Innovative uses of vegetated drainage ditches for reducing agricultural runoff

Vegetated agricultural ditches play an important role in mitigation of pesticides following irrigation and storm runoff events. In a simulated runoff event in the Mississippi (USA) Delta, the mitigation capacity of a drainage ditch using the pyrethroid esfenvalerate (Asana XL) was evaluated. The pesticide was amended to soil prior to the runoff event to simulate actual runoff, ensuring the presence of esfenvalerate in both water and suspended particulate phases. Water, sediment, and plant samples were collected temporally and spatially along the drainage ditch. Even with mixing of the pesticide with soil before application, approximately 99% of measured esfenvalerate was associated with ditch vegetation (Ludwigia peploides, Polygonum amphibium, and Leersia oryzoides) three hours following event initiation. This trend continued for the 112 d study duration. Simple modeling results also suggest that aqueous concentrations of esfenvalerate could be mitigated to 0.1% of the initial exposure concentration within 510 m of a vegetated ditch. Observed field half-lives in water, sediment, and plant were 0.12 d, 9 d, and 1.3 d, respectively. These results validate the role vegetation plays in the mitigation of pesticides, and that ditches are an indispensable component of the agricultural production landscape.

Acute toxicity of methyl-parathion in wetland mesocosms: assessing the influence of aquatic plants using laboratory testing with Hyalella azteca

Methyl-parathion (MeP) was introduced into constructed wetlands for the purpose of assessing the importance of distance from the source of contamination and the role of emergent vegetation on the acute toxicity to Hyalella azteca (Crustacea: Amphipoda). A vegetated (90% cover: mainly Juncus effuses) and a nonvegetated wetland (each with a water body of 50 x 5.5 x 0.2 m) were each exposed to a simulated MeP storm runoff event. H. azteca was exposed for 48 h in the laboratory to water samples taken from the wetlands at a distance of 5, 10, 20, and 40 m from the pesticide inlet 3 h, 24 h, 96 h, and 10 days following application. Methyl-parathion was detected throughout the nonvegetated wetland, whereas the pesticide was only transported halfway through the vegetated wetland. A repeated-measure three-way analysis of variance (ANOVA) using time, location, and vegetation indicated significantly lower toxicity in the vegetated wetland. Furthermore, the mortality decreased significantly with both increasing distance from the inlet and time (48-h LC50 +/- 95% CI: 9.0 +/- 0.3 microg/L). A significant three-way interaction of time x vegetation x location confirmed higher toxicity at the inlet area of the nonvegetated wetland immediately after contamination. Significant linear regressions of maximum mortality (independent of time) versus distance from the pesticide inlet indicated that 44 m of vegetated and 111 m of nonvegetated wetland would reduce H. azteca mortality to < or = 5%. These results suggest that vegetation contributes to reduced MeP effects in constructed wetlands.

Mitigation of chlorpyrifos runoff using constructed wetlands

Constructed wetlands have been proposed as a potential best management practice (BMP) to mitigate effects of pesticide-associated agricultural runoff. Wetland mesocosms (14 m x 59-73 m) were amended with chlorpyrifos to simulate a storm runoff event at concentrations of 73, 147 and 733 microg/l. Water, sediment and plant samples collected weekly for 12 weeks indicated that chlorpyrifos rapidly sorbed to sediment and plant material, with approximately 47-65% of measured chlorpyrifos mass retained within the first 30-36 m of wetland mesocosms. Of the measured mass, approximately 55% and 25% were retained by sediments and plants, respectively. A field-scale evaluation of a constructed wetland's mitigation capability was performed in the Lourens River watershed of Cape Town, South Africa. Results indicate that the wetland was able to retain and considerably decrease the concentration (and hence toxicity) of chlorpyrifos and suspended sediment entering the receiving waterbody (Lourens River). This research provides fundamental answers concerning constructed wetland capabilities that are necessary for constructing field-scale systems within agricultural watersheds.

The anaesthetic management of a case of severe upper airways obstruction due to an enlarging subglottic benign polyp

The use of a newly developed aid to jet ventilation of the lungs, a modified Ben-Jet tube (the Hunsaker Monjet tube), is described in a patient with partial upper airway obstruction. This report highlights an unusual use of this device. The Monjet is a fluoroplastic, monitored, self-centring, fine bore tube that can be inserted from the mouth through to the subglottic region. It was originally developed to anaesthetize healthy patients without airway obstruction who were undergoing suspension microlaryngoscopy.

