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PubMed2003

Effect of dietary moisture and sodium content on urine composition and calcium oxalate relative supersaturation in healthy miniature schnauzers and labrador retrievers.

The aim of this series of studies was to evaluate two possible feeding strategies as methods for reducing the risk of calcium oxalate (CaOx) formation in two breeds of healthy dog. The studies compared the effect of dietary moisture (Study 1) and dietary sodium (Na), (Study 2) on urine composition of labrador retrievers (LR) and miniature schnauzers (MS). A nutritionally complete dry dog food was fed to 16 dogs (eight LR, eight MS; Study 1) and 15 dogs (seven LR, eight MS; Study 2) for 24 days (Study 1), or 36 days (Study 2). The dogs were fed the diet alone (7% moisture, 0.06 g Na/100 kcal), or supplemented with deionised water to 73% moisture (Study 1), or dietary Na, to deliver 0.20 or 0.30 g Na per 100 kcal (Study 2). Urine pH, volume, specific gravity, and concentrations of 12 analytes were measured for each dog. Urinary relative supersaturations (RSS) with CaOx were calculated from these values. The effects of supplemental Na or water were established using t tests (Study 1) or analysis of variance, and multiple range tests (least significant difference) (Study 2); P<0.05 was considered significant. Increasing dietary moisture significantly increased total moisture intake (P=0.001), and reduced urine specific gravity (P=0.003), urinary oxalate concentration (P=0.04), and CaOx relative supersaturation (P=0.04) in the MS. Urinary parameters remained unchanged in the LR, indicating that feeding a high moisture diet may reduce the risk of CaOx formation in high-risk breeds. Increasing dietary Na led to production of urine with a significantly lower CaOx RSS in both breeds, indicating that sodium supplementation to dry diet formats may reduce the risk of CaOx formation. These feeding strategies should be considered when evaluating methods for preventing CaOx formation within high-risk groups.

Animal Feed↗
PubMed1999

Agonistic and antagonistic toxic effects observed with miniaturized growth and luminescence inhibition assays.

Kinetic data recordings with miniaturized growth and luminescence inhibition assays with prokaryotes (Pseudomonas putida and Vibrio fischeri) reveal typical sample and species specific growth and light emission patterns respectively. Growth inhibiting influences, based on toxicokinetic and toxicodynamic sample specificities appeared in each growth phase. Agonistic and antagonistic effects of combinations of heavy metals like Cd2+, Hg2+ and Pb2+ and other compounds were easily recognized after accurate curve discussions. Some of the influences that made it more difficult to evaluate toxicological results only by restriction on EC values (effective concentrations) were investigated. The findings may lead to a more comprehensive interpretation of toxicological data and a presumption on the composition of complex samples in terms of screening investigations. Therefore, the conclusions demonstrate the possibilities and limits of kinetic data recordings in chronic and acute toxicity testing.

Freezing↗
PubMed1977

A miniature syringe pump for continuous administration of drugs and hormones: The Mill Hill infuser.

A miniature syringe pump has been developed for intravenous or subcutaneous infusion of the many drugs and hormones which produce better therapeutic responses when continuously delivered at a controlled rate than by repeated separate injections. The infuser uses disposable plastic syringes and is designed for precise tamper-proof delivery of 2 ml/24 h or 2 ml/8 h with quartz-crystal control, unaffected bt the dose-rate can be precisely determined by prescribing solutions of appropriate strength.

Hormones↗
PubMed2000

Performance of a miniaturized bioreactor in space flight: microtechnology at the service of space biology.

We describe here the performance and the use of microtechnology in a miniaturized bioreactor developed for the continuous cultivation of yeast cells, Saccharomyces cerevisiae, in microgravity. This bioreactor has been used on two Shuttle missions, where its functionality was successfully demonstrated. In the future, bioreactors will become a key element for long-term experiments, and would also be applied in the cultivation of mammalian cells or tissues for medical applications.

Journal Article↗
PubMed1993

Miniature crystal models of cellulose polymorphs and other carbohydrates.

