HIV infection among rural trauma patients: a blind serosurvey and literature review

Human immunodeficiency virus (HIV) seroprevalence rates among rural trauma patients range between 0.15 and 1.32 per cent. A random sample of trauma patients treated at our rural trauma center between September 1994 and November 1995 was enrolled into a blind HIV serosurvey. Five hundred sixty-six of 1315 trauma patients (43%) were tested. Two of the 566 patients (0.35%) were HIV positive. A review of aggregate data for HIV infection among rural trauma patients in the United States show that 28 of the 4639 patients (0.60%) are HIV positive. We conclude that there was a low HIV incidence among our trauma patients from September 1994 to November 1995, and the cost-effectiveness of HIV testing for rural trauma patients is questionable with incidences between 0.5 and 1.0 per cent.

A comparison of the efficacy of injectable dexamethasone sodium phosphate versus placebo in postoperative podiatric analgesia

Forty-two patients undergoing identical bilateral foot surgery were evaluated in a double-blind study designed to evaluate the efficacy of injectable dexamethasone sodium phosphate versus placebo as an analgesic. Patients who had elective foot surgery on an outpatient basis received an injection of dexamethasone sodium phosphate in one foot and an equivalent injection of normal sterile saline in the contralateral foot. Both the patients and the surgeons were unaware of which foot was injected with each agent. The results suggest that there was not a difference in the patient perception of which foot was most painful. Forty-eight to 72 hours after surgery, 18 (44%) patients identified the foot that received steroid as less painful, 18 (44%) patients identified the foot that received placebo as less painful, and 5 (12%) patients did not perceive a difference. In addition, there was not a difference in outcome based on soft-tissue or osseous procedures.

Cycloserine-induced decrease of cerebroside in myelin

L-Cycloserine has been shown specifically to lower brain cerebroside levels in vivo, but the extent to which the decrease in whole brain cerebroside content reflects lower myelin cerebroside levels is not known since a substantial portion of cerebroside is found in nonmyelin membranes. The present report demonstrates that chronically administered cycloserine lowers the proportion of cerebroside in rat brain myelin. Cycloserine-induced decrease of myelin cerebroside should provide a useful tool in investigating the role of cerebroside in maintaining myelin stability.

Physiological evidence for arteriovenous anastomoses in the uterine circulation of late-pregnant ewes

1. The objective of the present study was to determine whether arteriovenous anastomoses (AVA) are present in the uterine circulation of conscious, late-pregnant ewes. 2. Twenty late-pregnant ewes were assigned to two groups. In group 1, 15 microm coloured microspheres were injected into the uterine artery of the pregnant horn and the relative proportion of microspheres trapped in the uterus and lungs was determined. The percentage shunting of blood measured by this method was 17+/-3%, representing a blood flow of 164+/-39 mL/min (n = 12). Any contribution of ovarian, cervical, rectal and other vascular beds was specifically excluded in this group. 3. In group 2, total uterine capillary flow was measured using the reference blood flow method, by injecting 15 microm microspheres into the heart. Calibrated flow probes, placed on both main uterine arteries, concurrently measured total uterine blood flow. Total blood flow to the uterus (flow probe) was significantly greater (t = 3.415; P = 0.027) than uterine capillary flow (microspheres), indicating AVA shunting in the uterine circulation. Mean total blood flow to the uterus was 1749+/-160 mL/min, of which an average 25+/-5% (n = 5 sheep) was shunted. 4. The percentage AVA shunting for groups 1 and 2 was not significantly different (t = 1.219; P = 0.24) and, when combined, the mean percentage of uterine blood flow passing through AVA in the late-pregnant sheep was determined to be 19+/-3%. 5. The present study shows that AVA are present and patent in the uterine circulation of late-pregnant ewes and that they account for the shunting of approximately 20% of the uterine blood flow into the maternal venous circulation.

Investigating family-based alternatives to institution-based mental health services for youth: lessons learned from the pilot study of a randomized field trial

The development and validation of family-based alternatives to out-of-home placements for children is an important goal in the mental health services field. The rigorous evaluation of such alternatives, however, can be difficult to accomplish. The purpose of this article is to describe initial barriers experienced during the pilot study of a randomized trial, funded by the National Institute of Mental Health, conducted in a field setting, and the strategies that were used to overcome these barriers. The randomized trial is examining home-based multisystemic therapy as an alternative to the psychiatric hospitalization of youths presenting psychiatric emergencies. The pilot study illuminated the interface of treatment and services research issues, prompting significant changes in the project's clinical procedures, organization, and supervisory processes, as well as in the project's interface with existing community resources for serving youths with serious emotional disturbances.

