Interactions between benthic predators and zooplanktonic prey are affected by turbulent waves.

Predators capture prey in complex and variable environments. In the ocean, bottom-dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, whereas motile benthic predators, such as burrow-dwelling fish, dart out to catch passing zooplankton. How does the flow of ambient water affect these contrasting modes of predation by benthic zooplanktivores? We studied the effects of turbulent, wavy flow on the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima). Predator-prey interactions were video-recorded in a wave-generating flume under two regimes of oscillating flow with different peak wave velocities and levels of turbulent kinetic energy ("weak" and "strong" waves). Rates of encounter (number of prey passing through a sea anemone's capture zone per time), capture (prey contacting and sticking to tentacles per time), and retention (prey retained on tentacles, without struggling free or washing off, per time) were measured at both strengths of waves. Strong waves enhanced encounter rates both for dead copepods and for actively swimming copepods, but there was so much variability in the behavior of the live prey that the effect of wave strength on encounter rates was not significant. Trapping efficiency (number of prey retained per number encountered) was the same in both flow regimes because, although fewer prey executed maneuvers to escape capture in strong waves, more of the captured prey was washed off the predators' tentacles. Although peak water velocities and turbulence of waves did not affect feeding rates of passive suspension-feeding sea anemones, increases in these aspects of flow have been shown to enhance feeding rates and efficiency of motile benthic fish that lunge out of their burrows to catch zooplankton. Faster, more turbulent flow interferes with the ability of prey to detect predators and execute escape maneuvers, and thus enhances capture rates both for passive suspension-feeding predators and for actively swimming predators. However, prey captured in the mouths of fish are not washed away by ambient flow, whereas prey captured on the tentacles of suspension feeders can be swept off before they are ingested. Therefore, the effects of flowing water on predation on zooplankton by benthic animals depend on the feeding mode of the predator.

Paternal inheritance of the primary sex ratio in a copepod.

Uniparentally inherited genetic elements are under strong selection to manipulate sex determination in their host and shift the host sex ratio towards the transmitting sex. For any sex-ratio trait, lineage analysis and quantitative genetics are important tools for characterizing the mode of inheritance (biparental vs. maternal vs. paternal) thereby narrowing the field of possible sex-determining mechanisms (e.g. polygenic, sex chromosomes with meiotic drive, cytoplasmic microorganisms). The primary sex ratio of the harpacticoid copepod, Tigriopus californicus is often male-biased and is highly variable among full sib families. We found that this extra-binomial variation for the primary sex ratio is paternally but not maternally transmitted in T. californicus. Paternal transmission of the primary sex ratio has been well documented in the haplo-diploid hymenoptera but is relatively rare in diplo-diploid organisms. If the sex-ratio trait is paternally transmitted in other closely related harpacticoid copepods it would explain why male biased primary sex ratios are so common in this group.

Surgical complications and long-term outcome in pediatric liver transplantation.

BACKGROUND/AIMS: Liver transplantation has been widely accepted for the treatment of children with end-stage liver disease over the last 10 years particularly with the advent of reduced-size liver transplant technique. This study reviewed the perioperative and long-term results in the pediatric program of the Queensland Liver Transplant Service, Brisbane, Australia. METHODOLOGY: Retrospective analysis was performed in 153 children who received 176 liver grafts between 1985 and 1995, including 109 (62%) reduced-size and 67 (38%) whole liver grafts. Median follow-up period was 5.3 years. RESULTS: One-, 5-, and 10-year patient and graft survival rates were 82% and 74%, 75% and 63%, and 70% and 60%, respectively. Normal physical and intellectual development was observed in 98% of survivors. There were no significant differences in patient or graft survival rates between transplants using reduced-size and whole liver grafts. Portal vein thrombosis was the most common vascular complication, occurring in 8%. Hepatic artery thrombosis occurred in 7%, including 11% of children less than 1 year old and 8% of those under 10 kg. Biliary complication was found in 16% and posttransplant gastrointestinal perforation in 19%. CONCLUSIONS: Liver transplantation has the potential to cure and allow development in children with end-stage liver disease.

