Insights into the metabolic functioning of a multipartner ciliate symbiosis from oxygen-depleted sediments.

Symbioses between anaerobic or microaerophilic protists and prokaryotes are common in anoxic and oxygen-depleted habitats ranging from marine sediments to gastrointestinal tracts. Nevertheless, little is known about the mechanisms of metabolic interaction between partners. In these putatively syntrophic associations, consumption of fermentative end products (e.g., hydrogen) by the prokaryotic symbionts is thought to facilitate protistan anaerobic metabolism. Here, we employed metagenomic and metatranscriptomic sequencing of a microaerophilic or anaerobic karyorelictid ciliate and its prokaryotic symbionts from oxygen-depleted Santa Barbara Basin (CA, USA) sediments to assess metabolic coupling within this consortium. This sequencing confirmed the predominance of deltaproteobacterial symbionts from the Families Desulfobacteraceae and Desulfobulbaceae and suggested active symbiont reduction of host-provided sulphate, transfer of small organic molecules from host to symbionts and hydrogen cycling among the symbionts. In addition, patterns of gene expression indicated active cell division by the symbionts, their growth via autotrophic processes and nitrogen exchange with the ciliate host. Altogether, this research underscores the importance of symbiont metabolism to host fermentative metabolism and, thus, likely its success in anoxic and low-oxygen habitats, but also suggests ciliate-associated prokaryotes play a role in important biogeochemical processes.

Molecular indicators of microbial diversity in oolitic sands of Highborne Cay, Bahamas.

Microbialites (stromatolites and thrombolites) are mineralized mat structures formed via the complex interactions of diverse microbial-mat communities. At Highborne Cay, in the Bahamas, the carbonate component of these features is mostly comprised of ooids. These are small, spherical to ellipsoidal grains characterized by concentric layers of calcium carbonate and organic matter and these sand-sized particles are incorporated with the aid of extra-cellular polymeric substances (EPS), into the matrix of laminated stromatolites and clotted thrombolite mats. Here, we present a comparison of the bacterial diversity within oolitic sand samples and bacterial diversity previously reported in thrombolitic and stromatolitic mats of Highborne Cay based on analysis of clone libraries of small subunit ribosomal RNA gene fragments and lipid biomarkers. The 16S-rRNA data indicate that the overall bacterial diversity within ooids is comparable to that found within thrombolites and stromatolites of Highborne Cay, and this significant overlap in taxonomic groups suggests that ooid sands may be a source for much of the bacterial diversity found in the local microbialites. Cyanobacteria were the most diverse taxonomic group detected, followed by Alphaproteobacteria, Gammaproteobacteria, Planctomyces, Deltaproteobacteria, and several other groups also found in mat structures. The distributions of intact polar lipids, the fatty acids derived from them, and bacteriohopanepolyols provide broad general support for the bacterial diversity identified through analysis of nucleic acid clone libraries.

Identity of epibiotic bacteria on symbiontid euglenozoans in O2-depleted marine sediments: evidence for symbiont and host co-evolution.

A distinct subgroup of euglenozoans, referred to as the 'Symbiontida,' has been described from oxygen-depleted and sulfidic marine environments. By definition, all members of this group carry epibionts that are intimately associated with underlying mitochondrion-derived organelles beneath the surface of the hosts. We have used molecular phylogenetic and ultrastructural evidence to identify the rod-shaped epibionts of the two members of this group, Calkinsia aureus and B.bacati, hand-picked from the sediments of two separate oxygen-depleted, sulfidic environments. We identify their epibionts as closely related sulfur or sulfide-oxidizing members of the epsilon proteobacteria. The epsilon proteobacteria generally have a significant role in deep-sea habitats as primary colonizers, primary producers and/or in symbiotic associations. The epibionts likely fulfill a role in detoxifying the immediate surrounding environment for these two different hosts. The nearly identical rod-shaped epibionts on these two symbiontid hosts provides evidence for a co-evolutionary history between these two sets of partners. This hypothesis is supported by congruent tree topologies inferred from 18S and 16S rDNA from the hosts and bacterial epibionts, respectively. The eukaryotic hosts likely serve as a motile substrate that delivers the epibionts to the ideal locations with respect to the oxic/anoxic interface, whereby their growth rates can be maximized, perhaps also allowing the host to cultivate a food source. Because symbiontid isolates and additional small subunit rDNA gene sequences from this clade have now been recovered from many locations worldwide, the Symbiontida are likely more widespread and diverse than presently known.

Archimedean copula model selection under dependent truncation.

