Preference Signaling for the Diagnostic Radiology Match: A Single Institution Experience

The Association of American Medical Colleges announced the addition of preference signaling to the 2022-2023 residency match cycle for Diagnostic and Interventional Radiology. This new offering provided applicants the option to indicate their specific interest in up to 6 residency programs during initial application submission. Our institutional diagnostic radiology residency program received a total of 1294 applications. One hundred and eight applicants signaled the program. Interview invitations were sent to 104 applicants, 23 of which signaled the program. Out of the top 10 ranked applicants, 6 applicants signaled the program. Out of the 5 matched applicants, 80% used the program signal, and 100% did the geographic preference. Opting to signal programs during the initial application submission may be beneficial for both the applicants and the programs in finding the optimal match.

Limits on Anisotropy in the Nanohertz Stochastic Gravitational Wave Background

The paucity of observed supermassive black hole binaries (SMBHBs) may imply that the gravitational wave background (GWB) from this population is anisotropic, rendering existing analyses suboptimal. We present the first constraints on the angular distribution of a nanohertz stochastic GWB from circular, inspiral-driven SMBHBs using the 2015 European Pulsar Timing Array data. Our analysis of the GWB in the ~2-90 nHz band shows consistency with isotropy, with the strain amplitude in l>0 spherical harmonic multipoles ≲40% of the monopole value. We expect that these more general techniques will become standard tools to probe the angular distribution of source populations.

Multiphasic changes in systemic VEGF following intravitreal injections of ranibizumab in a child

PURPOSE

To investigate whether intravitreal ranibizumab injections administered to a child alter systemic plasma levels of total and free VEGF 165.

METHODS

A 9-year-old child sustained a choroidal rupture from blunt trauma. He subsequently developed a secondary choroidal neovascular membrane, which was treated with five ranibizumab injections over a period of 8 months. Peripheral venous blood samples were taken at each visit over a period of 12 months and plasma was extracted. Plasma VEGF 165 levels were determined using enzyme-linked immunosorbent assay and were assayed both pre- and post-immunodepletion to remove complexed VEGF.

RESULTS

Plasma VEGF 165 levels proved labile following intravitreal injection of ranibizumab. Levels increased by 30% above baseline following the first intravitreal ranibizumab injection, but then returned to baseline despite two subsequent injections. There was then a rebound increase of 67% in total plasma VEGF levels following a further injection, which remained above baseline for 12 weeks despite two further intravitreal ranibizumab injections. Baseline levels were re-attained 26 weeks after the final injection.

CONCLUSIONS

These results suggest intravitreal ranibizumab injections can cause significant, multiphasic changes in systemic VEGF levels. This may be of particular clinical significance in children as VEGF is known to be vital in the development of major organs, in addition to its role in the maintenance of normal organ function in adults.

Cellular reprogramming into a brown adipose tissue-like phenotype by co-expression of HB-EGF and ADAM 12S

Abnormal adipogenesis leads to excessive fat accumulation and several health disorders. Mouse fibroblasts (MLC) transfected with ADAM 12S and HB-EGF promoted lipid accumulation. Addition of KBR-7785, an ADAM 12S inhibitor, to HB-EGF/ADAM 12S expressing cells suppressed adipogenesis. BrdU incorporation was attenuated and enhanced mitotracker staining was observed in HB-EGF/ADAM 12S cells. Quantitative real time RT-PCR resulted in elevated levels of expression of three brown adipose tissue (BAT) genes (PRDM16, PGC-1α, and UCP-1), while expression levels of the three white adipose tissue (WAT) genes (PPARγ, C/EBPα, and AKT-1) were unaltered in HB-EGF/ADAM 12S cells. Amino- or carboxy-terminal deletions of HB-EGF (HB-EGFΔN and HB-EGFΔC) co-expressed with ADAM 12S stimulated lipid accumulation. Human epidermoid carcinoma cells (A431) also exhibited lipid accumulation by HB-EGF/ADAM 12S co-expression. These studies suggest ADAM 12S and HB-EGF are involved in cellular plasticity resulting in the production of BAT-like cells and offers insight into novel therapeutic approaches for fighting obesity.

Role of disrupted in schizophrenia 1 (DISC1) in stress-induced prefrontal cognitive dysfunction

Recent genetic studies have linked mental illness to alterations in disrupted in schizophrenia 1 (DISC1), a multifunctional scaffolding protein that regulates cyclic adenosine monophosphate (cAMP) signaling via interactions with phosphodiesterase 4 (PDE4). High levels of cAMP during stress exposure impair function of the prefrontal cortex (PFC), a region gravely afflicted in mental illness. As stress can aggravate mental illness, genetic insults to DISC1 may worsen symptoms by increasing cAMP levels. The current study examined whether viral knockdown (KD) of the Disc1 gene in rat PFC increases susceptibility to stress-induced PFC dysfunction. Rats were trained in a spatial working memory task before receiving infusions of (a) an active viral construct that knocked down Disc1 in PFC (DISC1 KD group), (b) a 'scrambled' construct that had no effect on Disc1 (Scrambled group), or (c) an active construct that reduced DISC1 expression dorsal to PFC (Anatomical Control group). Data were compared with an unoperated Control group. Cognitive performance was assessed following mild restraint stress that had no effect on normal animals. DISC1 KD rats were impaired by 1  h restraint stress, whereas Scrambled, Control, and Anatomical Control groups were unaffected. Thus, knocking down Disc1 in PFC reduced the threshold for stress-induced cognitive dysfunction, possibly through disinhibited cAMP signaling at neuronal network synapses. These findings may explain why patients with DISC1 mutations may be especially vulnerable to the effects of stress.

Reliability of a field based 2D:4D measurement technique in children

BACKGROUND

There is limited literature on the relationship between second to fourth finger digit ratio (2D:4D) and health- and skill-related fitness in children. To examine this relationship it is important to establish a reliable method of assessing 2D:4D for use with large groups of children.

AIM

The aim of the study was to examine the reliability of a field-based 2D:4D measure in children. METHODS/RESEARCH DESIGN: Fifty 8-11 year olds had 2D:4D of the right hand measured using a Perspex table top, a digital camera, and Adobe Photoshop software. Second to fourth finger digit ratio (and 2D and 4D) intra-observer and inter-observer reliabilities were assessed on the same day and intraobserver reliability was measured between days. Limits of agreement (LoA), coefficient of variation (CV) and Pearson's correlation coefficient were used for statistical analysis.

