = 62.3 +/- 1.2 wk; irradiated = 64.0 +/- 1.6 wk), and rate of tumor growth. In general, histopathological examination revealed no significant differences in numbers of malignant, metastatic, or benign neoplasms between the two groups; a significantly greater incidence of alveolar-bronchiolar adenoma in the sham-irradiated mice was the only exception. In addition, survival analysis showed no significant difference in cumulative percent survival between sham and irradiated animals. Thus, results indicate that under the conditions of this study, long-term, low-level exposure of mammary-tumor-prone mice to 2450 MHz RFR did not affect mammary tumor incidence, latency to tumor onset, tumor growth rate, or animal longevity when compared with sham-irradiated controls.

Lack of effects on heart rate and blood pressure in ketamine-anesthetized rats briefly exposed to ultra-wideband electromagnetic pulses

Fourteen Sprague-Dawley rats were exposed to pulses produced by a Bournlea ultra-wideband (UWB) pulse generator (rise time, 318-337 ps; maximum E field, 19-21 kV/m). Exposures at a repetition frequency of 1 kHz for 0.5 s or to repetitive pulse trains (2-s exposure periods alternating with 2 s of no exposure, for a total of 2 min) resulted in no significant changes in heart rate or mean arterial blood pressure. These results suggest that acute whole-body exposure to UWB pulses does not have a detrimental effect on the cardiovascular system.

Chronic, low-level (1.0 W/kg) exposure of mice prone to mammary cancer to 2450 MHz microwaves

In a previous study (Frei et al., Bioelectromagnetics 19, 20-31, 1998), we showed that low-level (0.3 W/kg), long-term exposure of mice prone to mammary tumors to 2450 MHz radiofrequency (RF) radiation did not affect the incidence of mammary tumors, latency to tumor onset, tumor growth rate or animal survival when compared to sham-irradiated animals. In the current study, the specific absorption rate (SAR) was increased from 0.3 W/kg to 1.0 W/kg. The same biological end points were used. One hundred C3H/HeJ mice were exposed in circularly polarized waveguides for 78 weeks (20 h/day, 7 days/week) to continuous-wave, 2450 MHz RF radiation; 100 mice were sham-exposed. There was no significant difference between exposed and sham-exposed groups with respect to the incidence of palpated mammary tumors (sham-exposed = 30%; irradiated = 38%), latency to tumor onset (sham-exposed = 62.0 +/- 2.3 weeks; irradiated = 62.5 +/- 2.2 weeks) and rate of tumor growth. Histopathological evaluations revealed no significant difference in numbers of malignant, metastatic or benign neoplasms between the two groups. Thus long-term exposures of mice prone to mammary tumors to 2450 MHz RF radiation at SARs of 0.3 and 1.0 W/kg had no significant effects when compared to sham-irradiated animals.

The older adult with diabetes

Like their younger counterparts, older adults with diabetes need individualized treatment and educational programs based on personal glucose goals. Although most of the tools and therapies available to younger adults are also appropriate for the elderly, additional considerations and strategies are needed to meet the needs of this population for whom diabetes is a frequent and serious problem. To be effective, the therapeutic approach needs to take into consideration the aging process, other health problems, and the functional, psychosocial, cultural, and educational status of each patient. Along with these considerations, this article provides an overview of the treatment of diabetes for this age group and offers strategies for working with older adults.

Participation in a diabetes education and care program: experience from the diabetes care for older adults project

There is very little reported information concerning the participation of older adults in diabetes education and care programs, factors related to their attendance, and the influence of attendance on program outcomes. In this study, which was part of a larger study of insulin therapy, subjects (> or = 65 years old) assigned to the intensive management group (n = 53) were provided with educational sessions during the 18-month study period. Data for this group were examined to determine factors that influenced enrollment and attendance. Attendance rates for individual participants averaged 72% during the first 6 months and 68% during the subsequent 12 months. Demographic factors, baseline knowledge test scores, and baseline glycosylated hemoglobin levels did not significantly influence participation. Greater distance from the clinic and shorter time using insulin were significantly related (P = .05) to attendance. Perceived benefits of the program included diabetes education (45%), glucose control (23%), and interacting with others who have diabetes (23%).

Establishing orally self-administered cocaine as a reinforcer in rats using home-cage pre-exposure

1. Rats were force-exposed to a cocaine + saccharin solution in their home cage water bottles for five days. They were then given 5 h home-cage access to both cocaine and cocaine-free solutions for 40 days. 2. The subjects consumed large doses of the cocaine solution despite the ad libitum availability of water. 3. The animals were then trained on a task consisting of operant bar pressing rewarded on an intermittent schedule with a liquid cocaine reinforcer. 4. All subjects performed the operant task and consumed doses of cocaine solution which are preferred over water in other paradigms. 5. Levels of responding were significantly reduced in three of four subjects when vehicle was substituted for liquid cocaine as the reward. 6. This demonstrates that orally self-administered cocaine can be used as a reinforcer in rats.

