Magnetic phase transition in a nanonetwork of solid 3He in aerogel

When immersed in liquid 3He, the nanometer strands of aerogel are coated with a thin layer of solid 3He, forming a network of irregular nanotubes. Owing to its high purity and weak interactions, this system is ideal for studying fundamental processes. We report the first experiments on solid 3He in aerogel at ultralow temperatures, cooled by direct adiabatic demagnetization. Simultaneous nuclear magnetic susceptibility and heat capacity measurements indicate a magnetic phase transition.

Influence on energy kinetics and histology of different preservation solutions seen during cold ischemia in the liver

BACKGROUND AND PURPOSE

Cold flush preservation prolongs tissue viability during ischemia. However, there is little understanding of the effects of various preservation fluids on events during this period. A study of cold ischemia in rat livers was undertaken to compare biochemical and histological changes over time, using three preservation solutions: University of Wisconsin (UW), histidine-tryptophan-ketoglutarate (HTK), and Leeds solution (LS) under development at our institution. Leeds solution is a phosphate-based sucrose solution that like UW contains the impermeant lactobionate and the metabolite allopurinol (1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one) which acts as a competitive inhibitor of xanthine oxidase, stopping the breakdown of hypoxanthine to xanthine by oxidizing it to alloxanthine, inhibiting both the conversion of hypoxanthine to xanthine and the conversion of xanthine to uric acid.

MATERIALS AND METHODS

At various time points, samples were analyzed for adenosine triphospate (ATP) and metabolites by high-performance liquid chromatography as well as for histological changes.

RESULTS

In all livers, ATP, ADP, and AMP degraded over 4 hours. In UW and LS groups, degradation beyond hypoxanthine was halted, and it continued in the HTK group. This blockade led to a significant reduction in the accumulation of xanthine and uric acid. Histological analysis showed protected architecture and maintenance of reticulin scaffolds in the UW and LS groups, whereas tissue breakdown was seen from earlier time points in the HTK group. Additionally, throughout ischemia, signs of pathological injury were more pronounced with UW- than with LS-preserved tissue.

CONCLUSIONS

These results implied that cold ischemia in the liver is characterized by dynamic biochemical changes coincident with pathological injury which are initiated from the time of organ perfusion and influenced by the choice of the perfusion fluid. Allopurinol in UW and LS appears to be critical. We hypothesized that it may also affect the degree of subsequent reperfusion injury. The data supported the assertion that LS offerred improved preservation over UW, adding to the impetus to shorten ischemic times in clinical transplantation.

Addition of adenosine to University of Wisconsin solution: does it help?

Adenosine Triphosphate (ATP) precursors are sometimes added to preservation solutions in the belief that once the organ is reperfused, these precursors will build up ATP rapidly, returning it to its original metabolic state. This work studied ATP and metabolites during preservation of the rat liver using University of Wisconsin solution (UW), which contains adenosine, versus histidine tryptophan ketaglutarate solution a new phosphate-based preservation solution, or leeds solution (LS), which is under development at our institution (neither of the latter 2 contains adenosine). Tissue samples of perfused livers were analyzed for ATP and metabolites by high-performance liquid chromatography. UW did initially show the expected significant difference in overall adenosine levels, but the advantage had disappeared by 4 hours. At no time did UW show significantly higher levels of ATP; this was not seen following adenosine addition to LS. Only in living donor transplants where the cold ischemic time is short may there be some advantage to the addition of adenosine.

"The government must not dictate": rural-urban migrants' perceptions of Zimbabwe's land resettlement programme

"In the 1990s analyses of [Zimbabwe's land resettlement program] by both supporters and critics of land reform have generally been negative. Yet there is evidence that resettled people themselves have made real welfare and income gains. Strong support for the programme was also expressed by a large sample of rural-urban migrants in Harare in 1994. Their views, reported in this article, showed an appreciation of most aspects of the academic and policy debates, but clearly also tended towards the perception that redistribution of land in Zimbabwe is a moral issue."

Deck-chairs: putting a finger on the problem, rather than in it

Although often portrayed as something of a joke, injuries sustained in the setting-up and use of deck-chairs can have fairly serious consequences. Six patients who sustained finger injuries in some of London's Royal Parks during the Summer are presented together with data from the Department of Trade and Industry suggesting that, taken throughout the country as a whole, large numbers of injuries may be occurring. Notably, four of our patients were foreign tourists who may be less familiar with the traditional wooden folding deck-chair. Surprisingly no British Standards Institute (BSI) guidelines exist relating to deck-chair safety. These finger injuries can have marked morbidity if they involve victims who depend upon manual dexterity in their work or hobbies.