RESULTS

High correlation coefficients (r=0.95-0.99) and low CV's (0.4-1.2%) were reported for intra- and inter-observer reliabilities on the same day and between days. LoA revealed negligible systematic bias with random error ranging from 0.02 to 0.12.

CONCLUSION

These findings suggest that 2D:4D (and 2D and 4D) assessment in children using digital photography provides a reliable measure of 2D:4D that can be used during field-based testing.

Distribution-based sensitivity metric for highly variable biochemical systems

Classical sensitivity analysis is routinely used to identify points of fragility or robustness in biochemical networks. However, intracellular systems often contain components that number in the thousands to tens or less and consequently motivate a stochastic treatment. Although methodologies exist to quantify sensitivities in stochastic models, they differ substantially from those used in deterministic regimes. Therefore it is not possible to tell whether observed differences in sensitivity measured in deterministic and stochastic elaborations of the same network are the result of methodology or model form. The authors introduce here a distribution-based methodology to measure sensitivity that is equally applicable in both regimes, and demonstrate its use and applicability on a sophisticated mathematical model of the mouse circadian clock that is available in both deterministic and stochastic variants. The authors use the method to produce sensitivity measurements on both variants. They note that the rank-order sensitivity of the clock to parametric perturbations is extremely well conserved across several orders of magnitude. The data show that the clock is fragile to perturbations in parameters common to the cellular machinery ('global' parameters) and robust to perturbations in parameters that are clock-specific ('local' parameters). The sensitivity measure can be used to reduce the model from its original 73 ordinary differential equations (ODEs) to 18 ODEs and to predict the degree to which parametric perturbation can distort the phase response curve of the clock. Finally, the method is employed to evaluate the effect of transcriptional and translational noise on clock function. [Includes supplementary material].

Cardiorespiratory fitness and body mass index of 9-11-year-old English children: a serial cross-sectional study from 1998 to 2004

OBJECTIVE

To examine the changes over time in cardiorespiratory fitness and body mass index (BMI) of children.

DESIGN

Serial cross-sectional, population-based study.

SETTING

Primary schools in Liverpool, UK.

PARTICIPANTS

A total of 15,621 children (50% boys), representing 74% of eligible 9-11-year olds in the annual school cohorts between 1998/9 and 2003/4, who took part in a 20m multi-stage shuttle run test (20mMST).

MAIN OUTCOME MEASURES

Weight, height, BMI (kg/m(2)) and obesity using the International Obesity Taskforce definition.

RESULTS

Median (95% confidence interval) 20mMST score (number of runs) fell in boys from 48.9 (47.9-49.9) in 1998/9 to 38.1 (36.8-39.4) in 2003/4, and in girls from 35.8 (35.0-36.6) to 28.1 (27.2-29.1) over the same period. Fitness scores fell across all strata of BMI (P<0.001). Moreover, BMI increased over the same 6-year period even among children in fittest third of 20mMST.

CONCLUSION

In a series of uniform cross-sectional assessments of school-aged children, BMI increased whereas cardiorespiratory fitness levels decreased within a 6-year period. Even among lean children, fitness scores decreased. Public health measures to reduce obesity, such as increasing physical activity, may help raise fitness levels among all children - not just the overweight or obese.

The origin of the Earth

It is not possible to consider the formation of the Earth in isolation without reference to the formation of the rest of the solar system. A brief account is given of the current scientific consensus on that topic, explaining the origin of an inner solar system rocky planet depleted in most of the gaseous and icy components of the original solar nebula. Volatile element depletion occurred at a very early stage in the nebula, and was probably responsible for the formation of Jupiter before that of the inner planets. The Earth formed subsequently from accumulation of a hierarchy of planetesimals. Evidence of these remains in the ancient cratered surfaces and the obliquities (tilts) of most planets. Earth melting occurred during this process, as well as from the giant Moon-forming impact. The strange density and chemistry of the Moon are consistent with an origin from the mantle of the impactor. Core-mantle separation on the Earth was coeval with accretion. Some speculations are given on the origin of the hydrosphere.

Synthesis of phakellistatin 11: a micronesia (Chuuk) marine sponge cyclooctapeptide

The cyclic octapeptide phakellistatin 11 (1), a constituent of The Federated States of Micronesia (Chuuk) marine sponge Phakellia sp., was synthesized using solid-phase techniques. An initial solution-phase synthesis proved to be inadequate owing to spontaneous deprotection of the Fmoc group at the heptapeptide stage. Using the PAL resin attachment and proceeding from Fmoc-Glu-alpha-allyl ester, linear elongation of the octapeptide was performed until the final unit Pro was added. The allyl ester was removed using Pd(0)[P(C(6)H(5))(3)](4). Cleavage of the final Fmoc group and cyclization with PyAOP provided phakellistatin 11 (1) in 17% overall yield. The synthetic specimen of phakellistatin 11 (1) was found to be chemically but not biologically (cancer cell lines) identical to the natural product. The result suggested a conformational difference or more likely the presence of a trace amount of a highly active antineoplastic agent that binds noncovalently to the natural cyclic octapeptide 1.

Staircase-like potentiation of calcium release in mouse myotubes during repetitive short-term application of threshold caffeine

The release of Ca2+ in response to caffeine at threshold concentration (5 mM) was studied in mouse skeletal myotubes. Repeated 5-s applications of caffeine, each followed by a 30-s washout, caused Ca2+ releases of consecutively growing amplitude (staircase phenomenon). Each response declined rapidly and had a slow tail. Repeated applications of threshold caffeine lowered the threshold concentration. The interval between threshold applications could be increased to 30 min without loss of potentiation. When threshold caffeine was applied continuously for up to 10 min, the increase in Ca2+ concentration as seen with staircase potentiation did not occur. Depolarization by elevated [K+] or by voltage-clamp steps potentiated caffeine-induced Ca2+ release rapidly as compared to the slow exponential growth of staircase-like potentiation. Gd3+ prevented the depolarization-induced potentiation, but not the staircase phenomenon. Staircase-like potentiation of Ca2+ release was evident even when the voltage sensors were clamped in their resting state; in contrast, potentiated Ca2+ release and its rapid termination apparently require conversion of the voltage sensors to an activated state. Staircase potentiation was blocked when Ca2+ was omitted from the bath, thus pinpointing the source of Ca2+. We suggest that staircase-like potentiation is conditioned by a caffeine-dependent Ca2+ influx across the plasma membrane.