Dynamics of diffuse pollution from US southern watersheds

To understand the effects of diffuse pollution information on the source of pollutants, quantities in transport, mode of transport, transient nature of the pollution event, and most importantly, a consideration of remediation efforts need to be known. For example, water quality research in the Yazoo Basin uplands in Mississippi has shown sediment loads from a conventional-till upland soybean watershed to be about 19,000kg/ha/yr, and responsible for 77-96% of P and N in transport. In contrast, sediment loads from a comparable no-till soybean watershed were only 500 kg/ha/yr. transporting about 31% of P and N in transport. Sediment loads from a nearby forested area were low, about 200 kg/ha/yr, but responsible for about 47-76% of P and N in transport. Transient pollution events are responsible for the transport of large quantities of sediment, nutrients, and pesticides; in some storm events nearly the annual load. Best management practices (BMPs) must be designed to remediate diffuse pollution and the transient nature of pollution events which can have a profound effect on the ecological health of steams and reservoirs.

Arsenic and mercury concentrations in major landscape components of an intensively cultivated watershed

To provide an understanding of arsenic (As) and mercury (Hg) concentrations in soil, sediment, water, and fish tissues, samples were collected from a Mississippi River alluvial floodplain located in northwest Mississippi. As concentrations increased approximately an order of magnitude from water (5.12 micrograms/l) to fish tissues (36.99 micrograms/kg) and an additional two orders of magnitude in soils, lake sediments, and wetland sediments (5728, 5614, and 6746 micrograms/kg), respectively. Average Hg concentrations in water, soils, lake sediments, and fish were 2.16 micrograms/l, 55.1, 14.5 and 125 micrograms/kg, respectively. As and Hg concentrations were within published ranges for uncontaminated soil, water, and sediments. As concentrations represented a low risk. Hg concentrations were also low but showed a greater tendency to concentrate in fish tissue. The dominant mode of entry of these materials into aquatic systems is through storm-generated runoff. Since both metals accompany sediments, agricultural conservation practices such as reduced tillage, buffer riparian strips, and bordering sediment ponds or drainage wetlands will minimize watershed input to aquatic systems.

Constructed wetlands for mitigation of atrazine-associated agricultural runoff

Atrazine was amended into constructed wetlands (59-73x14x0.3 m) for the purpose of monitoring transport and fate of the pesticide to obtain information necessary to provide future design parameters for constructed wetlands mitigation of agricultural runoff. Following pesticide amendment, a simulated storm and runoff event equal to three volume additions was imposed on each wetland. Targeted atrazine concentrations were 0 microg/l (unamended control), 73 microg/l, and 147 microg/l. Water, sediment, and plant samples were collected weekly for 35 days from transects longitudinally distributed throughout each wetland and were analyzed for atrazine using gas chromatography. Between 17 and 42% of measured atrazine mass was within the first 30-36 m of wetlands. Atrazine was below detection limits (0.05 microg/kg) in all sediment and plant samples collected throughout the duration of this study. Aqueous half lives ranged from 16 to 48 days. According to these data, conservative buffer travel distances of 100-280 m would be necessary for effective runoff mitigation.

Analysis of neurogenesis and programmed cell death reveals a self-renewing capacity in the adult rat brain

The adult central nervous system was thought to be very limited in its regenerative potential; however, the discovery that stem cell populations produce neurons in the adult brain highlights the dynamics of a previously assumed 'static' organ. The continuous generation of new neurons in the adult brain, nevertheless, leads to the question of whether neurogenesis is counterbalanced by an accompanying cell death in the same regions. The objective of this study was to stereologically analyze neurogenesis and programmed cell death in adult brain regions with known neurogenic activity. Using bromodeoxyuridine (BrdU) to identify newborn cells we find that within a few days of BrdU-labeling the adult dentate gyrus and olfactory bulb generate high numbers of newborn neurons. More importantly, dUTP-nick end labeling (TUNEL) reveals that areas of adult neurogenesis also contain high numbers of apoptotic cells. We conclude that programmed cell death may have an important regulatory function by eliminating supernumerous cells from neurogenic regions and may thus contribute to a self-renewal mechanism in the adult mammalian brain.