Long-term, low-level exposure of mice prone to mammary tumors to 435 MHz radiofrequency radiation

The purpose of this study was to determine if chronic, low-level exposure of mice prone to mammary tumors to 435 MHz radiofrequency (RF) radiation promotes an earlier onset, a faster growth rate or a greater total incidence of mammary tumors than in sham-exposed controls. Two hundred female C3H/HeJ mice were exposed for 21 months (22 h/day, 7 days/week) to a horizontally polarized 435 MHz pulse-wave (1.0 micros pulse width, 1.0 kHz pulse rate) RF radiation environment with an incident power density of 1.0 mW/cm2 (SAR = 0.32 W/kg). An additional 200 mice were sham-exposed. Animals that died spontaneously, became moribund or were euthanized after 21 months of exposure were completely necropsied; tissues were subjected to histopathological examinations. Concerning mammary carcinomas, there were no significant differences between the two groups with respect to latency to tumor onset, tumor growth rate and overall tumor incidence. Histopathological examination revealed no significant differences in numbers of malignant, metastatic or benign neoplasms between groups. Survival probability was estimated by the Kaplan-Meier method; no significant difference between groups was noted (Cox's test). Under the conditions of this long-term study, low-level exposure of mice prone to mammary tumors to 435 MHz RF radiation did not affect the incidence of mammary tumors, tumor growth rate, latency to tumor onset or animal longevity when compared to sham-exposed controls.

Considerations for human exposure standards for fast-rise-time high-peak-power electromagnetic pulses

Development of new emitter systems capable of producing high-peak-power electromagnetic pulses with very fast rise times and narrow pulse widths is continuing. Such directed energy weapons systems will be used in the future to defeat electronically vulnerable targets. Human exposures to these pulses can be expected during testing and operations. Development of these technologies for radar and communications purposes has the potential for wider environmental exposure, as well. Current IEEE C95.1-1991 human exposure guidelines do not specifically address these types of pulses, though limits are stated for pulsed emissions. The process for developing standards includes an evaluation of the relevant bioeffects data base. A recommendation has been made that human exposure to ultrashort electromagnetic pulses that engender electromagnetic transients, called precursor waves, should be avoided. Studies that purport to show the potential for tissue damage induced by such pulses were described. The studies cited in support of the recommendation were not relevant to the issues of tissue damage by propagated pulses. A number of investigations are cited in this review that directly address the biological effects of electromagnetic pulses. These studies have not shown evidence of tissue damage as a result of exposure to high-peak-power pulsed microwaves. It is our opinion that the current guidelines are sufficiently protective for human exposure to these pulses.

No detectable bioeffects following acute exposure to high peak power ultra-wide band electromagnetic radiation in rats

A wide range assessment of the possible bioeffects of an acute exposure to high peak power ultra-wide band (UWB) electromagnetic radiation was performed in rats. The UWB-exposure consisted of 2 min of pulsed (frequency: 60 Hz, pulse width: 5-10 ns) UWB (bandwidth: 0.25-2.50 GHz) electromagnetic radiation. Rats were examined using one of the following: 1) a functional observational battery (FOB); 2) a swimming performance test; 3) a complete panel of blood chemistries; or 4) determination of the expression of the c-fos protein in immunohistologically-stained sections of the brain. No significant differences were found between UWB- or sham-exposed rats on any of the measured parameters.

Influence of microwave exposure on chlordiazepoxide effects in the mouse staircase test

To ascertain whether behavioral effects of benzodiazepines are altered by exposure to microwave radiation, we compared the performance of male, Swiss CD1 mice in the staircase test 30 min after pretreatment with chlordiazepoxide (8, 16, and 32 mg/kg, IP) and immediately following a 5-min exposure to microwave radiation (4, 12, and 36 W/kg, continuous wave, 1.8 or 4.7 GHz). In this paradigm, chlordiazepoxide reduction in the number of rears (NR) and number of steps ascended (NSA) is postulated to reflect anxiolytic and sedative drug effects, respectively. In sham-exposed mice, increasing doses of chlordiazepoxide increased NSA without affecting NR, increased NSA and decreased NR, then decreased both NSA and NR. Microwave exposure generally did not alter NSA or NR in mice pretreated with lower doses of chlordiazepoxide. However, in mice pretreated with 32 mg/kg chlordiazepoxide, exposure to 36 W/kg microwave radiation significantly reversed the reductions in NSA and NR at 4.7 GHz but not at 1.8 GHz. These findings indicate that exposure to microwave radiation can selectively alter effects of chlordiazepoxide in this psychopharmacological paradigm.