Miniature crystal models of cellulose and other carbohydrates were evaluated with the molecular mechanics program MM3. The models consisted of groups of 24 to 32 monosaccharide residues, with the models of mono- and disaccharides based on well-established, single-crystal work. Structures of the cellulose forms and cellotetraose were based on published work using fibre diffraction methods. A structure for the single-chain I alpha cellulose unit cell was also tested. A dielectric constant of about 4 was best for this type of work. Calculated intra- and intermolecular energy for glucose agreed with literature values for the heat of combustion. Cellulose II had the lowest calculated energy for a cellulose form, followed by I alpha, cellulose III(I), ramie I, IV(II) and IV(I). Optimization of cellulose IV caused larger mean atomic movements from the original crystallographic positions than the other cellulose forms, and cellotetraose had larger movements than any of the other structures. Lattice energies for the cellulose forms were about 20 kcal/mol of glucose residues, with a dominant van der Waals component.

Carbohydrates↗
PubMed2000

Miniature stereo radio transmitter for simultaneous recording of multiple single-neuron signals from behaving owls.

Wireless radiotelemetric transmission of neuronal activity is an elegant technique to study brain-behavior interaction in unrestrained animals. In the current study, a miniature FM-stereo radio transmitter is described that permitted simultaneous recordings from two microelectrodes in behaving barn owls. Input from two independent channels is multiplexed to form a stereo composite signal that modulates a radio frequency carrier. The high quality of broadcasted extracellular signals enabled separation of single units based on differences in spike waveforms. Recording several single cells from different electrodes allows the possibility of investigating correlations between small, distributed neuronal ensembles. Multi-channel radiotelemetry that meets the demands of modern electrophysiology might open a new perspective for combined behavioral/neurophysiological approaches in freely-behaving animals.

Action Potentials↗
PubMed2001

Miniature motorized microdrive and commutator system for chronic neural recording in small animals.

The use of chronically implanted electrodes for neural recordings in small, freely behaving animals poses several unique technical challenges. Because of the need for an extremely lightweight apparatus, chronic recording technology has been limited to manually operated microdrives, despite the advantage of motorized manipulators for positioning electrodes. Here we describe a motorized, miniature chronically implantable microdrive for independently positioning three electrodes in the brain. The electrodes are controlled remotely, avoiding the need to disturb the animal during electrode positioning. The microdrive is approximately 6 mm in diameter, 17 mm high and weighs only 1.5 g, including the headstage preamplifier. Use of the motorized microdrive has produced a ten-fold increase in our data yield compared to those experiments done using a manually operated drive. In addition, we are able to record from multiple single neurons in the behaving animal with signal quality comparable to that seen in a head-fixed anesthetized animal. We also describe a motorized commutator that actively tracks animal rotation based on a measurement of torque in the tether.

Action Potentials↗
PubMed1998

Using miniature sensor coils for simultaneous measurement of orientation and position of small, fast-moving animals.

A system is described that measures, with a sampling frequency of 1 kHz, the orientation and position of a blowfly (Calliphora vicina) flying in a volume of 0.4 x 0.4 x 0.4 m3. Orientation is measured with a typical accuracy of 0.5 degrees, and position with a typical accuracy of 1 mm. This is accomplished by producing a time-varying magnetic field with three orthogonal pairs of field coils, driven sinusoidally at frequencies of 50, 68, and 86 kHz, respectively. Each pair induces a voltage at the corresponding frequency in each of three miniature orthogonal sensor coils mounted on the animal. The sensor coils are connected via thin (12-microm) wires to a set of nine lock-in amplifiers, each locking to one of the three field frequencies. Two of the pairs of field coils produce approximately homogeneous magnetic fields, which are necessary for reconstructing the orientation of the animal. The third pair produces a gradient field, which is necessary for reconstructing the position of the animal. Both sensor coils and leads are light enough (0.8-1.6 mg for three sensor coils of 40-80 windings, and 6.7 mg/m for the leads, causing a maximal load of approximately 5.7 mg) not to hinder normal flight of the animal (typical weight 80 mg). In general, the system can be used for high-speed recordings of head, eye or limb movements, where a wire connection is possible, but the mechanical load on the moving parts needs to be very small.

Animals↗
PubMed1999

Evaluation of quantal neurosecretion from evoked and miniature postsynaptic responses by deconvolution method.

A new deconvolution algorithm has been developed for evaluation of quantal content and its variability at high-output synapses. The algorithm derives the distribution of the number of neurosecretory quanta released in a trial (M) from the measured sizes of evoked postsynaptic responses. The deconvolution employs the distribution of quantal sizes obtained by measuring sizes of miniature postsynaptic responses. The distribution of quantal content M is derived by ridge regression method from the distributions of sizes of the responses and of quantal sizes. The deconvolution method was applied to postsynaptic responses from the excitory innervation of lobster dactyl opener muscle obtained by focal extracellular recordings. The obtained solution (distribution of M) had six to eight components and was stable. The method was tested by the analysis of simulated multiquantal responses. For the simulated responses, the ridge regression solution reproduced the imposed distribution of M within the limits of the calculated confidence intervals. To further test the algorithm, the distribution of M at a low-output synapse was obtained both by deconvolution method and by the method of direct quantal counts. The results of these two methods were found to be in a very good agreement.

