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At least 1,387 records · Page 77Linked to original sources
PubMed1994

The combination of platelet-derived growth factor-BB and insulin-like growth factor-I stimulates bone repair in adult Yucatan miniature pigs.

The combination of insulin-like growth factor-I and platelet-derived growth factor-BB has previously been shown to stimulate healing of soft tissue wounds and the formation of bone and ligament around teeth. The purpose of the present study was to evaluate the effects of platelet-derived growth factor-BB and insulin-like growth factor-I individually and in combination on the healing of osseous wounds. Four standardized cortical wounds were created in each tibia of 11 adult Yucatan miniature pigs. The wounds in one tibia per animal were treated with either purified recombinant human insulin-like growth factor-I, platelet-derived growth factor-BB, or both in a methylcellulose gel. The wounds in each contralateral tibia received placebo gel alone. Coded serial sections of each wound were evaluated by computer-aided histomorphometry 21 days after surgery. The area and perimeter of the newly formed mineralized callus, the thickness of the total callus, and the percentage of mineralized tissue within the callus were significantly increased compared with the values of matched controls only in wounds treated with a combination of insulin-like growth factor-I and platelet-derived growth factor-BB. No significant differences in the measured parameters of callus formation were found in wounds treated with either insulin-like growth factor-I or platelet-derived growth factor-BB alone. Cartilage was present only in sites treated with insulin-like growth factor-I alone. These results suggest that the combination of platelet-derived growth factor-BB and insulin-like growth factor-I stimulates bone formation in wounds in long bones of adult animals and that these growth factors act via different pathways during the repair process.

Journal Article↗
PubMedDate not supplied

Idiopathic systemic granulomatous disease and macrophage expression of PTHrP in a miniature pony.

Idiopathic systemic granulomatous disease, which has been reported in horses, cattle and human beings, is characterized by perivascular granulomatous and lymphoplasmacytic inflammation in many organ systems. Diagnosis is based on the exclusion of possible viral, fungal or bacterial causes. The disease was identified in a miniature pony with widespread lymphoplasmacytic and granulomatous inflammation, special staining techniques having revealed no evidence of any aetiological agent. Skin lesions, which were severe, consisted of hyperkeratosis and serocellular crust formation, with inflammatory infiltrates in a perivascular to diffuse pattern in both the superficial and deep dermis. Inflammatory infiltrates were also present in lymph nodes and around the blood vessels in most organs. Immunohistochemically, both CD3-positive T lymphocytes and BLA36-positive B lymphocytes were identified in the inflammatory infiltrates, and macrophages were immunolabelled for parathyroid hormone-related protein, a factor associated with hypercalcaemia in human beings with granulomatous diseases.

Animals↗
PubMed1994

A new miniature ultrasonic probe for gastrointestinal scanning: feasibility and preliminary results.

A prototype of a new miniature ultrasonic probe (Aloka) was clinically evaluated in 37 patients with a variety of gastrointestinal lesions. The probe's diameter of 2.0 mm allowed passage through the working channel of conventional endoscopes; the ultrasonic frequencies used were 15 and 20 MHz. Fourteen patients with benign and malignant gastrointestinal tumors, and thirteen patients with a variety of benign conditions, were examined, 12 of whom also underwent conventional endoscopic ultrasonography with side-viewing echoendoscopes. The image quality of the two systems was well comparable, but the ultrasonic penetration depth of the miniprobes was inferior to that of conventional endoscopic ultrasonography (EUS). All but three lesions were adequately visualized by the ultrasonic probe, whereas conventional EUS failed to completely visualize four cases. Of the two ultrasonic frequencies used, we found 15 MHz to be superior, since it provided good image quality and adequate penetration depth. In conclusion, we feel that the probe can be used for EUS indications in the gastrointestinal tract, whereas further technical improvements, such as increasing the penetration depth, are necessary before pancreatobiliary EUS can be carried out.

Adult↗
PubMed1981

Determination of 24-hour insulin infusion pattern by an artificial endocrine pancreas for intravenous insulin infusion with a miniature pump.

