Importance of photoperiodic signal quality to entrainment of the circannual reproductive rhythm of the ewe

An endogenous circannual rhythm drives the seasonal reproductive cycle of a broad spectrum of species. This rhythm is synchronized to the seasons (i.e., entrained) by photoperiod, which acts by regulating the circadian pattern of melatonin secretion from the pineal gland. Prior work has revealed that melatonin patterns secreted in spring/summer entrain the circannual rhythm of reproductive neuroendocrine activity in sheep, whereas secretions in winter do not. The goal of this study was to determine if inability of the winter-melatonin pattern to entrain the rhythm is due to the specific melatonin pattern secreted in winter or to the stage of the circannual rhythm at that time of year. Either a summer- or a winter-melatonin pattern was infused for 70 days into pinealectomized ewes, centered around the summer solstice, when an effective stimulus readily entrains the rhythm. The ewes were ovariectomized and treated with constant-release estradiol implants, and circannual cycles of reproductive neuroendocrine activity were monitored by serum LH concentrations. Only the summer-melatonin pattern entrained the circannual reproductive rhythm. The inability of the winter pattern to do so indicates that the mere presence of a circadian melatonin pattern, in itself, is insufficient for entrainment. Rather, the characteristics of the melatonin pattern, in particular a pattern that mimics the photoperiodic signals of summer, determines entrainment of the circannual rhythm of reproductive neuroendocrine activity in the ewe.

Image processing algorithms for digital mammography: a pictorial essay

Digital mammography systems allow manipulation of fine differences in image contrast by means of image processing algorithms. Different display algorithms have advantages and disadvantages for the specific tasks required in breast imaging-diagnosis and screening. Manual intensity windowing can produce digital mammograms very similar to standard screen-film mammograms but is limited by its operator dependence. Histogram-based intensity windowing improves the conspicuity of the lesion edge, but there is loss of detail outside the dense parts of the image. Mixture-model intensity windowing enhances the visibility of lesion borders against the fatty background, but the mixed parenchymal densities abutting the lesion may be lost. Contrast-limited adaptive histogram equalization can also provide subtle edge information but might degrade performance in the screening setting by enhancing the visibility of nuisance information. Unsharp masking enhances the sharpness of the borders of mass lesions, but this algorithm may make even an indistinct mass appear more circumscribed. Peripheral equalization displays lesion details well and preserves the peripheral information in the surrounding breast, but there may be flattening of image contrast in the nonperipheral portions of the image. Trex processing allows visualization of both lesion detail and breast edge information but reduces image contrast.

Effects of various treatments on the quantitative recovery of endotoxin from water-soluble metalworking fluids

Three extraction methods were compared for their effectiveness in the quantitative removal of endotoxin from unused and used bulk water-soluble metalworking fluid (MWF) samples. Soluble, synthetic, and semisynthetic fluids were studied. The three modes of extraction consisted of (1) pyrogen-free water (PFW); (2) PFW and Tween 20 (polyoxyethylene sorbitan monolaurate); and (3) PFW, Tween 20, and sonication. Results suggest that vigorous recovery methods yield higher amounts of endotoxin from MWF samples than mild recovery methods in PFW alone. Additional studies are required to aid in the understanding of the factors that significantly affect endotoxin extraction yields from these fluids.

WW- and SH3-domain interactions with Epstein-Barr virus LMP2A

Epstein-Barr virus (EBV) is a human herpesvirus which establishes a lifelong latent infection in B lymphocytes. Latent membrane protein 2A (LMP2A) is expressed in both humans with EBV latent infection and EBV immortalized cell lines grown in culture. Previous studies have shown that the amino terminal domain of LMP2A, which contains eight tyrosines, associates with a variety of cellular proteins via SH2-phosphotyrosine interactions. Also contained within the LMP2A amino terminal domain are five proline-rich regions, three of which possess the PxxP core consensus sequence required for interacting with SH3 domains and two of which possess the PPxY core consensus sequence (PY motif) required for interacting with class I type WW domains. In the current study, the ability of LMP2A to interact with either modular SH3 or WW domains was investigated. The results of these studies indicate that the two LMP2A PY motifs interact strongly with representative class I WW domains, but not with representative class II WW domains. In contrast, no interactions were detected between LMP2A and any of the five different SH3 domains tested. These data demonstrate that a subset of the conserved proline-rich motifs within the amino terminus of LMP2A can potentially mediate interactions with cellular proteins and may play a role in EBV-mediated latency and/or transformation.

