Operational thermal remote sensing and lava flow monitoring at the Hawaiian Volcano Observatory

Hawaiian volcanoes are highly accessible and well monitored by ground instruments. Nevertheless, observational gaps remain and thermal satellite imagery has proven useful in Hawai‘i for providing synoptic views of activity during intervals between field visits. Here we describe the beginning of a thermal remote sensing programme at the US Geological Survey Hawaiian Volcano Observatory (HVO). Whereas expensive receiving stations have been traditionally required to achieve rapid downloading of satellite data, we exploit free, low-latency data sources on the internet for timely access to GOES, MODIS, ASTER and EO-1 ALI imagery. Automated scripts at the observatory download these data and provide a basic display of the images. Satellite data have been extremely useful for monitoring the ongoing lava flow activity on Kīlauea's East Rift Zone at Pu‘u ‘Ō‘ō over the past few years. A recent lava flow, named Kahauale‘a 2, was upslope from residential subdivisions for over a year. Satellite data helped track the slow advance of the flow and contributed to hazard assessments. Ongoing improvement to thermal remote sensing at HVO incorporates automated hotspot detection, effusion rate estimation and lava flow forecasting, as has been done in Italy. These improvements should be useful for monitoring future activity on Mauna Loa.

The assessment of vascular risk in men with erectile dysfunction: the role of the cardiologist and general physician

Erectile dysfunction (ED) and cardiovascular disease (CVD) share risk factors and frequently coexist, with endothelial dysfunction believed to be the pathophysiologic link. ED is common, affecting more than 70% of men with known CVD. In addition, clinical studies have demonstrated that ED in men with no known CVD often precedes a CVD event by 2-5 years. ED severity has been correlated with increasing plaque burden in patients with coronary artery disease. ED is an independent marker of increased CVD risk including all-cause and especially CVD mortality, particularly in men aged 30-60 years. Thus, ED identifies a window of opportunity for CVD risk mitigation. We recommend that a thorough history, physical exam (including visceral adiposity), assessment of ED severity and duration and evaluation including fasting plasma glucose, lipids, resting electrocardiogram, family history, lifestyle factors, serum creatinine (estimated glomerular filtration rate) and albumin:creatinine ratio, and determination of the presence or absence of the metabolic syndrome be performed to characterise cardiovascular risk in all men with ED. Assessment of testosterone levels should also be considered and biomarkers may help to further quantify risk, even though their roles in development of CVD have not been firmly established. Finally, we recommend that a question about ED be included in assessment of CVD risk in all men and be added to CVD risk assessment guidelines.

Relationships of isometric mid-thigh pull variables to weightlifting performance

AIM

The purpose of this study was to evaluate the relationship between weightlifting performance (snatch, clean and jerk, and total) and variables obtained from the isometric mid-thigh pull (IMTP).

METHODS

Twelve weightlifters, ranging from novice to advanced, performed the IMTP 10 days after a competition. Correlations were used to evaluate relationships between variables of the IMTP and absolute and scaled competition results.

RESULTS

Unscaled competition results correlated strongly with IRFD (0-200ms: r=0.567-0.645, 0-250ms: r=0.722-0.781) while results correlated weakly with Peak IRFD (5ms window, r=0.360-0.426). Absolute peak force values correlated very strongly with absolute values for the competition performance (r=0.830-0.838). Force at 100ms, 150ms, 200ms and 250ms also correlated strongly with competition results (r=0.643-0.647, r=0.605-0.636, r=0.714-0.732, r=0.801-0.804). Similar findings were noted for allometrically scaled values.

CONCLUSION

Measures of average IRFD probably represent a more relevant variable to dynamic performance than does Peak IRFD (5ms). Maximum isometric strength also is likely to have a strong role in weightlifting performance.

Biology of the Greenland shark Somniosus microcephalus

Greenland shark Somniosus microcephalus is a potentially important yet poorly studied cold-water species inhabiting the North Atlantic and Arctic Oceans. Broad-scale changes in the Arctic ecosystem as a consequence of climate change have led to increased attention on trophic dynamics and the role of potential apex predators such as S. microcephalus in the structure of Arctic marine food webs. Although Nordic and Inuit populations have caught S. microcephalus for centuries, the species is of limited commercial interest among modern industrial fisheries. Here, the limited historical information available on S. microcephalus occurrence and ecology is reviewed and new catch, biological and life-history information from the Arctic and North Atlantic Ocean region is provided. Given the considerable by-catch rates in high North Atlantic Ocean latitudes it is suggested that S. microcephalus is an abundant predator that plays an important, yet unrecognized, role in Arctic marine ecosystems. Slow growth and large pup sizes, however, may make S. microcephalus vulnerable to increased fishing pressure in a warming Arctic environment.