Action Potentials↗
PubMed1999

Miniature carrier with six independently moveable electrodes for recording of multiple single-units in the cerebellar cortex of awake rats.

Ensemble recording in cerebellar cortex of awake rats presents unique methodological challenges not encountered when recording from the cerebral cortex or from deep brain structures with more homogeneous cell populations. Compared to the cerebral cortex, removal of dura over the cerebellum evokes pronounced swelling, and insertion of multiple closely spaced electrodes in the cerebellar cortex causes considerable dimpling (Welsh JP, Schwartz C. Multielectrode recording from the cerebellum. In: Nicolelis MAL, editor. Methods for Neural Ensemble Recordings, CRC Methods in Neuroscience Series. Boca Raton, FL: CRC Press LLC, 1999, pp. 79-100). Also, a repetitious and well-defined neural circuit characterizes the cerebellar cortex across its entire surface. With conventional multi-electrode methods, such as chronically implanted bundles or arrays of microwires, the risk of disrupting the cerebellar cytoarchitecture is high. In most conventional multi-electrode systems, electrodes have rather low impedance and cannot be moved independently after implantation. These limitations make proper unit isolation, necessary to identify each of the recorded cerebellar units, very difficult. We designed a lightweight (14 g), miniature (base plate: 19 x 23 mm; total height: 16 mm) multi-electrode system to allow for the chronic implantation of six independently moveable sharp electrodes with high impedance, in the cerebellar cortex. The six electrodes are arranged in a 2 x 3 matrix (inter-electrode distance: 0.6 mm). At any time after the implantation the vertical position of each individual electrode can be adjusted by screwing spring-loaded electrode heads up or down. The system preserves the integrity of the cerebellar cytoarchitecture, and enables easy isolation and identification of individual cerebellar units in awake, freely moving rats.

Animals↗
PubMed1999

Developmental study of miniature IPSCs of CA3 hippocampal cells: modulation by midazolam.

Maturation of GABAA/benzodiazepine receptors is associated with changes in their subunit composition. We have investigated whether these changes are accompanied by a developmental modification in the kinetic properties of miniature IPSCs (mIPSCs) and sensitivity to midazolam, a benzodiazepine agonist. In the presence of TTX (10 microM) and excitatory amino acid antagonists, AP5 (50 microM) and CNQX (50 microM), we whole-cell recorded mIPSCs in CA3 cells of hippocampal slices of adult and young (4-8 days) rats. mIPSCs were mediated by GABAA receptors as they were suppressed by bicuculline (10 microM). In both the adult and young rats, mIPSCs were similar in amplitude and kinetic properties. However, the mIPSCs frequency markedly increased with age from 4+/-3 Hz in the young rats to 20+/-9 Hz in the adult rats. In both age groups, midazolam (0.01 microM(-10) microM) and pentobarbital (30 microM) did not affect the amplitude, frequency and rise time of the mIPSCs but they increased to a similar extent their decay time constant. The current responses to isoguvacine, a GABAA agonist, were potentiated by 0.1 microM midazolam in both age groups. It is concluded that in immature and adult rats, synaptic GABAA receptors of CA3 were not different in their kinetic properties and sensitivity to midazolam.

2-Amino-5-phosphonovalerate↗
PubMed2001

The role of desensitisation in decay time of miniature endplate currents in frogs Rana ridibunda and Rana temporaria.

A new comparative characteristic of endplate microphysiology has been introduced. It is the feasibility of receptors to become desensitised as demonstrated on two frog species, Rana temporaria and Rana ridibunda: the decay times (tau(MEPC)) of single quantum miniature endplate currents (MEPCs) in the sartorius muscles of both species were about 1 ms and were not affected by the desensitisation-promoting agent proadifen when AChE was active. However, when the desensitisation was induced by anticholinesterase neostigmine and promoted by proadifen, the prolongation of tau(MEPC) from 1 ms was almost twice as great in Rana temporaria (tau(MEPC) = 4.4 ms) than in Rana ridibunda (tau(MEPC) = 3.1). This indicates that desensitisation reduces the number of available receptors and lowers the number of available ACh molecules for repetitive binding by trapping them by desensitised, high-affinity receptors significantly more in Rana ridibunda than in Rana temporaria. The application of proadifen, a promoter of desensitisation, decreased the prolongation of MEPCs in both species, but this shortening was more rapid in Rana ridibunda than in Rana temporaria. It is concluded that the desensitisation-induced reduction in the density, and the number of postsynaptic receptors is significantly higher at Rana ridibunda than in Rana temporaria endplates.