Enhancement of the dense-core vesicle secretory cycle by glucocorticoid differentiation of PC12 cells: characteristics of rapid exocytosis and endocytosis

The secretory cycle of dense-core vesicles (DCVs) in physiologically stimulated patch-clamped PC12 cells was analyzed using both amperometry and capacitance measurements. Untreated cells had low or undetectable Ca currents and sparse secretory responses to short depolarizations. Dexamethasone (5 microM) treatment for 5-7 d tripled Ca current magnitude and dramatically increased quantal secretion in response to depolarization with action potentials. Such cells expressed L-, N-, and P-type Ca channels, and depolarization evoked rapid catecholamine secretion recorded as amperometric spikes; the average latency was approximately 50 msec. These spikes were much smaller and shorter than those of primary adrenal chromaffin cells, reflecting the smaller size of DCVs in PC12 cells. Depolarizing pulse trains also elicited a rapid increase in membrane capacitance corresponding to exocytosis in differentiated but not in naïve cells. On termination of stimulation, membrane capacitance declined within 20 sec to baseline indicative of rapid endocytosis (RE). RE did not take place when secretion was stimulated in the presence of Ba or Sr, indicating that RE is Ca-specific. RE was blocked when either anti-dynamin antibodies or the pleckstrin homology domain of dynamin-1 was loaded into the cell via the patch pipette. These studies indicate that neuroendocrine differentiation of PC12 cells with glucocorticoids enhances the development of the excitable membrane and increases the coupling between Ca channels and vesicle release sites, leading to rapid exocytosis and endocytosis. Slow catecholamine secretion in undifferentiated cells may be caused in part by a lack of localized secretory machinery rather than being an intrinsic property of dense-core vesicles.

Prostaglandins mediate the endotoxin-induced suppression of pulsatile gonadotropin-releasing hormone and luteinizing hormone secretion in the ewe

Five experiments were conducted to test the hypothesis that PGs mediate the endotoxin-induced inhibition of pulsatile GnRH and LH secretion in the ewe. Our approach was to test whether the PG synthesis inhibitor, flurbiprofen, could reverse the inhibitory effects of endotoxin on pulsatile LH and GnRH secretion in ovariectomized ewes. Exp 1-4 were cross-over experiments in which ewes received either flurbiprofen or vehicle 2 weeks apart. Jugular blood samples were taken for LH analysis throughout a 9-h experimental period. Depending on the specific purpose of the experiment, flurbiprofen or vehicle was administered after 3.5 h, followed by endotoxin, vehicle, or ovarian steroids (estradiol plus progesterone) at 4 h. In Exp 1, flurbiprofen reversed the endotoxin-induced suppression of mean serum LH concentrations and the elevation of body temperature. In Exp 2, flurbiprofen prevented the endotoxin-induced inhibition of pulsatile LH secretion and stimulation of fever, reduced the stimulation of plasma cortisol and progesterone, but did not affect the rise in circulating tumor necrosis factor-alpha. In Exp 3, flurbiprofen in the absence of endotoxin had no effect on pulsatile LH secretion. In Exp 4, flurbiprofen failed to prevent suppression of pulsatile LH secretion induced by luteal phase levels of the ovarian steroids progesterone and estradiol, which produce a nonimmune suppression of gonadotropin secretion. In Exp 5, flurbiprofen prevented the endotoxin-induced inhibition of pulsatile GnRH release into pituitary portal blood. Our finding that this PG synthesis inhibitor reverses the inhibitory effect of endotoxin leads to the conclusion that PGs mediate the suppressive effects of this immune/inflammatory challenge on pulsatile GnRH and LH secretion.

