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At least 1,675 records · Page 93Linked to original sources
PubMed1976

Automated enzymatic determination of L-lactate in serum, with use of a miniature centrifugal analyzer.

We describe an automated enzymatic reaction-rate method for spectrophotometric determination of lactate in serum with a miniature centrifugal analyzer. The L(+) -lactate is selectively oxidized in the presence of lactate dehydrogenase (EC 1.1.1.27) and NAD+ to form NADH, which is measured from its absorption. Reaction rates are determined automatically, and unknown concentrations are calculated from a computer-generated calibration curve with aqueous lithium lactate standards. Lactate concentrations in the range 0.32-1.6 mug/4 mul (80-400 mg/liter) of sample were determined with relative errors and coefficient of variation of 4.8%. Analytical recovery of lactate added to pooled serum was 89-112% (average, 101%). Comparison with a kit ("Rapid Lactate") method gave a correlation coefficient squared of 0.979 over a concentration range of 39-779 mg/liter.

Autoanalysis↗
PubMed1999

Chlorpromazine inhibits miniature GABAergic currents by reducing the binding and by increasing the unbinding rate of GABAA receptors.

Recent studies have emphasized that nonequilibrium conditions of postsynaptic GABAA receptor (GABAAR) activation is a key factor in shaping the time course of IPSCs (Puia et al., 1994; Jones and Westbrook, 1995). Such nonequilibrium, resulting from extremely fast agonist time course, may affect the interaction between pharmacological agents and postsynaptic GABAARs. In the present study we found that chlorpromazine (CPZ), a widely used antipsychotic drug known to interfere with several ligand and voltage-gated channels, reduces the amplitude and accelerates the decay of miniature IPSCs (mIPSCs). A good qualitative reproduction of the effects of CPZ on mIPSCs was obtained when mIPSCs were mimicked by responses to ultrafast GABA applications to excised patches. Our experimental data and model simulations indicate that CPZ affects mIPSCs by decreasing the binding (kon) and by increasing the unbinding (koff) rates of GABAARs. Because of reduction of kon by CPZ, the binding reaction becomes rate-limiting, and agonist exposure of GABAARs during mIPSC is too short to activate the receptors to the same extent as in control conditions. The increase in unbinding rate is implicated as the mechanism underlying the acceleration of mIPSC decaying phase. The effect of CPZ on GABAAR binding rate, resulting in slower onset of GABA-evoked currents, provides a tool to estimate the speed of synaptic clearance of GABA. Moreover, the onset kinetics of recorded responses allowed the estimate the peak synaptic GABA concentration.

Animals↗
PubMed1976

[Quantitative morphological studies on various organs of the MINI-LEWE miniature swine].

Quantitative morphological studies were conducted into 27 MINI-LEWE miniature pigs, with the view to exploring the correlations between a number of organs (liver, kidneys, heart, spleen, pancreas, adrenal gland, and thyroid gland) and parameters (live weight, age, weight at slaughter, length from snout to tail root, and internal length of slaughter body). The results are presented in 12 ilustrations and five tables.

Adrenal Glands↗
PubMed1976

Male pseudohermaphroditism, cryptorchism, and Sertoli cell neoplasia in three miniature Schnauzers.

A syndrome of male pseudohermaphroditism, cryptorchidism, and testicular neoplasia was diagnosed in 3 Miniature Schnauzers. The dogs had clinical signs of hyperestrogenism and were either unilateral or bilateral cryptorchids. At surgery, it was discovered that the dogs were male pseudohermaphrodites, having intra-abdominal testes containing Sertoli cell tumors and uteri that had undergone endometrial cystic hyperplasia.

Animals↗
PubMed1976

Follicular and reticular arrangements of medullary cells in the adrenal gland of Göttingen Miniature pigs.

