Intracellular pH measurements using perfluorocarbon nanoemulsions

We report the synthesis and formulation of unique perfluorocarbon (PFC) nanoemulsions enabling intracellular pH measurements in living cells via fluorescent microscopy and flow cytometry. These nanoemulsions are formulated to readily enter cells upon coincubation and contain two cyanine-based fluorescent reporters covalently bound to the PFC molecules, specifically Cy3-PFC and CypHer5-PFC conjugates. The spectral and pH-sensing properties of the nanoemulsions were characterized in vitro and showed the unaltered spectral behavior of dyes after formulation. In rat 9L glioma cells loaded with nanoemulsion, the local pH of nanoemulsions was longitudinally quantified using optical microscopy and flow cytometry and displayed a steady decrease in pH to a level of 5.5 over 3 h, indicating rapid uptake of nanoemulsion to acidic compartments. Overall, these reagents enable real-time optical detection of intracellular pH in living cells in response to pharmacological manipulations. Moreover, recent approaches for in vivo cell tracking using magnetic resonance imaging (MRI) employ intracellular PFC nanoemulsion probes to track cells using (19)F MRI. However, the intracellular fate of these imaging probes is poorly understood. The pH-sensing nanoemulsions allow the study of the fate of the PFC tracer inside the labeled cell, which is important for understanding the PFC cell loading dynamics, nanoemulsion stability and cell viability over time.

Two-color fluorescent (near-infrared and visible) triphasic perfluorocarbon nanoemuslions

Design and development of a new formulation as a unique assembly of distinct fluorescent reporters with nonoverlapping fluorescence spectra and a F19 magnetic resonance imaging agent into colloidally and optically stable triphasic nanoemulsion are reported. Specifically, a cyanine dye-perfluorocarbon (PFC) conjugate was introduced into the PFC phase of the nanoemulsion and a near-infrared dye was introduced into the hydrocarbon (HC) layer. To the best of our knowledge, this is the first report of a triphasic nanoemulsion system where each oil phase, HC, and PFC are fluorescently labeled and formulated into an optically and colloidally stable nanosystem. Having, each oil phase separately labeled by a fluorescent dye allows for improved correlation between in vivo imaging and histological data. Further, dual fluorescent labeling can improve intracellular tracking of the nanodroplets and help assess the fate of the nanoemulsion in biologically relevant media. The nanoemulsions were produced by high shear processing (microfluidization) and stabilized with biocompatible nonionic surfactants resulting in mono-modal size distribution with average droplet size less than 200 nm. Nanoemulsions demonstrate excellent colloidal stability and only moderate changes in the fluorescence signal for both dyes. Confocal fluorescence microscopy of macrophages exposed to nanoemulsions shows the presence of both fluorescence agents in the cytoplasm.

Critical transitions in early embryonic aortic arch patterning and hemodynamics

Transformation from the bilaterally symmetric embryonic aortic arches to the mature great vessels is a complex morphogenetic process, requiring both vasculogenic and angiogenic mechanisms. Early aortic arch development occurs simultaneously with rapid changes in pulsatile blood flow, ventricular function, and downstream impedance in both invertebrate and vertebrate species. These dynamic biomechanical environmental landscapes provide critical epigenetic cues for vascular growth and remodeling. In our previous work, we examined hemodynamic loading and aortic arch growth in the chick embryo at Hamburger-Hamilton stages 18 and 24. We provided the first quantitative correlation between wall shear stress (WSS) and aortic arch diameter in the developing embryo, and observed that these two stages contained different aortic arch patterns with no inter-embryo variation. In the present study, we investigate these biomechanical events in the intermediate stage 21 to determine insights into this critical transition. We performed fluorescent dye microinjections to identify aortic arch patterns and measured diameters using both injection recordings and high-resolution optical coherence tomography. Flow and WSS were quantified with 3D computational fluid dynamics (CFD). Dye injections revealed that the transition in aortic arch pattern is not a uniform process and multiple configurations were documented at stage 21. CFD analysis showed that WSS is substantially elevated compared to both the previous (stage 18) and subsequent (stage 24) developmental time-points. These results demonstrate that acute increases in WSS are followed by a period of vascular remodeling to restore normative hemodynamic loading. Fluctuations in blood flow are one possible mechanism that impacts the timing of events such as aortic arch regression and generation, leading to the variable configurations at stage 21. Aortic arch variations noted during normal rapid vascular remodeling at stage 21 identify a temporal window of increased vulnerability to aberrant aortic arch morphogenesis with the potential for profound effects on subsequent cardiovascular morphogenesis.