RESEARCH: Warmwater Stream Bank Protection and Fish Habitat: A Comparative Study

/ Fishes and their habitats were sampled in Harland Creek, Mississippi, for 3 years to compare the relative value of three types of bank treatment in an incised, warmwater stream. Semiannual samples were collected from 10 reaches: 3 reaches protected by each of the three types of protection (longitudinal stone toe, stone spurs, and dormant willow posts) and an unprotected, slowly eroding bend. Protection of concave banks of bends had no measurable effect on the habitat quality of downstream riffles. Although bends and adjacent downstream riffles were faunistically similar at the species level, catostomids and centrarchids were more dominant in pools and smaller cyprinids more dominant in riffles. Reaches with willow posts were slightly deeper than the others, most likely because of geomorphic factors rather than bank treatment. Mean water surface widths in reaches stabilized with stone spurs were 40% to 90% greater than for other treatments, and current velocities were greatest in reaches with stone toe. Patterns of fish abundance and species diversity did not differ significantly among treatments. However, principal components analysis indicated that the fish species distribution associated with the untreated reference site was distinct. Reaches stabilized with stone spurs supported significantly higher densities of large fish and higher levels of fish biomass per unit channel length than reaches with other bank treatments, generally confirming previous research in the region. Initial costs for spurs were comparable to those for stone toe and about three times greater than for willow posts.

Characterization of plasmin-mediated activation of plasma procarboxypeptidase B. Modulation by glycosaminoglycans

Plasma carboxypeptidase B (PCB) is an exopeptidase that exerts an antifibrinolytic effect by releasing C-terminal Lys and Arg residues from partially degraded fibrin. PCB is produced in plasma via limited proteolysis of the zymogen, pro-PCB. In this report, we show that the K(m) (55 nM) for plasmin-catalyzed activation of pro-PCB is similar to the plasma concentration of pro-PCB (50-70 nM), whereas the K(m) for the thrombin- or thrombin:thrombomodulin-catalyzed reaction is 10-40-fold higher than the pro-PCB level in plasma. Additionally, tissue-type plasminogen activator triggers activation of pro-PCB in blood plasma in a reaction that is stimulated by a neutralizing antibody versus alpha(2)-antiplasmin. Together, these results show that plasmin-mediated activation of pro-PCB can occur in blood plasma. Heparin (UH) and other anionic glycosaminoglycans stimulate pro-PCB activation by plasmin but not by thrombin or thrombin:thrombomodulin. Pro-PCB is a more favorable substrate for plasmin in the presence of UH (16-fold increase in k(cat)/K(m)). UH also stabilizes PCB against spontaneous inactivation. The presence of UH in clots prepared with prothrombin-deficient plasma delays tissue-type plasminogen activator-triggered lysis; this effect of UH on clot lysis is blocked by a PCB inhibitor from potato tubers. These results show that UH accelerates plasmin-catalyzed activation of pro-PCB in plasma and PCB, in turn, stabilizes fibrin against fibrinolysis. We propose that glycosaminoglycans in the subendothelial extracellular matrix serve to augment the levels of PCB activity thereby stabilizing blood clots at sites where there is a breach in the integrity of the vasculature.

Suspected recurrence of malignant hyperthermia after post-extubation shivering in the intensive care unit, 18 h after tonsillectomy

A 25-yr-old man, subsequently shown to be malignant hyperthermia (MH) susceptible by in vitro contracture testing, developed MH during anaesthesia for tonsillectomy. Prompt treatment, including dantrolene, led to rapid resolution of the metabolic crisis. Eighteen hours later the patient's trachea was extubated in the ICU, when he had been stable and apyrexial overnight. Twenty minutes after extubation, an episode of shivering was followed by the onset of tachycardia, hypertension, tachypnoea and a rapid increase in temperature. Recurrence of MH was suspected and the patient was given another dose of dantrolene with good clinical effect. Shivering in this patient may have been an indicator or a causative factor of recurrence of MH.

Selective inhibition of factor Xa in the prothrombinase complex by the carboxyl-terminal domain of antistasin

Studies of antistasin, a potent factor Xa inhibitor with anticoagulant properties, were performed wherein the properties of the full-length antistasin polypeptide (ATS-119) were compared with the properties of forms of antistasin truncated at residue 116 (ATS-116) and residue 112 (ATS-112). ATS-119 was 40-fold more potent than ATS-112 in prolonging the activated partial thromboplastin time (APTT), whereas ATS-119 inhibited factor Xa 2.2-fold less avidly and about 5-fold more slowly than did ATS-112. The decreased reactivity of ATS-119 suggests that the carboxyl-terminal domain of ATS-119 stabilizes an ATS conformation with a reduced reactivity toward factor Xa. The observation that calcium ion increases the reactivity of ATS-119 but not that of ATS-112 suggests that calcium ion may disrupt interactions involving the carboxyl terminus of ATS-119. Interestingly, ATS-119 inhibited factor Xa in the prothrombinase complex 2-6-fold more potently and 2-3-fold faster than ATS-112. These differences in affinity and reactivity might well account for the greater effectiveness of ATS-119 in prolonging the APTT and suggest that the carboxyl-terminal domain of ATS-119 disrupts interactions involving phospholipid, factor Va, and prothrombin in the prothrombinase complex. The peptide RPKRKLIPRLS, corresponding to the carboxyl domain of ATS-119 prolonged the APTT and inhibited prothrombinase-catalyzed processing of prothrombin, but it failed to inhibit the catalytic activity of isolated factor Xa. Thus, this novel inhibitor appears to exert its inhibitory effects at a site removed from the active site of factor Xa.