Sleep and 24 hour body temperatures: a comparison in young men, naturally cycling women and women taking hormonal contraceptives

Body temperature has a circadian rhythm, and in women with ovulatory cycles, also a menstrual rhythm. Body temperature and sleep are believed to be closely coupled, but the influence on their relationship of gender, menstrual cycle phase and female reproductive hormones is unresolved. We investigated sleep and 24 h rectal temperatures in eight women with normal menstrual cycles in their mid-follicular and mid-luteal phases, and in eight young women taking a steady dose of oral progestin and ethinyl oestradiol (hormonal contraceptive), and compared their sleep and body temperatures with that of eight young men, sleeping in identical conditions. All subjects maintained their habitual daytime schedules. Rectal temperatures were elevated throughout 24 h in the luteal phase compared with the follicular phase in the naturally cycling women, consistent with a raised thermoregulatory set-point. Rectal temperatures in the women taking hormonal contraceptives were similar to those of the naturally cycling women in the luteal phase. Gender influenced body temperature: the naturally cycling women and the women taking hormonal contraceptives attained their nocturnal minimum body temperatures earlier than the men, and the naturally cycling women had blunted nocturnal body temperature drops compared with the men. Sleep architecture was essentially unaffected by either menstrual cycle phase or gender. The women taking hormonal contraceptives had less slow wave sleep (SWS), however, than the naturally cycling women. Gender, menstrual cycle phase and hormonal contraceptives significantly influenced body temperature, but had only minor consequences for sleep, in the young men and women in our study.

Anaesthesia and saccadic eye movements

During the last 10 years, there has been a vast increase in day-case surgery under general anaesthesia, but this has not been accompanied by research into the residual cognitive and motor effects during recovery from anaesthesia. Part of the explanation for this phenomenon is the lack of a suitable biophysical monitor of anaesthetic sedation. This review discusses one of the most commonly used of these biophysical monitors - namely saccadic eye movements. In particular, the efficacy of peak saccadic velocity as a monitor of sedation will be evaluated. In addition, the physiology and pharmacology of saccadic eye movements will be discussed within the context of developing other parameters of saccadic eye movements as novel biophysical monitors of anaesthetic sedation.

A transient and a persistent calcium release are induced by chlorocresol in cultivated mouse myotubes

The effect of 4-chloro-m-cresol (4-CmC), a stabilizing agent used in commercial preparations of the muscle relaxant succinylcholine, on intracellular free calcium levels in cultivated mouse myotubes was studied. Calcium signals were monitored with an inverted microscope equipped for fluorescence photometry using fura-2 as the calcium indicator. Upon bath application of 500 microM 4-CmC for 90 s, two separate calcium signals, a transient and a sustained one, could be regularly discriminated. First, with a delay of 2 s, the intracellular calcium concentration increased from 41+/-13 to 541+/-319 nM, peaked after 2-5 s and declined within 10 s to nearly resting values (n=36). Then, after a delay of up to 20 s, intracellular calcium rose quickly again to almost the same value and stayed elevated as long as the drug was applied. Upon drug removal, intracellular calcium rapidly decreased to a new level that was always slightly higher than the original base line. At 250 microM 4-CmC, the response was small, whereas at 500 microM it was at its maximum. Thus, the concentration-response curve was very steep. Replacement of extracellular calcium by EGTA and application of calcium channel blockers revealed that, for both the transient and the sustained response, calcium was released from intracellular stores. Pre-treatment with thapsigargin (0.1 microM) or ryanodine (10 microM) abolished both signal components. Repeated short-term applications of 4-CmC suggest that the two components may arise from different systems.

Opposite effects of cooling on twitch contractions of skeletal muscle isolated from tropical toads (Leptodactylidae) and northern frogs (Ranidae)

Cooling increases the twitch force of frog skeletal muscle (Rana temporaria; Rana pipiens), but decreases the twitch force of tropical toad muscle (Leptodactylus insularis). Action potentials and intramembranous charge movement in frog and toad fibers were slowed identically by cooling. Cooling increased the integral of twitch Ca2+ detected by aequorin in frog fibers (1.4-fold), while also decreasing the peak and slowing the rate of decay. Conversely, cooling decreased the integral (0.6-fold) and the peak of twitch Ca2+ in toad fibers, without affecting the rate of decay. The difference in entire Ca2+ transients may account for cold-induced twitch potentiation in frogs and twitch paralysis in toads. In sustained contractions of toad fibers, cooling markedly decreased maximum force caused by: (i) tetanic stimulation, (ii) two-microelectrode voltage clamp steps, (iii) high [K+], or (iv) caffeine. Maximum force in sustained contractions was decreased moderately by cooling frog fibers. Rapid rewarming and simultaneous removal of high [K+] or caffeine during a sustained contraction, caused toad muscle force to rise towards the value corresponding to the warm temperature. This did not occur after removing high [K+] or caffeine from toad fibers kept in the cold. Transmission electron micrographs showed no relevant structural differences. Parvalbumins are thought to promote relaxation of frog muscle in the cold. The unique parvalbumin isoforms in toad muscle apparently lack this property.

Different nocturnal body temperatures and sleep with forced-air warming in men and in women taking hormonal contraceptives

We studied how forced-air warming, conventionally used to control body temperature during and after anaesthesia, affected the nocturnal rectal temperatures and sleep composition of young men and women. Seven healthy women who were taking oral or injection contraceptives, and six healthy men spent 3 nights in a controlled environment: an adaptation night followed by 2 nights when they slept under either a down duvet (baseline) or a quilt perfused with warm air (hot). Repeated analysis of variance (ANOVA) revealed significant gender differences in the body temperature responses. On the baseline night, despite sleeping under the same conditions, the women did not show a nocturnal drop in body temperature as shown by the men. Forced-air warming increased body temperature to a similar extent in the men and the women, and resulted in enhanced hyperthermia in the women, and blunted the drop in body temperature in the men, compared to their baseline nights. The significant increases in body temperature had no consequences, however, for the subjective sleep quality of either the men or women, and only minor consequences for objective sleep composition. Both men and women had increased amounts of Stage 2 sleep on the hot night (P < 0.04). In addition, the women had reduced rapid eye movement (REM) sleep when compared to their baseline night (P < 0.04). Our results confirm that in a passive thermal environment, women who are taking oral or injection contraceptives have higher nocturnal body temperatures than men. Also, as sleep architecture was minimally affected by the increases in body temperature of between 0.2 and 0.3 degree C on the hot night in the men and women, and subjective sleep quality was unaffected, our results question the existence of a tight association between sleep and body temperature.

