Geochemical constraints on chemolithoautotrophic reactions in hydrothermal systems.

Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of reduced hydrothermal fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O system together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of hydrothermal fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from hydrothermal fluids represents about 200,000 calories of chemical energy for metabolic systems able to catalyze H2S oxidation.

The effect of prefixation on the quality of vascular corrosion casts of rat heart.

To help define the optimal conditions for the preparation of vascular corrosion casts of rat heart, we examined the effect of prefixation with aldehyde fixatives on the perfusion rates of rat heart and on the quality of vascular casts. For these studies, beating hearts were removed from rats, cannulated via the aortic stump, arrested with KCl, perfused retrograde with buffered saline or fixative, and infused with resin to prepare corrosion casts. Fixatives used were 2.

Immunocytochemical evidence that quisqualate is selectively internalized into a subset of hippocampal neurons.

Quisqualic acid (QUIS) has been shown to interact with several glutamate receptor subtypes and uptake sites. We have previously demonstrated that a brief exposure of hippocampal cells to QUIS sensitizes them to depolarization by the alpha-amino-omega-phosphonate analogues of glutamate, AP4, AP5, and AP6. This QUIS-induced sensitization is accompanied by the active uptake of QUIS into hippocampal slices.

Synthesis of oxadiazolidinedione derivatives as quisqualic acid analogues and their evaluation at a quisqualate-sensitized site in the rat hippocampus.

The ability of quisqualic acid (1) to sensitize neurons to depolarization by omega-phosphono alpha-amino acid analogues of excitatory amino acids is a highly specific phenomenon and is termed the QUIS effect. In an attempt to elucidate the structure-activity relationships for this sensitization, analogues 2-6 of quisqualic acid have been synthesized. Compounds 4, 5, and 6 showed no quisqualate sensitization with respect to L-2-amino-6-phosphonohexanoic acid (L-AP6), while compounds 2 and 3 were 1/10 and 1/1000, respectively, as active as quisqualic acid in sensitizing neurons toward L-AP6.

Utilization of the resolved L-isomer of 2-amino-6-phosphonohexanoic acid (L-AP6) as a selective agonist for a quisqualate-sensitized site in hippocampal CA1 pyramidal neurons.

Brief exposure of rat hippocampal slices to quisqualic acid (QUIS) sensitizes neurons to depolarization by the alpha-amino-omega-phosphonate excitatory amino acid (EAA) analogues AP4, AP5 and AP6. These phosphonates interact with a novel QUIS-sensitized site. Whereas L-AP4 and D-AP5 cross-react with other EAA receptors, DL-AP6 has been shown to be relatively selective for the QUIS-sensitized site.

Community-acquired bacteremias from tunneled central intravenous lines: results from studies of a single vendor.

Tunneled central intravenous catheters are a common method for rendering prolonged outpatient intravenous therapy. Their safety, however, has not been well studied. We conducted a retrospective evaluation of bacteremias associated with tunneled central intravenous catheters managed by a single home health care vendor during a 1-year period.

[The value of ultrasound for correction of clinical diagnostic errors in soft tissue tumors].

In doubtful clinical diagnosis, ultrasound investigation may represent a workable diagnostic means in revealing the nature of soft tissue alterations, as will be demonstrated by 6 clinical examples; in all cases a wrong clinical diagnosis delayed the necessary therapy and possibly deteriorated the prognosis of disease. In these patients correction of the clinical diagnosis was of decisive importance for consecutive diagnostics and therapy.

Lens refilling and endocapsular polymerization of an injectable intraocular lens: in vitro and in vivo study of potential risks and benefits.

Endocapsular cataract removal and injection of a liquid artificial lens has several advantages, including restitution of accommodation, small corneoscleral incision, a more physiological position of the intraocular lens, and a reduced rate of secondary opacification. Our technique consists of bimanual phacofragmentation followed by injection of a fluid monomeric material that can be polymerized inside the capsular bag by short light exposure. Our study assessed the potential risks of the technique (e.