Efficacious, orally bioavailable thrombin inhibitors based on 3-aminopyridinone or 3-aminopyrazinone acetamide peptidomimetic templates

We have addressed the key deficiency of noncovalent pyridinone acetamide thrombin inhibitor L-374,087 (1), namely, its modest half-lives in animals, by making a chemically stable 3-alkylaminopyrazinone bioisostere for its 3-sulfonylaminopyridinone core. Compound 3 (L-375,378), the closest aminopyrazinone analogue of 1, has comparable selectivity and slightly decreased efficacy but significantly improved pharmacokinetics in rats, dogs, and monkeys to 1. We have developed an efficient and versatile synthesis of 3, and this compound has been chosen for further preclinical and clinical development.

Design and synthesis of a series of potent and orally bioavailable noncovalent thrombin inhibitors that utilize nonbasic groups in the P1 position

As part of an ongoing effort to prepare therapeutically useful orally active thrombin inhibitors, we have synthesized a series of compounds that utilize nonbasic groups in the P1 position. The work is based on our previously reported lead structure, compound 1, which was discovered via a resin-based approach to varying P1. By minimizing the size and lipophilicity of the P3 group and by incorporating hydrogen-bonding groups on the N-terminus or on the 2-position of the P1 aromatic ring, we have prepared a number of derivatives in this series that exhibit subnanomolar enzyme potency combined with good in vivo antithrombotic and bioavailability profiles. The oxyacetic amide compound 14b exhibited the best overall profile of in vitro and in vivo activity, and crystallographic studies indicate a unique mode of binding in the thrombin active site.

C6 modification of the pyridinone core of thrombin inhibitor L-374,087 as a means of enhancing its oral absorption

1 (L-374,087) is a potent, selective, efficacious, and orally bioavailable thrombin inhibitor that contains a core 3-amino-2-pyridinone moiety. Replacement of the C6 pyridinone methyl group of 1 by a propyl group gave 5 (L-375,052), which retained all the excellent properties of 1, and also yielded higher plasma levels after oral dosing in dogs and rats.

Toxicological evaluation of constructed wetland habitat sediments utilizing Hyalella azteca 10-day sediment toxicity test and bacterial bioluminescence

A toxicological evaluation was conducted on wetland habitats created as a result of run-off from agricultural areas. These temporary wetlands were created by using drop pipes as a means of reducing erosional cutting in agricultural fields. Toxicity bioassays utilizing bacterial bioluminescence and Hyalella azteca were used to assess sediment pore water and whole sediment, respectively. Inhibition of bacterial bioluminescence was initially used to determine relative toxicities of pore water from ten wetland sites. Constructed wetland sites were compared to the University of Mississippi Biological Field Station, a relatively pristine reference site. The H. azteca ten day sediment toxicity test was utilized to assess sediment from four selected sites using survival and growth as toxicological endpoints. Results from the toxicological evaluation, along with extensive ecological evaluations, were used to assess the best approach for implementation of temporary wetland habitats with existing agricultural practices.

Comparative Toxicity of Chlordane, Chlorpyrifos, and Aldicarb to Four Aquatic Testing Organisms

