Magnetic separation of general solid particles realised by a permanent magnet.

Most existing solids are categorised as diamagnetic or weak paramagnetic materials. The possibility of magnetic motion has not been intensively considered for these materials. Here, we demonstrate for the first time that ensembles of heterogeneous particles (diamagnetic bismuth, diamond and graphite particles, as well as two paramagnetic olivines) can be dynamically separated into five fractions by the low field produced by neodymium (NdFeB) magnets during short-duration microgravity (µg). This result is in contrast to the generally accepted notion that ordinary solid materials are magnetically inert. The materials of the separated particles are identified by their magnetic susceptibility (χ), which is determined from the translating velocity. The potential of this approach as an analytical technique is comparable to that of chromatography separation because the extraction of new solid phases from a heterogeneous grain ensemble will lead to important discoveries about inorganic materials. The method is applicable for the separation of the precious samples such as lunar soils and/or the Hayabusa particles recovered from the asteroids, because even micron-order grains can be thoroughly separated without sample-loss.

Magnetic alignment experiment of fine graphite-crystals dispersed in He gas oriented to study alignment of crystalline-axes of nano-sized non-magnetic particles.

The ensemble of nano-sized crystals is expected to attain additional physical properties when preferential alignments of certain crystal-axes are achieved by a magnetic field. The reduction of temperature T may realize alignment even if the mole number of the particle N and the diamagnetic anisotropy per mole (Deltachi)(DIA) are considerably small for the nano-sized diamagnetic oxides, since alignment proceeds by the balance between the energy of rotational Brownian motion and field-induced anisotropy energy. Alignment of various basic inorganic oxides such as gypsum, quartz, forsterite, KDP or calcite, having a size of 20 nm diameter, is expected to occur by a field intensity of approximately 50 T at T = 10 K; this intensity is presently available at a high magnetic-field laboratory. It is expected that the magnetic alignment of nano-sized particles can be observed by dispersing the particles in He gas, as achieved recently for micron-sized graphite crystals; a cryogenic liquid cannot be used as a dispersing medium. Measured (Deltachi)(DIA) values accumulated for basic inorganic-oxides are explained quantitatively by assuming that individual bonding-orbital composing the material possesses a constant amount of diamagnetic anisotropy; hence the majority of diamagnetic nano-sized insulators are expected to show magnetic alignment at finite field intensity.

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.

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.

Molecular cloning of cDNAs encoding bovine and human lactoperoxidase.

Peptide sequences obtained from cyanogen bromide fragments of bovine lactoperoxidase (bLPO) were used to design oligonucleotide probes for library screening. These probes were used to screen a cDNA library constructed from bovine mammary tissue. Three overlapping clones were obtained, the longest of which (T3) contained a reading frame of 712 amino acid residues. The encoded amino acid sequence was homologous to those recently reported for myelo-, thyro-, and eosinophil peroxidases. Two possible amino termini of the mature enzyme were identified, and the predicted mature protein matched previous molecular weight estimates of 78,500. Of eight bovine tissues tested, transcription of T3 sequences were detected in mammary tissue only. Using the bLPO cDNA as a probe, a single hybridizing clone was found in a human mammary gland cDNA library. This clone (M1) encoded the carboxy-terminal 324 residues of a peroxidase distinct from the other three known human peroxidases, and was closely related to bLPO. This result confirms the presence of at least one distinct lactoperoxidase in humans.

Rapid diagnosis of chlamydial infections with the MicroTrak direct test.

A direct test on clinical specimens, using fluorescein-labeled monoclonal antibodies, for Chlamydia trachomatis (MicroTrak [Syva Co.]) was evaluated for the rapid diagnosis of chlamydial infections. Asymptomatic females attending pregnancy or planned parenthood clinics were tested by the direct test and by a cell culture method. Of 401 paired, endocervical specimens, 398 (99.3%) gave identical direct and culture results. The overall sensitivity of the direct test was 96.3% (26 of 27), and the specificity was 99.5% (372 of 374) as compared with that of culture. More than four-fifths of the direct smears were read within ca. 2 min. In this study population, the performance of the direct specimen test was comparable to that of cell culture methods. Rapid turnaround time and elimination of the need for cell culture make the direct test a practical method for the specific diagnosis of chlamydial infections.

Evaluation of Gonochek-II as a rapid identification system for pathogenic Neisseria species.

The Gonochek-II test kit (E-Y Laboratories, San Mateo, Calif.) may be used to rapidly identify (within 30 min) Neisseria gonorrhoeae, Neisseria meningitidis, Neisseria lactamica, and Branhamella catarrhalis. The kit consists of oxidase swabs, chromogenic substrates, and EY-20 reagent (diazonium salt derivative). A beta-lactamase tube is also included. Fifty-two clinical isolates were tested from cervical (22 isolates), urethral (13), throat (11), rectal (5), and urine (1) sources. All strains were oxidase-positive, gram-negative diplococci isolated on Thayer-Mayer plates incubated at 35 degrees C in 5% CO2 for 18 to 24 h. Each strain was tested by Gonochek-II, RapID NH (Innovative Diagnostics, Decatur, Ga.), and conventional rapid carbohydrate utilization. Forty-four isolates of N. gonorrhoeae and six N. meningitidis were identified. Only two isolates tested (4%) were identified as species other than these two. Gonochek-II outperformed all other methods for identification of N. gonorrhoeae from cervical and urethral areas. N. meningitidis strains were correctly identified in all cases. Ease and rapidity of the procedure, coupled with a small inoculum requirement and reliable results, led us to favor Gonochek-II for routine identification of pathogenic Neisseria species.

Aberrant strain of group G Neisseria meningitidis.

A glucose-negative group B strain of Neisseria meningitidis isolated from a meningitis case is described. A brief review of Neisseria identification procedures is also presented.

Unidentified gram-negative rod infection. A new disease of man.

A Gram-negative bacillus that defies identification was isolated from blood cultures of 17 patients with fever. Fifteen patients were male adults, and 14 patients had underlying diseases, including previous splenectomy in five, which impair host defenses against infection. Illnesses occurred in the summer and autumn in 14 cases and had been recently preceded by dog bites in 10 cases. Clincal syndromes included cellulitis in seven cases, primary bacteremia without localization in four, purulent meningitis in four, and endocarditis in three. Three patients died. The organism grows slowly on blood or chocolate agar in 10% CO, is oxidase- and catalase-positive, and is negative for nitrate reduction, indole production, and urease. It produces acid from glucose, lactose, and maltose. These features distinguish it from all previously described and classified bacteria. Furthermore, the epidemiologic features of the patients suggest that this organism is an opportunistic invader and may have an animal reservoir in nature.

An immunofluorescent procedure for detection of Hb F (gamma chain) in peripheral erythrocytes.

A direct fluorescent method for the detection of the gamma chain of Hb F in erythrocytes is described. The method is easier to interpret and more sensitive than the classic Kleihauer-Betke procedure.