One-sided truncated survival data arise when a pair of time-to-event variables (X, Y) is observed only when X

Mobilization of broad host range plasmid from Pseudomonas putida to established biofilm of Bacillus azotoformans. I. Experiments.

A strain of Pseudomonas putida harboring plasmids RK2 and pDLB101 was exposed to a pure culture biofilm of Bacillus azotoformans grown in a rotating annular reactor under three different concentrations of the limiting nutrient, succinate. Experimental results demonstrated that the broad host range RSF1010 derivative pDLB101 was transferred to and expressed by B. azotoformans. At the lower concentrations, donor mediated plasmid transfer increased with increasing nutrient levels, but the highest nutrient concentration yielded the lowest rate of donor to recipient plasmid transfer. For transconjugant initiated transfer, the rate of transfer increased with increasing nutrient concentrations for all cases. At the lower nutrient concentrations, the frequency of plasmid transfer was higher between donors and recipients than between transconjugants and recipients. The reverse was true at the highest succinate concentration. The rates and frequencies of plasmid transfer by mobilization were compared to gene exchange by retrotransfer. The initial rate of retrotransfer was slower than mobilization, but then increased dramatically. Retrotransfer produced a plasmid transfer frequency more than an order of magnitude higher than simple mobilization.

Mobilization of broad host range plasmid from Pseudomonas putida to established biofilm of Bacillus azotoformans. II. Modeling.

A strain of Pseudomonas putida that harbors plasmids RK2 and pDLB101 was exposed to a pure culture biofilm of Bacillus azotoformans grown in a rotating annular reactor. Transfer of the RK2 mobilizable pDLB101 plasmid to B. azotoformans was monitored over a 4-day period. Experimental results demonstrated that the broad host range, RSF1010 derivative pDLB101 was transferred to and expressed by B. azotoformans. In the companion article to this work, the rate of plasmid transfer was quantified as a function of the limiting nutrient, succinate, and as a function of the mechanism of transfer. A biofilm process simulation program (AQUASIM) was modified to analyze resultant experimental data. Although the AQUASIM package was not designed to simulate or predict genetic events in biofilms, modification of the rate process dynamics allowed successful modeling of plasmid transfer. For the narrow range of substrate concentrations used in these experiments, nutrient level had only a slight effect on the rate and extent of plasmid transfer in biofilms. However, further simulations using AQUASIM revealed that under nutrient poor conditions, the number of transconjugants appearing in the biofilm was limited.

Surveillance of traumatic brain injuries in Utah.

From 1990 through 1992 we conducted surveillance of cases requiring hospital admission and of fatal cases of traumatic brain injury among residents of Utah and found an annual incidence rate of 108.8 per 100,000 population. The greatest number of injuries occurred among men and persons aged 15 to 24 years. Motor vehicles were the leading cause of injury, followed by falls and assaults. The incidence rate we found is substantially lower than previously published rates of traumatic brain injury. This may be the result of a decrease in the incidence of these injuries in the decade since earlier studies were done, as well as changing hospital admission criteria that serve to exclude less severe cases of injury. Despite the apparent decline in rates, our findings indicate the continued importance of traumatic brain injury as a public health problem and the need to develop more effective prevention strategies that will address the major causes of these injuries.

Risk factors and mechanisms of occurrence in motor vehicle-related spinal cord injuries: Utah.

The purpose of this paper is to describe the incidence, risk factors, and crash factors of motor-vehicle-related spinal cord injuries in Utah. The Utah Department of Health established a statewide registry of spinal cord injuries (SCIs) occurring in 1989-1991, analyzing data from hospital medical records and police reports. Forty-nine percent of all SCIs involved motor vehicles, including injuries arising from motor vehicle collisions with bicyclists and pedestrians. Adolescent and young adult males were at highest risk of injury. Among occupants of automobiles and trucks with SCI, 70% were involved in a vehicle rollover, while 39% were ejected from the vehicle. Only 25% reported using seatbelts. SCIs were much more likely to be associated with rollover compared with other types of motor vehicle-occupant injuries. These findings suggest areas in which SCI prevention programs and research should be focused.

Surveillance of spinal cord injuries in Utah, USA.