Effects of a low concentration of isoflurane on contrast sensitivity in volunteers

The effects of 0.15% quasi steady-state end-tidal isoflurane on the contrast sensitivity of five healthy volunteers were investigated by measuring their performance in computer generated letter discrimination tasks. A series of letters were displayed on a computer screen so that the luminance of the letter differed from that of the background. Two protocols were used: in the static protocol, the letter remained displayed on the screen until the subject responded, whereas in the dynamic protocol, the letter was displayed for 1/72 s only. Isoflurane significantly decreased contrast sensitivity in both protocols in all subjects.

Revising current two-process accounts of spacing effects in memory

Memory for repeated items improves when presentations are spaced during study. In Experiment 1A, words were repeated either immediately or after 6 intervening items. Intentional learning occurred under either focused or divided attention. Retention was tested by either free recall or yes-no recognition. Divided attention did not affect the influence of spacing in free recall, whereas it removed the spacing effect in recognition. In Experiment 1B, recognition memory was tested after incidental semantic study of words performed under either focused or divided attention. An equivalent spacing effect occurred in both attentional conditions. In Experiments 2 and 3, recognition memory for unfamiliar faces was assessed. A reliable spacing effect was found under both intentional learning and incidental structural study. These data are, collectively, incompatible with current theories of spacing effects. A theoretical proposal to account for these new findings is outlined.

Imaging caffeine-induced Ca2+ transients in individual fast-twitch and slow-twitch rat skeletal muscle fibers

Fast-twitch and slow-twitch rat skeletal muscles produce dissimilar contractures with caffeine. We used digital imaging microscopy to monitor Ca2+ (with fluo 3-acetoxymethyl ester) and sarcomere motion in intact, unrestrained rat muscle fibers to study this difference. Changes in Ca2+ in individual fibers were markedly different from average responses of a population. All fibers showed discrete, nonpropagated, local Ca2+ transients occurring randomly in spots about one sarcomere apart. Caffeine increased local Ca2+ transients and sarcomere motion initially at 4 mM in soleus and 8 mM in extensor digitorum longus (EDL; approximately 23 degrees C). Ca2+ release subsequently adapted or inactivated; this was surmounted by higher doses. Motion also adapted but was not surmounted. Prolonged exposure to caffeine evidently suppressed myofilament interaction in both types of fiber. In EDL fibers, 16 mM caffeine moderately increased local Ca2+ transients. In soleus fibers, 16 mM caffeine greatly increased Ca2+ release and produced propagated waves of Ca2+ (approximately 1.5-2.5 microns/s). Ca2+ waves in slow-twitch fibers reflect the caffeine-sensitive mechanism of Ca2(+)-induced Ca2+ release. Fast-twitch fibers possibly lack this mechanism, which could account for their lower sensitivity to caffeine.

Revising current two-process accounts of spacing effects in memory

Memory for repeated items improves when presentations are spaced during study. In Experiment 1A, words were repeated either immediately or after 6 intervening items. Intentional learning occurred under either focused or divided attention. Retention was tested by either free recall or yes-no recognition. Divided attention did not affect the influence of spacing in free recall, whereas it removed the spacing effect in recognition. In Experiment 1B, recognition memory was tested after incidental semantic study of words performed under either focused or divided attention. An equivalent spacing effect occurred in both attentional conditions. In Experiments 2 and 3, recognition memory for unfamiliar faces was assessed. A reliable spacing effect was found under both intentional learning and incidental structural study. These data are, collectively, incompatible with current theories of spacing effects. A theoretical proposal to account for these new findings is outlined.

Effects of training volume on sleep, psychological, and selected physiological profiles of elite female swimmers

Excessive training is reported to cause sleep disturbances and mood changes. We examined sleep and psychological changes in female swimmers across a competitive swimming season, that is, at the start of the season (onset), during peak training period (peak), and after a precompetition reduction in training (taper). For each phase, polysomnographic recordings, body composition, psychological parameters, and swimming performance were obtained. A daily training log and sleep diary were maintained for the entire study period. Sleep onset latency (SOL) time awake after sleep onset, total sleep time (TST), and rapid eye movement (REM) sleep times were similar at all three training levels. Slow wave sleep (SWS) formed a very high percentage of total sleep in the onset (26%) and peak (31%) training periods, but was significantly reduced following precompetition taper (16%), supporting the theory that the need for restorative SWS is reduced with reduced physical demand. The number of movements during sleep was significantly higher at the higher training volumes, suggesting some sleep disruption. In contrast to other studies, mood deteriorated with a reduction in training volume and/or impending competition.

Origin of the terrestrial planets and the moon

Our ideas about the origin and evolution of the solar system have advanced significantly as a result of the past 25 years of space exploration. Metal-sulfide-silicate partitioning seems to have been present in the early dust components of the solar nebula, prior to chondrule formation. The inner solar nebula was depleted in volatile elements by early solar activity. The early formation of the gas giant, Jupiter, affected the subsequent development of inner solar system and is responsible for the existence of the asteroid belt, and the small size of Mars. The Earth and the other terrestrial planets accreted in a gas-free environment, mostly from volatile-depleted planetesimals which were already differentiated into metallic cores and silicate mantles. The origin of the Moon by a single massive impact with a body larger than Mars explains the angular momentum, orbital characteristics and unique nature of the Earth-Moon system. The density and chemical differences between the Earth and Moon are accounted for by deriving the Moon from the mantle of the impactor.