In the adrenal gland of Göttingen miniature pigs adrenaline- and noradrenaline-storing cells showed follicular and reticular arrangements, which were not observed in the domesticated form (German land race) of Sus scrofa. Chromaffin cells could contain vacuoles, which were sometimes connected with follicles and filled with a material indistinguishable from that in follicles. Coated and smooth vesicles with contents of various electron densities were particularly abundant around vacuoles and Golgi areas, which were often found to be closely associated. Chromaffin cells were unconspicious with respect to other ultrastructural details. A comparison was made between this mode of arrangement and that seen after intense stimulation of the adrenal medulla using insulin, reserpine, or vinblastine. The possible significance of this particular pattern of arrangement of chromaffin cells is discussed.

Adrenal Medulla↗
PubMed1999

Entire course and distinct phases of day-lasting depression of miniature EPSC amplitudes in cultured Purkinje neurons.

The cerebellar long-term depression (LTD) is the long-lasting reduction of transmission efficacy at the granule neuron-Purkinje neuron (G-P) synapses and is a candidate mechanism for the motor learning. Despite extensive studies on its induction and expression mechanisms, it has not been known how long the LTD lasts. The LTD is accompanied by the decrease in the postsynaptic responsiveness to glutamate, the transmitter at G-P synapses. Therefore, during the LTD, the amplitude of miniature EPSCs (mEPSCs) at G-P synapses should decrease. We studied the depression of mEPSC amplitudes (DME) as a possible contributing factor for the LTD and found that the conditioning treatment of cultured cerebellar neurons with 50 mM K(+) and 100 microM glutamate, an analogous condition used to induce the LTD, induced the long-lasting DME. The mEPSC amplitudes recovered to the original level 48 hr after the 5 min conditioning treatment. Changing the duration of the conditioning revealed that the DME consisted of two distinct phases: the early phase lasting for a few hours and the late phase for >1 d. The latter was distinguished from the former by its requirement of prolonged conditioning treatment and syntheses of mRNA and protein for the induction. There were critical periods for mRNA and protein syntheses. The critical period for protein synthesis was much longer than that for mRNA synthesis. These results demonstrate that the DME lasts for 1-2 d and that it consists of two phases, whose induction and maintenance mechanisms are distinct.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2000

The effect of carbachol and alpha-bungarotoxin on the frequency of miniature endplate potentials at the frog neuromuscular junction.

The effects of an acetylcholine analogue, carbachol (CCh), and a purified irreversible nicotinic antagonist, -bungarotoxin (BTX), on the frequency of the miniature endplate potentials (mEPPs) at the neuromuscular junction of the frog were tested at 20 and 10 C. CCh (5 10-6 m) reduced the frequency of mEPPs to about 60 %; this reduction was not affected by 1 10-7 g ml-1 BTX. BTX also reversibly decreased the mEPP frequency by 40 %, but not in the presence of CCh or in Ringer solution with 0 or 8 mM Ca2+. The present data show that BTX, which inhibits a class of nicotinic ACh receptors, does not block the decrease of mEPP frequency evoked by CCh and can itself suppress the frequency of spontaneous quantal release.

Animals↗
PubMed2000

Effects of trap design and CO2 presentation on the measurement of adult mosquito abundance using Centers for Disease Control-style miniature light traps.

Centers for Disease Control miniature light traps augmented with CO2 provide an effective method of monitoring Culex abundance and may provide a useful supplement to New Jersey light traps used by the California Mosquito Surveillance Program. To assist in standardizing sampling protocols, the present research compared the catch of adult mosquitoes collected using 4 trap designs and 3 CO2 presentation methods. When augmented with dry ice, the Arbovirus Field Station (AFS) trap (consisting of a 3-in. fan mounted into a white polyvinyl chloride pipe and operated without a light source or rain shield) collected as many or more Culex females than similar traps purchased from John W. Hock and American Biophysics, or a trap with a 4.25-in. 2-bladed fan constructed by the Orange County Vector Control District (similar to the Encephalitis Virus Surveillance model distributed by Bioquip). Few blooded or gravid females and males were collected, indicating that CO2 released from the dry ice and not light probably was the primary attractant. Catch of Culex tarsalis females in traps baited with CO2 released at 0.5-1.5 liters/min from gas cylinders was significantly greater than in traps baited with dry ice, even though the CO2 release rates from the dry ice at dusk probably were comparable to that released from the cylinders and averaged 0.4-0).5 liters/min for the night. Traps baited with 0.5 liters/ min of CO2 gas released in 15 3- or 2-sec bursts per hour collected the fewest mosquitoes. In all experiments, trap location effects were significant and accounted for as much variability in catch size as trap design or CO2 presentation. Sampling efficiency of all trap designs or CO2 presentations were consistent over time, space, and different levels of mosquito abundance.