Prebiotic synthesis of diaminopyrimidine and thiocytosine

The reaction of guanidine hydrochloride with cyanoacetaldehyde gives high yields (40-85%) of 2,4-diaminopyrimidine under the concentrated conditions of a drying lagoon model of prebiotic synthesis, in contrast to the low yields previously obtained under more dilute conditions. The prebiotic source of cyanoacetaldehyde, cyanoacetylene, is produced from electric discharges under reducing conditions. The effect of pH and concentration of guanidine hydrochloride on the rate of synthesis and yield of diaminopyrimidine were investigated, as well as the hydrolysis of diaminopyrimidine to cytosine, isocytosine, and uracil. Thiourea also reacts with cyanoacetaldehyde to give 2-thiocytosine, but the pyrimidine yields are much lower than with guanidine hydrochloride or urea. Thiocytosine hydrolyzes to thiouracil and cytosine and then to uracil. This synthesis would have been a significant prebiotic source of 2-thiopyrimidines and 5-substituted derivatives of thiouracil, many of which occur in tRNA. The applicability of these results to the drying lagoon model of prebiotic synthesis was tested by dry-down experiments where dilute solutions of cyanoacetaldehyde, guanidine hydrochloride, and 0.5 M NaCl were evaporated over varying periods of time. The yields of diaminopyrimidine varied from 1 to 7%. These results show that drying lagoons and beaches may have been major sites of prebiotic syntheses.

Selective loss of myelin-associated glycoprotein from myelin correlates with anti-MAG antibody titre in demyelinating paraproteinaemic polyneuropathy

The IgM monoclonal autoantibodies of patients with demyelinating paraproteinaemic polyneuropathy recognize a carbohydrate structure present on both myelin-associated glycoprotein (MAG) and protein zero (P0). These autoantibodies are sufficient to cause the disease but the mechanism of demyelination remains unclear. We have analysed nerve biopsies from eight patients with polyneuropathy and anti-MAG antibodies by quantitative immunohistochemistry and find a concordant pattern of reduced expression of myelin markers with the loss of myelinated fibres. We report here novel features of this disease, in particular a selective lack of detectable MAG in a large proportion of myelinated-fibres containing P0, myelin basic protein (MBP) and periaxin. There is also an inverse correlation of the distribution of MAG in peripheral nerve myelin with the serum anti-MAG antibody titres but no correlation of these titres with the loss of myelinated fibres. Double immunofluorescence staining of paraproteinaemic polyneuropathy (PPN) nerves shows anti-MAG IgM deposited on the periphery of myelinated fibres associated with or lacking MAG staining. These data suggest that the binding of anti-MAG antibodies to MAG and/or other myelin component(s) results in MAG downregulation and may have an essential role in the molecular mechanisms leading to demyelination and partial regeneration in this disease.

Metabolism of N-acetyl-L-aspartate in rat brain

The abundance and developmental regulation of N-acetylaspartate (NAA) in brain suggest that it plays an important role in brain metabolism. Previous studies demonstrated that NAA transports acetate from the mitochondrion to the cytoplasm where it is utilized for lipid synthesis, however, the metabolic fate of NAA-derived aspartate is not established. To investigate NAA metabolism, rats were injected intracranially with N-([2H3]acetyl)-L-[15N]aspartate ([2H3,15N]NAA) and whole brain metabolites were analyzed using gas chromatography and mass spectrometry techniques (GC/MS). The rapid decline of [2H3,15N]NAA was associated with a rapid appearance of [15N]glutamate, indicating rapid transamination of the [15N]aspartate that was derived from the enzymatic hydrolysis of [2H3,15N]NAA. Inability to detect [15N]NAA in brain extracts in several experiments indicates that the 15N moiety is not reutilized for NAA synthesis and suggests one metabolic role of NAA may be the transport of amino nitrogen from the mitochondrion to the cytoplasm.

Was ferrocyanide a prebiotic reagent?

Hydrogen cyanide is the starting material for a diverse array of prebiotic syntheses, including those of amino acids and purines. Hydrogen cyanide also reacts with ferrous ions to give ferrocyanide, and so it is possible that ferrocyanide was common in the early ocean. This can only be true if the hydrogen cyanide concentration was high enough and the rate of reaction of cyanide with ferrous ions was fast enough. We show experimentally that the rate of formation of ferrocyanide is rapid even at low concentrations of hydrogen cyanide in the pH range 6-8, and therefore an equilibrium calculation is valid. The equilibrium concentrations of ferrocyanide are calculated as a function of hydrogen cyanide concentration, pH and temperature. The steady state concentration of hydrogen cyanide depends on the rate of synthesis by electric discharges and ultraviolet light and the rate of hydrolysis, which depends on pH and temperature. Our conclusions show that ferrocyanide was a major species in the prebiotic ocean only at the highest production rates of hydrogen cyanide in a strongly reducing atmosphere and at temperatures of 0 degrees C or less, although small amounts would have been present at lower hydrogen cyanide production rates. The prebiotic application of ferrocyanide as a source of hydrated electrons, as a photochemical replication process, and in semi-permeable membranes is discussed.

