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At least 19 recordsLinked to original sources

PubMed1978

Further studies of periodic miniature response in squid giant axons.

Electric responses of extremely small amplitudes (1-30 muV peak-to-peak) repeating with more-or-less definite periodicity could be induced by a variety of chemical stimulants applied to squid giant axons either extracellularly or intracellularly. The chemical stimulants studied include allethrin, aminopyridines, N-bromosuccinimide, dimethylamino-pyridine, glutaraldehyde, osmium tetroxide, parachloromercuribenzoate, rose bengal, scorpion venoms and veratridine. With several mild stimulants, it was possible to evoke periodic miniature responses unaccompanied by a fall in the resting membrane potential. The frequency of miniature responses could be lowered by intracellular injection of TEA (tetraethylammonium). These miniature responses could readily be suppressed by external application of TTX (tetrodotoxin). The miniature responses evoked by 4-aminopyrine were characterized by a large variation in the frequency of responses. Cross-linking of the membrane proteins with a dilute solution of glutaraldehyde produced miniature responses repeating at progressively falling frequencies. Analyses of the processes of production of miniature responses with these and other stimulants have clarified several aspects of the physicochemical properties of the excitable sites of the axon membrane.

Animals↗

PubMed1976

Local anesthetic alteration of miniature endplate currents and endplate current fluctuations.

The effect of the local anesthetic QX222 on the kinetics of miniature endplate currents and acetylcholine induced endplate current fluctuations was studied in voltage clamped cutaneous pectoris muscle of Rana pipiens. Both the endplate current fluctuation spectra and the miniature endplate current decay consisted of two or three components depending upon the holding potential and local anesthetic concentration. The cutoff frequency of each spectral component was equal to the decay rate of its corresponding constituent of the miniature endplate current. Comparison of the relative amplitudes of the spectral and miniature endplate components indicated that QX222 did not act by creating two kinetically distinct populations of acetylcholine receptors. QX222 action could be explained by alteration of the acetylcholine receptors such that they sequentially change conformation form one open state to another. A specific case in which QX222 binds to the open state of the acetyl-choline receptor creating a blocked state, was found to account for the observed relationship between the relative amplitudes of the miniature endplate current and spectral components, as well as the previously observed voltage and concentration sensitivity of the decay rates of endplate current components.

Anesthetics, Local↗

PubMed1979

[Miniaturized methods to monitor intracranial pressure. Technical and clinical results (author's transl)].

The prognosis of numerous diseases of the central nervous system is essentially determined by the intracranial pressure (ICP) and its therapeutic influencing. Long-term monitoring of the ICP must therefore be the objective in neurological and neurosurgical patients at risk. For this purpose, miniaturized methods were tested and developed. To monitor the intracranial pressure in patients who were not operated on, a miniature pressure transducer the size of a match head was used which was directly implanted 'percutaneously' in the intensive care unit: After a stab wound had been made in the skin, a 5-mm burrhole is made; the specially constructed miniature coaxial burr which disengages as soon as it touches the dura automatically enables coplanar epidural implantation of the transducer by means of an adapter capsule. The skin is closed without tension. For monitoring the pressure after trepanation, a spiralled miniature pressure transducer is implanted. The equally flattened receiver with lateral membranes is placed intracranially as desired, e.g., epidurally or subdurally, durin the operation. The zero point can be checked from outside without danger of infection. After the end of the measurements the recorder is easily extracted. Up to the present time, the epidural pressure has been reliably monitored for several weeks by this method in 86 patients. Ten comparative measurements showed corresponding cerebrospinal fluid pressures to within a few mm Hg with very good reproduction of frequency and amplitude. Small zero drift and the external zero control give an accuracy of measurement +/- 5 mm Hg independently of the time of measurement. The measurement permits early recognition of progressive intracranial space-occupying lesions. In 14 patients (16%) a measured rise in intracranial pressure was an essential basis for indication for neurosurgical operations. In addition, the pressure measurement provides an objective assessment of the effect of measures to lower the ICP; progressive increases in intracranial pressure which cannot be influenced conservatively can be brought for surgical decompression in good time before the brain has been irreversibly damaged by pressure. In craniocerebral traumata, monitoring the intracranial pressure permits the differentiation of primary damage to the brain stem with uniform, normal intracranial pressure from secondary constrictions of the brain stem with considerable rise of intracranial pressure and disturbed autoregulation. Only in chronic subdural haematomata are considerable displacements of intracranial masses to be seen with only slightly increased ICP ( less than 30 mm Hg). Besides space-occupying lesions, the measurement of pressure also detects generalised epileptic attakcs due to a considerable rise in intracranial pressure caused by hyperemia. Also disorders of respiration are recognised by supervision of ICP. The procedures described seem suitable for routine monitoring of ICP in patients at risk, with little operative effort and minimum danger...