Animals↗
PubMed2000

Effects of ammodytin L on miniature and endplate potentials in neuromuscular junction of frog m. cutaneus pectoris.

Neurotoxic effects of ammodytin L (AtnL), a potent phospholipase A2 homologue, was studied in frog neuromuscular preparation m. cutaneous pectoris by measuring the influence of the toxin on the amplitude and the frequency of miniature and endplate potentials (MEPPs, EPPs). AtnL, in 100 nM concentration, significantly increases spontaneous quantal acetylcholine release from the motor nerve endings, observed as the increase in MEPPs frequency. At 100 nM or higher concentration the toxin decreases EPPs amplitude and the membrane potential (MP) simultaneously. No significant effect of AtnL on EPPs was observed at any concentration bellow 100 nM. Our results indicate that in frog AtnL shows the typical myotoxic effects, but it also exerts presynaptic effects.

Animals↗
PubMed2000

Miniature single-particle immunoassay for prostate-specific antigen in serum using recombinant Fab fragments.

BACKGROUND: Quantitative, miniaturized nucleic acid assays and immunoassays can be developed with single microparticles, microfluorometric detection, and intrinsically fluorescent lanthanide chelates in a multiple assay format to decrease reagent consumption, cost, and assay time. We used recombinant Fab fragments to capture and detect free and total prostate-specific antigen (PSA) from serum in a submicroliter volume single-particle immunoassay. METHODS: Genetically engineered thiol-Fab or thiolated monoclonal antibodies (mAbs) were covalently attached onto uniformly sized 60-microm maleimide-activated microparticles. Free and total PSA were detected with europium- or terbium-labeled Fab fragments on a single microparticle using a microfluorometer in a time-resolved mode. RESULTS: The detection limit of the free- and total-PSA assays (mean + 3 SD of zero calibrator) was 0.35 microg/L, with a total volume of 330 nL per particle. An excellent correlation was found in microparticle and microtiter-well assays for 21 serum samples: slopes for free and total PSA were 1.06+/-0.03 and 1.03+/-0.02, respectively (S(y|x) = 0.084 and 0.057 microg/L), with intercepts of 0.013+/-0.018 and 0.013+/-0.017 microg/L (R>0.99). Furthermore, the particle-immobilized Fab fragment had a PSA binding capacity 1.5-fold higher than the intact mAb capacity on a single microparticle. Capacity, kinetics, and sensitivity of the Fab fragment and intact mAb assays in the microparticle and microtiter well formats are discussed. CONCLUSIONS: With site-specific (cysteine tail) covalent attachment of Fab fragments on a microparticle, subattomole amounts of PSA can be detected quantitatively.

Antibodies, Monoclonal↗
PubMed1975

Intestinal intubation in the unanaesthetised miniature pig: technique for sampling and measurement of gut length per fistulam.

Techniques have been developed and are described for the surgical preparation of long-term jejunal and ileal fistulas in miniature swine and for the management and restraint of the fistulated swine for laboratory investigation. An apparatus and procedure is described for per fistulam intubation which allows sampling of intestinal contents at any site in the jejuno-ileum of the unanaesthetised pig. A comparison between in vivo intestinal length, measured by intubation between jejunal and ileal fistulas, and post mortem intestinal length demonstrates that, as in the human, the intestine becomes remarkably elongated after death.

Anesthesia↗
PubMed1975

Coagulation-time determination with automatic multivariable analysis, by use of a miniature centrifugal fast analyzer.