Differences in ultra-endurance exercise in performance-matched male and female runners

Our study investigated endurance performances in a performance-matched (running 42.2 km) group of females (N = 10) and males (N = 10). The distances examined were 10 km, 21.1 km, 42.2 km, and 90 km. Measurements included VO2max, running economy, lactate accumulation, and running speeds. Although our female subjects performed as well as their male counterparts at 42.2 km (194.8 +/- 12.9 m.min-1 vs 192.6 +/- 16.3 m.min-1), the performance for 90 km was significantly better (P < 0.05) in the female group (171.0 +/- 11.7 m.min-1 vs 155.2 +/- 14.7 m.min-1). The average fraction of the VO2max (F) sustained by each subject indicated that the females achieved their performances by working at a higher (P < 0.01) F (73.4 +/- 5.5% vs 66.3 +/- 3.7% for 42.2 km and 59.8 +/- 6.2% vs 50.2 +/- 3.1% for 90 km). The degree of decline in the fraction of the VO2max sustained as the distance of running increased was significantly less (P < 0.05) in the females. The better performance by the females at 90 km was not related to greater maximal aerobic capacity, running economy, training level, or fatty acid metabolism.

Modulation of caffeine contractures in mammalian skeletal muscles by variation of extracellular potassium

Caffeine contractures were induced after K(+)-conditioning of skeletal muscles from pigs and mice. K(+)-conditioning is defined as the partial depolarization caused by increasing external potassium (K+0) with [K+]x[Cl-] constant. Conditioning depolarizations that rendered muscles refractory to brief electrical stimulation still enhanced the contracture tension elicited by subsequent direct caffeine stimulation of sarcoplasmic reticulum (SR) calcium release. The effects of K(+)-conditioning on caffeine-induced contractures of intact cell bundles reached a maximum at 15-30 mM K+0 and then progressively declined at higher [K+]0. Conditioning with 30 mM K+ for 5 min, which inactivates excitation-contraction (EC) coupling in response to action potentials, both increased the magnitude of caffeine contractures 2-10-fold and shifted the contracture threshold toward lower caffeine concentrations. Enhanced sensitivity to caffeine was inhibited by dantrolene (20 microM) and its watersoluble analogue azumolene (150 microM). These drugs decreased caffeine-induced contractures following depolarization with 4-15 mM K+ to 25-50% of control tension. The inorganic anion perchlorate (CIO-4), which like caffeine potentiates twitches, increased caffeine-induced contractures approximately twofold after K(+)-conditioning (> 4 mM). The results suggest that CIO-4 and dantrolene, in addition to caffeine, also influence SR calcium release either directly or by mechanism(s) subsequent to depolarization of the sarcolemma. Moreover, since CIO-4 is known to shift the voltage-dependence of intramembrane charge movement, CIO-4 may exert effects on the transverse-tubule voltage sensors as well as the SR.

DNA ploidy and clonal selection in ras + myc-induced mouse prostate cancer

An important goal in prostate cancer research is to define specific molecular and cellular alterations that are associated with malignant progression. The mouse prostate reconstitution model is a relevant and useful system as it allows the study of early events in cancer progression under conditions where oncogene-initiated cells are surrounded by normal tissue. Using this model, activated ras and myc oncogenes are introduced into urogenital sinus cells via the recombinant retrovirus Zipras/myc 9. After 4 weeks' growth as subcapsular renal grafts, poorly differentiated carcinomas are produced in C57BL/6 mice. In this study we examined the temporal relationships between morphological alterations, growth, DNA ploidy status and clonal selection as determined by Southern blotting in ras + myc-initiated carcinomas. Nuclear image analysis demonstrated that the emergence of a cycling DNA tetraploid cell population strongly correlated with growth and histologic progression. These tightly linked events culminated in the outgrowth of mono- or oligoclonal cancer.

Some small prostate cancers are nondiploid by nuclear image analysis: correlation of deoxyribonucleic acid ploidy status and pathological features

The biological behavior of a prostate cancer can be predicted to some degree by the volume and extent (stage) of the tumor, and its histological grade. The deoxyribonucleic acid (DNA) ploidy status has been reported by some to be another independent prognostic factor for localized prostate cancer. We determined the DNA ploidy value of each individual focus of cancer in radical prostatectomy specimens using nuclear image analysis (CAS 200 system). Ploidy results were correlated with the volume, Gleason grade and zone of origin (transition zone or peripheral zone) of each tumor, and with the presence of extracapsular extension or seminal vesicle invasion. There were 141 separate cancers in 68 patients (mean 2.1 per prostate): 9 clinical stage A1, 22 stage A2, 23 stage B1 and 14 stage B2. DNA ploidy correlated significantly (p < 0.0001) with volume, grade, extraprostatic spread and zone of origin. Remarkably, some small cancers (1 cc or less) were nondiploid (3 as small as 0.03 cc). Overall, 15% of cancers 0.01 to 0.1 cc and 31% of those 0.11 to 1.0 cc in volume were nondiploid. Of 101 cancers confined to the prostate 76% were diploid, compared to only 13% of those with extraprostatic spread. Most cancers of transition zone origin (86%) were diploid, compared to only 49% of peripheral zone cancers, and ploidy and volume relationships were significantly different for peripheral zone cancers compared to transition zone cancers. All small nondiploid cancers arose in the peripheral zone, while in the transition zone the smallest nondiploid cancer was 1.17 cc. We conclude that prostate cancers that are nondiploid are highly likely to have adverse pathological features. Some small prostate cancers contain a nondiploid cell population and these cancers arise predominantly within the peripheral zone of the prostate. Ploidy and volume relationships provide further support for the hypothesis that there is a difference in malignant potential between cancers of peripheral zone and transition zone origin.

Prenatal diagnosis of unilateral megalencephaly by real-time ultrasonography

Unilateral megalencephaly is a rare anomaly of neuronal cell migration. We recently diagnosed this condition in a fetus at 20 weeks' gestation with ultrasonography and magnetic resonance imaging. The pregnancy was terminated and postmortem magnetic resonance imaging and autopsy confirmed the diagnosis. To our knowledge this represents the first case to be prenatally diagnosed with certainty.

Ploidy studies by image analysis on fine needle aspirates of the breast

Quantitative DNA analysis was performed on preoperative fine needle aspirates of 12 breast cancers and 1 benign lesion using the Cell Analysis Systems (CAS) Model 200 image analysis system. The smears were prepared on CAS slides, routinely processed for Papanicolaou staining, and then destained and restained with Feulgen stain after cytologic evaluation. Four cases were DNA diploid, 3 were tetraploid, 1 was diploid/tetraploid, and 5 were aneuploid. When compared to analysis of samples from the resected tumor, both DNA index and S-phase fraction were constant.

