Nematode community dynamics over an annual production cycle in the central North Sea.

Nematode species composition, trophic structure and body size distributions were followed over an annual production cycle in the central North Sea; to test responses to temporally changing food quality and quantity in the sediment. Changes in the phytoplankton concentration in the water column were quantitatively reflected in the concentration of chlorophyll a and breakdown products in the sediment, with higher concentrations in spring and autumn following blooms, and lower concentrations in summer and winter. The taxonomic and trophic structure of nematode communities differed significantly among stations over relatively short distances, potentially masking some of the temporal dynamics. Spatio-temporal differences in nematode species composition were linked to changes in the quality and quantity of organic material reaching the seabed, reflecting a species-specific response to the nutritional quality of sedimenting organic material and the biochemical changes in the sediment associated with its decomposition. The size distributions of selected nematode species indicated that most species bred continuously throughout the sampling period, although one species, the epigrowth feeder Spilophorella paradoxa, had periods of increased growth following the deposition of the spring phytoplankton bloom. There was no consistent temporal relationship between the trophic composition of nematode communities and spring chlorophyll a or carbon sedimentation, most likely a result of the trophic plasticity of most feeding types and the capacity of the community to use both freshly sedimented material as well as the subsequent breakdown products and refractory organic matter. Community metrics implied that there were small responses to the seasonal production cycle, but these belied strong responses of a few species with life histories that allowed them to track the availability of suitable food resources.

Human trampling as short-term disturbance on intertidal mudflats: effects on macrofauna biodiversity and population dynamics of bivalves.

The effect of physical disturbance in the form of trampling on the benthic environment of an intertidal mudflat was investigated. Intense trampling was created as unintended side-effect by benthic ecologists during field experiments in spring and summer 2005, when a mid-shore area of 25 × 25 m was visited twice per month by on average five researchers for a period of 8 months. At the putatively-impacted location (I) (25 × 25 m) and two nearby control locations (Cs) (25 × 25 m each), three sites (4 × 4 m) were randomly selected and at each site, three plots (50 × 50 cm) were sampled after 18 and 40 days from the end of the disturbance. Multivariate and univariate asymmetrical analyses tested for changes in the macrofaunal assemblage, biomass of microphytobenthos and various sediment properties (grain-size, water content, NH4 and NO3 concentrations in the pore water) between the two control locations (Cs) and the putatively-impacted location (I). There were no detectable changes in the sediment properties and microphytobenthos biomass, but variability at small scale was observed. Microphytobenthos and NH4 were correlated at I to the number of footprints, as estimated by the percentage cover of physical depressions. This indicated that trampling could have an impact at small scales, but more investigation is needed. Trampling, instead, clearly modified the abundance and population dynamics of the clam Macoma balthica (L.) and the cockle Cerastoderma edule (L.). There was a negative impact on adults of both species, probably because footsteps directly killed or buried the animals, provoking asphyxia. Conversely, trampling indirectly enhanced recruitment rate of M. balthica, while small-sized C. edule did not react to the trampling. It was likely that small animals could recover more quickly because trampling occurred during the growing season and there was a continuous supply of larvae and juveniles. In addition, trampling might have weakened negative adult-juvenile interactions between adult cockles and juvenile M. balthica, thus facilitating the recruitment. Our findings indicated that human trampling is a relevant source of disturbance for the conservation and management of mudflats. During the growing season recovery can be fast, but in the long-term it might lead towards the dominance of M. balthica to the cost of C. edule, thereby affecting ecosystem functioning.

The safety and efficacy of combined spinal and epidural analgesia/anesthesia (6,002 blocks) in a community hospital.

