Clinical application of the Biotrack 516 system for determination of theophylline by a turbidimetric latex agglutination inhibition reaction

Reaction of bromophenol blue with proteins results in an enhanced resonance light scattering at 334 nm. Based on this, a new quantitative determination method for proteins in the aqueous solution is established. This assay is characterized by high sensitivity (0.34-18.7 microg/ml), short reaction time (>2 min), and simplicity (a one-step assay). Due to protein-to-protein variability, this method gave results higher than that of the bromocresol green assay in detection of human serum albumin.     

Reversed passive latex agglutination assay for detection of toxigenic Corynebacterium diphtheriae

A reversed passive latex agglutination (RPLA) assay for determining the toxigenicity of Corynebacterium diphtheriae is presented. Rabbit antitoxin antiserum was raised by using commercially available diphtheria toxoid. This antiserum reacted with the diphtheria toxin when the culture supernatant was assayed by Western blotting, and it did not cross-react with other extracellular antigens. Affinity-purified antibodies for latex sensitization were obtained by using a Hi Trap N-hydroxysuccinimide-activated column. Demonstration of toxin in five of seven clinical isolates was in accordance with the PCR assay and the Vero cell cytotoxicity test. Culture of the bacteria for 6 h was sufficient for toxin production, and an additional 6 h was needed to observe latex agglutination. Therefore, diphtheria toxin can be detected in 12 h by this method. The lowest concentration of diphtheria toxin detectable by the RPLA assay was about 5 ng/ml. The RPLA assay can provide a convenient and reliable method for laboratories involved in the identification of toxinogenic corynebacteria.     

A rapid direct latex agglutination test for HCG (author's transl)

792 urine samples from pregnant patients were investigated by a direct latex agglutination test (LA). Results of this slide test were compared with data derived from a haemagglutination inhibition test (HI). The same results were obtained by both pregnancy tests in 768 (96.7%) out of 792 urine samples. The pregnancy test was negative in 20 cases (2.5%) as assessed by HI, whereas a positive result was recorded with the LA in these cases. Seven were cases of early pregnancy and control tests performed by HI became positive at a later date. The remaining 13 (1.6%) of these patients belonged to a group of pathological pregnancies (missed abortion, threatened abortion, incomplete abortion and ectopic pregnancy). The slide test is more sensitive (1000 I.U. HCG/1 urine) than the HI (1500 I.U.HCG/1 urine). No false positive results were obtained with the LA; false negative results were registered in only 0.5% of cases. A semi-quantitative HCG determination was performed by means of the tube and slide test in 29 urine samples. However, agreement of the data by the two methods was relatively poor, owing to the higher sensitivity of the LA, with consequent inaccurate assessment of HCG excretion. Not much importance need be attached to this finding in view of the diagnostic and prognostic deficiencies of HCG determination. The new slide test was found to be a rapid, simple and accurate pregnancy test.     

Rapid detection of infectious mononucleosis-associated heterophile antibodies by a novel immunochromatographic assay and a latex agglutination test

A novel immunochromatographic assay, the CARDS O.S. MONO test (Pacific Biotech, San Diego, Calif.), and a latex agglutination test, the Infectious Mononucleosis Kit (Unipath Ltd., Hampshire, United Kingdom) were compared with the Paul-Bunnell-Davidsohn test. Of the 957 serum specimens studied, 78 were positive and 879 were negative by the Paul-Bunnell-Davidsohn test. After discrepancies were resolved by determining Epstein-Barr virus serology, the sensitivities of the CARDS O.S. MONO test and the Infectious Mononucleosis Kit were 91.0 and 96.2%, respectively, and both tests had a specificity and a positive predictive value of 100% and a negative predictive value and overall agreement of greater than 99%. The results show that both tests can accurately detect infectious mononucleosis-associated heterophile antibodies.     

A rapid latex agglutination assay for the detection of penicillin-binding protein 2'

A simple and rapid slide latex agglutination assay was developed to detect penicillin-binding protein 2' (PBP2') from isolates of staphylococi. PBP2' present in the membranes of methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant coagulase negative staphylococci (MRCNS) was rapidly extracted by alkaline treatment and, by combining with a slide agglutination reaction using latex particles sensitized with monoclonal antibodies raised against it, PBP2' could be detected from a single loopful of cells taken from agar plates not containing beta-lactum antibiotics within 15 min. In a study of clinical isolates previously characterized as either MRSA or methicillin-susceptible Staphylococcus aureus (MSSA) by antibiotic susceptibility testing, 231 specimens of 232 MRSA were PBP2' positive by latex agglutination, and the 87 specimens of MSSA were all negative. One specimen identified as MRSA by susceptibility testing but PBP2' negative by latex agglutination was confirmed as mecA gene negative by PCR. This simple and rapid slide latex reagent should be useful in clinical diagnostics.     