Carcinoma of prostate metastatic to parotid gland

A rare case of prostate cancer with metastasis to the parotid salivary gland is reported. The prostatic origin of the mass was proven by incisional biopsy and immunohistochemical staining for prostate-specific antigen. Additional studies of the tumor included ultrastructural and quantitative deoxyribonucleic acid (DNA) analysis.

DNA content and other prognostic features in childhood medulloblastoma. Proposal of a scoring system

The authors reviewed clinical features, surgical extent of resection, histologic parameters, and DNA content in 55 children with medulloblastomas and found that complete or near total resection, absence of tumor dissemination, tumor DNA aneuploidy, and low proliferative index correlated with a favorable clinical outcome. A scoring system was developed based upon these features to identify patients who, in the future, may benefit from more aggressive or novel therapeutic regimens. Patient age and sex and adjuvant chemotherapy did not significantly correlate with long-term survival. The data also suggest that tumors that have been designated as cerebellar neuroblastomas may be a distinct group of posterior fossa tumors, which may have a better prognosis.

Volume changes during contraction of isolated frog muscle fibers

A microscope objective and electronic imaging system were used to determine how isolated frog skeletal muscle fibers adjust their volume during an isometric tetanus. Cross-sectional area and volume of the middle third of a fiber increased rapidly with the development of active tension, which indicates that contraction produced components of force perpendicular to the long axis. The extreme ends are known to shorten whether or not the middle of a fiber is isometric or stretched. Shortening of the ends may shift water towards the middle, which could account for the volume changes we observed. The cytoskeletal matrices of muscle evidently adjust rapidly during contraction to maintain a dynamic equilibrium between the axial and radial forces that stabilize the whole cell. The Z disks have been shown to expand during active, but not passive, tension development. Z disks might be the elastic elements of the muscle cytoskeleton primarily involved in rapid balancing of the radial components of active force.

Effects of putative modulators of relaxation microinjected into intact amphibian smooth muscle cells

1. Single smooth muscle cells were isolated intact from the stomach of the toad Bufo marinus. The relaxation of cells following cessation of electrical stimulation was compared with those relaxed by pressure microinjection of either metal ion chelators or cyclic nucleotides. 2. Injection of either a Ca2+ chelator or 3',5'-cyclic AMP slowed or halted shortening and promoted re-extension of a cell or collapse of membrane evaginations (blebs) in a manner similar to that following cessation of electrical stimulation. Collapse of blebs occurred first and was then followed smoothly by the next stage with cells re-extending at maximum rates in one of three ranges at 22 degrees C. These rates, in order of increasing speed, were 0.005, 0.009 and 0.03 cell lengths s-1 after electrical stimulation, 3',5'-cyclic AMP and EDTA injection, respectively. On the other hand, shortening began at a maximum rate of about 0.1 cell lengths s-1 unless a Ca2+ chelator or 3',5'-cyclic AMP was injected about 30 s or less before electrical stimulation. Injection of these agents reduced the speed of shortening by about half. 3. Injection of a liquid per se (e.g. 140 mM-KCl) neither altered action potentials nor duplicated the changes produced by the aforementioned relaxing agents. Large, sustained injections of substances that were not relaxing agents (e.g. dilute KCl) ruptured the membrane without producing any bleb collapse or re-extension of a contracted cell. Blebs not only collapsed rapidly when a relaxing agent was injected but bleb collapse was a much more sensitive indication of relaxation than cell re-extension; small injections of relaxing agents could clearly collapse blebs with no associated measurable change in cell length. This supports the idea previously inferred from fixed or permeabilized cells, that filaments in smooth muscle are organized to produce force over short distances at points along the cell membrane, in addition to shortening along the long axis. 4. Physiological relaxation of smooth muscle can evidently be mimicked by 3',5'-cyclic AMP elevation. Restoring forces may develop during shortening of isolated smooth muscle cells in elements of their cytoskeleton, surface membrane, or contractile filaments. However, these putative forces may not be able to produce physiological re-extension in the absence of a rise in cyclic AMP and/or a fall in [Ca2+].

Isolation and characterization of parvalbumins from skeletal muscles of a tropical amphibian, Leptodactylus insularis

Parvalbumins were isolated from skeletal muscles of a tropical amphibian, Leptodactylus insularis, and three new isotypes were identified. The total concentration of parvalbumins in L. insularis was the same as the total amounts found in an amphibian from the temperate or variable zone (Rana temporaria). Muscles of the thigh and foreleg had the maximum parvalbumin concentration (0.35 mmol.kg wet weight-1). Samples from pectoralis and rectus abdominis muscles had significantly less (0.29 mmol.kg-1). Three previously unknown parvalbumin isotypes (IV, IIIa, and IIIb) were isolated from the tropical amphibian. They were different from the isotypes (IVa and IVb) predominant in R. temporaria skeletal muscle. Parvalbumins are thought to have a role in the short-term removal of myoplasmic Ca2+ during muscle relaxation. Hence, the unique isotypes in L. insularis may reflect optimal molecular adaptations retained during the animal's evolution in a constantly warm environment.

Fatal pulmonary aspergillosis presenting as acute eosinophilic pneumonia in a previously healthy child

A previously healthy boy presented with cough and diffuse pulmonary interstitial infiltrates. Acute eosinophilic pneumonia was diagnosed by bronchoalveolar lavage in the absence of a demonstrable infectious etiologic agent. Corticosteroid therapy resulted in immediate improvement but was followed by respiratory distress and death from invasive aspergillosis and Pseudomonas cepacia sepsis.