Interaction between alk1 and blood flow in the development of arteriovenous malformations

Arteriovenous malformations (AVMs) are fragile direct connections between arteries and veins that arise during times of active angiogenesis. To understand the etiology of AVMs and the role of blood flow in their development, we analyzed AVM development in zebrafish embryos harboring a mutation in activin receptor-like kinase I (alk1), which encodes a TGFβ family type I receptor implicated in the human vascular disorder hereditary hemorrhagic telangiectasia type 2 (HHT2). Our analyses demonstrate that increases in arterial caliber, which stem in part from increased cell number and in part from decreased cell density, precede AVM development, and that AVMs represent enlargement and stabilization of normally transient arteriovenous connections. Whereas initial increases in endothelial cell number are independent of blood flow, later increases, as well as AVMs, are dependent on flow. Furthermore, we demonstrate that alk1 expression requires blood flow, and despite normal levels of shear stress, some flow-responsive genes are dysregulated in alk1 mutant arterial endothelial cells. Taken together, our results suggest that Alk1 plays a role in transducing hemodynamic forces into a biochemical signal required to limit nascent vessel caliber, and support a novel two-step model for HHT-associated AVM development in which pathological arterial enlargement and consequent altered blood flow precipitate a flow-dependent adaptive response involving retention of normally transient arteriovenous connections, thereby generating AVMs.

Aortic arch morphogenesis and flow modeling in the chick embryo

Morphogenesis of the "immature symmetric embryonic aortic arches" into the "mature and asymmetric aortic arches" involves a delicate sequence of cell and tissue migration, proliferation, and remodeling within an active biomechanical environment. Both patient-derived and experimental animal model data support a significant role for biomechanical forces during arch development. The objective of the present study is to quantify changes in geometry, blood flow, and shear stress patterns (WSS) during a period of normal arch morphogenesis. Composite three-dimensional (3D) models of the chick embryo aortic arches were generated at the Hamburger-Hamilton (HH) developmental stages HH18 and HH24 using fluorescent dye injection, micro-CT, Doppler velocity recordings, and pulsatile subject-specific computational fluid dynamics (CFD). India ink and fluorescent dyes were injected into the embryonic ventricle or atrium to visualize right or left aortic arch morphologies and flows. 3D morphology of the developing great vessels was obtained from polymeric casting followed by micro-CT scan. Inlet aortic arch flow and cerebral-to-lower body flow split was obtained from 20 MHz pulsed Doppler velocity measurements and literature data. Statistically significant variations of the individual arch diameters along the developmental timeline are reported and correlated with WSS calculations from CFD. CFD simulations quantified pulsatile blood flow distribution from the outflow tract through the aortic arches at stages HH18 and HH24. Flow perfusion to all three arch pairs are correlated with the in vivo observations of common pharyngeal arch defect progression. The complex spatial WSS and velocity distributions in the early embryonic aortic arches shifted between stages HH18 and HH24, consistent with increased flow velocities and altered anatomy. The highest values for WSS were noted at sites of narrowest arch diameters. Altered flow and WSS within individual arches could be simulated using altered distributions of inlet flow streams. Thus, inlet flow stream distributions, 3D aortic sac and aortic arch geometries, and local vascular biologic responses to spatial variations in WSS are all likely to be important in the regulation of arch morphogenesis.