Projection of wing nerves to spinal cord and brain stem of the pigeon as studied by transganglionic transport of Fast Blue.

To see whether there is a topographic organization of forelimb nerves in the CNS of birds, the termination pattern of afferents from wing nerves of the pigeon in the cervical spinal cord and the brain stem was determined by the transganglionic transport of Fast Blue and HRP. Fast Blue turned out to be a very sensitive and nonselective tracer with a wider distribution of terminal labeling than with HRP. Thus, Fast Blue is a useful marker for complete mapping of the terminal fields of peripheral nerves.

Effect of age, calcium source, and radiolabeling method on whole body 47Ca retention in the rat.

In a longitudinal study we determined the effect of animal age as well as Ca source and radiolabeling method on Ca bioavailability by measuring whole body 47Ca retention (WBR) in male Sprague-Dawley rats. The WBR assay was performed without surgery or anesthesia, and the same groups of animals were studied at 8, 16, 20, and 32 wk of age. Rats were administered a 6-mg radiolabeled oral dose of Ca as Ca citrate malate (CCM) or intrinsically or extrinsically labeled CaCO3 or hydroxyapatite (HAP).

Short-term dietary calcium fortification increases fecal saturated fat content and reduces serum lipids in men.

The effect of dietary calcium on fecal fatty acid excretion and serum lipids was tested in a randomized, single-blind metabolic study in 13 healthy men with moderate hypercholesterolemia. A low calcium base diet containing 34% of energy from fat, 13% from saturated fatty acids, 240 mg cholesterol/d and 410 mg Ca/d was compared with a fortified version in which calcium citrate malate was added to orange juice, (550 mg) muffins (750 mg), and two tablets (500 mg) for a total calcium intake of 2200 mg/d. Fecal collections (72 h, d 8, 9, 10) and blood from fasting subjects for lipids and lipoproteins (d 9, 10, 11) were obtained.

Complementary medicine: are patients' expectations being met by their general practitioners?

Complementary, or alternative, medicine has increased in popularity among patients during the past 20 years. The purpose of this study was to determine whether general practitioners met their patients' expectations with regard to complementary medicine. In a postal survey all 71 accredited general practitioners in the district of Kassel, Germany, received a structured questionnaire about their experience with complementary medicine.

[Tumor resection and reconstructive intervention in spinal tumors].

Modern techniques of resection and reconstructive surgery in patients with primary and metastatic spine tumors are presented. These techniques are delineated along an algorithm that allows us to develop an adequate oncological protocol, find a rational approach for preoperative embolization and for tumor resection and choose the proper materials and implants for bridging bone defects. The aim is to achieve short-term and long-term stability, respectively.

Quisqualic acid induced sensitization and the active uptake of L-quisqualic acid by hippocampal slices.

Hippocampal CA1 pyramidal cell neurons are sensitized to depolarization by L-2-amino-4-phosphonobutanoic acid (L-AP4) following exposure to L-quisqualic acid (QUIS). It has been proposed that induction of this 'QUIS-effect' involves uptake of L-QUIS by hippocampal cells. We have used o-phthaldialdehyde (OPA) derivatization and high performance liquid chromatographic (HPLC) separation of extracts from hippocampal slices which have been exposed to varied concentrations of L-QUIS to investigate L-QUIS uptake into hippocampal slices.

Sponsor/contract laboratory communication: a team approach to quality.

The true measure of any successful quality endeavor is the final product. The final product generated at contract facilities conducting nonclinical studies is the final report. This should be accurate, complete, and consistent with regard to the raw data, and in compliance itself.

Aldehydes in hydrothermal solution: standard partial molal thermodynamic properties and relative stabilities at high temperatures and pressures.