BACKGROUND AND OBJECTIVES: This study examined the safety and efficacy of combined spinal and epidural (CSE) analgesia/anesthesia performed in a community hospital. METHODS: Labor and Surgical Anesthesia Quality Assessment Worksheets were completed by the responsible anesthesiologist for 7,893 general anesthetics and 7,931 regional anesthetics from January 1, 1994 to December 31, 1997. A retrospective computerized analysis of these data tabulated the number of regional anesthesia techniques and identified anesthesia effectiveness and complications associated with these procedures. The safety and efficacy of CSE analgesia/anesthesia (6,002 blocks) was assessed by comparing these results with reported complications and failure rates for spinal and epidural anesthesia. RESULTS: The CSE technique did not increase the risk of anesthesia complications, as compared with the reported prevalence associated with major regional anesthesia. It provided decreased failure rates for labor analgesia and comparable or decreased failure rates for surgical anesthesia, when compared with reported failure rates for epidural anesthesia. Apnea did not occur in parturients who received 4,164 CSE blocks with intrathecal sufentanil (ITS; 10, 15, or 20 microg) for labor pain relief. However, the prevalence of laboring patients requiring intravenous medication for side effects was related to the dose of ITS: 10 microg (1.1%), 15 microg (4.6%), and 20 microg (5.5%) (P < .001). Patients who received prior systemic narcotics less than 6 hours before ITS were twice as likely to require intravenous treatment for low oxygen saturation/drowsiness (21%) than were those who experienced dysphagia or pruritus (10%) (P < .001). CONCLUSIONS: This review of 6,002 CSE blocks performed in a community hospital has demonstrated that CSE labor analgesia, surgical anesthesia are safe and efficacious. We believe that patient observation and continuous pulse oximetry for 1-2 hours after administration of ITS and prompt treatment with intravenous naloxone for severe drowsiness, low oxygen saturation (PaO2 < 90% unresponsive to mask oxygen), or dysphagia should be used to minimize the risk of apnea.

Does combined spinal-epidural analgesia with subarachnoid sufentanil increase the incidence of emergency cesarean delivery?

BACKGROUND AND OBJECTIVES: The purpose of this review was to determine if patients who receive combined spinal-epidural (CSE) analgesia with subarachnoid sufentanil have an increased incidence of emergency cesarean delivery for fetal distress when compared with patients who receive systemic or no medication (S/NM) for labor analgesia. METHODS: A retrospective computerized analysis of data on all 2,560 deliveries at Bellevue Woman's Hospital for 14 months summarized practice parameters for 1,240 patients who received regional analgesia (98% CSE analgesia), identified 1,140 patients who received S/NM, and classified the urgency of 479 cesarean deliveries. In the CSE group there were 168 cesarean deliveries (emergency 16, urgent 58, semiurgent 70, and nonurgent 24) as compared with a total of 128 (emergency 16, urgent 43, semiurgent 69, nonurgent 0) in the S/NM group. Scheduled cesarean sections (180) were excluded from the study. RESULTS: The incidence of emergency cesarean delivery in 1,217 patients who received CSE analgesia with subarachnoid sufentanil (10-15 micrograms) compared with 1,140 patients who received S/NM for labor analgesia was 1.3% versus 1.4%, respectively. More importantly, there was no case in which emergency cesarean delivery was required for acute fetal distress in the absence of obstetric factors during the 90 minutes following administration of subarachnoid sufentanil. General anesthesia was required for emergency cesarean delivery in only one patient (6%) in the CSE group, as against eight patients (50%) in the S/NM group who required general anesthesia for emergency cesarean section (P < .05). CONCLUSIONS: This experience indicates that patients who receive CSE analgesia do not have a higher incidence of emergency cesarean delivery than patients who have S/NM for labor analgesia. Emergency cesarean section for fetal distress within 90 minutes of the administration of intrathecal sufentanil only occurred in association with obstetric factors. However, caution should be exercised in extrapolating these results to other practice settings, particularly high-risk referral centers.

Effect of oxygen free radicals on Mg2+ efflux from erythrocytes.

Hydrogen peroxide destroyed the Na+/Mg2+ antiport in Mg(2+)-loaded human and rat erythrocytes and increased the leakage of intracellular Mg2+ and K+. These effects are opposite to the increase of Na+/Mg2+ antiport and unchanged Na(+)-independent Mg2+ efflux from erythrocytes of patients with cystic fibrosis score 3. Thus, the increase of Na+/Mg2+ antiport in these patients is not caused by increased formation of free radicals.

Recurrent ventricular tachycardia associated with gangrene.

Ventricular tachycardia occurs with myocardial ischaemia, hypoxia, hypercarbia, hypokalaemia, and digitalis toxicity. We report recurrent ventricular tachycardia occurring in a patient with gangrene of the lower extremities in whom none of the common aetiologies for dysrhythmia could be demonstrated. Ventricular tachycardia stopped and did not recur after amputation. This course leads us to speculate that release of a toxic substance from gangrenous tissue may contribute to the development of ventricular tachycardia.

Phenobarbital in the acute management of febrile convulsions.

Blood levels of phenobarbital were determined after a single oral or intramuscular (IM) dose in children in the hospital after febrile convulsions. At a dose of 15 mg/kg, both the oral and IM routes gave therapeutic blood levels within 90 minutes. Absorption from the IM route before 90 minutes was inconsistent and would be unlikely to arrest an established convulsion within a critical time period. For use as a drug to prevent convulsions, oral phenobarbital at 15 mg/kg deserves further study.