Reproductive allocation and costs in gynodioecious Leucopogon melaleucoides (Ericaceae): implications for the evolution of gender dimorphism

In dioecious species, females typically allocate more resources to reproduction and incur greater costs of reproduction than males. In gynodioecious species, sex-based differences in reproductive allocation (RA) and costs have been less studied. Such knowledge, however, is relevant to address how females establish and increase in frequency in populations. We examine RA and reproductive costs by comparing fruit set, the proportion of biomass allocated to reproduction, and the responses of fruit set and vegetative growth to shoot defoliation in females and hermaphrodites in gynodioecious Leucopogon melaleucoides. Relative to hermaphrodites, females exhibited a two-fold fruit set advantage. Female fruit set increased proportionately with flower number, but hermaphrodite fruit set was reduced on plants with more flowers. Sex-based differences in allocation to other traits were small. Thus, female RA at flowering was similar to hermaphrodite RA, but was 1.4-fold greater at fruiting. Relative to controls, defoliation reduced fruit set and the percentage of shoots that produced new vegetative growth similarly in both sexes. However, females had a lower proportion of shoots with new growth overall. Further, defoliation on females reduced the dry mass of new growth by 44% compared with controls, whereas hermaphrodites were not affected. These results indicate a trade-off between reproduction and vegetative growth, and greater female costs of reproduction, particularly under resource-limiting conditions. In the absence of compensatory traits to offset higher female reproductive costs, such trade-offs have the potential to retard the spread of females in gynodioecious populations.

Steroid signaling and temperature-dependent sex determination-Reviewing the evidence for early action of estrogen during ovarian determination in turtles

The developmental processes underlying gonadal differentiation are conserved across vertebrates, but the triggers initiating these trajectories are extremely variable. The red-eared slider turtle (Trachemys scripta elegans) exhibits temperature-dependent sex determination (TSD), a system where incubation temperature during a temperature-sensitive period of development determines offspring sex. However, gonadal sex is sensitive to both temperature and hormones during this period-particularly estrogen. We present a model for temperature-based differences in aromatase expression as a critical step in ovarian determination. Localized estrogen production facilitates ovarian development while inhibiting male-specific gene expression. At male-producing temperatures aromatase is not upregulated, thereby allowing testis development.

Steroid signaling system responds differently to temperature and hormone manipulation in the red-eared slider turtle (Trachemys scripta elegans), a reptile with temperature-dependent sex determination

Many reptiles, including the red-eared slider turtle (Trachemys scripta elegans), exhibit temperature-dependent sex determination (TSD). Temperature determines gonadal sex during the middle of embryogenesis, or the temperature-sensitive period (TSP), when gonadal sex is labile to both temperature and hormones--particularly estrogen. The biological actions of steroid hormones are mediated by their receptors as defined here as the classic transcriptional regulation of target genes. To elucidate estrogen action during sex determination, we examined estrogen receptor alpha (Esr1, hereafter referred to as ERalpha), estrogen receptor beta (Esr2, hereafter referred to as ERbeta), and androgen receptor (Ar, hereafter referred to as AR) expression in slider turtle gonads before, during and after the TSP, as well as following sex reversal via temperature or steroid hormone manipulation. ERalpha and AR levels spike at the female-producing temperature while ovarian sex is determined, but none of the receptors exhibited sexually dimorphic localization within the gonad prior to morphological differentiation. All three receptors respond differentially to sex-reversing treatments. When shifted to female-producing temperatures, embryos maintain ERalpha and AR expression while ERbeta is reduced. When shifted to male-producing temperatures, medullary expression of all three receptors is reduced. Feminization via estradiol (E(2)) treatment at a male-producing temperature profoundly changed the expression patterns for all three receptors. ERalpha and ERbeta redirected to the cortex in E(2)-created ovaries, while AR medullary expression was transiently reduced. Although warmer incubation temperature and estrogen result in the same endpoint (ovarian development), our results indicate different steroid signaling patterns between temperature- and estrogen-induced feminization.