Laboratory toxicity data contrasting responses of aquatic organisms to insecticides are important for focusing on sensitive species (steepest exposure-response slope) exposed to aqueous concentrations of these insecticides in field studies. These data also allow prediction of expected responses of aquatic species to a range of insecticide concentrations in situ. Aqueous 48-h toxicity tests were performed to contrast responses of Daphnia magna Straus, Hyalella azteca Saussure, Chironomus tentans Fabricius, and Pimephales promelas Rafinesque to acetylcholinesterase-inhibiting insecticides: chlorpyrifos, aldicarb, and chlordane. As expected, invertebrates tested (H. azteca, C. tentans, and D. magna) were >/= 200 times more sensitive than the vertebrate P. promelas to chlorpyrifos exposures. H. azteca was approximately 3.5 times more sensitive to chlorpyrifos (453% mortality/&mgr;g/L) than D. magna (128% mortality/&mgr;g/L). For both aldicarb and chlordane, C. tentans was the most sensitive species tested (2.44 and 2.54% mortality/&mgr;g/L, respectively). Differences in chlordane potency for test species varied only by a factor of approximately 2-3 (0.88% mortality/&mgr;g/L for H. azteca to 2.54% mortality/&mgr;g/L for C. tentans). Although point estimates of population responses such as LC50s, NOECs, and LOECs are of some utility for predicting effects of pesticides in aquatic systems, exposure-response slopes are also useful for extrapolation of laboratory data to diverse field situations, especially where sediment sorption may regulate insecticide exposure or bioavailability.

Synthesis of a series of potent and orally bioavailable thrombin inhibitors that utilize 3,3-disubstituted propionic acid derivatives in the P3 position

As part of an effort to prepare efficacious and orally bioavailable analogs of the previously reported thrombin inhibitors 1a, b, we have synthesized a series of compounds that utilize 3,3-disubstituted propionic acid derivatives as P3 ligands. By removing the N-terminal amino group, the general oral bioavailability of this class of compounds was enhanced without excessively increasing the lipophilicity of the compounds. The overall properties of the molecules could be drastically altered depending on the nature of the groups substituted onto the 3-position of the P3 propionic acid moiety. A number of the compounds exhibited good oral bioavailability in rats and dogs, and numerous compounds were efficacious in a rat FeCl3-induced model of arterial thrombosis. Compound 7, the 3,3-diphenylpropionic acid derivative, showed the best overall profile of in vivo and in vitro activity. Molecular modeling studies suggest that these compounds bind in the thrombin active site in a manner essentially identical to that previously reported for compound 1a.

Enzyme-linked immunosorbent assay for the detection of Cryptosporidium parvum IgG in the serum of cats

The objective was to develop an enzyme-linked immunosorbent assay (ELISA) for the detection of Cryptosporidium parvum IgG in the serum of cats. The ELISA was an indirect ELISA using soluble C. parvum oocyst antigens and a peroxidase-labeled anti-feline IgG secondary antibody. Sera from cats with Toxocara felis, Giardia spp., Aelurostrongylus abstrusus, Isospora felis, Isospora rivolta, Toxoplasma gondii, or Taenia spp. infections were assayed in specificity studies. Following optimization, the ELISA and fecal examination for oocysts were performed on samples from 170 client-owned or humane society source cats and 1 cat inoculated orally with C. parvum oocysts. Cryptosporidium parvum oocysts were detected in feces (4/170; 2.4%), and C. parvum IgG was detected in serum (26/170; 15.3%) from naturally exposed cats. The seroprevalence data suggest that some cats in the geographical area studied were exposed to C. parvum, but persistent oocyst shedding was less common. The ELISA is not useful for predicting oocyst shedding in individual cats.

Evidence for protein X binding to a discontinuous epitope on the cellular prion protein during scrapie prion propagation

Studies on the transmission of human (Hu) prions to transgenic (Tg) mice suggested that another molecule provisionally designated protein X participates in the formation of nascent scrapie isoform of prion protein (PrPSc). We report the identification of the site at which protein X binds to the cellular isoform of PrP (PrPC) using scrapie-infected mouse (Mo) neuroblastoma cells transfected with chimeric Hu/MoPrP genes even though protein X has not yet been isolated. Substitution of a Hu residue at position 214 or 218 prevented PrPSc formation. The side chains of these residues protrude from the same surface of the C-terminal alpha-helix and form a discontinuous epitope with residues 167 and 171 in an adjacent loop. Substitution of a basic residue at positions 167, 171, or 218 also prevented PrPSc formation: at a mechanistic level, these mutant PrPs appear to act as "dominant negatives" by binding protein X and rendering it unavailable for prion propagation. Our findings seem to explain the protective effects of basic polymorphic residues in PrP of humans and sheep and suggest therapeutic and prophylactic approaches to prion diseases.