Aldehydes are common in a variety of geologic environments and are derived from a number of sources, both natural and anthropogenic. Experimental data for aqueous aldehydes were taken from the literature and used, along with parameters for the revised Helgeson-Kirkham-Flowers (HKF) equations of state, to estimate standard partial molal thermodynamic data for aqueous straight-chain alkyl aldehydes at high temperatures and pressures. Examples of calculations involving aldehydes in geological environments are given, and the stability of aldehydes relative to carboxylic acids is evaluated.

Quisqualic acid analogues: synthesis of beta-heterocyclic 2-aminopropanoic acid derivatives and their activity at a novel quisqualate-sensitized site.

Hippocampal CA1 pyramidal cell neurons are sensitized over 30-fold to depolarization by L-2-amino-4-phosphonobutanoic acid (L-AP4) following exposure to L-quisqualic acid. This phenomenon has been termed the QUIS effect. In the present study several novel L-quisqualic acid analogues have been synthesized and tested for their interaction with the different components of the QUIS-effect system.

An angiographic method for in vivo study of arteries of the circle of Willis in small animals.

An X-ray imaging technique designed to allow sequential diameter measurements of the cerebral vessels in intact, anesthetized small animals under relatively physiological conditions is described. The ferret and the rabbit were chosen as potentially useful animal models for studying the cerebrovascular system because of the advantageous anatomic characteristics of these relatively small species. A commercially available and relatively inexpensive X-ray imaging system with a small focal spot provides good spatial resolution.

Structure-function relationships for analogues of L-2-amino-4-phosphonobutanoic acid on the quisqualic acid-sensitive AP4 receptor of the rat hippocampus.

Hippocampal CA1 pyramidal cell neurons are sensitized to depolarization by L-2-amino-4-phosphonobutanoic acid (L-AP4) following exposure to L-quisqualic acid (QUIS). We have examined the interaction of 43 structural analogues of L-AP4 with both the 'induction' site and the QUIS-sensitive AP4 site in rat hippocampus. The synthesis of cis- and trans-4-phosphonoxy-L-proline, 3-(RS)-amino-5-phosphonopentanoic acid and 2(RS)-amino-5-phenyl-4(RS)-phosphonopentanoic acid (gamma-benzyl AP4) are described.

Nonsynonymous polymorphic sites in the apolipoprotein (apo) A-IV gene are associated with changes in the concentration of apo B- and apo A-I-containing lipoproteins in a normal population.

The aims of this study were to detect polymorphic sites in the apolipoprotein (apo) A-IV gene, to establish their frequencies, to determine potential haplotypes, and to investigate the role of these polymorphisms in lipid metabolism. A sequencing study of four individuals led to the identification of two synonymous mutations (codons 9 and 54) and three nonsynonymous mutations (Val-8----Met, Gln360----His, and Thr347----Ser) and of a VNTR polymorphism within a series of three or four CTGT repeats in the noncoding region of exon 3. Frequencies of these polymorphisms were determined in 291 students by using naturally occurring (BstEII for the synonymous mutation in codon 54, HinfI for Thr347----Ser, and Fnu4HI for Gln360----His) or artificially introduced restriction-enzyme cutting sites (BstEII for the synonymous mutation in codon 9 and MamI for Val-8----Met), subsequent to PCR amplification.

Lower esophageal sphincter pressure, acid secretion, and blood gastrin after coffee consumption.

This study tested the hypothesis that differences in the processing of raw coffee beans can account for some of the variability in gastric effects of coffee drinking. Coffees were selected to represent several ways that green coffee beans are treated, ie, processing variables. These included instant and ground coffee processing, decaffeination method (ethyl acetate or methylene chloride extraction), instant coffee processing temperature (112 degrees F or 300 degrees F), and steam treatment.

[Surgical therapy of metastases of the proximal femur and acetabulum].

An analysis of indications and operative techniques was carried out in 166 patients with skeletal metastases of the proximal femur and acetabulum. Complications as well as functional and oncological results clearly show advantages and disadvantages of different methods such as osteosyntheses, standard hip prostheses and tumour prostheses referring to the tumour's localization and extent.