Sexual and social stimuli elicit rapid and contrasting genomic responses

Sensory physiology has been shown to influence female mate choice, yet little is known about the mechanisms within the brain that regulate this critical behaviour. Here we examine preference behaviour of 58 female swordtails, Xiphophorus nigrensis, in four different social environments (attractive and unattractive males, females only, non-attractive males only and asocial conditions) followed by neural gene expression profiling. We used a brain-specific cDNA microarray to identify patterns of genomic response and candidate genes, followed by quantitative PCR (qPCR) examination of gene expression with variation in behaviour. Our microarray results revealed patterns of genomic response differing more between classes of social stimuli than between presence versus absence of stimuli. We identified suites of genes showing diametrically opposed patterns of expression: genes that are turned ‘on’ while females interact with attractive males are turned ‘off’ when interacting with other females, and vice versa. Our qPCR results identified significant predictive relationships between five candidate genes and specific mate choice behaviours (preference and receptivity) across females exposed to males, with no significant patterns identified in female or asocial conditions or with overall locomotor activity. The identification of stimulus- and behaviour-specific responses opens an exciting window into the molecular pathways associated with social behaviour and mechanisms that underlie sexual selection.

Gonadal expression of Sf1 and aromatase during sex determination in the red-eared slider turtle (Trachemys scripta), a reptile with temperature-dependent sex determination

Many egg-laying reptiles have temperature-dependent sex determination (TSD), where the offspring sex is determined by incubation temperature during a temperature-sensitive period (TSP) in the middle third of development. The underlying mechanism transducing a temperature cue into an ovary or testis is unknown, but it is known that steroid hormones play an important role. During the TSP, exogenous application of estrogen can override a temperature cue and produce females, while blocking the activity of aromatase (Cyp19a1), the enzyme that converts testosterone to estradiol, produces males from a female-biased temperature. The production of estrogen is a key step in ovarian differentiation for many vertebrates, including TSD reptiles, and temperature-based differences in aromatase expression during the TSP may be a critical step in ovarian determination. Steroidogenic factor-1 (Sf1) is a key gene in vertebrate sex determination and regulates many steroidogenic enzymes, including aromatase. We find that Sf1 and aromatase are differentially expressed during sex determination in the red-eared slider turtle, Trachemys scripta elegans. Sf1 is expressed at higher levels during testis development while aromatase expression increases during ovary determination. We also assayed Sf1 and aromatase response to sex-reversing treatments via temperature or the modulation of estrogen availability. Sf1 expression was redirected to low-level female-specific patterns with feminizing temperature shift or exogenous estradiol application and redirected to more intense male-specific patterns with male-producing temperature shift or inhibition of aromatase activity. Conversely, aromatase expression was redirected to more intense female-specific patterns with female-producing treatment and redirected toward diffuse low-level male-specific patterns with masculinizing sex reversal. Our data do not lend support to a role for Sf1 in the regulation of aromatase expression during slider turtle sex determination, but do support a critical role for estrogen in ovarian development.

Learning effects on sperm competition and reproductive fitness

Learning and other common psychological processes presumably evolved because they contribute to reproductive fitness, but reproductive outcomes are rarely measured in psychology experiments. We examined the effects of Pavlovian conditioning on reproductive fitness in a sperm-competition situation. Typically, two males mating with the same female in immediate succession sire similar numbers of offspring. In a study with domesticated quail (Coturnix japonica), we increased paternity success by presenting a Pavlovian signal that permitted one of two competing males to predict copulatory opportunity. Using microsatellite-based DNA fingerprinting, we found that signaled males sired 72% of the offspring when competing with control males, and this effect was independent of copulation order. In the absence of Pavlovian conditioning, rates of fertilization were not significantly different for two males that copulated with the same female. These findings demonstrate that Pavlovian conditioning contributes to reproductive fitness and suggest that individual past experience can bias genetic transmission and the evolutionary changes that result from sexual competition.