Enhanced aqueous solubility of long wavelength voltage-sensitive dyes by covalent attachment of polyethylene glycol

Long wavelength voltage-sensitive dyes (VSDs) called Pittsburgh (PGH) dyes were recently synthesized by coupling various heterocyclic groups to a styryl-thiophene intermediate forming extended, partially rigid chromophores. Unlike most styryl VSDs, dyes with a sulfonic acid anchor directly attached to the chromophore showed no solvatochromic absorption shifts. The limited water solubility of many long wavelength VSDs requires the use of surfactants to transport the dye through physiological saline solutions and effectively label biological membranes. Here, we tested the chemical substitution of the sulfonic acid moiety with polyethyleneglycol (PEG) chains, ranging from MW 750 to 5000, to overcome the poor solubility of VSDs while retaining their properties as VSDs. The chemical synthesis of PGH dyes and their PEG derivatives are described. The PEG derivatives were soluble in aqueous solutions (>1 mM) and still reported membrane potential changes. In frog and mouse hearts, the voltage sensitivity (DeltaF/F per action potential) and spectral properties of PEG dyes were the same as the sulfonated analogues. Thus, the solubility of VSDs can be considerably improved with small polyethyleneglycol chains and can provide an effective approach to improve staining of excitable tissues and optical recordings of membrane potential.

Properties of new, long-wavelength, voltage-sensitive dyes in the heart

Membrane potential measurements using voltage-sensitive dyes (VSDs) have made important contributions to our understanding of electrophysiological properties of multi-cellular systems. Here, we report the development of long wavelength VSDs designed to record cardiac action potentials (APs) from deeper layers in the heart. The emission spectrum of styryl VSDs was red-shifted by incorporating a thienyl group in the polymethine bridge to lengthen and retain the rigidity of the chromophore. Seven dyes, Pittsburgh I to IV and VI to VIII (PGH I-VIII) were synthesized and characterized with respect to their spectral properties in organic solvents and heart muscles. PGH VSDs exhibited 2 absorption, 2 excitation and 2 voltage-sensitive emission peaks, with large Stokes shifts (> 100 nm). Hearts (rabbit, guinea pig and Rana pipiens) and neurohypophyses (CD-1 mice) were effectively stained by injecting a bolus (10-50 microl) of stock solution of VSD (2-5 mM) dissolved in in dimethylsulfoxide plus low molecular weight Pluronic (16% of L64). Other preparations were better stained with a bolus of VSD (2-5 mM) Tyrode's solution at pH 6.0. Action spectra measured with a fast CCD camera showed that PGH I exhibited an increase in fractional fluorescence, DeltaF/F = 17.5 % per AP at 720 nm with 550 nm excitation and DeltaF/F = - 6% per AP at 830 nm with 670 nm excitation. In frog hearts, PGH1 was stable with approximately 30% decrease in fluorescence and AP amplitude during 3 h of intermittent excitation or 1 h of continuous high intensity excitation (300 W Xe-Hg Arc lamp), which was attributed to a combination of dye wash out > photobleaching > dynamic damage > run down of the preparation. The long wavelengths, large Stokes shifts, high DeltaF/F and low baseline fluorescence make PGH dyes a valuable tool in optical mapping and for simultaneous mapping of APs and intracellular Ca(2+).

Ectoparasite associations of bats from central Pennsylvania

Between April and October 1997, 689 bats representing seven species were captured at Pennsylvania's Canoe Creek State Park. Each bat was sampled for ectoparasitic arthropods, and four species were collected from 13.2% of the host individuals. Ectoparasites include the bat flea Myodopsylla insignis (Rothschild), the wing mite Spinturnix americanus (Banks), the bed bug Cimex adjunctus Barber, and the soft tick Ornithodoros kelleyi Cooley & Kohls. Prevalence, relative density, and mean intensity were calculated for ectoparasites of Myotis lucifugus (Le Conte), which harbored all four ectoparasite species and was the most commonly captured host. Patterns of ectoparasite associations were examined with respect to host sex and habitat (roost characteristics). Female M. lucifugus hosted higher densities of ectoparasites than did males. Moreover, relative densities of ectoparasites from M. lucifugus were dependent on the proximate roost; hosts captured near Bat Church were more heavily parasitized than those captured near Hartman Mine. Two other bat species were infested with at least one ectoparasite, but sample sizes were too small to analyze statistically. These bat species included Myotis septentrionalis (Trouessart), harboring M. insignis, S. americanus, and O. kelleyi, and Eptesicus fuscus (Beauvois), which harbored M. insignis and O. kelleyi.