From 1989 through 1991, we conducted surveillance of spinal cord injury (SCI) among residents of Utah. We found an annual incidence rate of 4.3 per 100,000, with the highest rates occurring among males 15-24 years of age. Motor vehicles were the leading cause of injury, followed by falls, and sports and recreation. We also examined the accuracy and completeness of reporting in this surveillance system. We found the predictive value positive of SCI diagnoses reported in hospital discharge data to be only 61%. When we considered only patients who received acute hospital care in-state, we found that the sensitivity of hospital discharge data 89%. These findings indicate serious problems in the reporting of spinal cord injury diagnoses in hospital discharge data and the need to verify case reports based on these data. There is also a need to study this problem in other jurisdictions to determine if overreporting is widespread.

[Motherhood at any price]. / La maternité à tout prix.

What are the real benefits of in-vitro fertilization? (IVF) Does it offer a service to women and couples or does it present itself more as a type of controlled reproduction for which all the consequences are yet unknown? To uncover the answers to these questions, the authors explore the reasons that attract certain women to choose IVF. The authors question if it is appropriate in all infertility cases. They describe IVF including the various stages involved in the process. An overview of the inherent risks and problems with this type of reproductive therapy provide some food for thought. An account of a professional experience illustrates this point. Lucy's story is filled with trials and setbacks. It is the story of a woman exhausted from the IVF process, unhappy, powerless and misunderstood. The nurse is ultimately able to communicate with her. The authors suggest that a "woman's touch" is essential in helping women who are undergoing IVF treatment because of the special comfort and understanding that can be provided to the client. During the IVF process some of the nursing interventions suggested include: using a global approach; providing an empathetic attitude and a reassuring presence; being a good listener; and offering support and encouragement. The nurse must not only create an atmosphere of confidence but should also be able to differentiate between the client's true desire to have a baby and her fantasy of being pregnant. It is essential for the nurse to be able to help the "mother to be" examine and discuss her views and feelings.(ABSTRACT TRUNCATED AT 250 WORDS)

The epidemiology of school-related injuries: new perspectives.

Among school-aged children, unintentional injuries are the leading cause of morbidity and mortality. We began this prospective study in a sample of nine schools within the Boulder Valley School District (Colorado) during the 1988-1989 school year in an effort to explore the etiology of school-related injuries and to provide information relevant to their prevention. During the study period, 509 injuries were reported among a population of 5,518 students, yielding an incidence of 9.22 per 100 students. Boys were nearly one and one-half times more likely to have sustained a school-related injury than girls (risk ratio (RR) = 1.41; 95% confidence intervals [CIs] 1.18, 1.68). We found a significant difference among injury rates by school level (P less than .001). Middle/junior high students had the highest rate, followed closely by elementary students and distantly by high school students. Sports activities accounted for the largest percentage of school injuries (53%), and the percentage of sports-related injuries increased with increasing grade level. Analysis of injury rates by school location revealed that high school students were most frequently injured in the gym (1.52 per 100), middle/junior high students on the athletic field (4.26 per 100), and elementary students on the playground (6.12 per 100). Using injury location as the focal point, we examined relationships among the variables sport/activity, body site, and nature of injury. We found that a large percentage of injuries sustained on the athletic field or in the gym were similar and affected similar body sites, whereas playground injuries differed in their nature and in body site affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of cytosolic calcium in the control of cAMP content by calcium in bovine parathyroid cells.

In the present studies we used the calcium (Ca2+)-sensitive dye Quin-2 to determine whether the cytosolic (Cyt) Ca2+ mediates the effects of extracellular (EC) Ca2+ on cAMP accumulation through changes in adenylate cyclase and phosphodiesterase activity in bovine parathyroid cells (bPTC). In dispersed (d) bPTC, increasing the EC Ca2+ from 0.5 to 2 mM produces a rise in the Cyt Ca2+ from 179 to 646 nM which is associated with a 52% inhibition of agonist-stimulated cAMP accumulation. Over this range of free Ca2+ adenylate cyclase activity decreased by approx. half (57%) and phosphodiesterase activity increases 2-fold (101%) suggesting that changes in the Cyt Ca2+ can account for the effects of EC Ca2+ on cAMP through changes in these enzymes. Unlike dbPTC, 4-day-old cultured bPTC show only a 23% suppression of cAMP by high EC Ca2+ and a reduced rise in the Cyt Ca2+ from 0.5 to 3 mM EC Ca2+. Although there is no reduction in the Ca2+ sensitivity of adenylate cyclase, phosphodiesterase activity shows no change at varied free Ca2+. Thus, this diminished Ca2+ sensitivity of phosphodiesterase activity, and the decreased rise in Cyt Ca2+ relative to EC Ca2+ may both contribute to the resistance to the effects of EC Ca2+ on cAMP content in cultured cells. Because in addition to Cyt Ca2+, protein kinase C may also mediate the effects of EC Ca2+ on PTH release, we studied the effects of TPA (12-alpha-tetradecanoylphorbol 13-acetate) on agonist-stimulated cAMP in dbPTC.(ABSTRACT TRUNCATED AT 250 WORDS)

[Rapidly progressing glomerulonephritis with mesangial IgA deposits in sarcoidosis]. / Glomérulonéphrite rapidement progressive à dépôts mésangiaux d'IgA au cours d'une sarcoïdose.