Feline ocular and cerebrospinal fluid Toxoplasma gondii-specific humoral immune responses following specific and nonspecific immune stimulation

Toxoplasma gondii-naive cats and cats previously infected orally with T. gondii tissue cysts were inoculated with soluble tachyzoite antigens plus adjuvant or adjuvant alone. Toxoplasma gondii-specific IgM and IgG were measured in serum, aqueous humor, and cerebrospinal fluid (CSF). The Goldman-Witmer coefficient (C value) for ocular or central nervous system (CNS) antibody production was calculated for aqueous humor or CSF samples positive for T. gondii-specific antibodies. Following inoculation with adjuvant plus soluble tachyzoite antigens, ocular and CNS T. gondii-specific IgG C values increased in the three previously infected cats. Following inoculation with adjuvant, the two previously infected cats had increases in ocular and CNS T. gondii-specific IgG C values. Ocular (2/3 cats) or CNS (1/3 cats) T. gondii-specific IgG C values of over 1 were detected in some T. gondii-naive cats following inoculation with adjuvant plus soluble tachyzoite antigens. The results of this study suggest that T. gondii-specific IgG C values of over 1 in aqueous humor or CSF do not prove active ocular or CNS infection in all cats.

Toxoplasma gondii antigen recognition by serum immunoglobulins M, G, and A of queens and their neonatally infected kittens

OBJECTIVE

To evaluate antigen recognition patterns of serum IgM, IgG, and IgA from queens and their kittens as a method of diagnosing neonatal toxoplasmosis.

ANIMALS

5 pregnant queens were inoculated orally with Toxoplasma gondii tissue cysts during gestation (18 to 44 days). On various days after parturition (0 to 97), serum was obtained from queens and kittens (n = 19).

PROCEDURE

Tissues from most kittens were assessed for T gondii infection by bioassay in mice. Serum samples were evaluated by IgM, IgG, and IgA western blot immunoassays for the presence of T gondii antibodies. Antigens recognized by kitten serum samples, but not by the corresponding queen serum sample, were considered to indicate neonatal infection with T gondii.

RESULTS

Using the results of western blot immunoassay, 8 of 19 kittens (age, 2 to 97 days) were determined to be infected with T gondii. Western blot immunoassay results correlated well with bioassay results, identifying 7 of 8 bioassay-positive kittens. Western blot immuno-assay additionally identified 1 kitten as infected, but tissues from the kitten had not been bioassayed. In each of the 5 kittens that developed clinical signs of toxoplasmosis, the diagnosis of neonatal toxoplasmosis was supported by results of the western blot immunoassays.

CONCLUSION AND CLINICAL RELEVANCE

Comparison of queen and kitten T gondii antigen recognition patterns of IgM, IgG, and IgA can be used for antemortem diagnosis of neonatal toxoplasmosis.

Health promotion in human immunodeficiency virus-infected patients through psychosocial interventions

The extreme fear, prejudice, and stigmatization associated with human immunodeficiency virus disease make the acquired immune deficiency syndrome epidemic a unique phenomenon of the modern era. A fundamental understanding of the phychosocial issues surrounding the disease is essential, if nurses are to design interventions that promote optimal health among those infected and those at risk for infection.

Toxoplasma gondii-specific antibodies in the aqueous humor of cats with toxoplasmosis

We decided to determine whether Toxoplasma gondii-specific IgM or IgG is produced locally or is deposited in the aqueous humor of T gondii-naive cats after primary or secondary inoculation with T gondii. Cats were orally inoculated with T gondii tissue cysts during weeks 0 and 36. Aqueous humor and serum T gondii-specific IgM and IgG were measured, using ELISA, during weeks 0, 2, 4, 6, 8, 12, 16, 20, 26, 34, 38, 40, 42, 44, 48, 56, 62, 66, and 72 after primary oral inoculation. Total immunoglobulin-based Goldmann-Witmer coefficients were calculated to verify intraocular antibody production. Toxoplasma gondii-specific IgM was not detected in the aqueous humor of any cat. Data indicate that cats have transient local production of T gondii-specific IgG in the aqueous humor after primary and secondary oral inoculations with T gondii tissue cysts. The intraocular immune response to systemic T gondii infection may signal ocular recruitment of antigen-specific lymphocytes that function independently from the general humoral response to T gondii infection. Cautious interpretation of results that suggest intraocular production of T gondii-specific IgG in cats with uveitis is warranted.