Discovery of a Brown Dwarf Companion to Gliese 570ABC: A 2MASS T Dwarf Significantly Cooler than Gliese 229B

We report the discovery of a widely separated (258&farcs;3+/-0&farcs;4) T dwarf companion to the Gl 570ABC system. This new component, Gl 570D, was initially identified from the Two Micron All-Sky Survey. Its near-infrared spectrum shows the 1.6 and 2.2 µm CH4 absorption bands characteristic of T dwarfs, while its common proper motion with the Gl 570ABC system confirms companionship. Gl 570D (MJ=16.47+/-0.07) is nearly a full magnitude dimmer than the only other known T dwarf companion, Gl 229B, and estimates of L=&parl0;2.8+/-0.3&parr0;x10-6 L middle dot in circle and Teff=750+/-50 K make it significantly cooler and less luminous than any other known brown dwarf companion. Using evolutionary models by Burrows et al. and an adopted age of 2-10 Gyr, we derive a mass estimate of 50+/-20 MJup for this object.

Evidence for crystalline water and ammonia ices on Pluto's satellite charon

Observations have resolved the satellite Charon from its parent planet Pluto, giving separate spectra of the two objects from 1.0 to 2.5 micrometers. The spectrum of Charon is found to be different from that of Pluto, with water ice in crystalline form covering most of the surface of the satellite. In addition, an absorption feature in Charon's spectrum suggests the presence of ammonia ices. Ammonia ice-water ice mixtures have been proposed as the cause of flowlike features observed on the surfaces of many icy satellites. The existence of such ices on Charon may indicate geological activity in the satellite's past.

Preliminary report on the results of the second phase of a round- robin endotoxin assay study using cotton dust

In an on-going endotoxin assay study, a two-part interlaboratory endotoxin assay study has been completed. The purpose of the study was to compare the variation in assay results between different laboratories, and, if the variation was high, to see if a common protocol would reduce the variation. In both parts of the study, membrane filters laden with the same approximate amount and type of cotton dust were sent for analysis to laboratories that "routinely" perform endotoxin analyses. First, each of these laboratories performed the analysis using the methodology common to its laboratory. In the second part of the study, membrane filters with cotton dust were again sent to the same laboratories where the analyses were performed as before but with a common extraction protocol. The preliminary results from the first phase of the study have been collected and showed that intra-laboratory variations were small, but large and significant interlaboratory variation was observed. The results were reported elsewhere. The preliminary results from the second part of the study consisting of the data currently collected are presented here. Again, intra-laboratory variations were small, but, also again, large and significant inter-laboratory variation was observed. However, in this part of the study, the range between the highest and lowest average results was narrower than in the first part of the study. Influence of the assay kit type was examined. The variation within assay kit type was small but significant differences in results were observed between assay kit types. The findings suggest that endotoxin concentration in samples can be ranked within laboratories, but not necessarily between laboratories. However, some of the variation between laboratories has been reduced by a common extraction protocol which suggests the possibility of further standardization that may lead to better comparability between laboratories.

Pharmaceutical applications of the Prout-Tompkins rate equation

More than 50 years ago, a paper by E.G. Prout and F.C. Tompkins was published in the Transactions of the Faraday Society. The paper dealt with the kinetics of the thermal decomposition of crystals of potassium permanganate, and suggested a rate equation, which has become known as the Prout-Tompkins equation, for use in the kinetic analysis of solid state reactions. The paper has been extensively cited in the literature. Applications of the Prout-Tompkins equation in pharmaceutical stability studies are reviewed in this short review.

Imaging the Haro 6-10 Infrared Companion

We present an infrared imaging study of the low-mass pre-main-sequence binary system Haro 6-10. This system is one of a handful in which the optically visible primary has the characteristics of a normal T Tauri star, while the secondary is a so-called "infrared companion" (IRC), a strongly extincted object that emits most of its luminosity in the infrared. A speckle holographic technique was used to produce nearly diffraction-limited images on three nights over a 1 yr period starting in late 1997. The images show that the IRC is obscured and surrounded by a compact, irregular, and variable nebula. This structure is in striking contrast to the well-ordered edge-on disk associated with HK Tauri B, the extincted companion to another T Tauri star of similar age. A new, resolved intensity peak was found 0&farcs;4 southwest of the IRC. We suggest that it may represent light scattered by a clump of dusty material illuminated by starlight escaping along an outflow-carved cavity in the IRC envelope. The primary star became fainter and the companion became more extended during the observing period.