DNA ploidy by image analysis of individual foci of prostate cancer: a preliminary report

The malignant potential of an individual focus of prostate cancer is difficult to determine. The established pathological features associated with malignant behavior include tumor volume, grade, and invasiveness (local extension or metastasis). We used nuclear image analysis to determine the DNA ploidy value of each cancer in a series of 30 radical prostatectomy specimens from patients with early stage prostate cancer in order to further explore the malignant potential of each separate focus of cancer. The volume, grade, invasiveness (extracapsular extension or seminal vesicle invasion), and zone of origin of each of the 63 separate cancers were determined. The DNA ploidy histogram of 200 cancer cells was compared with 50 normal epithelial nuclei on the same Feulgen-stained tissue sections. Sixty % of the cancers were diploid, and 40% were nondiploid. Ploidy correlated with volume and grade. All cancers less than 0.02 cm3 were diploid; 26% of foci 0.02 to 2.0 cm3 and 82% of foci greater than 2.0 cm3 were nondiploid. There were 16 cancers of transition zone origin ranging in size from 0.02 to 12.1 cm3 and only one (7.3 cm3) was nondiploid. There were 47 cancers of peripheral zone origin (range, 0.01 to 18.98) and 24 (51%) were nondiploid. Eight of the 24 nondiploid cancers were small (less than 1.0 cm3), and two were only 0.03 cm3. We conclude that some very small prostate cancers are nondiploid and that progression of prostate cancer is not a function of volume alone, whereby tumors only acquire full malignant potential at large volumes. Cancers of peripheral zone origin acquire a nondiploid cell population at a smaller volume than do cancers of transition zone origin, further supporting a fundamental difference between cancers arising in these zones.

Vagal paragangliomas: a clinical, pathological, and DNA assessment

Ten vagal paragangliomas were studied by image analysis and the results correlated with clinicopathologic features to determine if the DNA ploidy pattern could be used to separate benign from malignant paragangliomas. The tumours occurred in 8 women and 2 men ranging in age from 23 to 75 years (average 54 years). Follow-up was available in all 10 patients and ranged from 3 months to 27 years (average 7.8 years). Of the 10 tumours examined for DNA, 5 were diploid, 4 diploid-tetraploid, and 1 aneuploid. Two patients experienced local recurrences. One of these had a diploid tumour that recurred 22 years after excision and the other had an aneuploid tumour which recurred 4 years 4 months later and was associated with cervical lymph node metastasis. Two patients had malignant tumours with histologically confirmed metastases to noncontiguous cervical lymph nodes. One of the malignant tumours was diploid and the other aneuploid. This study concludes that DNA abnormalities are common in vagal paragangliomas and that tumour ploidy can not be used to assess malignant potential.

Nonuniform volume changes during muscle contraction

We measured dynamic changes in volume during contraction of live, intact frog skeletal muscle fibers through a high-speed, intensified, digital-imaging microscope. Optical cross-sections along the axis of resting cells were scanned and compared with sections during the plateau of isometric tetanic contractions. Contraction caused an increase in volume of the central third of a cell when axial force was maximum and constant and the central segment was stationary or lengthened slightly. But changes were unequal along a cell and not predicted by a cell's resting area or shape (circularity). Rapid local adjustments in the cytoskeletal evidently keep forces in equilibrium during contraction of living skeletal muscle. These results also show that optical signals may be distorted by nonuniform volume changes during contraction.

Quantitative DNA analysis of small renal cortical neoplasms

DNA aneuploidy is common in large renal cortical neoplasms (RCNs), but the incidence in small RCNs is not known. This study was undertaken to investigate whether the traditional 3.0-cm size distinction between small (benign) and large (malignant) tumors might have an objective correlate in the form of abnormal DNA content. Quantitative DNA analysis was performed retrospectively, by image analysis, on 59 RCNs measuring 5.0 cm or less from 30 nephrectomy specimens with solitary tumors and 17 with multiple tumors. DNA indices and the proportion of cells with DNA content greater than that of the G0/G1 population were evaluated with respect to tumor size, stage, and histologic parameters. There was a relationship between the presence of detectable nondiploid stem lines (NDSLs) and tumor size, stage, nuclear grade, and proportion of non-G0/G1 cells, but not histologic pattern. The relationship of NDSLs to tumor size was more apparent in the solitary tumor group, while the relationship of a high proportion of non-G0/G1 cells to tumor size was stronger in the multiple tumor group. Our results show that the incidence of NDSLs increases with tumor size and nuclear grade, and suggest that as RCNs enlarge, the emergence of NDSLs heralds potential biologic aggressiveness. Further, solitary tumors and multiple synchronous tumors may be biologically different in terms of etiologic factors and growth potential.

DNA analysis of multiple synchronous renal cell carcinomas

The authors used retrospective quantitative DNA analysis to study interrelationships between multiple synchronous renal cell carcinomas in seven patients. DNA content was determined by image analysis on Feulgen-stained nuclear smears prepared from multiple paraffin blocks from each tumor. Tumors were unilateral in four cases and bilateral in three. Ten tumors had homogeneous, and four heterogeneous DNA stemlines. Intertumoral heterogeneity in four cases suggested multifocal origin. Identical DNA aneuploid indices in bilateral tumors in one case suggested metastasis from a solitary origin. Abnormal DNA content and heterogeneous populations began to appear in the size range 2.0 to 5.0 cm. All tumors over 5.0 cm contained nondiploid populations. Although the interrelationships between these multiple synchronous neoplasms are not entirely clear, the DNA analysis suggests that the occurrence of nondiploid stemlines and heterogeneous DNA content may parallel both tumor growth and more aggressive behavior.

Typical and atypical carcinoid tumors of lung: a clinicopathologic and DNA analysis of 20 tumors

Twelve typical carcinoid tumors (TCT) and eight atypical (malignant) carcinoid tumors (ACT) of the lung were studied for quantitative DNA content by image analysis in order to identify prognostic features. No correlation of any histologic variables of the TCTs and ACTs with abnormal DNA content were noted. Furthermore, it was concluded that although abnormalities of DNA content, particularly aneuploidy, are common in ACTs, DNA ploidy cannot be used independently to assess malignant potential.

Carotid body paragangliomas. A clinicopathologic and DNA analysis of 13 tumors

The clinical and pathological features of 13 carotid body paragangliomas from 12 patients were examined and correlated with the DNA ploidy pattern as determined by image analysis. These tumors occurred in 7 women and 5 men aged 19 to 62 years (average, 42 years). All presented with a slowly enlarging, usually asymptomatic mass of 2 weeks' to 25 years' duration. Two patients were related and had a family history of paragangliomas. The tumors ranged from 2 to 6 cm. All contained scattered chief cells with pleomorphic nuclei, two exhibited mitoses, and three showed perineural and three vascular invasion. Follow-up was available in all 12 patients and ranged from 15 months to 28 years (average, 7.3 years). None of the tumors recurred locally, but one did metastasize to a single cervical lymph node that was apparent at the time of diagnosis. Of 13 carotid body paragangliomas examined for DNA, 4 were diploid, 3 diploid-tetraploid, 3 tetraploid, 2 aneuploid, and 1 polyploid. The only malignant tumor was polyploid. From these observations, we conclude that abnormalities in DNA content of carotid body paragangliomas are common and that tumor ploidy cannot be used to assess malignant potential. We also found no apparent relationship among nuclear pleomorphism, mitotic activity, perineural invasion, or vascular invasion and clinical behavior. Perineural and vascular invasion, however, were observed only in tumors with abnormal DNA histograms.