Adrenal-kidney-gonad complex measurements may not predict gonad-specific changes in gene expression patterns during temperature-dependent sex determination in the red-eared slider turtle (Trachemys scripta elegans)

Many turtles, including the red-eared slider turtle (Trachemys scripta elegans) have temperature-dependent sex determination in which gonadal sex is determined by temperature during the middle third of incubation. The gonad develops as part of a heterogenous tissue complex that comprises the developing adrenal, kidney, and gonad (AKG complex). Owing to the difficulty in excising the gonad from the adjacent tissues, the AKG complex is often used as tissue source in assays examining gene expression in the developing gonad. However, the gonad is a relatively small component of the AKG, and gene expression in the adrenal-kidney (AK) compartment may interfere with the detection of gonad-specific changes in gene expression, particularly during early key phases of gonadal development and sex determination. In this study, we examine transcript levels as measured by quantitative real-time polymerase chain reaction for five genes important in slider turtle sex determination and differentiation (AR, ERalpha, ERbeta, aromatase, and Sf1) in AKG, AK, and isolated gonad tissues. In all cases, gonad-specific gene expression patterns were attenuated in AKG versus gonad tissue. All five genes were expressed in the AK in addition to the gonad at all stages/temperatures. Inclusion of the AK compartment masked important changes in gonadal gene expression. In addition, AK and gonad expression patterns are not additive, and gonadal gene expression cannot be predicted from intact AKG measurements.

Expression ofSox9,Mis, andDmrt1 in the gonad of a species with temperature-dependent sex determination

Sex determination in vertebrates, the process of forming an ovary or testis from a bipotential gonad, can be initiated by genetic or environmental factors. Elements of the downstream molecular pathways underlying these different sex-determining mechanisms have been evolutionarily conserved. We find the first evidence that Sox9 expression is preferentially organized in the testis early in the temperature-sensitive period in a species with temperature-dependent sex determination (Trachemys scripta). This pattern occurs before sexually dimorphic Mis expression and in a temporal hierarchy that is similar to mammals. Furthermore, we extend previous findings that Dmrt1 expression at early stages of sex determination has a dimorphic pattern consistent with a possible upstream role in determining the fate of the bipotential gonad.

Does inbreeding avoidance maintain gender dimorphism in Wurmbea dioica (Colchicaceae)?

The maintenance of females in gender dimorphic populations requires that they have a fitness advantage to compensate for their loss of male reproductive function. We assess whether inbreeding avoidance provides this advantage in two subdioecious Wurmbea dioica populations by estimating seed production, outcrossing rates and inbreeding depression. Fruiting males produced less than half as many seeds as females, owing to low outcrossing rates and early acting inbreeding depression. Inbreeding coefficients of fruiting males demonstrated that progeny were more inbred than their parents, implying that few selfed progeny reach maturity, as confirmed by inbreeding depression estimates that exceeded 0.85. In a glasshouse experiment, open-pollinated females exhibited a fitness advantage of 3.7 relative to fruiting males, but when we increased fruiting male outcrossing rate, female advantage was only 1.4. This reduced advantage is insufficient to maintain females if nuclear genes control sex. Thus, inbreeding avoidance could maintain females at high frequencies, although this is contingent upon high frequencies of fruiting males, which can be altered by environmentally determined gender plasticity.

The parachute technique: valgus impaction osteotomy for two-part fractures of the surgical neck of the humerus

Fourteen elderly patients with a two-part fracture, in osteopenic bone, of the surgical neck of the humerus were treated with a valgus impaction osteotomy and tension band fixation--that is, the parachute technique. Thirteen patients were followed, and all were able to perform activities of daily living without difficulty and were satisfied with the result of the surgery. The average age of these thirteen patients was sixty-eight years, and the average duration of follow-up was 18.5 months. Union was achieved in all patients, at an average of 45.5 days. No patient demonstrated osteonecrosis of the humeral head. This technique of valgus impaction osteotomy with Dacron-tape tension band fixation leads to rapid union. Patient satisfaction and function were excellent.

The floating shoulder: a biomechanical basis for classification and management

BACKGROUND

The floating shoulder (ipsilateral fractures of the clavicular shaft and the scapular neck) is thought to be an unstable injury pattern requiring operative stabilization in most instances. This recommendation has been made with little biomechanical data to support it. The purpose of this study was to determine the osseous and ligamentous contributions to the stability of experimentally created scapular neck fractures in a cadaver model.