Stable expression of the human kinin B1 receptor in Chinese hamster ovary cells. Characterization of ligand binding and effector pathways.

To delineate ligand binding and functional characteristics of the human B1 kinin receptor, a stable clone of Chinese hamster ovary cells expressing a single class of binding sites for [3H]des-Arg10-lysylbradykinin with a Kd of 0.3 nM and a Bmax of 38 fmol/mg protein ( approximately 40,000 receptors/cell) was isolated. Studies with peptide analogs showed that a lysine residue at position 1 (based on the lysylbradykinin sequence) of ligands was essential for high affinity binding to the human B1 receptor. In marked contrast to cloned Chinese hamster ovary cells expressing the human kinin B2 receptor, which internalized approximately 80% of the ligand within 5 min upon exposure to 2 nM [3H]bradykinin, exposure of cells expressing the B1 receptor to 1 nM [3H]des-Arg10-lysylbradykinin resulted in minimal ligand internalization. Stimulation of the B1 receptor led to inositol phosphate generation and transient increases in intracellular calcium, confirming coupling to phospholipase C, while immunoprecipitation of photoaffinity-labeled G-proteins from membranes indicated specific coupling of the receptor to Galphaq/11 and Galphai1,2. The B1, unlike the B2, receptor does not desensitize (as demonstrated by continuous phosphoinositide hydrolysis), enhancing the potential role of this receptor during inflammatory events.

Neuroleptic-induced striatal dopamine receptor supersensitivity in mice: relationship to dose and drug.

Clozapine and molindone administered to mice for 21 days did not elevate the density of striatal 3H-spiperone binding sites at doses clinically equivalent to 1.5 mg/kg haloperidol, which elevated binding by 29%. Thioridazine (25 mg/kg) elevated binding by 25%. It appears that clinically equivalent doses of clozapine and molindone have reduced ability to induce striatal D-2 dopamine receptor supersensitivity. These data are discussed in relationship to in vitro potencies and toxicity. The dose-response relationship of chronic haloperidol treatment and specific striatal 3H-spiperone binding was complex, i.e., binding was elevated at all doses, but the dose-response curve was concave upward. These data suggest that supersensitization is a complex interactive phenomenon comprised of elevation of striatal D-2 dopamine receptor density and other compensatory mechanisms.

Self-induced orbital emphysema as a presenting sign of Munchausen's syndrome.

A bizarre case of severe, debilitating pneumo-orbit resulting in proptosis, blindness, and eventual exenteration of the right eye and threatening the same fate for the left eye was worked up painstakingly for over 10 years before a final diagnosis of Munchausen's syndrome was uncovered. Five days after the diagnosis was made and appropriate management was instituted the severely proptotic left eye had returned to normal and the patient was discharged for out-patient psychiatric follow-up. A discussion of the differential diagnosis of pneumo-orbit is presented and Munchausen's syndrome, the final diagnosis in this case, is discussed from both an historical and psychiatric perspective.

Maxillary sinus development in patients with cleft palates as compared to those with normal palates.

Maxillary sinusitis appears to be more prevalent in the cleft palate population than in the normal population. The increase in sinusitis may be due to the fact that the maxillary sinus develops differently embryonically in cleft palate patients than in those patients with normal palates. A double blind study was done by measuring the maxillary sinus cephalometric x-rays in cleft palate patients and then comparing them to patients with normally developed palates. The groups studied were 3 months to 20 years of age. It was concluded that in each of these groups there was no significant difference in size, shape, or rate of development of the maxillary sinus in cleft palate patients compared to the normal population. It is probable that the increased incidence of maxillary sinusitis in cleft palate patients is due mainly to the open palate with constant contamination of the nasal mucosa by food pushed into the nares and sinus ostia, resulting in maxillary sinusitis.