Matrix metalloproteinase and tissue inhibitors of metalloproteinase secretion by haematopoietic and stromal precursors and their production in normal and leukaemic long-term marrow cultures.

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) regulate the turnover of the extracellular matrix and may modulate the biology of haematopoietic cells. We investigated whether MMPs and TIMPs are produced in long-term marrow cultures (LTMCs) established from normal donors and acute myelogenous leukaemia (AML) patients, and by fibroblast- (F), granulocyte macrophage- (GM) and megakaryocyte- (Meg) colony-forming unit (CFU) and erythroid burst-forming unit (BFU-E)-derived precursor cells. ProMMP-9 levels were highest (> 400 ng/ml) at week 1 of normal LTMC, whereas proMMP-2, TIMP-1, TIMP-2 and TIMP-3 levels peaked (up to 1000 ng/ml) after the establishment of the adherent layer. In LTMC from AML patients, these patterns of secretion were reversed. Moreover, we found that after a 24 h incubation in serum-free media, normal CFU-GM-, BFU-E- and CFU-Meg-derived cells secreted proMMP-9 and CFU-F-derived cells proMMP-2, in contrast to cells from LTMC adherent layer which secreted both active and latent forms of MMP-2 and MMP-9 under serum-free conditions. However, when these adherent cells were incubated in 12.5% fetal calf or horse serum or complete LTMC growth media, active forms of MMP-2 and MMP-9 were no longer detectable, and TIMP levels increased. Hence, we concluded that (i) MMPs/TIMPs are secreted by normal human bone marrow haematopoietic and stromal cells and may play an important role in intercellular cross-talk in haematopoiesis; and (ii) only latent forms of MMPs are present under LTMC conditions, indicating that the specific media used for weekly re-feeding of LTMC can block activation of MMP-2 and MMP-9, maintaining the integrity of the stromal layer and supporting haematopoiesis in vitro.

Acute urinary retention and urinary incontinence.

AUR is a commonly seen genitourinary emergency. It has many etiologies, including obstructive, neurogenic, pharmacologic, and extraurinary causes. Treatment is immediate bladder decompression by transurethral catheterization and treatment of the provoking etiology. Urinary incontinence is less commonly seen as a presenting complaint in the ED. For the emergency physician, the key lies in recognizing its underlying cause. Neurologic and pharmacologic causes need to be considered in all patients. Urinary incontinence that is not caused by a neurologic emergency can be referred for further outpatient evaluation.

In vitro pharmacologic effect of two endothelin-1 antagonists on equine colonic arteries and veins.

OBJECTIVE: To evaluate the effectiveness of 2 potential endothelin (ET)-1 antagonists in blocking the contractile responses of equine colonic vessels to increasing concentrations of ET-1. SAMPLE POPULATION: Mesenteric vessels from 6 clinically healthy horses. PROCEDURE: Colonic vessels (arterial and venous rings) were placed in organ baths with oxygenated Tyrode solution at 37 C. Each was attached to a force transducer interfaced with a polygraph, and 2 g of tension was applied and equilibrated for 45 minutes. Then, B-1 (PD 142893) and B-2 (PD 145065) ET-1 antagonists were tested. One ring from each vessel type was used as a control for determining concentration-response relationships of ET-1 (10(-10) to 10(-6)M). Three rings of each vessel type were incubated with 3 concentrations of each antagonist (10(-7), 10(-6), and 10(-5) M) for 30 minutes before ET induced contractions were determined. The maximum contractile response and pA2 values were determined. RESULTS: Vessels contracted in a concentration-dependent manner to ET-1. Arteries responded slowly but reached greater contractions. Veins responded immediately with sustained contractions. Both antagonists inhibited contractions in a concentration-dependent manner with significant differences at 10(-6) and 10(-5)M for arteries and 10(-5) M for veins. Complete blockade of contractions was observed with B-2 (10(-5)M). The pA2 values for B-1 were 8.26 and 6.82 for arteries and veins, respectively, whereas they were 8.25 and 7.21 for B-2. CONCLUSION AND CLINICAL RELEVANCE: Both antagonists effectively blocked ET-1-induced contractions of equine colonic vessels. Because B-2 is water soluble and caused complete blockade at 10(-5) M, it appears to be the preferred antagonist.

A perspective on the ecology of trematode communities in snails.

This paper presents a perspective on the ecology of trematodes in snail hosts based on recent evidence. Because flukes use snails almost obligatorily as first intermediate hosts, we highlight the role of gastropods as keystone species for trematodes and their communities. After reviewing recent developments in the transmission of trematodes to and from snails, we discuss trematode communities within individual snails (infracommunities) and in snail populations (component communities). Results garnered using various protocols at the infracommunity level are reviewed. The few data available, all from marine systems, indicate that low colonization rates characterize infracommunities, suggesting that trematode infracommunities tend to be isolationist in character rather than interactive. The variety of trematode species present in a component community seems to be determined by spatial overlap of definitive hosts. Relative abundance of species in a component community shows little dependence on negative interspecific interactions at the level of the infracommunity. Temporal aspects of trematode communities are related to the life history of the host snail. The component communities of long-lived snails (mostly marine) integrate many infection episodes whereas shorter-lived snails (mostly freshwater) acquire new component communities each time host cohorts turnover.