A week in the country: a model respite program

A family-oriented camping program for caregivers of children who are HIV infected is described. Major goals of the camping program consisted of: (1) providing respite care to mother and child, and, (2) training health care and mental health workers to provide special services, emphasizing the mental health needs of this population.

Potentially prebiotic syntheses of condensed phosphates

In view of the importance of a prebiotic source of high energy phosphates, we have investigated a number of potentially prebiotic processes to produce condensed phosphates from orthophosphate and cyclic trimetaphosphate from tripolyphosphate. The reagents investigated include polymerizing nitriles, acid anhydrides, lactones, hexamethylene tetramine and carbon suboxide. A number of these processes give substantial yields of pyrophosphate from orthophosphate and trimetaphosphate from tripolyphosphate. Although these reactions may have been applicable in local areas, they are not sufficiently robust to have been of importance in the prebiotic open ocean.

Hydrolysis of dihydrouridine and related compounds

Dihydrouridine is absent from the tRNA of almost all hyperthermophiles and most Archaea but is ubiquitous in the tRNA of Eubacteria and Eukaryotes. In order to investigate whether this could be due to instability, the rate of ring opening of dihydrouridine was measured between 25 and 120 degrees C. The dihydrouridine ring is stable at 25 degrees C, but the half-life at 100 degrees C and pH 7 is 9.1 h, which is comparable to the doubling time of hyperthermophiles. This suggests an explanation for the absence of dihydrouridine from the tRNA of hyperthermophiles. The rates of ring opening of dihydrouracil, dihydrothymine, and 1-N-methyldihydrouracil were measured at 100 degrees C and pH 6-9, as were the equilibrium constants for ring closure of the ureido acids to the dihydrouracils. The pH rate profiles for ring opening and ring closing were calculated from the data. Possible roles for dihydrouracils in the pre-RNA world are discussed.

Temporal processing deficits of language-learning impaired children ameliorated by training

Children with language-based learning impairments (LLIs) have major deficits in their recognition of some rapidly successive phonetic elements and nonspeech sound stimuli. In the current study, LLI children were engaged in adaptive training exercises mounted as computer "games" designed to drive improvements in their "temporal processing" skills. With 8 to 16 hours of training during a 20-day period, LLI children improved markedly in their abilities to recognize brief and fast sequences of nonspeech and speech stimuli.

Language comprehension in language-learning impaired children improved with acoustically modified speech

A speech processing algorithm was developed to create more salient versions of the rapidly changing elements in the acoustic waveform of speech that have been shown to be deficiently processed by language-learning impaired (LLI) children. LLI children received extensive daily training, over a 4-week period, with listening exercises in which all speech was translated into this synthetic form. They also received daily training with computer "games" designed to adaptively drive improvements in temporal processing thresholds. Significant improvements in speech discrimination and language comprehension abilities were demonstrated in two independent groups of LLI children.

Investigation of the prebiotic synthesis of amino acids and RNA bases from CO2 using FeS/H2S as a reducing agent

An autotrophic theory of the origin of metabolism and life has been proposed in which carbon dioxide is reduced by ferrous sulfide and hydrogen sulfide by means of a reversed citric acid cycle, leading to the production of amino acids. Similar processes have been proposed for purine synthesis. Ferrous sulfide is a strong reducing agent in the presence of hydrogen sulfide and can produce hydrogen as well as reduce alkenes, alkynes, and thiols to saturated hydrocarbons and reduce ketones to thiols. However, the reduction of carbon dioxide has not been demonstrated. We show here that no amino acids, purines, or pyrimidines are produced from carbon dioxide with the ferrous sulfide and hydrogen sulfide system. Furthermore, this system does not produce amino acids from carboxylic acids by reductive amination and carboxylation. Thus, the proposed autotrophic theory, using carbon dioxide, ferrous sulfide, and hydrogen sulfide, lacks the robustness needed to be a geological process and is, therefore, unlikely to have played a role in the origin of metabolism or the origin of life.

Are polyphosphates or phosphate esters prebiotic reagents?