Detection of water ice on Nereid

We report the detection of the 1.5 and 2.0 micrometers absorption bands of water ice in the near-infrared reflection spectrum of Neptune's distant irregular satellite Nereid. The spectrum and albedo of Nereid appear intermediate between those of the Uranian satellites Umbriel and Oberon, suggesting a surface composed of a combination of water ice frost and a dark and spectrally neutral material. In contrast, the surface of Nereid appears dissimilar to those of the outer solar system minor planets Chiron, Pholus, and 1997 CU26. The spectrum thus provides support for the hypothesis that Nereid is a regular satellite formed in a circumplanetary environment rather than a captured object.

Systemic challenge with endotoxin stimulates corticotropin-releasing hormone and arginine vasopressin secretion into hypophyseal portal blood: coincidence with gonadotropin-releasing hormone suppression

We tested the hypothesis that systemic immune/inflammatory challenge (endotoxin) activates the neuroendocrine stress axis centrally by stimulating the secretion of CRH and arginine vasopressin (AVP) into hypophyseal portal blood. In addition, we examined the temporal association between this stimulation of the stress neuropeptides and the inhibition of pulsatile GnRH and LH secretion. Using alert, normally behaving ewes, hypophyseal portal and peripheral blood were sampled simultaneously at 10-min intervals for 14 h. Temperature was monitored remotely by telemetry at the same interval. Endotoxin (400 ng/kg, i.v. bolus) or saline as a control was injected after a 4-h baseline period. Portal blood was assayed for CRH, AVP, and GnRH, and peripheral blood was assayed for cortisol, progesterone, and LH. In controls, hypophyseal portal CRH and AVP remained just above or at assay sensitivity, and cortisol showed a regular rhythmic pattern unaffected by saline and typical of basal secretion. In contrast, endotoxin potently stimulated CRH and AVP secretion into portal blood, and cortisol and progesterone into peripheral blood. Both CRH and AVP generally rose and fell simultaneously, although the peak of the AVP response was approximately 10-fold greater than that of CRH. The AVP in portal blood was not due to recirculation of hormone secreted into the peripheral circulation by the posterior pituitary gland, because the AVP increase in peripheral blood was negligible relative to the marked increase in portal blood. The stimulation of CRH and AVP coincided with significant suppression of GnRH and LH pulsatile secretion in these same ewes and with the generation of fever. We conclude that endotoxin induces central activation of the neuroendocrine stress axis, stimulating both CRH and AVP release into the hypophyseal portal blood of conscious, normally behaving ewes. This response is temporally coupled to inhibition of pulsatile GnRH and LH release as well as with stimulation of adrenal cortisol and progesterone secretion and generation of fever.

Build consensus and develop collaborative practice guidelines

With differing treatment guidelines available from many sources, collaborating advanced practice nurses and physicians at this facility recognized the need for one clear, acceptable set. Survey results show that clinicians incorporate all or most of the guidelines into practice (91%).

Monitoring the consequences of uninsurance: a review of methodologies

The proportion of the United States population without health insurance continues to grow. How will this affect the health of the nation? Prior research suggests that the uninsured are at risk for poor health outcomes. They use fewer medical services and have higher mortality rates than do insured persons. The episodic nature of uninsurance and its prevalence among disadvantaged groups makes it difficult to ascertain the health effects of uninsurance. The goal of this review is to assist researchers and policy makers in choosing methodologies to assess the effects of uninsurance. It provides a compendium of methods that have been used to examine the health consequences of uninsurance, the populations in which these methods have been used, and the strengths and weaknesses of different approaches. The review highlights the need for more longitudinal studies that focus on community-based samples of the uninsured.

Hunger in an adult patient population

CONTEXT

Although clinical observations suggest that some patients experience hunger and food insecurity, there are limited data on the prevalence of hunger in adult patients.

OBJECTIVE

To determine the prevalence of hunger and food insecurity in adult patients at an urban county hospital.

DESIGN

Cross-sectional survey conducted in 1997.