UNLABELLED: Intravenous insulin infusion with a glucose controlled insulin infusion system (GCIIS) is known to restore glucose homeostasis. A simpler approach to improve blood glucose regulation is preprogrammed intravenous insulin infusion with portable pumps without sensor-mediated feedback. We report a study designed to evaluate whether the preprogrammed insulin infusion pattern to be used in the miniature insulin infusion pump (MIIP) could be optimized by concomitant employment of the GCIIS for blood glucose control. Six juvenile-onset insulin-dependent diabetics (mean age 31 yrs) were studied. Mean blood glucose (MBG) was 6.2 mmol/l +/- 0.5 (SD) during glucose controlled infusion and 5.3 +/- 0.6 during the combined MIIP + GCIIS-day. The insulin requirements calculated from the s.c. regimen (56 U +/- 10 SD) were identical to the GCIIS-measured (51 U +/- 14) and to the amounts delivered during the combined MIIP-GCIIS infusion day (54 U +/- 13). A mean surplus of 3 U was given by the GCIIS. Mean amplitude of glycaemic excursions (MAGE) was 3.0 mmol/l during GCIIS-control, and 3.3 mmol/l during combined infusion. IN CONCLUSION: The GCIIS was found capable of calculating the 24-hour insulin dose in well-known, unstable diabetics; however, it did not improve the preprogrammed insulin infusion profile obtained by the MIIP.

Artificial Organs↗
PubMed1981

Assessment of pancreatic and hepatic function in Yucatan miniature swine exhibiting impaired glucose tolerance.

A group of Yucatan miniature swine exhibiting impaired glucose tolerance (Kq = .91 +/- .04), were examined with respect to their portal and hepatic vein insulin levels following a fasting intravenous glucose tolerance test. The majority of these animals (9 of 11) were found to exhibit the expected portal vein insulin deficiency. This deficiency was found to encompass all phases of the insulin response and was not limited to the acute secretory phase. The remaining two animals were found to have normal portal vein insulin concentrations while exhibiting reduced hepatic vein insulin levels, and impaired glucose tolerance. An excessive rate of hepatic insulin extraction is proposed to explain the etiology of the insulin deficiency and glucose intolerance observed in these latter two animals.

Animals↗
PubMed1997

[Measuring leukocyte velocity in macular capillaries using a miniaturized blue field simulator: effect of aperture of the pupil].

BACKGROUND: In this paper we present a miniaturized blue field simulator (BFS) which allows the measurement of the velocity (V) pulsatility (P) and number (D) of leukocytes in the macular retinal capillaries. A study on the effect of the aperture size of the blue light source at the subject's pupil on the measured flow parameters was performed. METHODS: A blue field entoptoscope with a small halogen lamp was used to induce the perception of the "flying corpuscles" and a flat color screen was selected to display a computer simulation of this entoptic phenomenon. The aperture of the blue light source at the pupil was varied by a diaphragm placed at a conjugate pupil plane while the size and retinal irradiance of the blue field stimulus at the fundus was held constant. RESULTS: The results show significant correlations between log pupil area and both V (-18% per log unit) and D (+42% per log unit). When the retinal illuminance is expressed in Log Trolands, V shows no dependency, but D is strongly correlated (+40% per log Troland). CONCLUSIONS: When applying the BFS technique, the size of the blue light stimulus at the pupil, if undilated, must be well controlled to minimize instrument-related variations of the blood flow measurements.

Adult↗
PubMed2002

Ca2+ marks: miniature calcium signals in single mitochondria driven by ryanodine receptors.