METHODS

Standardized scapular neck fractures were made in twelve fresh-frozen human cadaveric shoulders. Each specimen was mounted in a specially designed testing apparatus and secured to a standard materials testing device. In group 1 (six shoulders), resistance to medial displacement was determined following sequential creation of an ipsilateral clavicular fracture, coracoacromial ligament disruption, and acromioclavicular capsular disruption. In group 2 (six shoulders), resistance to medial displacement was determined following sequential sectioning of the coracoacromial and coracoclavicular ligaments.

RESULTS

The average measured force for all specimens (groups 1 and 2) after scapular neck fracture was 183 +/- 3.3 N (range, 166 to 203 N). The addition of a clavicular fracture (group 1) resulted in an average measured force of 128 +/- 10.5 N (range, 83 to 153 N), which corresponds to only a 30% loss of stability. Subsequent sectioning of the coracoacromial and acromioclavicular capsular ligaments yielded an average force of 126 +/- 9.1 N (range, 114 to 144 N), a 31% loss of stability, and 0 N, a complete loss of stability, respectively. Sectioning of the coracoacromial and coracoclavicular ligaments after scapular neck fracture (group 2) resulted in an average force of 103 +/- 8.4 N (range, 89 to 118 N), a 44% loss of stability, and 0 N, a complete loss of stability, respectively.

CONCLUSIONS

Ipsilateral fractures of the scapular neck and the clavicular shaft do not produce a floating shoulder without additional disruption of the coracoacromial and acromioclavicular capsular ligaments. These and other unstable combined injury patterns are likely to be accompanied by substantial medial displacement of the glenoid fragment.

Variation in summer dormancy in the lilioid geophyte Burchardia umbellata (Colchicaceae)

Plant dormancy is a form of phenotypic plasticity that minimizes exposure to seasonally stressful conditions. We examined variation in summer dormancy in two highland and two lowland populations of the lilioid geophyte Burchardia umbellata to test the prediction that facultative dormancy is advantageous in habitats with variable summer conditions. Consistent with this prediction fewer highland plants than lowland plants became dormant under wet common garden conditions. Also, significant among-family variance occurred within highland but not lowland populations, indicating genetic differences among and within populations. Most lowland plants became dormant when exposed to wet or dry conditions (∼92%), indicating that dormancy was primarily obligate. In contrast, dormancy in highland plants increased from 44% under wet conditions to 93% under dry conditions, indicating that dormancy of some highland plants was facultative and induced by drought. Survival, growth, and flowering were reduced in lowland populations, and in dormant vs. nondormant highland plants, indicating costs of dormancy that could negate the advantages of dormancy under variable summer conditions. Summers in lowland populations are predictably hot and dry, favoring a phenotype that responds invariably to environmental cues that are correlated to future dry conditions. In highland populations, variable summer conditions probably maintain polymorphism in dormancy.

Rotation of the clavicular portion of the pectoralis major for soft-tissue coverage of the clavicle. An anatomical study and case report

BACKGROUND

The purposes of this study were to describe the anatomical features of a rotational flap consisting of the clavicular portion of the pectoralis major and to report the surgical technique and the outcome of use of this flap in a patient with poor soft-tissue coverage following multiple operations for a clavicular fracture complicated by nonunion and infection.

METHODS

Ten shoulders from five cadavera were dissected to isolate the clavicular portion of the pectoralis major. The vascular pedicle, thoracoacromial artery, and axillary artery were identified, and the length of the vascular pedicle from the axillary artery to the muscle was measured. The angle of rotation of the flap about its intact clavicular origin was measured before and after division of the acromial branch of the thoracoacromial artery. The clavicular origin was then incised, and the overall length, width, and thickness of the muscle as well as the distance from each end of the muscle to the vascular pedicle were measured.

RESULTS

The average length of the vascular pedicle from the axillary artery to the pectoralis muscle belly was 5.3 centimeters (range, 3.7 to 6.5 centimeters). The average maximum angle of rotation with the clavicular origin intact was 60 degrees (range, 55 to 67 degrees) before division of the acromial branch and 73 degrees (range, 65 to 82 degrees) after division. The average total length of the clavicular head was 20.2 centimeters (range, 18.0 to 23.0 centimeters). The average width of the clavicular head was 2.9 centimeters (range, 2.0 to 4.0 centimeters), and the average thickness was 0.5 centimeter (range, 0.2 to 0.7 centimeter). The vascular pedicle entered the muscle an average of 8.7 centimeters (range, 5.2 to 10.7 centimeters) lateral to the most medial extent of the muscle and an average of 11.5 centimeters (range, 9.5 to 14.0 centimeters) medial to the most lateral extent of the muscle. The rotational flap was successfully used clinically to provide soft-tissue coverage after bone-grafting and internal fixation of a clavicular nonunion that had been complicated by infection.