PATIENTS

The primary survey included all patients aged 18 years or older who were admitted to the medicine, surgery, and neurology services during a 2-week period, and all patients who attended the hospital's general medicine clinic during 1 week. A second survey included primary care patients who received insulin from the hospital pharmacy during a 1-month period.

MAIN OUTCOME MEASURES

Rates of hunger and food insecurity.

RESULTS

Of 709 eligible patients, 567 (participation rate, 80%) were interviewed in either the clinic (n=281) or hospital (n=286). An additional 170 patients who received insulin were interviewed by telephone (response rate, 75%). Of the primary sample, 68 (12%) respondents reported not having enough food, 75 (13%) reported not eating for an entire day, and 77 (14%) reported going hungry but not eating because they could not afford food. A total of 222 (40%) had received food stamps in the previous year and of those, 113 (50%) had their food stamps reduced or eliminated. Recipients whose food stamps had been eliminated or reduced were more likely to report not having enough food (18% vs 13%, P=.006), not eating for a whole day (20% vs 16%, P=.01), going hungry but not eating (20% vs 16%, P=.08), and cutting down on the size of meals or skipping meals (33% vs 27%, P=.01). In multivariate analysis, independent predictors of hunger included an annual income of less than $10000 (odds ratio [OR], 7.55; 95% CI, 3.01-18.92), drug use (OR, 3.56; 95% CI, 1.46-8.66), and a reduction in food stamp benefits (OR, 1.73; 95% CI, 1.01-2.96). Predictors of food insecurity included an annual income of less than $10000 (OR, 4.12; 95% confidence interval [CI], 1.98-8.58), drug use (OR, 2.11; 95% CI, 1.66-5.08), and a reduction in food stamps (OR, 2.02; 95% CI, 1.23-3.32). In addition, 103 (61%) patients in the sample of diabetics reported hypoglycemic reactions; 32 (31%) of these were attributed to inability to afford food.

CONCLUSION

Hunger and food insecurity are common among patients seeking care at an urban county hospital.

The response of Jupiter's magnetosphere to an outburst on Io

A 6-month-long monitoring campaign of the Io plasma torus and neutral cloud was conducted to determine the characteristics of their interaction. During the observations, a large outburst of material from Io-inferred to be caused by the eruption of a volcanic plume on Io-caused a transient increase in the neutral cloud and plasma torus masses. The response of the plasma torus to this outburst shows that the interaction between Io and Jupiter's magnetosphere is stabilized by a feedback mechanism in which increases in the plasma torus mass cause a nonlinear increase in loss from the plasma torus, limiting plasma buildup.

Protein-bound and unbound forms of plasma cortisol in piglets after castration at seven or 14 days of age

Male piglets from seven litters were used to evaluate the long-term effects of castration and age at castration on the concentrations of cortisol and its distribution in peripheral plasma. The piglets were allotted to one of three groups of 12 animals according to whether they had been castrated at seven or 14 days old or left intact. The animals were weighed and blood samples were collected from the anterior vena cava at three, seven, 10, 14, 17, 21, 28, 35 and 42 days of age. The plasma concentrations of albumin, total protein, cortisol, and the percentage distribution of cortisol among corticosteroid binding globulin-bound (CBG-bound), albumin-bound and unbound forms, were determined. Castration at seven or 14 days of age had no effect on any of the parameters measured. In all the piglets, the percentage of unbound cortisol decreased (P < 0.001) from 24.5 to 11.6 per cent over the period of sampling. The percentage of CBG-bound cortisol increased (P < 0.001) from 19 per cent on day 17 to 47 per cent on day 21, and albumin-bound cortisol declined from 61 to 37 per cent over the same period. These results agree with previous findings of age-related changes in the percentage distribution of cortisol in the piglet and demonstrate that these patterns are unaffected by castration.