Adolescent↗

PubMed1979

The disposition of [14C]iprindole in man, dog, miniature swine, rhesus monkey and rat.

1. Absorption of a single oral dose of [14C]iprindole was rapid in rats, rhesus monkeys, miniature swine, dogs and human volunteers. In all species except the rat, most of the radioactivity in the blood resided in the plasma. Small amounts of unchanged iprindole were detected in the plasma of rats and rhesus monkeys but not in man and miniature swine. 2. Radioactivity was excreted mainly in the urine of man, miniature swine and rhesus monkey, but in the faeces of rat and dog. 3. Urinary radioactivity was associated with basic (free and conjugated), acidic and highly polar, water soluble metabolites. At least 20 metabolites as well as small amounts of unchanged drug were detected in the basic fractions of each species' urine. 4. Many of these metabolites were common to all species; however, qualitative as well as quantitative differences were apparent. Mass-spectrometric analysis of several metabolites indicated N-demethylation and oxidation of the alicylic ring or a combination of both pathways.

Animals↗

PubMed1975

Restraint, venipuncture, endotracheal intubation, and anesthesia of miniature swine.

Miniature swine are useful as experimental animals for investigations involving major surgical procedures, provided that proper restraint and anesthetic methods are employed. The methods and drugs described herein are not intended to be all-inclusive but rather those found most applicable to a wide variety of studies with miniature swine at this laboratory. This report is intended primarily to guide those unfamiliar in handling miniature swine during initiation of studies with that species. For chemical restraint during minor procedures, diazepam, at a dose of 5.5-8.5 mg/kg im, has become the drug of choice. For surgical anesthesia, optimal results have been obtained using thiamylal sodium iv for induction of anesthesia and maintained by 0.5-1.5% halothane administered via an endotracheal cannula. Pentobarbital sodium may be used to produce surgical anesthesia but is generally unsatisfactory except for terminal procedures. Electroanesthesia, even with concomitant use of tranquilizing drugs, is difficult to control and results in very poor muscle relaxation.

Anesthesia↗

PubMed1975

Hypotrichosis in Miniature Poodle siblings.

Progressive hypotrichosis was detected in 2 silver male Miniature Poodle siblings at 5 weeks of age. A male and 2 female siblings had normal black coats. The sire, a 3-year-old black Miniature Poodle, and the dam, a 2-year-old silver Miniature Poodle, also had normal coats. Microscopically, the hypotrichotic skin had accumulations of keratotic debris and melanin in dilated hair canals and melanin deposits in and around inactive hair bulbs. Sex-linked or sex-limited inheritance may have been involved, inasmuch as both affected dogs were males.

Alopecia↗

PubMed1978

Use of vectorcardiography for the detection of +Gz-related cardiac pathology in miniature swine.

Vectorcardiograms were recorded from anesthetized, adult miniature swine 1-2 weeks before high sustained +Gz exposure and 2-6 h after exposure. Each +Gz run consisted of one 60-s exposure, respectively, to 3, 5, 7, and 9 +Gz, with 3 min rest between each +Gz plateau. The full range, from severe to minor, of +Gz-induced cardiac pathology was observed in this group of miniature swine. In spite of the large variation in the amount and degree of cardiac pathology, there were no post-exposure vectorcardiographic changes which might be diagnostic of +Gz-induced cardiac pathology. The results of this study indicate that vectorcardiography, performed after +Gz exposure, is not a reliable technique for detecting the presence of +Gz-induced cardiac pathology in miniature swine.

Aerospace Medicine↗

PubMedDate not supplied

A miniature segment-length strain gauge arch for the assessment of myocardial function.