Trematode accumulation by the estuarine gastropod Ilyanassa obsoleta.

The accumulation of larval trematodes by Ilyanassa obsoleta (Gastropoda) at 2 estuarine sites in Delaware was studied. Initial infection status of snails was assayed by looking for shed cercariae. Native snails (most already infected) were deployed at sites A and B, and sentinel snails (putatively uninfected) were deployed at site B. All were individually marked and, if found, reassessed for infection after being free 1-3 summers. Himasthla quissetensis, Lepocreadium setiferoides, Zoogonus rubellus, Austrobilharzia variglandis, and Gynaecotyla adunca infections were observed in recovered snails. At site A, in 1993, 62 natives were recovered. Among the 26 initially testing uninfected, 15 had infections at recovery. Of 36 that released cercariae, 26 had the infection initially indicated. Of sentinels released at site B in 1996, 3 of 16 had infections when recollected. One probably was infected before transplant; at least 2 were infected at site B during 1996-1997. Among site B natives, 26 were later examined by dissection in 1996; 22 had the infection status initially revealed. Some site B natives (n = 35) escaped recapture in 1996 but were found in 1997, or 1998, or both, and were reexamined, most by cercarial release. The same cercariae were produced by 30. Among natives (both sites, n = 123), 27.6% exhibited some difference in infection status compared to the initial assay. This probably overestimates changes. Some differences were real but most can be discounted as cases where initial infection status was misrepresented.

A potential role for glucagon in the treatment of drug-induced symptomatic bradycardia.

Nine cases of symptomatic bradycardia are presented in which treatment with intravenous glucagon was administered when atropine failed to improve the patient's condition significantly. Although the cause often was not obvious at presentation, all nine subjects took oral medications that could have contributed to the development of symptomatic bradycardia. Eight of nine patients demonstrated clinical improvement 5 to 10 min after glucagon administration, which was consistent with its peak clinical action. Beta-blockers, calcium channel blockers, and digoxin were ultimately thought to have contributed to the majority of these presentations. This report suggests that glucagon may have a role in the treatment of symptomatic bradycardia, particularly in the presence of beta-adrenergic blockade and perhaps calcium channel blockade. Furthermore, the results in these cases suggest that future clinical trials should not be limited to drug-induced symptomatic bradycardia.

Ilyanassa obsoleta (Gastropoda) as a host for trematodes in Delaware estuaries.

Extensive data characterizing larval trematode communities in marine gastropods do not exist for many systems. The purpose here is to report on the infections encountered in Delaware Ilyanassa obsoleta and to compare this trematode community with certain others that have been well studied. Over 15 yr, 11,774 I. obsoleta from 9 different estuarine habitats were examined. Trematode parasitism, sex, and size were determined for each snail. In the total collection, 9 trematode species were encountered; 51.04% of snails were infected with 1 or more species. The sexes were equally susceptible to being parasitized. Smaller snails were less likely to be infected than larger ones. Juvenile snails can be infected, but few have been colonized because of the short time they have been exposed to infective stages. Other studies of trematodes in this snail have revealed few multispecies infections. In contrast, they were strikingly common in this study (12.57% of all snails). Himasthla quissetensis seldom infects the same snail with Lepocreadium setiferoides or Austrobilharzia variglandis, but other species combinations can coexist. The important element in this trematode community seems to be time. The observed frequencies of different infracommunities (single and multispecies combinations) in samples of snails are considered to result from a variety of causes. These include commonness of the trematode species in the system, where and how the sample was collected, definitive host behavior, the low probability of a snail becoming infected, the long life of the snail and its infections, the vagility of the snail, and the incompatibility of certain species in terms of infecting the same snail.

The probability of a marine gastropod being infected by a trematode.

Sentinel snails were employed to determine the likelihood of an estuarine snail becoming infected with a trematode under natural conditions. In summers of 1991 and 1993, Ilyanassa obsoleta (Mollusca: Gastropoda) (n = 1,400) were collected from a saltmarsh in Lewes, Delaware, where parasite prevalence was low, and screened for infections. Putatively uninfected snails were individually marked and released onto the nearby Cape Henlopen sandflat where prevalence of trematodes among native snails is very high (approximately 80%). Most sentinels were free in the field for 1-5 mo and 186 were ultimately recovered. The overall estimate of probability of infection is 1.6%. The snail lives for many years and this low probability of becoming infected indicates that high prevalence of trematodes in this host is brought about not by rapid colonization, but by slow accumulation over time.