Analysis of basic fibroblast growth factor in rats with inherited retinal degeneration

In RCS rats, photoreceptors degenerate between postnatal days 20 and 60, secondary to a genetic defect expressed in the neonatal retinal pigmented epithelium (RPE). Previous work has shown delay of the photoreceptor degeneration in this model by intraocular injection of basic fibroblast growth factor (bFGF). Evidence is presented here, from bFGF immunostaining and Northern analysis of bFGF mRNA, for reduced bFGF expression in uncultured RPE of dystrophic RCS pups. It is also shown that in the mutant eyes angiogenesis in the underlying choroid, which normally occurs between postnatal days 7 and 10, is markedly delayed, with irregular distribution of vessels, consistent with a reduction in this known angiogenesis factor. Mutational analysis of the bFGF transcript and gene by denaturing gradient gel electrophoresis and Southern analysis did not, however, reveal abnormalities in the coding sequence of this gene in RCS rats.

The secretion of active recombinant human gastric lipase by Saccharomyces cerevisiae

The expression of the complete human gastric lipase (HGL) gene in Saceharomyces cerevisiae grown in defined medium resulted in the secretion of active recombinant HGL (rec.HGL) to levels of up to approximately 11 mg/liter. Of the total measurable HGL activity, 90% was detected by assaying intact cells, suggesting that the majority of rec.HGL produced was secreted but stayed attached to the cell wall. The remaining 10% was present in the growth medium and from this source active rec.HGL was purified 300-fold by a combination of hydrophobic interaction and ion-exchange chromatography. Rec.HGL migrated on reduced SDS-PAGE as three bands with estimated molecular masses of 47,45, and 43 kDa. All three forms cross-reacted with an antibody raised to natural HGL and their treatment with Endo H showed them to be N-linked glycosylation variants of a single polypeptide. The 47-kDa species was isolated using lentil lectin Sepharose 4B and shown to possess a specific activity comparable to that of the natural enzyme. Rec.HGL had an acid pH activity optimum using either tributyrin or olive oil as substrate and did not lose activity if incubated in the presence of pepsin at pH 2.0. These results demonstrate that HGL secreted by Saccharomyces cerevisiae retained those properties of the natural enzyme required for its use in the treatment of pancreatic insufficiency.

An improved left ventricular cannula for chronic dynamic blood pump support

Ventricular unloading with dynamic blood pumps can be markedly affected by the geometry of the cannula tip within the ventricular chamber. Due to the ability of these pumps to develop significant negative inflow pressure, existing cannula tips designed for passively filling blood pumps can be predisposed to inflow occlusion by intraventricular anatomic structures. A novel "trumpet" mouth cannula was constructed to overcome this limiting problem. This design was based on two criteria: to provide additional stenting to the ventricular apex, and to assure placement of the tip opening relative to the endocardial surface. This prototype cannula was evaluated in vivo against conventional caged, blunt, and tapered designs to assess anatomic and hemodynamic interaction within the ventricular apex. Post mortem examination revealed the inflow tract to be devoid of myocardial obstruction in all cases. These initial studies indicate that a trumpet mouth cannula can provide satisfactory hemodynamic performance required by dynamic blood pumps.

The fragment R collision: W. M. Keck telescope observations of SL9

The W. M. Keck telescope was used to observe the impact of comet Shoemaker-Levy 9 (SL9) fragment R at a wavelength of 2.3 micrometers on 21 July 1994. The data showed three outbursts. The first flash lasted about 40 seconds and was followed 1 minute after its peak by a second flash that lasted about 3 minutes. A third, longer lasting flare began 6 minutes after the first flash and lasted for 10 minutes. At its maximum brightness, the flare outshone Jupiter. The two short flashes are probably associated with the initial meteor trail and the subsequent fireball, respectively. The bright flare occurred when the impact site rotated into view. These data show that the explosion ejected material at least 1300 kilometers above the visible cloud tops. The luminosity of the impact site during the long bright flare was probably maintained by the release of gravitational potential energy, as this material fell back onto the lower atmosphere.

Acquired cor triatriatum after orthotopic cardiac transplantation

Orthotopic cardiac transplantation was performed in a 42-year-old woman with idiopathic cardiomyopathy. Postoperative right ventricular failure developed and a transesophageal echocardiogram demonstrated acquired cor triatriatum with marked obstruction to mitral valve inflow and severe right ventricular dilatation. At reexploration, redundant donor atrial tissue was excised correcting the cor triatriatum. She was alive and well with normal hemodynamic parameters 12 months after transplantation.