Biotic and abiotic effects on endoparasites infecting Dipodomys and Perognathus species

Between 1989 and 1998, 3,504 rodents of the genera Dipodomys and Perognathus were collected from 4 permanent collecting sites on the University of New Mexico's Long Term Ecological Research station, located on the Sevilleta National Wildlife Refuge (SNWR), Socorro County. New Mexico. All animals were killed and examined for endoparasites (acanthocephalans, cestodes, coccidia, and nematodes). The present report focuses on 3 endoparasite groups, cestodes, coccidia, and nematodes. Specific analyses address how prevalence changes were related to abiotic factors such as habitat, season, or precipitation, and how prevalence of each parasite species in each host species differed in relation to host age, host sex, host reproductive status, host body mass, host density, parasite-parasite interactions, and host specificity. A logistic regression was used to determine which host characters and which abiotic factors are correlated with a parasite infection. Significant variables for at least half of the parasites include season, site, and winter precipitation. However, no parasite prevalences were correlated, and significant variables were not identical between parasites, indicating that each parasite species varied independently and that no generalizations can be drawn. The parasite prevalences in these rodents on the SNWR vary in independent and complex ways.

Eimeria spp. (Apicomplexa: Eimeriidae) from the eastern chipmunk (Tamias striatus) in Pennsylvania with a description of one new species

Intestinal contents of 41 eastern chipmunks (Tamias striatus) from Armstrong County, Pennsylvania, were examined for the presence of Eimeria spp. Three previously named species were identified: E. lateralis (prevalence = 9%), E. ovata (3%), and E. vilasi (74%); 1 new species, Eimeria tamiensis n. sp. (74%), is described here. This report extends the geographic ranges of the named species into Pennsylvania. Sporulated oocysts of E. tamiensis n. sp. are ovoid and 18.6 x 14.5 (16-23 x 12-17) microm, with no micropyle or residuum. Sporocysts are ellipsoid and 8.6 x 5.4 (7-10 x 4-8) microm. with a Stieda body and granular residuum. Prevalences of E. lateralis and E. vilasi were similar to those reported previously. The differences in prevalences may be due to different life-history strategies of high- and low-prevalence Eimeria species.

Ectoparasites and gastrointestinal helminths of southern flying squirrels in southeast Georgia

Southern flying squirrels (Glaucomys volans) from southeastern Georgia were examined for ectoparasites and gastrointestinal helminths. Ten species of ectoparasites were recovered, including 3 species of sucking lice (Hoplopleura trispinosa, Microphthirus uncinatus, and Neohaematopinus sciuropteri), 1 species of flea (Orchopeas howardi), 2 species of ticks (Amblyomma maculatum and Ixodes scapularis), 3 species of mesostigmatid mites (Androlaelaps casalis, A. fahrenholzi, and Haemogamasus ambulans), and 1 species of chigger (Leptotrombidium peromysci). Only the sucking lice and fleas were common on this host. M. uncinatus is reported for the first time from eastern North America. The 2 most commonly collected ectoparasites, N. sciuropteri (prevalence = 63%) and O. howardi (prevalence = 47%), have previously been shown to be vectors of the rickettsial zoonotic agent that causes sporadic epidemic typhus. Also, 3 nematodes (Citellinema bifurcatum, Strongyloides robusius, and Syphacia thompsoni), 1 unidentified cestode, and 1 acanthocephalan (Moniliformis clarki) were found in flying squirrel gastrointestinal tracts. With the exception of S. thompsoni, which was common and relatively abundant in the cecum (prevalence = 94%, intensity = 51+/-12), both the prevalence and intensity of helminth parasites were low. The nematode S. thompsoni and the acanthocephalan M. clarki are new state records for tree squirrels in Georgia.

Gastrointestinal helminths from the endangered Hualapai vole, Microtus mogollonensis hualpaiensis (Rodentia: Cricetidae)

The Hualapai vole (Microtus mogollonensis haulpaiensis) is an endangered rodent occurring in northwestern Arizona. Helmiths were examined from 47 voles collected from 9 localities in northwestern Arizona. A toal of 375 helminths was collected, including 2 species of cestodes Anoplocephaloides troeschi and Paranoplocephala macrocephala, and 1 cecal nematode Syphacia obvelata. Pinworms were the most common helminth, but prevalence and abundance varied among localities. Comparison of the pinworms we found with the types of S. obvelata and Syphacia nigeriana indicate that those in M. m. hualpaiensis were S. obvelata.