'Bats below the bridge': is a potentially treatable neurovascular disorder being underdiagnosed in accident and emergency departments?

Basilar artery thrombosis (BATS) is a progressive disorder which may present with fluctuating neurological signs of varying degrees of severity. Unless the diagnosis is considered, the confused young patient may be thought to be under the influence of drugs or to be psychologically ill, and indeed the Munchausen syndrome may be considered. The more elderly patient may be diagnosed simply as having had a cerebrovascular accident. This paper presents the cases of three patients admitted through the accident and emergency (A&E) department of St Mary's Hospital, London with basilar artery thrombosis during a 6-month period. All these patients demonstrated the classic triad for this syndrome of: (1) long tract neurological signs, (2) impaired conscious level, and (3) complex ocular signs. The concern is that, for patients with more subtle signs, a diagnosis of BATS may not be considered, and a neurological opinion may be thus delayed and no treatment with anticoagulants or thrombolytic agents would be given. Two of the three patients were treated with anticoagulants and improved, while in the third patients anticoagulation was judged inappropriate and the patients died from progression of the disease with respiratory complications.

A cluster of severe postoperative bleeding following open heart surgery

OBJECTIVE

To investigate a cluster of postoperative bleeding following open heart surgery.

DESIGN

A cohort and case/control study.

SETTING

Palo Alto Veterans Administration Medical Center, Palo Alto, California.

PARTICIPANTS

Six (21.4%) of 28 patients undergoing open heart surgery who developed severe, nonsurgical, postoperative bleeding from July 1 through August 30, 1988 (outbreak period). All case-patients had chest tube drainage of greater than or equal to 1000 ml within 4 hours of surgery but did not have identifiable bleeding vessel(s) on exploration.

RESULTS

Upon comparison of the pre-outbreak (January 1986 through June 1988) and the outbreak period, a significant increase was found in the incidence of postoperative nonsurgical bleeding (5/440 versus 6/28, p = .0006), but not of postoperative surgical bleeding (8/440 versus 0/28, p = 1.0). Of all patients undergoing open heart surgery during the outbreak period, case patients were found to be older (67.8 versus 60.6, p = .02) and to have received a larger volume of hetastarch (HES), a synthetic colloidal plasma-volume expander (mean = 19.4 ml/kg versus 14.1 ml/kg, p = .02).

CONCLUSIONS

We conclude that the use of large volumes of HES during surgery in the elderly open heart surgery patient may increase the risk for severe, nonsurgical postoperative bleeding, probably caused by alterations of the coagulation system. As the incidence of open heart surgery increases among the elderly, surgeons and anesthesiologists should be alert to possible adverse reactions from exposures not associated with adverse reactions in younger patients.

Efficient fermentation of Pinus sp. acid hydrolysates by an ethanologenic strain of Escherichia coli

Process conditions for the acid hydrolysis of pine hemicellulose and cellulose have been described which provide a biocompatible sugar solution. By using an improved strain of recombinant Escherichia coli, strain KO11, hydrolysates supplemented with yeast extract and tryptone nutrients were converted to ethanol with an efficiency of 85% to over 100% on the basis of monomer sugar content (approximately 72 g/liter) and with the production of 35 g of ethanol per liter in 48 h. In the process described, approximately 347 liters of ethanol could be produced per dry metric ton of lignocellulose.

Bacteriologic and endotoxin analysis of salvaged blood used in autologous transfusions during cardiac operations