A miniature myocardial segment-length strain gauge arch utilizing solid-state strain gauge elements is described. The arch weighs 0.25 g, has a frequency response flat to 30 Hz, requires simple circuitry, and is stable in situ for periods exceeding 6 hours. Its miniaturization and ease of insertion offer distinct advantages over similar devices previously described. Miniature arches have been applied simultaneously to multiple sites to assess left ventricular function in dogs. The response of these arches to a variety of interventions indicates that this device may be used to follow localized segment-length and velocity changes. The study also clearly demonstrates that the orientation of strain gauge arches with respect to muscle fiber direction in the ventricular wall qualitatively and quantitatively affects the recorded segment-length alterations.

Animals↗

PubMed1979

The free focus concept in dental and maxillofacial radiography. The present status of the miniaturized dental x-ray machines.

"Free focus" radiography has shown promise in the examination of complex anatomy in many parts of the body, where conventional and tomographic exposures provide limited information. The approach was introduced in dentistry three decades ago and applied clinically from the time the miniaturized x-ray machines with rod anodes became available in the early 1960's. Yet it has received little attention in the international literature. Recent generations of the unique machines allow free focus surveys of the dentition in two exposures with a film quality comparable to or better than conventional periapical surveys and with a fraction of the radiation load. There is a need for evaluation of such procedures for use in dental practice. Additional applications of free focus radiography promise unusual flexibility in the use x-ray examinations in endodontics, pedodontics, periodontics, and oral surgery, which may justify further development of the miniaturized equipment for such new approaches. Specific suggestions for technical improvements are discussed.

Dental Equipment↗

PubMed1977

Rapid miniaturized chromatographic quality-control procedures for Tc-99m radiopharmaceuticals.

Our laboratory has adopted a complete miniaturized charomatography system for Tc-99m radiopharmaceuticals in order to improve upon the commercial systems currently available. Three distinct, separate, chromatographic procedures are used to determine the labeling efficiencies of Tc-99m-labeled sulfur colloid, MAA, stannous chloride, phytate, DMSA, DTPA, pyrophosphate, diphosphonate, methylene diphosphonate, polyphosphate, and glucoheptonate. The chromatographic systems include Whatman 31 ET paper and acetone, Gelman ITLC-SG and 0.9% sodium chloride, and Gelman ITLC-SA and acetone. The chromatographic strips are miniaturized (1 X 6 cm), colored-coded, marked, and numbered. All the chromatographic quality-control procedures are simple, rapid, and can easily be incorporated into the routine quality-control program of any nuclear medicine facility.

Chromatography↗

PubMed1979

Gas exchange, pulmonary mechanics and haemodynamics in adult respiratory distress syndrome: experimental results in Lewe miniature pigs.

Adult respiratory distress syndrome (ARDS) is a common medical emergency in respiratory care complicating a great variety of traumas and diseases. An animal model from Lewe miniature pigs has been developed to study the ARDS under standardized conditions; it is based on aspiration pneumonitis, a disorder often observed in ARDS, injuring the lung alveolar surfactant system. The experimental study was conducted under neuroleptanalgesia. ARDS was produced by intratracheal application of hydrochloric acid (0.2 mol/l) in an amount of 1.0 ml/kg body wt. The animals were ventilated automatically by a standardized ventilatory pattern in IPP mode. In all animals the time course of oxygenation ratio (Pa,O2/F1O2), arterial CO2 tension (Pa,CO2), ratio of alveolo--arterial oxygen tension difference to inspired oxygen fraction (Aa,DO2/F1O2), oxygen exchange ratio ((AaDO2/Pa,O2), lung compliance (CL), inspiratory airway resistance (RrsI), dead space ratio VD/VT), pulmonary artery pressure (PAP) and systemic blood pressure were studied. Changes in quasi-static volume--pressure curves, percentage change in lung water content and gross pathological finding were used to integrate the findings into a system of pathophysiological changes in ARDS. The animal group to which hydrochloric acid was administered shows severe pulmonary distress leading to death within 3.5--7.5 h. No significant changes in the measured parameters could be observed in the control group over a 14 h period. The results suggest that aspiration pneumonitis in Lewe miniature pigs is very suitable to investigate various problems in pathogenesis of ARDS. The model provides reproducible results which correlate very well with findings in different ARDS states. The models serves both to compare clinical states and to search for newer therapeutic manoeuvres.