Use of a miniature Centrifugal Fast Analyzer for the parallel photometric monitoring of the coagulation process is shown to have a number of advantages. These include a choice of optical modes, virtually simultaneous initiation and observation of the coagulation process for a number of patient-plasma samples and an on-board control sample, small sample and reagent volume requirements, and automatic determination of a number of diagnostically useful variables (including relative fibrinogen content) from the data recorded in a single run. Also, the system is shown to give results that correlate well with those obtained by conventional techniques for determination of prothrombin time.

Autoanalysis↗
PubMed2001

Miniaturization of enantioselective gas chromatography.

In the context of the Titan Chiral Organics Explorer (TCOE) mission, the theoretical and practical aspects of the miniaturization of enantioselective gas chromatography are discussed. The use of short columns (0.5-10 m) with a conventional inside diameter of 250 microm is proposed. The inside diameter should be increased for vacuum-assisted GC-MS using a restrictor at the inlet of the capillary. The feasibility of cryogenic enantioselective gas chromatography is demonstrated. The hitherto elusive use of chiral mobile phase additives in enantioselective gas chromatography is proposed.

Journal Article↗
PubMed2002

Activity deprivation reduces miniature IPSC amplitude by decreasing the number of postsynaptic GABA(A) receptors clustered at neocortical synapses.

Maintaining the proper balance between excitation and inhibition is necessary to prevent cortical circuits from either falling silent or generating epileptiform activity. One mechanism through which cortical networks maintain this balance is through the activity-dependent regulation of inhibition, but whether this is achieved primarily through changes in synapse number or synaptic strength is not clear. Previously, we found that 2 d of activity deprivation increased the amplitude of miniature EPSCs (mEPSCs) onto cultured visual cortical pyramidal neurons. Here we find that this same manipulation decreases the amplitude of mIPSCs. This occurs with no change in single-channel conductance but is accompanied by a reduction in the average number of channels open during the mIPSC peak and a reduction in the intensity of staining for GABA(A) receptors (GABA(A)Rs) at postsynaptic sites. In addition, the number of synaptic sites that express detectable levels of GABA(A)Rs was decreased by approximately 50% after activity blockade, although there was no reduction in the total number of presynaptic contacts. These data suggest that activity deprivation reduces cortical inhibition by reducing both the number of GABA(A)Rs clustered at synaptic sites and the number of functional inhibitory synapses. Because excitatory and inhibitory synaptic currents are regulated in opposite directions by activity blockade, these data suggest that the balance between excitation and inhibition is dynamically regulated by ongoing activity.

Animals↗
PubMed2002

[Discussing the current situation of tuberculosis case-finding by mass miniature radiography in Japan].

The system of tuberculosis (TB) case-finding by mass miniature radiography (MMR) was established and expanded for almost all Japanese citizens in the 1950s. And, as stipulated by the TB Prevention Law, periodic mass screenings for schools, inhabitants, employees and institutions have been carried out. Among those aged over 25 years, the proportion of people screened by MMR was estimated to be 60.3%. This means that about 54 million people aged over 25 years are receiving medical service with MMR every year. However, the detection rates of TB cases by MMR have declined markedly compared with those in 1950s. As of 1998, the detection rate was 0.03 per 1,000 for school children and students, 0.06 per 1,000 for employees, and 0.16 per 1,000 for inhabitants. The proportion of cases detected by MMR among newly notified TB cases was 12.8% in 1998, and this ratio has been almost constant for the last 10 years. This ratio was greater among young adult TB cases. Approximately 20% of notified TB cases aged 20-39 years were detected by MMR for employees. Although the purpose of MMR is to find the cases before discharging TB bacilli, 35.1% of the cases were bacteriologically confirmed, and this proportion was greater among elderly TB cases. The Japan Anti-Tuberculosis Association (JATA) has been carrying out MMR for a long time. Eight selected branches of JATA that has been doing high quality case-finding reported 228 TB cases out of 965,440 inhabitants aged over 40 years examined by MMR in 1996. Based on these results, the cost per TB case detected by MMR was calculated. The cost was 4.4 millions yen (yen) per case for all forms of TB, yen 2.3 millions for male, yen 8.4 millions for female, yen 7.3 millions for those aged 40-49 years and yen 1.8 millions for those aged over 80 years. TB detection rate by MMR for inhabitants was correlated with TB incidence rate in various areas, and based on this correlation, the cost was calculated for various incidence rates. For all forms of TB, the cost was yen 4.0 millions per case for an incidence rate of 30 per 100,000, and yen 6.7 millions for an incidence rate of 20 per 100,000. MMR is not economically cost-effective even among elderly people and in areas with incidence rate less than 50 per 100,000, because the medical expense for a TB patient treated under hospitalization for 2 months and outpatient's clinic for 4 months is approximately yen 0.9 millions in 1996. The decision making in continuation or abolition or limitation of MMR should be discussed from a wide range of cost-effectiveness analyses as well as from the view of public health service and willingness of people. For the purpose of decision making, this study provides the detection rates; the costs stratified by sex, age and incidence; and the proportion of cases detected by MMR among newly notified TB cases by age-group and bacteriological status.