The challenges of diabetes and older adults

Diabetes is a chronic illness that affects a disproportionate number of older adults and members of ethnic minorities. It is an illness that requires long-term active patient participation to maintain metabolic control and challenges both the patient and health care provider. The need for the patient to carry out daily self-care behaviors is no less important simply because the person is older. Older adults, however, experience unique challenges because of the physical and functional changes that may be imposed by the aging process and the prevalence of multiple chronic illnesses and complications. Because diabetes self-care is carried out within the context of all aspects of a person's life, it is important, then, for the health professional to recognize these social, functional, and psychological challenges. All aspects of physical, functional, and psychosocial status need to be taken into account, and diabetes education needs to be provided based on jointly identified goals, interests, abilities, and needs.

The epidemiology of exposure to electromagnetic fields: an overview of the recent literature

Epidemiologic studies of exposure to electromagnetic fields (EMF) have been reviewed. Possible links to incidences of cancer and abnormal fetal development have been suggested by some investigators. In general, the results have been inconsistent. There are many deficiencies in the studies, and many questions have been raised about the validity of some of the conclusions proposed. There is currently no definitive evidence of an association between exposure to EMF and the alleged risks. Due to problems and limitations inherent in future studies (misconceptions about exposure levels, uncertainty about field variability, criticisms of surrogate measures), this question is unlikely to ever be answered with certainty. Unfortunately, many highly-publicized accounts of speculative and unsubstantiated claims have caused undue concern among the general public.

Orbital decompression for optic neuropathy secondary to thyroid eye disease

To improve our management of optic neuropathy from thyroid eye disease, we have refined the external ethmoidectomy approach, which permits the removal of the medial orbital wall and adjacent floor. We now report our experience with six patients (11 eyes) selected for this surgical technique. These patients are part of a larger population of patients with thyroid eye disease who have been surgically managed by us over the last 6 years.

Effects of 20-MHz radiofrequency radiation on rat hematology, splenic function, and serum chemistry

In this study, Sprague-Dawley rats were exposed in a TEM chamber to 20-MHz (HF-band) continuous-wave radiofrequency radiation (RFR) for 6 hr/day, 5 days/week up to 6 weeks. The average E-field intensity was 2686 +/- 164 V/m (mean +/- SD) and the calculated specific absorption rate was 0.3 W/kg. Randomly sampled rats killed on Days 8, 22, 39, and 42 after initiation of exposure showed no statistically significant differences from controls for body mass, spleen cell density, erythrocyte and leukocyte counts, hematocrit, hemoglobin, methemoglobin, erythrocyte fragility, bilirubin, creatinine, SGPT, alkaline phosphatase, calcium, sodium, potassium, and spleen cell chemiluminescence. Splenic mass differences were statistically significant (p less than 0.05) only on Day 22. Spleen to body mass ratios differed significantly between exposed and control groups on Days 22 and 39 (P less than 0.05 and P less than 0.025, respectively). Histologic examination of the rats revealed the successive accumulation of phagocytic cells, lymphoid proliferation, development of lesions, and tissue necrosis characteristic of respiratory mycoplasmosis. In a followup experiment, a separate set of rats was exposed for 6 weeks to identical levels of RFR. No significant differences were found in splenic parameters and spleen cell peroxidative activity. Histologic examination of these animals revealed no evidence of mycoplasma infection. The observed differences between exposed and control animals of the first experiment appear to have resulted from subclinical respiratory mycoplasmosis rather than exposure to RFR.

In utero exposure to low-level microwaves does not affect rat foetal development

Forty pregnant Sprague-Dawley rats were used in a study to determine low-level microwave effects on foetal development. Animals were continuously exposed to 2450 MHz radiation from day 2 to day 18 of gestation, at a specific absorption rate of 0.4 W/kg. Foetuses were removed, weighed and measured. They were then either fixed in Bouin's fluid, sectioned at 6 microns, stained with hematoxylin and eosin and examined by light microscopy, or cleared and stained with alizarin red. No significant difference was noted with respect to foetal weight, length, resorption rate or abnormality rate.

In utero exposure to microwave radiation and rat brain development

Timed-pregnancy rats were exposed in a circular waveguide system starting on day 2 of gestation. The system operated at 2,450 MHz (pulsed waves; 8 microseconds PW; 830 pps). Specific absorption rate (SAR) was maintained at 0.4 W/kg by increasing the input power as the animals grew in size. On day 18 of gestation the dams were removed from the waveguide cages and euthanized; the fetuses were removed and weighed. Fetal brains were excised and weighed, and brain RNA, DNA and protein were determined. Values for measured parameters of the radiated fetuses did not differ significantly from those of sham-exposed fetuses. A regression of brain weight on body weight showed no micrencephalous fetuses in the radiation group when using as a criterion a regression line based on two standard errors of the estimate of the sham-exposed group. In addition, metrics derived from brain DNA (ie, cell number and cell size) showed no significant differences when radiation was compared to sham exposure. We conclude that 2,450-MHz microwave radiation, at an SAR of 0.4 W/kg, did not produce significant alterations in brain organogenesis.