Reverse transcription-PCR detection of LaCrosse virus in mosquitoes and comparison with enzyme immunoassay and virus isolation.

A reverse transcription-PCR (RT-PCR) assay was developed and compared with enzyme immunoassay (EIA) and virus isolation for detecting LaCrosse virus (LAC) in mosquito pools. All three techniques were able to detect a single LAC-infected mosquito in a pool of 99 negative mosquitoes. Virus isolation was the most sensitive of the three techniques; it was possible to isolate virus immediately following intrathoracic inoculation of mosquitoes. RT-PCR was second in sensitivity; LAC RNA was detected 1 day postinfection. EIA detected LAC antigen 2 days postinfection. Additionally, RT-PCR and EIA were able to detect LAC RNA and protein, respectively, from mosquito samples which were subjected to seven freeze-thaw cycles, and RT-PCR was able to detect LAC RNA from mosquito samples which remained at room temperature for up to 7 days.

Species Relationships in a Marine Gastropod-Trematode Ecological System.

Individual snails (Ilyanassa obsoleta) on Cape Henlopen, Delaware, frequently are host to one or more trematode species. When different species occupy the same host, interactions might be expected. We investigated five species of parasites to determine whether their existence in different combinations would lead to altered withinhost distributions or changed numbers of shed cercariae. Snails (32 samples, total = 379) were collected from June to August, in 1989, and microscopically examined. Parasite species and stages present in five sections through each snail were recorded. Before examination, 206 of these snails were held in individual chambers in the field. After two high tides (ca. 24 h), the chambers were checked for species and the numbers of cercariae shed. Overall, 22 trematode combinations in single hosts were observed. Analysis revealed that co-occurrence with other species had no significant effects on any trematode. Further, analyses of species richness of infecting assemblages over two distinct intervals failed to show that competition is important in determining assemblage richness. One pair of trematodes (Himasthlaquissetensis and Lepocreadium setiferoides) has been reported not to co-occur. We observed co-occurrences, but so few that the apparent conflict between them could not be statistically demonstrated. We suggest that, in this system, parasites are adapted to the host only; they may interact, but they are not adapted to each other. Chances for a parasite to live free from other parasites seem too great for evolved (adapted) relationships to develop. The host, for similar reasons, is probably not adapted to the parasites.

Sexual anomalies in the estuarine snail Ilyanassa obsoleta: imposex in females and associated phenomena in males.

The spatial distribution of the "imposex" phenomenon (the imposition of male characters on females) among populations of Ilyanassa obsoleta in southern Delaware, USA estuaries was studied. Imposex was most frequent among females in a segment of the Lewes and Rehoboth Canal (68%, n=376) and there was significant spatial heterogeneity of imposex frequencies (range=43-98%) even within this habitat. Two lines of evidence indicate that conditions which generated female imposex (organotin molecules in the water) also affected male sexuality: 1) healthy males normally lose the penis following reproduction but they tended to retain it where imposex-inducing conditions were strong; and 2) males parasitized by trematodes usually lose the penis but tended not to under strong imposex-inducing conditions. The altered biology associated with imposexinducing environments extends beyond female I. obsoleta to males and to other species. This must be recognized when studying organisms exposed to these conditions.

Parasitism and the Movements of Intertidal Gastropod Individuals.

Movements of marked individuals of Ilyanassa obsoleta (n = 500) were charted in an intertidal environment for about one week. At the end of observations, 260 marked individuals, which had been sighted 1017 times collectively, were recollected and examined for trematode infections. Six trematode species were found in 19 infection combinations including uninfected, singly, doubly, and triply infected snails. We know that most snails found high on beaches and on sandbars carry Gynaecotyla adunca infections. It has been hypothesized that this host behavior modification is a parasite adaptation to enhance cercarial transmission to a semi-terrestrial next host. Observations reported here support this hypothesis and reveal some of the complexity in the behavior imposed on I. obsoleta by G. adunca. Individuals that were uninfected or infected with other parasites demonstrated no unique movement patterns, but individuals infected with G. adunca made repeated excursions into the upper shore habitat. These excursions were timed so that host-parasites were left emerged at high elevations primarily during nighttime low tides. Because many snails were multiply infected, data presented support the idea that gastropod populations have the potential to be used as systems for the study of the nature of ecological and evolutionary interactions among parasite species.

Vertical distribution of an estuarine snail altered by a parasite.

Estuarine snails Ilyanassa obsoleta bearing larvae of the trematode Gynaecotyla adunca behave singularly in comparison with conspecifics lacking this parasite. Following high tides, and especially at night, infected snails were found stranded high on beaches and sandbars. Semiterrestrial crustaceans living well up on the shore serve as the next host, and the modified (induced) snail behavior is apparently a parasite adaptation facilitating cercarial transmission to these crustaceans. The altered behavior is unusual because of its apparent enhancement of host-to-host transmission by cercariae rather than predation, the process commonly recognized as being enhanced by parasitic modification of host behavior.