CONCLUSIONS

The clavicular head of the pectoralis major may be used as a local rotational flap to cover soft-tissue deficiencies over the clavicle. It can be harvested with relative ease without damaging the sternocostal head.

Pollen quality limits seed set in Burchardia umbellata (Colchicaceae)

In self-incompatible plants, interference by self pollen or genetically related pollen can potentially exacerbate pollen limitation, although this has rarely been demonstrated. We examined the breeding system, pollen limitation, and pollen interference using self- and cross- pollinations and pollen supplementations in Burchardia umbellata, an insect-pollinated lilioid monocot. Ovule fertilization and seed set were less following selfing than crossing (22 vs. 78% and 4 vs. 73%, respectively), indicating partial self-incompatibility. Flowers were partially protandrous, and flowers opened concurrently on plants potentially allowing self pollen interference. Natural seed set was pollen limited and varied within and among years, probably due to variation in flowering plant density. Interference by self or genetically related pollen caused pollen limitation as evidenced by increased seed set of bagged cross-pollinated plants compared to unbagged pollen-supplemented plants in two years. In 1996, both fertilization and seed set increased in response to cross-pollination, indicating that interference occurred in the style and ovary. In 1997, only seed set increased after cross-pollination indicating that interference occurred in the ovary. Inappropriate pollen deposition may contribute to pollen limitation more often than previously recognized and should select for floral traits that decrease deposition of self or related pollen.

Saline irrigation in the prevention of otorrhea after tympanostomy tube placement

OBJECTIVES

Comparison of intraoperative saline irrigation to otic drops in the prevention of postoperative otorrhea in children with middle ear effusion undergoing bilateral myringotomy with ventilation tubes.

STUDY DESIGN

This study was designed as a blinded, controlled, prospectively randomized trial.

METHODS

Study children were randomly assigned to receive either otic drops for 3 days postoperatively or saline irrigation of the middle ear space at the time of myringotomy. Only children with effusion present at the time of surgery were included. All children were evaluated for drainage 7 to 14 days postoperatively, and the degree of drainage was graded from 0 to 4.

RESULTS

Of the 84 patients entered into the study, 62 patients were eligible for data analysis (16 failed follow-up, 6 records were lost). Of the patients who completed the study, not all had bilateral effusions, resulting in 111 ears for inclusion in the study. Fifty-two ears underwent irrigation, and 10 were noted to have otorrhea (19.2%). Fifty-nine ears received otic drops, resulting in 21 ears with otorrhea (35.6%). Evaluating the degree of otorrhea with a five-point Leichert scale, the average score per ear was 0.42 for the saline irrigation group and 1.07 for the control group. The rate and degree of drainage were both statistically reduced in the saline irrigation group (P < .05).

CONCLUSIONS

Using middle ear irrigation at the time of tympanostomy may be more effective than antibiotic drops in preventing postoperative otorrhea.

Creating a large-scale content-based airphoto image digital library

This paper describes a content-based image retrieval digital library that supports geographical image retrieval over a testbed of 800 aerial photographs, each 25 megabytes in size. In addition, this paper also introduces a methodology to evaluate the performance of the algorithms in the prototype system. There are two major contributions: we suggest an approach that incorporates various image processing techniques including Gabor filters, image enhancement and image compression, as well as information analysis techniques such as the self-organizing map (SOM) into an effective large-scale geographical image retrieval system. We present two experiments that evaluate the performance of the Gabor-filter-extracted features along with the corresponding similarity measure against that of human perception, addressing the lack of studies in assessing the consistency between an image representation algorithm or an image categorization method and human mental model.

Setting up a nurse-led anticoagulant clinic

People on anticoagulation therapy need regular monitoring. With appropriate training, nurse specialists can improve patient care in anticoagulant clinics.