Parasites of the Abert's squirrel (Sciurus aberti) and red squirrel (Tamiasciurus hudsonicus) of New Mexico

Between 1989 and 1991, 29 Abert squirrels (Sciurus aberti) and 45 red squirrels (Tamiasciurus hudsonicus) were collected in New Mexico and examined for parasites. Of 29 S. aberti examined, 86.2% (25/29) were infected with at least 1 parasite species. Helminths were found in 62.1% (18/29) of S. aberti; 37.9% (11/29) were infected with fleas and 37.9% (11/29) with the coccidian Eimeria tamiasciuri. Among T. hudsonicus, 82.5% of the squirrels examined were infected with at least 1 parasite. Helminths were found in 57.8% (26/45) of T. hudsonicus; 22.2% (10/45) were infected with fleas and 26.7% (12/45) with Eimeria tamiasciuri. Citellinema quadrivittati was found in squirrels of both species; 55.2% (16/29) of S. aberti were infected, with 57.8% (26/45) of T. hudsonicus carrying the parasite. Enterobius sciuri was only found in S. aberti with 17.2% (5/29) carrying the infection. One cestode, Hymenolepis sp., was found only in T. hudsonicus with 6.7% (3/45) carrying the infection. Four species of flea were found on squirrels of both species. Ceratophyllus vison was found on 6.9% (2/29) of S. aberti and 6.7% (3/45) of T. hudsonicus examined. Opisodasys robustus was found on 6.9% (2/29) of S. aberti and 8.8% (4/45) of T. hudsonicus examined. Orchopeas caedens caedens was found on 3.4% (1/29) of S. aberti and 6.7% (3/45) of T. hudsonicus examined. Orchopeas neotomae was found on 10.3% (3/29) of S. aberti and 6.7% (3/45) of T. hudsonicus examined. Two species of flea were only found on T. hudsonicus; Orchopeas leucopus was found on 2.2% (1/45) and Oropsylla idahoensis was found on 2.2% (1/45) of the T. hudsonicus examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Fleas on gray foxes in New Mexico

From April 1992 to April 1993, fleas were collected from 15 gray foxes, Urocyon cinereoargenteus Schreber, in New Mexico. Flea species collected were Cediopsylla inaequalis inaequalis Baker (14/15), Echidnophaga gallinacea (Westwood) (1/15), Euhoplopsyllus glacialis affinis Baker (10/15), Foxella ignota Baker (1/15), Pulex irritans (L.) (6/15), and Pulex simulans Baker (15/15). C. i. inaequalis and F. ignota are new host records for gray foxes. The collection of C. i. inaequalis, E. g. affinis, F. ignota, and P. simulans are new host records for New Mexico. Fleas on gray foxes in the Southwest are reviewed.

Eimerians in harvest mice, Reithrodontomys spp., from Mexico, California and New Mexico, and phenotypic plasticity in oocysts of Eimeria arizonensis

Between May 1979 and August 1991, 48.7% (57/117) of the harvest mice (Reithrodontomys spp.) examined from 10 localities in Mexico, California and New Mexico had coccidian oocysts in their feces. A total of 46.7% (49/105) of the Reithrodontomys megalotis examined were positive for coccidian oocysts; this included samples from five states in Mexico (47.1%, 8/17), three counties in California (66.7%, 4/6) and two counties in New Mexico (45.1%, 37/82); 66.7% (8/12) of the Reithrodontomys montanus from one county in New Mexico also were infected. Only two coccidian species, Eimeria arizonensis and Eimeria langebarteli, were found in these hosts. Oocysts of E. langebarteli were found only in R. megalotis: in all three infected mice from Madera County, California, in the only mouse from San Bernardino County, California, and in 63% (5/8) of the infected mice from four states in Mexico. Oocysts of E. arizonensis were found in R. megalotis in Mexico, California, and New Mexico and in R. montanus from New Mexico. Sporulated oocysts of E. langebarteli differed slightly from those in previously published reports by having wider oocysts and larger sporocysts. Sporulated oocysts of E. arizonensis were variable in size, with those recovered from R. montanus significantly larger in length and width and sporocyst width than those from R. megalotis. The structure of the oocyst residuum was polymorphic, both within and between host species, and within the same mouse; it could appear as one large globule, two globules, several to many smaller globules, or as a compact mass of many small granules. Oocysts with a variable residuum were larger than those with one globule in all oocyst/sporocyst dimensions.(ABSTRACT TRUNCATED AT 250 WORDS)