Autologous blood transfusion is a common method of reducing the need for heterologous blood transfusion during cardiac operations. Recently we investigated an outbreak of severe, nonsurgical postoperative bleeding among patients undergoing heart operations and receiving intraoperative transfusion of blood from a cell conservation device (Cell Saver System, Haemonetics Corp., Braintree, Mass.). As a result of this investigation, we conducted a prospective study to determine if bacterial or endotoxin contamination of the blood collected in the Cell Saver System and used for reinfusion during heart operations contributes to postoperative bleeding complications. Patients' blood samples were collected immediately before operation, at the end of cardiopulmonary bypass, 1 hour postoperatively, and from the Cell Saver System. All blood samples were cultured for bacteria, and all plasma samples were assayed for endotoxin. Preoperatively all patients having heart operations were without signs of infection, 33 of 37 blood cultures taken were negative, and none of the plasma samples had detectable endotoxin. After discontinuance of cardiopulmonary bypass but before delivery of blood from the Cell Saver System, bacteria and endotoxin were detected in 11 of 36 (30.6%) and five of 35 (14.3%) of the patients' blood samples, respectively. The blood aspirated from the open chest and collected by the Cell Saver System was culture positive in 30 of 31 (96.8%) samples, and seven of 29 (24.1%) contained endotoxin. One of 28 blood samples collected 1 hour postoperatively was culture positive, and five of 25 samples contained endotoxin. Of 61 total microorganisms isolated, 50 (82%) were coagulase-negative staphylococci, four (6.6%) aerobic diphtheroids, five (8.2%) anaerobic "diphtheroids" (Propionibacterium acnes), and two (3.2%) gram-negative bacilli. Plasma endotoxin concentrations ranged from 10 to 765 pg/ml. No signs of endotoxemia or unusual bleeding were observed intraoperatively or postoperatively in any of the 38 patients. Although blood collected in the Cell Saver System and used for reinfusion during heart operations often was contaminated with gram-positive bacterial commensals of the skin and low concentrations of endotoxin, no adverse effects were noted in the patients.

Evaluation of a computerised system for medical records in an accident and emergency department

This paper deals with the impact of the installation of a computerised record and data handling system in an urban Accident and Emergency department. This system became fully operational on the 14th of August, 1989 and replaced the previous manual method of administration. The new system allows 'real time' handling of patient details and generation of letters to both specialists and general practitioners. Audit of the department workload and data generation for research are improved. The current situation is described as well as potential benefits and constraints of the system.

Code teams and the review of cardiac arrests

A new system for responding to Codes, or resuscitations of patients with cardiopulmonary arrest, was implemented at St Luke's Medical Center, Milwaukee. A teaching program was begun to establish the Advanced Cardiac Life Support (ACLS) guidelines as the standard of care. A task force defined the composition of the Code team and was then designated the Code Review Committee, meeting monthly to review all Codes. Indicators for review were established. Code review is followed by a letter to the physician Code team leader and/or registered nurse. Data for 18 months, still preliminary, show improved compliance with indicators for documentation and for adherence to ACLS guidelines.

Comparison of paired-ion liquid chromatographic method with AOAC fluorometric and microbiological methods for riboflavin determination in selected foods

A paired-ion liquid chromatographic (LC) technique coupled with fluorometric detection to determine riboflavin in various food matrices is described. Chromatograms of many foods showed 2 peaks of interest due to presence of riboflavin and flavin mononucleotide (FMN). Relatively high levels of FMN were found in raw beef, corned beef, chicken liver, and canned mushrooms. When riboflavin and FMN contents were summed, LC values were comparable to those obtained by the AOAC standard procedures. The LC technique was sensitive, rapid, and simple, yielding a mean standard deviation of 3.1% which was comparable to the AOAC fluorometric method (3.0%) and better than the AOAC microbiological assay (9.6%). Mean spike recoveries were 91.8% for LC compared to 90.5% and 89.6% for the AOAC fluorometric and microbiological methods, respectively.

Acid proteases of vitreal macrophages

Macrophage invasion in rabbits was elicited by intravitreal injection of trypan blue or latex particles; as after hemorrhage, there are two periods of macrophage invasion with elevated numbers of intravitreal cells at three and 21 days. Release of acid proteolytic activity by macrophages from both time periods was assayed by analysis of the cell-free vitreal supernate and of the medium of cultured cells. Lysates of freshly-isolated macrophages and of adjacent ocular tissues were also analyzed. Although some quantitative differences were observed, a similar profile of acid proteolytic activity toward hemoglobin at pH 2.0 to 6.5 was found in the vitreal supernate and in the cells from both periods. Most macrophages invade via the ciliary processes and during invasion elevated levels of acid proteolytic activity were found in this tissue. Although some macrophages transmigrate the retina, normal acid protease levels were low in sensory retina and essentially unchanged during macrophage invasion. Protease inhibitor studies indicated the presence of carboxyl, cysteinyl, serine and metallo proteases in macrophages and in macrophage-containing tissues. The inhibitor data also suggested qualitative differences in acid protease activities in macrophages from the two invasive periods. During macrophage invasion vitreal pH was reduced from 7.4 to 6.2 suggesting that some macrophage-derived acid proteases may be active in that compartment. Thus, although the phagocytic activity of macrophages aids vitreal clearing, action of macrophage proteases may also contribute to vitreal pathology by cleavage of vitreal proteins.