This report concerns a patient with sarcoidosis who developed acute renal failure due to rapidly progressive glomerulonephritis. Renal biopsy revealed severe endo and extracapillary proliferation with diffuse mesangial deposits of IgA, C3 and beta 1-H on immunofluorescence. The possibility of a common immunopathogenic pathway between sarcoidosis and IgA nephritis is briefly discussed.

Regulation of parathyroid hormone release and cytosolic calcium by extracellular calcium in dispersed and cultured bovine and pathological human parathyroid cells.

Alterations in parathyroid glandular sensitivity to calcium may contribute to the hypersecretion of PTH in hyperparathyroidism. Since the cytosolic calcium concentration may mediate the effects of extracellular calcium on PTH release, we have employed the calcium-sensitive intracellular dye QUIN-2 to examine the relationship between extracellular calcium, cytosolic calcium, and PTH secretion in adult, neonatal, and cultured bovine as well as pathological human parathyroid cells. PTH release was measured using C- and N-terminal radioimmunoassays. Neonatal bovine parathyroid cells showed a greater set-point for secretion (the Ca++ concentration causing half of the maximal inhibition of PTH release) than adult cells (1.27 +/- 0.11 vs. 1.06 +/- 0.11 mM extracellular calcium, P less than 0.01), and a slightly higher extracellular calcium was necessary to raise the cytosolic calcium concentration to a given level in neonatal than in adult bovine parathyroid cells. In individual neonatal and adult cell preparations, there was a close correlation between the set-point for secretion and the "set-point" for cytosolic calcium (r = 0.832, P less than 0.001). In cells from five human parathyroid adenomas, which had an increase in set-point for secretion, the extracellular calcium concentration necessary to raise the cytosolic calcium concentration to a given level was slightly greater than in the neonatal cells. In four preparations of human parathyroid cells there was a significant correlation between the set-points for secretion and cytosolic calcium (r = 0.856, P less than 0.01). Because neonatal bovine and pathological human parathyroid glands show cellular hyperplasia, we studied the temporal relationship between cellular proliferation and the regulation of PTH release and cytosolic calcium concentration in cultured bovine parathyroid cells. Cellular proliferation, estimated by 3H-thymidine incorporation, increased significantly in culture from 104 +/- 10.1 counts/well on day 1 (first 24 h in culture) to 588 +/- 188 and 6,156 +/- 649 counts/well on days 2 and 4, respectively. In cultured cells on day 1, highly Ca++ (2-3 mM) inhibited maximal PTH release by 58.8 +/- 3.2%, which decreased significantly (P less than 0.001) to 38.2 +/- 1.9 and 17.1 +/- 3.7% on days 2 and 4, respectively. The cytosolic calcium observed at 3 mM calcium on day 1 was 701 +/- 43 nM, which declined to 466 +/- 60 and 314 +/- 14 nM on days 2 and 4 (P less than 0.05). There was a close correlation between this progressive decrease in maximal inhibition of PTH release and the cytosolic calcium at high extracellular calcium in cultured cells (r = 0.99, P < 0.001). Thus, during active proliferation of cultured cells, there is an alteration in the regulation of cytosolic calcium at a given extracellular calcium concentration, and changes in the regulation of PTH release and cytosolic calcium by extracellular calcium may be related to enhanced cellular proliferation.

5-Hydroxytryptamine receptors in neurones and glia.

Crude membranal fractions isolated from mammalian brain tissue contain two classes of recognition sites capable of binding [3H]5-HT with high affinity constants. These classes of sits are characteristics of the postsynaptosomal membrane fraction for the higher affinity and of a glial cell membrane fraction for the lowest. They are observed with similar properties in cultured neuronal and glial cell respectively. Two 5-HT stimulated adenylate cyclases are present in crude membrane fraction; they are also separable as neuronal and glial components. These observations correspond likely to the existence of two classes of receptors for 5-HT. Their mechanisms of regulation involve presumably structural conformation changes of the recognition site coupled to various states of the activity of the receptor.