False-negative cerebrospinal fluid cryptococcal latex agglutination tests for patients with culture-positive cryptococcal meningitis

Three cases of false-negative cerebrospinal fluid latex agglutination test results for patients with culture-positive cryptococcal meningitis are reported. False-negative results occurred in settings of low cryptococcal antigen concentrations in cerebrospinal fluid and were dependent on the latex agglutination test kit used. Investigation of each case revealed that prozone phenomena or interference from bound antibody or protein could not account for the false-negative results.     

Exfoliative toxin detection using reversed passive latex agglutination: clinical and epidemiologic applications

A rapid and simple method for detecting exfoliative toxin serotypes A and B from clinical isolates has been developed as a test kit (EXT-RPLA; Denka Seiken Co. Ltd., Niigata, Japan). This method is based on reversed passive latex agglutination. The detection limit of the EXT-RPLA observed for purified exfoliative toxin serotypes A and B was 1 ng/ml. We evaluated the clinical and epidemiologic uses of the EXT-RPLA. A total of 381 isolates of Staphylococcus aureus, 292 from various clinical specimens and 89 from the skin of dermatologic patients, were studied. The EXT-RPLA detected 19 exfoliative toxin producers, including 16 serotype A producers and 3 serotype B producers, but no double producers. The sensitivity and specificity of the EXT-RPLA were confirmed by the newborn mouse bioassay and a PCR assay for the structural genes for exfoliative toxin serotypes A and B (eta and etb, respectively). The overall positivity rate of exfoliative toxin producers was 5.0% (19 of 381), including 16 serotype A isolates and 3 serotype B isolates. Of the 89 isolates from the skin of dermatologic patients, 12 (13.5%) were positive for exfoliative toxin production. Only 2 (1.3%) of the 153 methicillin-resistant S. aureus isolates produced exfoliative toxin, while 17 (7.5%) of the 228 methicillin-sensitive isolates produced exfoliative toxin. The EXT-RPLA assay is a simple and reliable method for detecting exfoliative toxin, and we recommend its use for the rapid diagnosis of staphylococcal scalded skin syndrome. We also recommend its use for detection of this syndrome so that effective control measures can be taken against the spread of this syndrome.     

消解乳化-火焰原子吸收光谱法测定胶乳中镁和锌

用消解 乳化法处理胶乳样品 ,即先用浓硝酸消解样品 ,以乙醇 甲基异丁基酮混合溶剂溶解消解产物 ,然后用乳化剂Tween -80乳化成乳浊液。建立了快速测定胶乳中镁、锌的FAAS法。以工作曲线法测定。对样品处理方法、消解产物的溶解性质、乳化剂的选择、试液与空白溶液粘度的一致性、线性范围、干扰及检出限进行了考察。测定结果与灰化法一致 ,相对标准偏差小于 3.2 % ,镁、锌的加标回收率分别为 95.85 %～ 10 0 .0 %和 99.0 %～ 10 3. 0 %。方法简便     

Evaluation of latex agglutination for detecting chlamydial antibody activity in psittacine bird sera by comparison with direct complement fixation

Two patients presented with unilateral ciliary block angle closure glaucoma and bilateral pseudoexfoliation (PSX) syndrome and were treated successfully with posterior sclerotomy (one case), extracapsular cataract extraction and posterior chamber lens implantation. None of the eyes had undergone previous ocular surgery except Nd: YAG-laser iridotomy. Axial lengths as measured with A-scan ultrasonography were 22.48 mm and 24.30 mm. During follow-up of 5 and 12 months, intraocular pressure was well controlled without antiglaucoma medication in both patients. We suspect that the well-known changes of the zonula origin at the ciliary epithelium in PSX syndrome lead to anterior subluxation of the lens with consecutive ciliary block angle closure glaucoma. Ciliary block angle closure glaucoma seems to be another serious complication in PSX syndrome. Therefore, miotics should probably be used with care in PSX eyes with signs of zonular alterations because they may trigger this mechanism.     