Propagation of cytosolic [Ca(2+)] ([Ca(2+)](c)) signals to the mitochondria is believed to be supported by a local communication between Ca(2+) release channels and adjacent mitochondrial Ca(2+) uptake sites, but the signaling machinery has not been explored at the level of elementary Ca(2+) release events. Here, we demonstrate that [Ca(2+)](c) sparks mediated by ryanodine receptors are competent to elicit miniature mitochondrial matrix [Ca(2+)] signals that we call "Ca(2+) marks." Ca(2+) marks are restricted to single mitochondria and typically last less than 500 ms. The decay of Ca(2+) marks relies on extrusion of Ca(2+) from the mitochondria through the Ca(2+) exchanger, whereas [Ca(2+)](c) sparks decline primarily by diffusion. Mitochondria also appear to have a direct effect on the properties of [Ca(2+)](c) sparks, because inhibition of mitochondrial Ca(2+) uptake results in an increase in the frequency and duration of [Ca(2+)](c) sparks. Thus, a short-lasting opening of a cluster of Ca(2+) release channels can yield activation of mitochondrial Ca(2+) uptake, and the competency of mitochondrial Ca(2+) handling may be an important determinant of cardiac excitability through local feedback control of elementary [Ca(2+)](c) signals.

Animals↗
PubMed2004

Identification of mushroom body miniature, a zinc-finger protein implicated in brain development of Drosophila.

The mushroom bodies are bilaterally arranged structures in the protocerebrum of Drosophila and most other insect species. Mutants with altered mushroom body structure have been instrumental not only in establishing their role in distinct behavioral functions but also in identifying the molecular pathways that control mushroom body development. The mushroom body miniature(1) (mbm(1)) mutation results in grossly reduced mushroom bodies and odor learning deficits in females. With a survey of genomic rescue constructs, we have pinpointed mbm(1) to a single transcription unit and identified a single nucleotide exchange in the 5' untranslated region of the corresponding transcript resulting in a reduced expression of the protein. The most obvious feature of the Mbm protein is a pair of C(2)HC zinc fingers, implicating a function of the protein in binding nucleic acids. Immunohistochemical analysis shows that expression of the Mbm protein is not restricted to the mushroom bodies. BrdUrd labeling experiments indicate a function of Mbm in neuronal precursor cell proliferation.

5' Untranslated Regions↗
PubMed2001

Terminal-repeat retrotransposons in miniature (TRIM) are involved in restructuring plant genomes.

A new group of long terminal repeats (LTR) retrotransposons, termed terminal-repeat retrotransposons in miniature (TRIM), are described that are present in both monocotyledonous and dicotyledonous plant. TRIM elements have terminal direct repeat sequences between approximately 100 and 250 bp in length that encompass an internal domain of approximately 100-300 bp. The internal domain contains primer binding site and polypurine tract motifs but lacks the coding domains required for mobility. Thus TRIM elements are not capable of autonomous transposition and probably require the help of mobility-related proteins encoded by other retrotransposons. The structural organization of TRIM elements suggests an evolutionary relationship to either LTR retrotransposons or retroviruses. The past mobility of TRIM elements is indicated by the presence of flanking 5-bp direct repeats found typically at LTR retrotransposon insertion sites, the high degree of sequence conservation between elements from different genomic locations, and the identification of related to empty sites (RESites). TRIM elements seem to be involved actively in the restructuring of plant genomes, affecting the promoter, coding region and intron-exon structure of genes. In solanaceous species and maize, TRIM elements provided target sites for further retrotransposon insertions. In Arabidopsis, evidence is provided that the TRIM element also can be involved in the transduction of host genes.

Amino Acid Sequence↗
PubMed1978

Natural killing and antibody-dependent cellular cytotoxicity are independent immune functions in the Minnesota miniature swine.

Peripheral blood lymphocytes from Minnesota miniature pigs were tested for natural killing (NK) and antibody-dependent cellular cytotoxicity (ADCC) in a 2- to 4-hr 51Cr release assay against human myeloid and lymphoid tumor target cells. Adult specific pathogen-free and germfree animals exhibited normal levels of activity in both assays. In addition, the NK and ADCC activities of peripheral blood lymphocytes from colostrum-deprived newborn piglets were examined. These animals were obtained by hysterectomy and previously shown to be immunologically "virgin." We found that these newborn piglets exhibited normal ADCC but lacked NK activity. The differences in the ontogeny of the two activities suggest that they are distinct. Preliminary effector cell characterization studies suggest that: (i) NK and ADCC in the pig are physically not separable; (ii) the majority of the cytotoxic activity on a cell-per-cell basis is mediated by the non-T lymphocyte fraction; and (iii) the rosetted T cells, which account for about 60% of the total pig peripheral blood lymphocytes, have low but demonstrable cytotoxic activity as well.