Animals↗

PubMed1978

Sugar pucker geometries at the intercalation site of propidium diiodide into miniature RNA and DNA duplexes in solution.

We have evaluated the sugar pucker geometry at the intercalation site of propidium diiodide into the self-complementary dinucleoside monophosphate duplexes cytidylylguanosine and deoxycytidylyldeoxyguanosine as a function of the nucleotide/drug ratio in aqueous solution. Our solution results support the observation by Sobell and coworkers [Sobell, H.M., Tsai, C.C., Jain, S.C. & Gilbert, S.G. (1977) J. Mol. Biol. 114, 333--365] of a C3' endo (3'-5')C2' endo sugar pucker geometry in the 2:2 intercalation complex of ethidium bromide into the iodocytidylylguanosine duplex in the crystalline state. We demonstrate further that the mixed sugar pucker observed for the intercalation of propidium diiodide into the miniature RNA duplex in solution persists in the intercalative complex of this trypanocidal drug into the corresponding miniature DNA duplex in solution.

Deoxyribose↗

PubMed1976

Transplantation in miniature swine. I. Fixation of the major histocompatibility complex.

Three strains of miniature swine, each homozygous for a different allele of the major histocompatibility locus (MHC), have been developed by a selective breeding scheme based on tissue typing of the offspring of each generation. Prior to breeding, the original parents were reciprocally immunized by skin grafts and lymphocyte injections to produce lymphocytotoxic antisera. These antisera were then used to assess the MHC genotype of the offspring by an analysis based on selective absorption of cytotoxicity. Offspring inheriting the same serologically determined genotype were then bred sequentially. Subsequent mixed lymphocyte cultures showed a pattern of reactivity consistent with the serological genotyping, further confirming the homology between the MHC of these miniature swine and those of man and mouse. In addition to their usefulness as a model for large animal surgical transplantation, these animals provide an abundant homozygous source of histocompatibility antigens and of antihistocompatibility antisera for use in chemical characterization of products of the MHC.

Animals↗

PubMed1976

Blood groups and serum protein polymorphisms in the Pitman-Moore and Ohmini strains of miniature pigs.

The variations of blood groups and biochemical polymorphisms in the populations of the two miniature pig strains reared in Japan were investigated in this report. The variations in eight blood group systems were investigated by using serological techniques, and five serum protein systems by using starch gel electrophoresis. The Pitman-Moore strain showed no variations in K, O, Tf, Cp and Am systems, but showed plymorphisms in A,E,F,G,H,L,Pa and Hpx systems. The Ohmini strain showd no or little variations in E,F,G,Tf,Pa and Cp systems, but showed polymorphisms in A,H,K,L,O,Hpx and Am systems. From the results of investigation of genetic similarities among nine pig populations including various breeds, it was made clear that the two miniature pig strains were very different genetically, and the Pitman-Moore strain was genetically closer to European large pig breeds than to East Asian native pigs, while the Ohmini strain was close to Thai and Philippine natives.

Animals↗

PubMed1976

A miniaturized counting technique for anaerobic bacteria.

A miniaturized counting technique gave results as good as the pour-plate and Most Probable Number (MPN) techniques for enumeration of clostridia spp. and anaerobic isolates from the gut. Highest counts were obtained when ascorbic acid (1%) and dithiothreitol (0.015%) were added to the reinforced clostridial medium used for counting. This minimized the effect of exposure to air before incubation. The miniature technique allowed up to 40 samples to be plated and incubated in one McIntosh-Filde's-type anaerobic jar, compared with 3 or 4 by the normal pour plate.

Anaerobiosis↗

PubMed2024

Adaptive or non-adaptive? Cranial evolution in a radiation of miniaturized day geckos.