A role for the Ras signalling pathway in synaptic transmission and long-term memory

Members of the Ras subfamily of small guanine-nucleotide-binding proteins are essential for controlling normal and malignant cell proliferation as well as cell differentiation. The neuronal-specific guanine-nucleotide-exchange factor, Ras-GRF/CDC25Mm, induces Ras signalling in response to Ca2+ influx and activation of G-protein-coupled receptors in vitro, suggesting that it plays a role in neurotransmission and plasticity in vivo. Here we report that mice lacking Ras-GRF are impaired in the process of memory consolidation, as revealed by emotional conditioning tasks that require the function of the amygdala; learning and short-term memory are intact. Electrophysiological measurements in the basolateral amygdala reveal that long-term plasticity is abnormal in mutant mice. In contrast, Ras-GRF mutants do not reveal major deficits in spatial learning tasks such as the Morris water maze, a test that requires hippocampal function. Consistent with apparently normal hippocampal functions, Ras-GRF mutants show normal NMDA (N-methyl-D-aspartate) receptor-dependent long-term potentiation in this structure. These results implicate Ras-GRF signalling via the Ras/MAP kinase pathway in synaptic events leading to formation of long-term memories.

Placement of pedicle screws in the thoracic spine. Part I: Morphometric analysis of the thoracic vertebrae

We studied the morphology of the thoracic vertebrae in the spines of seventeen human cadavera in order to define parameters that could be used as guidelines for the placement of hooks and screws in the pedicles to obtain internal fixation. We also reviewed computerized tomographic scans of nineteen thoracic spines in living patients who had no evidence of any vertebral deformity. The transverse diameter of the pedicle, which helps to determine the size of the screw, ranged from a mean (and standard deviation) of 4.5 +/- 1.2 millimeters in the fourth thoracic vertebra to a mean of 7.8 +/- 2.0 millimeters in the twelfth thoracic vertebra. The pedicles were inclined anteromedially throughout the thoracic spine, and the angle ranged from 0.3 degree toward the midline in the twelfth thoracic vertebra to 13.9 degrees in the fourth thoracic vertebra. The morphometric data revealed wide variations in the dimensions of the pedicles, demonstrating the importance of accurate preoperative imaging with transaxial computerized tomographic scans to visualize the precise osseous margins and angles of insertion of the thoracic pedicles.

Further characterisation of forms of haemosiderin in iron-overloaded tissues

The biochemical and biophysical properties of isolated haemosiderins have been compared to that of another iron-containing protein, termed prehaemosiderin, which sediments through chaotropic potassium iodide only after 20 h of ultracentrifugation, in contrast to that of haemosiderin which is recovered after 2 h of ultracentrifugation. The iron/protein ratio and iron/phosphate ratio were less that that of the corresponding haemosiderin, while the elemental composition was also reduced in many of the prehaemosiderin samples. Mossbauer spectroscopy and electron diffraction identified the predominant presence of ferrihydrite in prehaemosiderin species even though the secondary haemochromatosis haemosiderin iron cores were essentially goethite-like. The majority of the prehaemosiderins isolated showed the presence of an additional peptide band at 17 kDa in addition to that at 21 kDa. Further Mossbauer studies of haemosiderin isolated from untreated secondary haemochromatosis patients showed that goethite was the predominant form of iron present, thereby indicating that the presence of this form of ferrihydrite was not wholly attributable to chelation therapy.

The "Torrstick": a ruler calibrated in millimeters of mercury for measurement of hydrostatic pressure

We have designed and constructed a ruler ("Torrstick") calibrated in millimeters of mercury for the measurement of hydrostatic pressure differences. Marks are placed on a measuring stick every 1.34 cm, to afford the best compromise between a column of 0.9% saline solution and a column of blood. Several uses for this ruler are proposed, including the measurement of central venous pressure.

Utilization of image-derived computer-assisted stereotaxis in a community-based practice setting

The success of a community-based stereotactic program is dependent upon community commitment, technological capability, referral base, patient/family support and, most importantly, proper patient selection. To develop a program of superior quality requires not only a substantial financial commitment, but also a basic philosophical approach which fully supports acquisition and education of support staff, physical plant renovation and an establishment of an expanding referral base. This report details the development of a highly sophisticated stereotactic program in Cedar Rapids, Iowa, a semirural community with a base referral population of approximately 300,000.