Animals↗
PubMed1980

Acetylcholine receptor site density affects the rising phase of miniature endplate currents.

The relationship between acetylcholine receptor (AcChoR) site density (sigma) and the rising phase of the miniature endplate current was determined in esterase-inactivated lizard intercostal neuromuscular junctions. The currents were recorded by using a voltage clamp. The receptor site density was determined by electron microscope autoradiography after labeling with 125I-labeled alpha-bungarotoxin in normal endplates and in those partially inactivated with nonradioactive alpha-bungarotoxin. We found that as sigma is decreased the rise time in increased and the amplitude is decreased. These results are compatible with a previously stated "saturating disk" model, which suggests that a quantum of acetylcholine (AcCho) acts on a small postsynaptic area at saturating concentration. We conclude that in the normal neuromuscular junction the most likely number of AcCho molecules needed to open an ion channel is 2, and that the 20--80% rise time of < 100 musec is influenced both by the sigma-dependent factors such as diffusion and binding of AcCho to AcChoR and by the sigma-independent time delays such as the conformation change time to open the ion channels. From our data we calculate the lower limits to the forward rate constant of AcCho binding to AcChoR greater than or equal to 3 X 10(7) M-1 sec-1 and the diffusion constant for AcCho in the cleft greater than or equal to 4 X 10(-6) cm2 sec-1.

Acetylcholine↗
PubMed1984

Diffusion and binding constants for acetylcholine derived from the falling phase of miniature endplate currents.

In previous papers we studied the rising phase of a miniature endplate current (MEPC) to derive diffusion and forward rate constants controlling acetylcholine (AcCho) in the intact neuromuscular junction. The present study derives similar values (but with smaller error ranges) for these constants by including experimental results from the falling phase of the MEPC. We find diffusion to be 4 X 10(-6) cm2 s-1, slightly slower than free diffusion, forward binding to be 3.3 X 10(7) M-1 s-1, and the distance from an average release site to the nearest exit from the cleft to be 1.6 micron. We also estimate the back reaction rates. From our values we can accurately describe the shape of MEPCs under different conditions of receptor and esterase concentration. Since we suggest that unbinding is slower than isomerization, we further predict that there should be several short "closing flickers" during the total open time for an AcCho-ligated receptor channel.

Acetylcholine↗
PubMed1989

Miniature Paul-Straubel ion trap with well-defined deep potential well.

In some recently proposed experiments using ion traps, a Paul trap of conventional size and design is insufficient. We have constructed a miniature Paul-Straubel trap. It has a small elliptic ring ( approximately 0.2 mm) and three pairs of planar electrodes ( approximately 2 cm part) arranged so that they form a cube. The two conventional end-cap electrodes are replaced by the six planar electrodes. The ring is heatable to a high temperature for improving the uniformity of the dc potential on the ring surface. With this trap, we hope to do such fundamental studies as the true zero-point confinement of a single ion.

Journal Article↗
PubMed1994

Lasting potentiation of inhibition is associated with an increased number of gamma-aminobutyric acid type A receptors activated during miniature inhibitory postsynaptic currents.

Whole-cell patch-clamp recordings unveiled a substantial increase in the amplitude, but no change in the frequency, of miniature inhibitory postsynaptic currents (mIPSCs) in dentate gyrus granule cells following chronic epilepsy induced by kindling. This novel and persistent enhancement of gamma-aminobutyric acid type A (GABAA) receptor-mediated inhibition lasted for at least 48 hr following its induction. Nearly a doubling of the number of activated functional postsynaptic GABAA receptor channels during mIPSCs without any change in single-channel conductance or kinetics could be demonstrated using nonstationary fluctuation analysis. As postsynaptic GABAA receptors are likely to be pharmacologically saturated by the transmitter concentration in the cleft, incrementing the number of functional receptor channels may be the most effective means to augment inhibition in the mammalian brain.