A comparative analysis of nuclear DNA content and N-myc gene amplification in neuroblastoma

Nuclear DNA content and N-myc amplification have been found to have prognostic significance in neuroblastoma. To investigate the interrelationships between these two parameters, tumor samples from 18 patients with neuroblastoma were analyzed for both total DNA and N-myc gene content. Quantitative DNA analysis was performed by image analysis. Quantitative Southern blot hybridization was used to determine N-myc gene copy number and to distinguish between low level gene amplification or excess gene copies secondary to aneuploidy. Six of the 18 patients have died. Five of the six had nonaneuploid tumors, but only two of the six exhibited major N-myc amplification. Low-level amplification was detected in one Stage II patient. The authors' results suggest that neuroblastomas with N-myc amplification are a subset of nonaneuploid tumors.

Severe chemotherapy-related hepatic toxicity associated with MZ protease inhibitor phenotype

We describe a 10 1/2-month-old boy in whom fulminant hepatic failure following chemotherapy for Wilms' tumor developed. He then received an orthotopic liver transplant. An unexpected finding was the accumulation of alpha 1-antitrypsin (AAT) in periportal hepatocytes. A pretransplant serum sample showed a Pi MZ phenotype. The rarity of hepatic failure following treatment for Wilms' tumor raises the possibility of an increased susceptibility to toxic injury in the presence of AAT accumulation. Determination of the frequency of protease inhibitor MZ phenotype in patients who have chemotherapy-related hepatotoxicity could be used to initiate a prospective study aimed at identifying an at-risk population for chemoradiotherapy-related hepatoxicity.

Three infants with acute megakaryoblastic leukemia simulating metastatic tumor

The diagnosis of acute megakaryoblastic leukemia (AMKL) (M7, French-American-British [FAB] classification) has rarely been made in children due, in part, to its pleomorphic morphology and ability to mimic other malignancies common in the pediatric age group. Three infants are described who had thrombocytopenia and the classical criteria of metastatic solid tumor in the bone marrow: patchy infiltration by cohesive clusters of cells with high nuclear cytoplasmic ratio and myelofibrosis in the bone marrow biopsy infiltrated area. This finding prompted clinical evaluation for solid tumor. The megakaryocytic lineage was ascertained by immunocytochemical studies and/or electron microscopic examinations of the bone marrow aspirates. The blasts in all three patients showed cytogenetic abnormalities that also were demonstrated by quantitative DNA analysis. None of the infants had Down's syndrome. Two of the patients are alive; one is off of therapy and the other is in remission. The third patient was transferred to another institution and lost to follow-up. Two children had wheezing that disappeared in remission. It is proposed that the clinical symptoms may be due to a substance produced, stored, or released by the leukemic cells.

Central values and variation of measured nuclear DNA content in imprints of normal tissues determined by image analysis

A total of 109 slides derived from 37 normal tissues were analyzed for nuclear DNA content using the Cell Analysis Systems (CAS) model 100 image analysis system with the Quantitative DNA Analysis (QDA) software module in order to determine the central values of DNA content and define normal limits. Analysis of the 109 slides revealed an overall mean measured DNA index of 0.997 with a standard deviation of 0.04. Analysis of replicate samples was essentially constant. There were no differences between samples obtained from autopsy and surgical specimens. Small variations were detected among stain batches, individual patients, and tissue types. These results indicate a high degree of accuracy and reproducibility of DNA content determinations using this system.

Comparison of activity of deferoxamine with that of oral iron chelators against human neuroblastoma cell lines

The iron chelator, deferoxamine, has demonstrated cytotoxicity against neuroblastoma cells. In this study we examined the in vitro antineuroblastoma activity of several potentially less expensive oral chelating agents. On a mole for mole basis, 1-hydroxypyridine-2-thionine (omadine) had 100 times the cytotoxicity of deferoxamine. 1,2-Dimethyl-3-hydroxypyrid-4-one also caused demonstrable cell death but at considerably higher molar concentrations than those required for deferoxamine. 2,3-Dihydroxybenzoic acid had no effect on neuroblastoma cell viability over a range of concentrations. In contrast to the effect of both deferoxamine and 1,2-Dimethyl-3-hydroxypyrid-4-one, those due to omadine were permanent within 24 hours of incubation, were not significantly altered by the presence of ionic iron, and correlated with an increase in the percentage of cells in the S-G2-M phases of the cell cycle. On the basis of these in vitro studies, we believe that the use of omadine in particular and iron chelators in general, by themselves or as cell cycle-recruiting agents together with standard cell cycle specific drugs, is an approach to the treatment of cancer worth further investigation.

Flow cytometry DNA ploidy analysis and catecholamine secretion profiles in neuroblastoma

Previous studies have shown that catecholamine secretion patterns have been imperfect predictors of clinical behavior of neuroblastomas. Recently, studies of nuclear DNA content in neuroblastoma have shown that an aneuploid DNA content predicts favorable clinical behavior. To determine if a correlation exists between these tumor biologic indicators, the authors analyzed both in a series of 39 patients with neuroblastoma. Flow cytometric DNA analysis performed on paraffin blocks determined that 23 patients had tumors with aneuploid DNA content (aneuploid tumors) and 16 patients showed no demonstrable anomalies of tumor DNA content (nonaneuploid tumors). Comparison of catecholamine levels in urine and tumor homogenates with DNA content data indicate that nonaneuploid neuroblastomas include a significant number (P less than 0.02) of biochemically primitive tumors which secrete high levels of 3,4 dihydroxyphenylalanine (DOPA), dopamine and homovanillic acid (HVA). This suggests a dopamine-norepinephrine pathway block, which supports previous reports of deficiency of dopamine beta-hydroxylase activity in some neuroblastomas. The study shows that in contrast to aneuploid tumors, nonaneuploid neuroblastomas secrete higher levels of early pathway catecholamine metabolites and are more likely to present in higher (unfavorable) clinical stages of disease.