Group V Chalcogenide Complexes of Boron Trihalides

The preparation of the complexes BX3•R3PY (X=Cl, Br, I; R=Me, Ph, cyclohexyl; Y=S, Se) is reported. The corresponding BF3 adducts could not be isolated. The infrared spectra for all complexes are presented as well as the n.m.r. spectra for the methyl adducts. The shifts in ν(P—Y) upon co-ordination are amongst the largest ever reported for these ligands when they function as non-bridging species, and are in fact comparable to shifts observed in bridging situations. The spectral data are consistent with an increase in the B—Y bond strength as the atomic weight of X increases.

Trimethylgermanium Nitrate

The spectroscopic and solution properties of trimethylgermanium nitrate have been determined and compared with those of other known Group IV alkyl nitrates. The vibrational spectra show that the nitrato group is covalently bound to the germanium atom in a unidentate manner. Ultraviolet spectra and conductivity measurements indicate that the compound behaves as a 1:1 electrolyte in water and dimethylsulfoxide, but is a non-electrolyte in methyl cyanide, nitromethane, and ethyl acetate. Attempts to prepare methylgermanium trinitrate are also described.

Dimethylgermanium Dinitrate

Dimethylgermanium dinitrate has been prepared by the reaction of dimethylgermanium dichloride and nitrogen pentoxide in carbon tetrachloride. The properties of this compound have been investigated and compared with those of other known Group IVA alkyl nitrates. The vibrational spectra show that the nitrato groups are covalently bound to the germanium in a unidentate manner. Ultraviolet spectra and conductivity measurements indicate that the compound behaves as a 1:2 electrolyte in water and dimethyl sulfoxide but is a non-electrolyte in methyl cyanide, nitromethane, and ethyl acetate. The complexes Me2Ge(NO3)2•py and Me2Ge(NO3)2•2,2′dipy have been prepared and the infrared spectra of these compounds indicate considerable weakening of the germanium-nitrato bonds.

Methyltin trinitrate and a comparison of its properties with other methyltin nitrates

Methyltin trinitrate has been prepared by the reaction of dinitrogen pentoxide on methyltin trichloride in carbon tetrachloride, followed by sublimation in vacuo at 60 °C. Conductivities and ultraviolet spectra of methyltin trinitrate in several solvents are reported. Vibrational spectra indicate that the three nitrato groups are all bonded in the same bidentate manner and the reactivity of the compound towards aliphatic hydrocarbons and diethyl ether shows that the compound is chemically similar to tin(IV) nitrate. The vibrational spectrum of methyltin trinitrate is compared with those for trimethyltin nitrate, dimethyltin dinitrate, and tin(IV) nitrate. Nuclear magnetic resonance spectra have been determined for the series MenSn(NO3)4−n (n = 1,…, 4), and a comparison of the 117Sn– and 119Sn–proton coupling constants for the series has been made showing that the tin atom becomes more electron deficient and has more s character in its bonding orbital to carbon as n decreases. The pyridine adduct MeSn(NO3)3•2py has been prepared and the infrared spectrum of this compound indicates that the nitrate groups are unidentate.

Diethyl lead dinitrate

The reaction, at 0 °C, between tetra-ethyl lead and dinitrogen tetroxide in both nitromethane and diethyl ether as solvents has been studied. The product in both solvents is always diethyl lead dinitrate, the properties of which have been investigated and compared with both dimethyl tin dinitrate and triethyl lead nitrate. The infrared spectrum is consistent with covalent unidentate nitrate groups, while molecular weight and conductivity measurements indicate that the compound behaves essentially as a 1:2 electrolyte in water and dimethyl sulfoxide. Decomposition of diethyl lead dinitrate in solution and in the solid state is discussed with the aid of ultraviolet spectroscopy and thermogravimetric analysis.