Vitreous fluorophotometry: identification of sources of variability

Slit-lamp vitreous fluorophotometry (VF) has been used by several investigators to document the early breakdown of the blood-ocular barrier. After an injection of fluorescein, levels of fluorescein in the vitreous humor are reported to be elevated in diabetic patients compared with controls even when there is no retinal pathologic condition discernible by angiography or ophthalmoscopy. We have examined the technique of VF in normal persons and have identified several potential sources of error in the determination of vitreous fluorescein levels. Fluorescein in the choroidal circulation significantly influences VF readings taken at the retinal surface and in the posterior vitreous. This effect is modulated by ocular pigmentation, with heavy pigmentation of dark-eyed normals more effectively screening out choroidal fluorescence than the light pigmentation of blue-eyed subjects. Influence of choroidal fluorescein extends toward the midvitreous, and the range of influence is directly related to the slit width of the exciting light. At narrow slit widths the effect is diminished but can never be completely eliminated. Blood fluorescein levels decrease with time, and since choroidal fluorescein contributes to VF values, the time after injection that VF reading are taken is a critical parameter.

In vitro study of microwave effects on calcium efflux in rat brain tissue

In this study we investigated the prospect of microwave-induced alteration of 45Ca2+ efflux from rat neural tissue at low pulse repetition frequencies and low power densities under in vitro conditions. Rat cerebral tissue, preloaded with 45Ca2+, was exposed to pulsed-microwave radiation (1-GHz carrier frequency) according to one of several PRF-power density exposure schemes: 16 Hz at 0.5, 1.0, 2.0, or 15 mW/cm2, or 32 Hz at 1.0 or 2.0 mW/cm2 average power density. Measurements of radioactivity in the efflux medium and in the tissue sample were used to calculate an efflux value for each sample. The results indicate that the radiation conditions used did not alter calcium efflux in rat brain tissue.

Orientation effects on microwave-induced hyperthermia and neurochemical correlates

This paper describes the effect of field orientation on the hyperthermia produced by microwave irradiation. Rats exposed in the E-orientation (long-axis of animal parallel to E-field) to 1600 tmhz radiation become significantly hotter than those exposed in the H-field at the same power density. Norepinephrine and dopamine, but not serotonin content of the basal hypothalamus is reduced as a concomitant of microwave-induced brain hyperthermia.

Microwave fixation of brain tissue as a neurochemical technique- a review

Microwave devices have been developed for rapidly inactivating brain enzymes by focusing the power output into the heads of small laboratory animals. The rapid inactivation achieved prevents postmortem changes and permits the measurement of neurochemicals such as acetylcholine at concentrations close to those obtained in vivo. The technique promises the assay of neurochemical parameters not possible before.

Radioimmunoassay technology in mass drug screening: an evaluation of an absorbent paper disk transport system

These studies have demonstrated the feasibility of using urine-saturated paper disks in place of urine in the RIA system for drug abuse detection. Results with the disks are consistent with those using urine. A satisfactory procedure has been devised which provides reproducibility of results with no loss of sensitivity or specificity. Further, the procedure is essentially the same as the current procedure requiring urine except that a paper disk punched from a filter paper strip impregnated with urine is used. Complete flexibility is retained to switch from urine to disk. No new or additional equipment is required. It is envisioned that the urine would remain at the collection site and dried filter paper strips containing urine under test be shipped to toxicology laboratories. Sould the disk assay be positive, the urine specimen identified with that disk could then be shipped to the laboratory for confirmation by gas-liquid chromatography or other acceptable methods. The time and expense incurred in shipping large volumes of urine would thus be eliminated.

A semiautomated radioimmunoassay for mass screening of drugs of abuse

A rapid, semiautomated radioimmunoassay system for detection of morphine, barbiturates, and amphetamines is described. The assays are applicable to large drug abuse screening programs. The heart of the system is the automatic pipetting station which can accomplish 600 pipetting operations per hour. The method uses 15 to 30 mul or urine for the morphine and barbiturate assay and 100 mul for the amphetamine and combined morphine/barbiturate assays. A number of other drugs were tested for interference with the assays and the results are discussed.

Neurotransmitter content of mouse brain after inactivation by microwave heating

Mice were sacrificed by either microwave inactivation of brain enzymes or by cervical dislocation. The norepinephrine, serotonin, 5-hydroxyindoleacetic acid and homovanillic acid content of the brains of the irradiated animals was significantly greater than that of the conventionally sacrificed controls.