Homozygosity for prion protein alleles encoding glutamine-171 renders sheep susceptible to natural scrapie

Natural scrapie has been viewed both as a recessive trait and as a contagious disease modulated by a host locus. To address this conundrum, we determined the structure of the sheep prion protein (PrP) gene, which contains three exons and extends over 20 kb of DNA. In the United States 86.4% of scrapie cases occur in Suffolk sheep, and within this breed 49 +/- 6% (+/- S.D., n = 69) of healthy animals carry one or more PrP alleles encoding Arg (R)-171. Four scrapie-affected sheep were homozygous for wild-type PrP open reading frames encoding the alternative Gln (Q)-171 allele. Analysis of additional cases revealed that all were Q/Q-171 homozygotes (n = 31), yielding a probability of 0.000004 that PrP genotype is unrelated to susceptibility. These data imply that homozygosity for Q-171 codons is necessary but not sufficient for the development of natural scrapie, echo reports of recessive manifestation, and parallel over-representation of PRNP codon 129 homozygotes in Creutzfeldt-Jakob disease of humans. Whereas progress has been substantial regarding experimental scrapie in rodents, the occurrence and spread of disease in flocks of sheep has remained enigmatic. Appreciation of the relationship between codon 171 genotype and susceptibility may help define the molecular basis of natural scrapie.

Cutaneous cryptococcosis: recurrence following oral fluconazole treatment

A case of recurrent cutaneous cryptococcosis in an immunocompromised patient is described. The patient presented with a non-healing cutaneous ulcer due to infection with Cryptococcus neoformans. Extensive investigation failed to reveal any evidence of associated systemic cryptococcosis. Treatment with oral fluconazole resulted in complete resolution of the ulcer but after several months a second cutaneous cryptococcal lesion appeared, strongly suggesting dissemination from an underlying systemic focus. This case illustrates the hazards associated with making a diagnosis of isolated cutaneous cryptococcosis and the necessity for prolonged follow-up of patients who present in this way.

Serum F-protein concentration following halothane or isoflurane anaesthesia

We have investigated the prevalence of hepatic injury following uncomplicated anaesthesia using a sensitive and specific marker of hepatic damage, the serum F-protein concentration. The median variation in serum F-protein in fit adults over six days is 16 ng/ml, minimum 0 ng/ml, maximum 36 ng/ml. A significant rise in serum F-protein was demonstrated six days following anaesthesia and surgery, but not earlier after 3 or 24 h. There was no significant difference between patients who received halothane (n = 12) or isoflurane (n = 13). These changes were not related to duration of anaesthesia, quantity of delivered volatile agent or mode of ventilation. Hepatocellular damage may occur following anaesthesia for minor surgery.

Multicenter evaluation of TDx test for assessing fetal lung maturity

"TDx Fetal Lung Maturity," an automated assay that measures the relative concentrations of surfactant and albumin in amniotic fluid, was compared with the lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol determination at five clinical sites. A total of 695 amniotic fluid samples were analyzed, of which 312 were followed by delivery of the infant within three days of sample collection. Of these 312, 24 developed respiratory distress syndrome and seven developed transient tachypnea. With the cutoff for maturity set at a surfactant/albumin value of 50 mg/g, the assay showed a sensitivity of 0.96 and a specificity of 0.88 for all samples, compared with a sensitivity of 0.96 and a specificity of 0.83 for the L/S ratio. The combination of rapid assay (30 min), accurate results, and uniformity among testing centers makes the TDx assay a very promising method.

Multicenter evaluation of TDx test for assessing fetal lung maturity

"TDx Fetal Lung Maturity," an automated assay that measures the relative concentrations of surfactant and albumin in amniotic fluid, was compared with the lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol determination at five clinical sites. A total of 695 amniotic fluid samples were analyzed, of which 312 were followed by delivery of the infant within three days of sample collection. Of these 312, 24 developed respiratory distress syndrome and seven developed transient tachypnea. With the cutoff for maturity set at a surfactant/albumin value of 50 mg/g, the assay showed a sensitivity of 0.96 and a specificity of 0.88 for all samples, compared with a sensitivity of 0.96 and a specificity of 0.83 for the L/S ratio. The combination of rapid assay (30 min), accurate results, and uniformity among testing centers makes the TDx assay a very promising method.

Treatment of shivering after epidural lidocaine

The effectiveness of intravenous meperidine and warm local anesthetic for prevention of postanesthetic shivering was evaluated in urology patients undergoing epidural blockade for extracorporeal shockwave lithotripsy. When administered before the blockade, meperidine, 12.5 mg or 25 mg, was not significantly better than saline placebo for preventing postepidural shivering. Changes in the concentrations of catecholamines or lidocaine did not result in differences between patients who shivered and those who did not shiver. In a second experiment, patients receiving body-temperature or room-temperature epidural lidocaine did not differ with respect to the incidence of postanesthetic shivering, onset of sensory blockade, or core temperature during a 30-minute observation period. The authors concluded that neither meperidine, in doses employed, nor body-temperature lidocaine prevents shivering after epidural blockade. This shivering appears to be different from that observed during emergence from general anesthesia.