Adult↗
PubMed1999

Influence of Age on the Electrocardiographic Waves in Taiwanese Lan-Yu Miniature Pigs.

The purpose of the study reported here was to determine baseline information of the electrocardiogram (ECG) and the influence of age on cardiac function in Taiwanese Lan-Yu (TLY) miniature pigs. Non-anesthetized TLY minipigs (from birth to 6 months of age) were placed on a webbed stanchion, simulating a standing position, for acquisition of an ECG, using six limb leads (I, II, III, aVR, aVL, and aVF), with each as a single-channel ECG recorder. The P and T waves obtained from leads I, III, and aVL were useful in determining the subtle cardiac changes during maturation of TLY minipigs. Interestingly, changes in the QT interval analyzed from all 6 leads were almost indistinguishable. Shortening of the QT interval was induced (p < 0.05) between days 1 and 7 of postnatal life. The QT interval lengthened to a steady state at day 60, and paralleled pigs' physical maturation. The longer QT interval was conversely correlated to heart rate as pigs matured. In the QRS complex interval, only lead aVR was significantly decreased at day 7 (p < 0.05). Further changes in the QRS interval from day 21 were not observed in any lead. Because the duration of the ventricular complex represents the period required for the excitation front to reach the terminals of the Purkinje fibers in the ventricular myocardium, the increase in QRS interval observed within 21 days of birth could be attributed to an increase in the thickness of ventricular myocardium. The data suggest that cardiac maturation was achieved at 60 days of age, although the body weight of minipigs continued to increase beyond 60 days of age. Because the body weight of these newly developed TLY minipigs can be maintained within 25 to 30 kg at one year of age and their major ECG findings did not significantly differ from those of domestic pigs and humans, they may be useful as a model for cardiovascular and pharmacologic research. The similarity of ECG profiles between pigs and humans also was evaluated.

Journal Article↗
PubMed1975

Heart biochemical responses in miniature swine subjected to +Gz acceleration.

Myocardial biochemical systems which are sensitive to hypoxic and ischemic insult were studied to determine the possible etiology of ventricular endocardial hemorrhage in miniature swine following +GZ stress. Unanesthetized animals were subjected to a single, 120-s +9 GZ acceleration. Approximately 1-2 h following +GZ exposure, the animals were anesthetized and the hearts removed for analyses. Acceleration exposure resulted in the loss of acid phosphatase enzyme activity from the membrane-bound lysosomal fraction with concomitant increased activity in the soluble fraction. This suggests that lysosomal membrane integrity had been disrupted. Mitochondrial preparations from +GZ-stressed hearts exhibited marked increases in active respiratory rate and rate of calcium transport while oxidative phosphorylation efficiency was unchanged. The results clearly indicate that +GZ acceleration is capable of altering myocardial biochemical systems. However, the results tend to suggest that these alterations in cellular processes may be mediated by influences other than hypoxia or ischemia.

Acid Phosphatase↗