Short-term effects of propranolol on portal venous pressure

The present study was designed to investigate the effect of propranolol on portal pressure of patients with alcoholic cirrhosis and portal hypertension and to correlate these effects with clinical and laboratory parameters. The mean baseline hepatic venous pressure gradient in the 50 patients studied was of 18.2 +/- 4.1 mm Hg. It decreased significantly 2 hr after the oral administration of 40 mg of propranolol to 15.7 +/- 4.2 mm Hg (a mean reduction of 13.4 +/- 17%). This reduction in hepatic venous pressure gradient resulted mainly from a decrease in mean wedged hepatic venous pressure. There was no correlation between the decrease in hepatic venous pressure gradient and the decrease in heart rate. When results were analyzed individually, only 15 (30%) showed a large decrease in hepatic venous pressure gradient (greater than 20%), 15 (30%) showed a moderate decrease (10 to 19%), and in 20 patients (40%) there was no reduction or an increase in hepatic venous pressure gradient. Comparison of "responders" (those that reduced hepatic venous pressure gradient greater than 10%) and "nonresponders" (hepatic venous pressure gradient reduction less than 10%) showed no significant differences in baseline laboratory and hemodynamic parameters, in the severity of the liver disease, in the heart rate and blood pressure response to propranolol, nor in the propranolol plasma levels achieved 2 hr after propranolol administration. Propranolol plasma levels correlated with the reduction in heart rate but not with the reduction in hepatic venous pressure gradient. Of 14 nonresponders to 40 mg of propranolol who received additional doses, six showed a reduction in hepatic venous pressure gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Neonatal screening for hypothyroidism in Scotland: results of a pilot study

We have assessed the feasibility of screening for neonatal hypothyroidism based on thyroxine (T4) or thyrotrophin (TSH) assays on dried blood spots collected for the phenylketonuria (PKU) screening programme in Scotland. The TSH assay was both more sensitive and specific than T4 in detecting primary hypothyroidism and was sufficiently rugged and rapid for routine application. Using a labelled antibody assay for TSH, 99.7 per cent of the first 30,000 babies tested had values less than 25 mU/l, and 0.24 per cent had values between 25 and 50 mU/l. Of the 11 suspected positives (TSH greater than 50 mU/l), nine were confirmed on serum specimens as primary hypothyroidism (prevalence 1:3,300) and the two false positives (0.007% of total) were explicable by inappropriate time of sampling. No false negatives have so far been identified. The median time to detection by blood spot assay was 16 days (range 6 to 22 days). Five of the nine cases were not suspected clinically at the time of screening. It is concluded that TSH fulfils most of the criteria for an ideal screening test for primary hypothyroidism and a screening programme based on blood spot TSH will allow therapy to be commenced within one month of birth.

Isoimmune neonatal thrombocytopenic purpura

Ten cases of isoimmune neonatal thrombocytopenic purpura (4 pairs of siblings and 2 singletons) are described. The condition was diagnosed by excluding other causes of thrombocytopenia , and in 8 cases it was confirmed by detecting antiplatelet antibodies in the mother. Perhaps steroids should be given to affected infants as soon as the condition is diagnosed in order to stabilise the capillary membrane. Exchange transfusion, using platelet antigen-negative blood if available, helps to remove antibodies and should be followed by the infusion of antigen-negative platelets, easily obtained from the mother by platelet-phoresis. The use of random donor platelets (as in 3 of these cases) was ineffective because 98% of the population are platelet antigen-positive. Nine of the infants recovered completely. The exception was an infant who developed hydrocephalus, possibly as a result of intracranial haemorrhage.

Mother and child in hospital--two years' experience

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