Use of the protective antigen of Erysipelothrix rhusiopathiae in the enzyme-linked immunosorbent assay and latex agglutination

To establish a safe and convenient serodiagnostic method for swine erysipelas, a purified protective protein antigen of Erysipelothrix rhusiopathiae, which included a large amount of protective protein (64 kDa protein), was used for enzyme-linked immunosorbent assay (ELISA) and the latex agglutination (LA) test. In the ELISA, the antisera to four different serovars (1a, 2, 5 and 20) of E. rhusiopathiae exhibit a positive reaction, while antisera to other species of bacteria (Listeria monocytogenes, Staphylococcus aureus, Streptococcus suis, Rhodococcus equi and Corynebacterium pseudotuberculosis) exhibit a negative reaction. In the LA test, the antisera to three different serovars (1a, 2 and 5) of E. rhusiopathiae reacted with P64-sensitized latex beads, while the antiserum to serovar 20 (2553 strain) did not. Moreover, the antisera to other species of bacteria (Listeria monocytogenes, Staphylococcus aureus, Streptococcus suis, Rhodococcus equi and Corynebacterium pseudotuberculosis) did not in this test. Comparing the results of the growth agglutination (GA), ELISA and LA tests of 284 swine sera, there was a high degree of correlation among the results. The detection of anti-E. rhusiopathiae antibodies in the GA, ELISA and LA tests were compared using sera from pigs immunized with P64, alkaline extract (AE) and live-cell vaccine (LV). In all three tests, anti-E. rhusiopathiae antibodies could be detected 1 week after immunization. The serum antibody titre as determined by the LA test increased moderately, as did that by the GA test, while that determined by ELISA increased rapidly. These results suggested that ELISA could be used to monitor changes in anti-E. rhusiopathiae antibody titre and the LA test could be used in the screening test for swine erysipelas.     

Subserogrouping of 49 Legionella pneumophila serogroup 1 strains with monoclonal antibodies by slide latex agglutination method and its usefulness for epidemiologic study

Pulmonary lung-function testing plays an important role in surveillance programs for occupational respiratory disorders. Spirometry is usually utilized by applying preset cut-off values to discriminate between healthy and unhealthy subjects. This article demonstrates the usefulness of decision analysis techniques to arrive at an optimal diagnosis. The diagnostic performance of FEV1 and FEV1/FVC was evaluated by relative operating characteristics curves (ROCs) applied to data of a cohort gathered in 1965. Both parameters showed quite similar ROCs, with a maximal sensitivity of 40% at a specificity of 95% relative to the physician's diagnosis of respiratory disorder. The area under the curves was. 75 for both FEV1 and FEV1/FVC, illustrating that misclassification of 25% of the subjects is likely to occur. Regarding the consequences of a false-positive and a false-negative decision as of equal importance, the 5%-percentile (FEV1 residual less than -1.2 L) would be the optimal cut-off. An FEV1 residual below the lower 5%-percentile was six times more likely to appear in subjects with chronic nonspecific lung disease (CNSLD) than in subjects without. The post-test probability of CNSLD was three to four times the pre-test probability. In occupational or public health practice, however, false-positive results need to be avoided, even at the expense of a higher false-negative rate. In those situations, a more rigid cut-off between normal and abnormal values may be warranted.     

The mechanism of inhibition of neuronal activity by opiates in the spinal cord of cat

Extra- and intracellular recordings from motoneurones, interneurones and dorsal horn neurones (laminae 4 and 5) were obtained from the lumbar segments (L6-L7) of spinalised (Th 9/10) or pentobarbital-anaesthetised and anaemically decorticated cats. In the majority of spinal neurones microelectrophoretically applied morphine and levorphanol reversibly depressed spontaneous as well as stimulus-evoked and L-glutamate- or acetylcholine-induced activity. There is evidence that opiates block L-glutamate-induced depolarisations by impairing the Na+-influx triggered at the postsynaptic membrane. These depressant effects of opiates could be antagonised by naloxone, and, except in a few cases, were not associated with hyperpolarisation of the cell. Dextrorphan, the D+ enantiomer of levorphanol, displayed no such depressant actions, indicating that stereospecific receptors mediate the depressant effects of opiates. Phoretically applied atropine, procaine and Ca2+ ions have anti-glutamate and anti-acetylcholine actions similar to opiates, but these actions were not antagonised by naloxone. The hyperpolarising effect of glycine was not influenced at dose levels of opiates sufficient to suppress depolarisation induced by L-glutamate or acetylcholine. Microelectrophoretically administered morphine and levorphanol slowed the rate of rise of mono- and polysynaptic EPSPs by a naloxone-antagonisable mechanism at dose levels where almost no alteration in spike shape was detectable. Increased doses of morphine and levorphanol reduced the amplitude of IPSPs and completely blocked or reduced the amplitude of both direct- and antidromically-evoked spikes. These effects of increased doses of opiates were not antagonised by naloxone. Intravenous injection of 2 mg/kg of morphine or 20 mug/kg of Fentanyl mimicked the suppression of spontaneous and evoked neuronal activity observed after phoretic administration. This depressant action of systemically applied opiates could be transiently antagonised by phoretic administration of naloxone. The results are discussed with respect to a stereospecific action of opiates at a postsynaptic receptive site in the spinal cord.     