Animals↗
PubMed2001

How do miniature pigs discriminate between people?. Discrimination between people wearing coveralls of the same colour.

Seven experiments were conducted on four miniature pigs to determine: (1) whether the pigs can discriminate between people wearing the same coloured clothing; (2) what cues they rely on if they could discriminate. For 2 weeks before the experiments began, the pigs were conditioned in a Y-maze to receive raisins from the rewarder wearing dark blue coveralls. They were then given the opportunity to choose the rewarder or non-rewarder in these experiments. Each session consisted of 20 trials. Successful discrimination was that the pig chose the rewarder at least 15 times in 20 trials (P<0.05: by chi(2)-test). In Experiment 1, both rewarder and non-rewarder wore dark blue coveralls. By 20 sessions, all pigs successfully identified the rewarder. In Experiment 2: (1) both wore coveralls of the same new colours or (2) one of them wore coveralls of new colours. They significantly preferred the rewarder even though the rewarder and/or non-rewarder wore coveralls of new colours. In Experiment 3, both wore dark blue coveralls but olfactory cues were obscured and auditory cues were not given. The pigs were able to identify the rewarder successfully irrespective of changing auditory and olfactory cues. In Experiment 4, both wore dark blue coveralls but covered part of their face and body in different ways. The correct response rate decreased when a part of the face and the whole body of the rewarder and non-rewarder were covered. In Experiment 5, both wore dark blue coveralls and changed their apparent body size by shifting sitting position. The correct response rate increased as the difference in body size between the experimenters increased. In Experiment 6, the distance between the experimenters and the pig was increased by 30cm increments. The correct response rate of each pig decreased as the experimenters receded from the pig, but performance varied among the pigs. In Experiment 7, the light intensity of the experimental room was reduced from 550 to 80lx and then to 20lx. The correct response rate of each pig decreased with the reduction in light intensity, but all the pigs discriminated the rewarder from the non-rewarder significantly even at 20lx.In conclusion, the pigs were able to discriminate between people wearing coveralls of the same colour after sufficient reinforcement. These results indicate that pigs are capable of using visual cues to discriminate between people.

Journal Article↗
PubMed1999

Fractal dimensions in the occurrence of miniature end-plate potential in a vertebrate neuromuscular junction.

1. Occurrence of miniature endplate potentials (MEPP) in the sartorius muscle of Rana catesbiana in high Mg2+ Ringer solution were observed in standard intracellular recording. Intervals and amplitudes of sequentially occurring MEPP were registered and analyzed. 2. Interval histograms of a time series of MEPP showed exponential-like pattern as reported in the classical study by Fatt and Katz (1952). The cumulative distribution of the intervals plotted in logarithmic axes showed two distinct phases. In shorter intervals (< 1s), curve along exponential decay was observed, and in longer intervals (> or = 1s) linear decay can be seen. The latter power-law relation gave dimensions of 4.111 +/- 0.812 (mean and S.D.). Self-similarity in longer range implies a time-scale invariant nature and may suggest fractal nature in restoration process of synaptic vesicles, while exponential decay in the short time interval range implies random release of transmitter packet from the readily releasable pool. 3. Fluctuation of amplitudes in sequentially occurred MEPP were analyzed according to Higuchi's cumulative route-length analysis. The estimates for sequential amplitude curve showed the power-law relation in a logarithmic plot whose inclination (= D) estimated with linear regression analysis was 1.996 +/- 0.007 (mean and S.D.). This results indicate that fluctuation in the amplitude of MEPP shows possible maximum complexity as a graphic curve in 2-D plane. Similar result was obtained for fluctuation of intervals of successively occurring MEPP.

Algorithms↗
PubMed2002

The Autosow raised miniature swine as a model for assessing the effects of dietary soy trypsin inhibitor.