Comparison of outcome of asymptomatic to symptomatic patients older than 20 years of age with valvular aortic stenosis

A 2-part prospective study was performed to evaluate the clinical outcome of patients with hemodynamically confirmed asymptomatic valvular aortic stenosis (AS). During phase 1, linear regression analysis showed continuous wave Doppler to be highly accurate in predicting catheterization measured peak systolic aortic valve pressure gradients in 101 consecutive patients aged 36 to 83 years (mean 65 +/- 8) with symptomatic AS. During phase 2, 90 additional patients (51 asymptomatic and 39 symptomatic) with Doppler-derived peak systolic aortic valve gradients greater than or equal to 50 mm Hg (range 50 to 132 [mean 68 +/- 19]) were followed for 1 to 45 months. Both groups of patients in phase 2 had similar Doppler gradients and clinical and auscultatory evidence of moderate to severe AS at baseline. Asymptomatic patients were younger (p = 0.01), had higher ejection fractions (p = 0.001) and were less likely to have an electrocardiographic strain pattern (p = 0.01) and left atrial enlargement (p = 0.02). End-diastolic wall thickness, left ventricular cross-sectional myocardial area and estimated left ventricular mass were 18% (p = 0.0001), 20% (p = 0.0008), and 29% (p = 0.002) greater in symptomatic patients. During 17 +/- 9 months of follow-up, 21 asymptomatic patients (41%) became symptomatic. Dyspnea was the most common initial complaint, occurring 2.5 and 4.8 times more often than angina and syncope, respectively. Compared with the 39 symptomatic patients, the 51 asymptomatic patients had a lower cumulative life table incidence of death from any cause (p = 0.002), and from cardiac causes (p = 0.0001) including sudden death (p = 0.013).(ABSTRACT TRUNCATED AT 250 WORDS)

Retrograde intubation. Management of a 4.8-kg, 5-month infant

An infant with Goldenhar's syndrome is presented in whom two-stage plastic surgery was undertaken. The first operation, at the age of 5 months, necessitated a retrograde technique for tracheal intubation while in the second, at 10 months of age, conventional intubation was possible. The discussion highlights those refinements that promote a successful outcome when retrograde intubation is indicated, particularly in infants.

EMLA cream reduces the pain of venepuncture in children

EMLA cream (eutectic mixture of local anaesthetics) was tested in a double-blind clinical trial to examine its effect on the pain of venepuncture at induction of anaesthesia in 40 children (aged 3-13 yrs). Four pain-assessment methods were used and an assessment of the technical ease of venepuncture was made. EMLA was found to reduce significantly the pain and technical difficulty of venepuncture. This study confirms that EMLA is an effective method of reducing the pain and technical difficulty of paediatric venepuncture using 25-gauge needles for induction of anaesthesia in children.

Pharmacokinetics of single-dose i.v. morphine in normal volunteers and patients with end-stage renal failure

Morphine 0.125 mg kg-1 was administered i.v. to 11 normal subjects and nine patients with chronic renal failure requiring regular haemodialysis. Plasma morphine concentrations were measured using high pressure liquid chromatography (HPLC). Although there was considerable individual variation in both groups, mean plasma concentrations of morphine were significantly higher in the patients with renal failure for 15 min after administration. The decay of plasma concentration fitted a three-compartment mamillary pharmacokinetic model in all subjects. Derived values (mean +/- SEM) of T 1/2 alpha, volume of distribution of the second compartment (V2), total volume of distribution at steady state (Vss) and transfer rate constant from the first to the second compartment (k12), were significantly different between groups. Mean values of terminal elimination half-life (T 1/2 gamma) and total body clearance were similar in the two groups. It was concluded that elimination of unchanged morphine is not impaired significantly in patients with chronic renal failure, although accumulation of morphine-3-glucuronide probably occurs. Although the pharmacological effect of morphine is not related temporally to plasma morphine concentrations, the higher values in patients with renal failure may be implicated in their increased sensitivity to the drug.

Image data-processing system for solar astronomy

Image processing has become an invaluable tool in the analysis of solar astronomy and other scientific data. In particular, a number of powerful and intricate image-processing systems have been developed. One such system is the MSFC/S-056 Image Data Processing System (IDAPS), especially designed for the analysis of the Skylab/ATM S-056 X-Ray Telescope experiment data. This paper describes the IDAPS, discusses its unique interactive capabilities, and shows some recent results obtained using the IDAPS.