It is widely held that there was a phosphate compound in prebiotic chemistry that played the role of adenosine triphosphate and that the first living organisms had ribose-phosphate in the backbone of their genetic material. However, there are no known efficient prebiotic synthesis of high-energy phosphates or phosphate esters. We review the occurrence of phosphates in Nature, the efficiency of the volcanic synthesis of P4O10, the efficiency of polyphosphate synthesis by heating phosphate minerals under geological conditions, and the use of high-energy organic compounds such as cyanamide or hydrogen cyanide. These are shown to be inefficient processes especially when the hydrolysis of the polyphosphates is taken into account. For example, if a whole atmosphere of methane or carbon monoxide were converted to cyanide which somehow synthesized polyphosphates quantitatively, the polyphosphate concentration in the ocean would still have been insignificant. We also attempted to find more efficient high-energy polymerizing agents by spark discharge syntheses, but without success. There may still be undiscovered robust prebiotic syntheses of polyphosphates, or mechanisms for concentrating them, but we conclude that phosphate esters may not have been constituents of the first genetic material. Phosphoanhydrides are also unlikely as prebiotic energy sources.

Rates of decomposition of ribose and other sugars: implications for chemical evolution

The existence of the RNA world, in which RNA acted as a catalyst as well as an informational macromolecule, assumes a large prebiotic source of ribose or the existence of pre-RNA molecules with backbones different from ribose-phosphate. The generally accepted prebiotic synthesis of ribose, the formose reaction, yields numerous sugars without any selectivity. Even if there were a selective synthesis of ribose, there is still the problem of stability. Sugars are known to be unstable in strong acid or base, but there are few data for neutral solutions. Therefore, we have measured the rate of decomposition of ribose between pH 4 and pH 8 from 40 degrees C to 120 degrees C. The ribose half-lives are very short (73 min at pH 7.0 and 100 degrees C and 44 years at pH 7.0 and 0 degrees C). The other aldopentoses and aldohexoses have half-lives within an order of magnitude of these values, as do 2-deoxyribose, ribose 5-phosphate, and ribose 2,4-bisphosphate. These results suggest that the backbone of the first genetic material could not have contained ribose or other sugars because of their instability.

Recovery of Pasteurella multocida from experimentally-exposed freshwater snails

We determined how long Pasteurella multocida could survive in experimentally-exposed freshwater snails. Physa virginea were collected from the Sacramento National Wildlife Refuge, Glenn County, California (USA), an enzootic site for avian cholera. Exposure to water containing up to 10(7) P. multocida per ml did not produce observable changes or mortality in snails. A minimum of 84 P. multocida per snail was necessary for detection among the normal snail bacterial flora. When snails were exposed to P. multocida in vials containing 10(7) bacteria per ml, P. multocida was detected for up to 72 hours in snails. When uninoculated snails were placed in aquaria containing 10(6) P. multocida per ml, P. multocida was not detected within the snails; further, P. multocida was detected in the water for only 24 hours at this level. Based on these results, we propose that P. virginea is not an effective reservoir for P. multocida.

An efficient prebiotic synthesis of cytosine and uracil

In contrast to the purines, the routes that have been proposed for the prebiotic synthesis of pyrimidines from simple precursors give only low yields. Cytosine can be synthesized from cyanoacetylene and cyanate; the former precursor is produced from a spark discharge in a CH4/N2 mixture and is an abundant interstellar molecule. But this reaction requires relatively high concentrations of cyanate (> 0.1 M), which are unlikely to occur in aqueous media as cyanate is hydrolysed rapidly to CO2 and NH3. An alternative route that has been explored is the reaction of cyanoacetaldehyde (formed by hydrolysis of cyanoacetylene) with urea. But at low concentrations of urea, this reaction produces no detectable quantities of cytosine. Here we show that in concentrated urea solution--such as might have been found in an evaporating lagoon or in pools on drying beaches on the early Earth--cyanoacetaldehyde reacts to form cytosine in yields of 30-50%, from which uracil can be formed by hydrolysis. These reactions provide a plausible route to the pyrimidine bases required in the RNA world.

The stability of amino acids at submarine hydrothermal vent temperatures

It has been postulated that amino acid stability at hydrothermal vent temperatures is controlled by a metastable thermodynamic equilibrium rather than by kinetics. Experiments reported here demonstrate that the amino acids are irreversibly destroyed by heating at 240 degrees C and that quasi-equilibrium calculations give misleading descriptions of the experimental observations. Equilibrium thermodynamic calculations are not applicable to organic compounds under high-temperature submarine vent conditions.