Toxicological effects of dietary soy trypsin inhibitor (TI) were assessed in male miniature swine, a model chosen for its similarities to human digestive physiology and anatomy. The TI preparation was extracted from defatted raw soy flour. From 1 through 5 weeks of age, piglets were automatically fed either a TI liquid diet [Autosow TI group (ASTI)] or a control liquid diet [Autosow control group (ASC)]. From 6 to 39 weeks of age, these animals received either swine chow and TI or swine chow and control article. The TI diets were formulated to contain a TI activity of approximately 500 mg TI/100 g dry matter. A sow control (SC) group suckled from birth to 6 weeks of age and then fed as the ASC group with swine chow plus control article from 6 to 39 weeks of age. The SC piglets grew faster than ASC piglets during postnatal weeks 1 and 2; however, the ASC piglets were significantly heavier than the SC piglets (P=0.001) at 6 weeks of age. Compared with the ASC group, TI caused a moderate decrease in feed consumption and a moderate but reversible decrease in growth from 2 to 5 weeks of age, but not thereafter. Some control and TI-fed Autosow-reared piglets had loose stools until 6 weeks of age; the effect was significantly greater in the TI-fed group. Otherwise, all swine were active and had normal appearance and behavior.

Administration, Oral↗
PubMed2002

Tissue microarrays for miniaturized high-throughput molecular profiling of tumors.

New high-throughput screening technologies such as complementary (cDNA) microarrays allow identification of hundreds of candidate genes in one experiment. To prioritize the leads obtained in such studies, it is necessary to analyze a large number of tissues for candidate gene expression. Tissue microarray (TMA) technology greatly facilitates such analyses. In this method, hundreds of minute tissue samples (0.6-mm diameter) can be placed on one microscope glass slide. The TMA approach allows simultaneous analysis of all tissues with in situ methods (immunohistochemistry, fluorescence in situ hybridization, RNA in situ hybridization) of all tumors in one experiment under highly standardized conditions. TMAs are not restricted to solid tumors but can be manufactured from a variety of other sources, including cell lines, xenografts, and hematologic tissues. In addition to tumor type-specific applications that comprise large numbers of one particular tumor type with extensive histopathologic and clinical data, TMAs are well suited for large-scale molecular epidemiologic studies. For example, genes of interest can be analyzed in multitissue TMAs containing a variety of different human normal tissues and tumor entities. Once tumor types are identified, where a given molecular alteration plays a role, the clinical significance of this molecular alteration can be investigated on tumor-specific TMAs. Thus, TMA technology allows miniaturized high-throughput molecular epidemiologic studies. The TMA technique will markedly accelerate the transition from basic research to clinical applications.

Gene Expression Profiling↗
PubMed2002

Norepinephrine depresses the capsaicin-evoked miniature excitatory postsynaptic currents in substantia gelatinosa of the rat spinal cord.

Capsaicin selectively excites nociceptive primary afferent fibers and increases the frequency of glutaminergic miniature excitatory postsynaptic currents (mEPSCs) in the substantia gelatinosa of the spinal dorsal horn. The whole-cell voltage-clamp recording technique was used to examine the effect of norepinephrine (NE) on the capsaicin-induced increase in the frequency of mEPSCs. In the presence of tetrodotoxin, bath application of capsaicin (1 microM) remarkably enhanced the frequency of mEPSCs (295+/-52% of control). Following pretreatment with NE (10 microM), the capsaicin-induced frequency facilitation of mEPSCs was significantly depressed to 151+/-17% of the control. NE-induced depression in capsaicin action was blocked by yohimbine, a selective alpha(2)-adrenergic receptor antagonist, indicating that NE exerts depression by activating the alpha(2)-adrenergic receptor. As the postsynaptic action of NE has been precluded in the present study, the results suggest that NE inhibits nociceptive input at a presynaptic site, the primary afferent terminal, during the nociceptive transmission in the spinal dorsal horn.

Adrenergic alpha-Agonists↗
PubMed2003

Amiloride inhibition of glycinergic miniature IPSCs in mechanically dissociated rat spinal neurons.

The effect of amiloride on glycinergic transmission in mechanically dissociated rat spinal dorsal horn neurons was examined with the use of whole-cell patch-clamp recording. Amiloride reversibly reduced both the frequency and amplitude of spontaneous glycinergic miniature IPSCs (mIPSCs) and its inhibitory effect on glycinergic mIPSCs persisted in either Ca2+-free or Na+-free external solutions while it disappeared in K+-free external solution. Analysis of the relationship between mIPSCs amplitude and frequency at various holding potentials shows that amiloride inhibition of glycinergic mIPSC frequency could result indirectly from its inhibition of amplitude.

Amiloride↗