Detection of enterotoxigenic Clostridium perfringens in food and fecal samples with a duplex PCR and the slide latex agglutination test

A duplex PCR procedure was evaluated for the detection of Clostridium perfringens in food and biological samples and for the identification of enterotoxigenic strains. This method uses two sets of primers which amplify in the same reaction two different DNA fragments simultaneously: the 283-bp C. perfringens phospholipase C gene fragment and the 426-bp enterotoxin gene fragment. Internal primers within the two primer sets confirmed the specificity of the method by DNA-DNA hybridization with the PCR products. No cross-reaction was observed with other Clostridium species or with other bacteria routinely found in food. The detection level was approximately 10(5) C. perfringens cells per g of stool or food sample. When overnight enrichment culture was used, 10 C. perfringens cells per g was detected in 57 artificially contaminated food samples. The duplex PCR is a rapid, sensitive, and reliable method for the detection and identification of enterotoxigenic C. perfringens strains in food samples. A slide latex agglutination test was also evaluated as a rapid, simple technique for the detection of C. perfringens enterotoxin in stool samples.     

Verification and determination of opiates in the urine and blood with thin-layer chromatography followed by densitometry in fatal cases of drug abuse

This article shows that in oxygen transported and antioxidative systems considerable changes take place during dynamic of adaptation to oxygen deficiency of inhaled air (every day 4 hours stay of animals in barochamber under pO2 7.45 kPa during 12 days). Single influence of hypoxic factor induced in erythrocytes peripheral blood increasing of haemoglobin affinity to oxygen, decreasing SOD and catalase activity on the background of increasing of malon aldehyde level. On 12-th day of adaptation of animals contents of TBA-active products in erythrocytes is saved on high level, activity of antioxidative enzymes is approached to original meanings, haemoglobin affinity to oxygen is decreased in comparison with control. Detected increasing content of creatine in erythrocytes during dynamic of rat adaptation to hypoxic hypoxia witnessed about erythropoiesis activation and quickened exit out of marrow young forms of erythrocytes.     

Comparison of an enzyme immunoassay and a latex agglutination system for the diagnosis of invasive aspergillosis in bone marrow transplant recipients

The performance of two Aspergillus antigenemia systems, the sandwich enzyme-linked immunosorbent assay (ELISA), Platelia Aspergillus test, and the latex agglutination (LA), Pastorex Aspergillus test, in the diagnosis of invasive aspergillosis were compared by testing 364 serum samples from 22 bone marrow transplant (BMT) recipients. Sensitivity and specificity for the ELISA test were 60% and 82% respectively, vs 40% and 94% for the LA test. In the two patients found positive with both methods, the ELISA test became positive earlier than the LA test or remained positive after the LA test had become negative. These results encourage further evaluation of the Platelia Aspergillus test, to assess its role in the management of invasive aspergillosis in BMT patients.     

The effects of opiates and opioid neuropeptides on mosquito hemocytes

The effects of morphine, Met-enkephalin, and its synthetic analogue DAMA on the hemocytes of Culex pipiens mosquitoes were examined in vitro. Morphine caused the cells to round up and decrease in area. Met-enkephalin caused the cells to become ameboid and increase in area. This effect was accentuated with the addition of the neutral endopeptidase blocker phosphoramidon. DAMA caused a similar but greater enhancement of immune activation which was blocked by the opiate antagonist, naloxone. These results were similar to those seen in other invertebrate hemocytes.