Lygodactylus geckos represent a well-documented radiation of miniaturized lizards with diverse life-history traits that are widely distributed in Africa, Madagascar, and South America. The group has diversified into numerous species with high levels of morphological similarity. The evolutionary processes underlying such diversification remain enigmatic, because species live in different ecological biomes, ecoregions and microhabitats, while suggesting strikingly high levels of homoplasy. To underscore this evolutionary pattern, here we explore the shape variation of skull elements (i.e., cranium, jaw and inner ear) using 3D geometric morphometrics and phylogenetic comparative methods on computed tomography scans (CT-scan) of a sample encompassing almost all recognized taxa within Lygodactylus. The results of this work show that skull and inner ear shape variation is low (i.e., there is high overlapping on the morphospace) across geographic regions, macrohabitats and lifestyles, implying extensive homoplasy. Furthermore, we also found a strong influence of allometry shaping cranial variation both at intra and interspecific levels, suggesting a major constraint underlying skull architecture, probably as a consequence of its miniaturization. The remaining variation that is not allometric is independent of phylogeny and ecological adaptation and can probably be interpreted as the result of intrinsic developmental plasticity. This, in turn, supports the interpretation that speciation in this group is largely concordant with a non-adaptive hypothesis, which results mainly from vicariant processes.

Animals↗

PubMed2024

High-throughput DNA extraction and cost-effective miniaturized metagenome and amplicon library preparation of soil samples for DNA sequencing.

Reductions in sequencing costs have enabled widespread use of shotgun metagenomics and amplicon sequencing, which have drastically improved our understanding of the microbial world. However, large sequencing projects are now hampered by the cost of library preparation and low sample throughput, comparatively to the actual sequencing costs. Here, we benchmarked three high-throughput DNA extraction methods: ZymoBIOMICS™ 96 MagBead DNA Kit, MP BiomedicalsTM FastDNATM-96 Soil Microbe DNA Kit, and DNeasy® 96 PowerSoil® Pro QIAcube® HT Kit. The DNA extractions were evaluated based on length, quality, quantity, and the observed microbial community across five diverse soil types. DNA extraction of all soil types was successful for all kits, however DNeasy® 96 PowerSoil® Pro QIAcube® HT Kit excelled across all performance parameters. We further used the nanoliter dispensing system I.DOT One to miniaturize Illumina amplicon and metagenomic library preparation volumes by a factor of 5 and 10, respectively, with no significant impact on the observed microbial communities. With these protocols, DNA extraction, metagenomic, or amplicon library preparation for one 96-well plate are approx. 3, 5, and 6 hours, respectively. Furthermore, the miniaturization of amplicon and metagenome library preparation reduces the chemical and plastic costs from 5.0 to 3.6 and 59 to 7.3 USD pr. sample. This enhanced efficiency and cost-effectiveness will enable researchers to undertake studies with greater sample sizes and diversity, thereby providing a richer, more detailed view of microbial communities and their dynamics.

Metagenome↗

PubMed1976

A fluidic-controlled, miniature respirator with a new positive airway pressure device.

A simple and miniature respirator was developed providing controlled ventilation and application of a positive airway pressure. The positive airway pressure is achieved by an airflow through a canula into the airways. During expiration the direction of this insufflated air-flow is changed and the dynamic pressure necessary for it manifests itself as a positive airway pressure. Mechanical ventilation functions according to the principle of the Ayre-T-Piece: flow direction and, therefore ventilation, is controlled by occlusion of the expiratory limb. Occlusion is brought about by inflating a balloon. The inflation of the balloon is controlled by fluidic-circuits. They allow setting of frequency, duration of inspiration and pressure limit. As the above mentioned system for creating a positive airway pressure is integrated, mechanical ventilation with PEEP is achieved. Tests on a lung model were performed to establish the variables which influence the amount of positive pressure produced by an air-flow through a canula into a tube. Results indicate that the positive pressure obtained is inversely correlated to the diameter of tube and canula and varies with the angle of inflow (Tab. I, II, Fig. 4). The pressure-rise-velocity depicted in Fig. 5 suggests that sighing is possible in an open system. On an anencephalic newborn pressure-flow-ratios were established (Fig. 6). Pressure-time curves during spontaneous breathing, CPAP assisted breathing and sighing combined with CPAP were recorded in a 3 month old baby (Fig. 7, 8, 9). The discussion states the technical performance of the respirator (frequency 100/min-1/3 min., tidal volume 5-100 ml, controlled ventilation with pressure limitation, application of PEEP) and additional advantages (no apparatus deadspace, disposable i.e. sterile air supply-system, the miniature dimensions 10 x 10 x 5 cm, versatility and simple therefore technically reliable construction).

Humans↗