Animals↗
PubMed1996

Miniature endplate current rise times less than 100 microseconds from improved dual recordings can be modeled with passive acetylcholine diffusion from a synaptic vesicle.

We recorded miniature endplate currents (mEPCs) using simultaneous voltage clamp and extracellular methods, allowing correction for time course measurement errors. We obtained a 20-80% rise time (tr) of approximately 80 micros at 22 degrees C, shorter than any previously reported values, and tr variability (SD) with an upper limit of 25-30 micros. Extracellular electrode pressure can increase tr and its variability by 2- to 3-fold. Using Monte Carlo simulations, we modeled passive acetylcholine diffusion through a vesicle fusion pore expanding radially at 25 nm x ms(-1) (rapid, from endplate omega figure appearance) or 0.275 nm x ms(-1) (slow, from mast cell exocytosis). Simulated mEPCs obtained with rapid expansion reproduced tr and the overall shape of our experimental mEPCs, and were similar to simulated mEPCs obtained with instant acetylcholine release. We conclude that passive transmitter diffusion, coupled with rapid expansion of the fusion pore, is sufficient to explain the time course of experimentally measured synaptic currents with trs of less than 100 micros.

Acetylcholine↗
PubMed1996

Expression of Drosophila mushroom body mutations in alternative genetic backgrounds: a case study of the mushroom body miniature gene (mbm).

Mutations in 12 genes regulating Drosophila melanogaster mushroom body (MB) development were each studied in two genetic backgrounds. In all cases, brain structure was qualitatively or quantitatively different after replacement of the "original" genetic background with that of the Canton Special wild-type strain. The mushroom body miniature gene (mbm) was investigated in detail. mbm supports the maintenance of MB Kenyon cell fibers in third instar larvae and their regrowth during metamorphosis. Adult mbm1 mutant females are lacking many or most Kenyon cell fibers and are impaired in MB-mediated associative odor learning. We show here that structural defects in mbm1 are apparent only in combination with an X-linked, dosage-dependent modifier (or modifiers). In the Canton Special genetic background, the mbm1 anatomical phenotype is suppressed, and MBs develop to a normal size. However, the olfactory learning phenotype is not fully restored, suggesting that submicroscopic defects persist in the MBs. Mutant mbm1 flies with full-sized MBs have normal retention but show a specific acquisition deficit that cannot be attributed to reductions in odor avoidance, shock reactivity, or locomotor behavior. We propose that polymorphic gene interactions (in addition to ontogenetic factors) determine MB size and, concomitantly, the ability to recognize and learn odors.

Animals↗
PubMed1996

Nitric oxide-related species inhibit evoked neurotransmission but enhance spontaneous miniature synaptic currents in central neuronal cultures.

Nitric oxide (NO.) does not react significantly with thiol groups under physiological conditions, whereas a variety of endogenous NO donor molecules facilitate rapid transfer to thiol of nitrosonium ion (NO+, with one less electron than NO.). Here, nitrosonium donors are shown to decrease the efficacy of evoked neurotransmission while increasing the frequency of spontaneous miniature excitatory postsynaptic currents (mEPSCs). In contrast, pure NO donors have little effect (displaying at most only a slight increase) on the amplitude of evoked EPSCs and frequency of spontaneous mEPSCs in our preparations. These findings may help explain heretofore paradoxical observations that the NO moiety can either increase, decrease, or have no net effect on synaptic activity in various preparations.

Animals↗
PubMed1997

Three novel families of miniature inverted-repeat transposable elements are associated with genes of the yellow fever mosquito, Aedes aegypti.

Three novel families of transposable elements, Wukong, Wujin, and Wuneng, are described in the yellow fever mosquito, Aedes aegypti. Their copy numbers range from 2,100 to 3,000 per haploid genome. There are high degrees of sequence similarity within each family, and many structural but not sequence similarities between families. The common structural characteristics include small size, no coding potential, terminal inverted repeats, potential to form a stable secondary structure, A+T richness, and putative 2- to 4-bp A+T-biased specific target sites. Evidence of previous mobility is presented for the Wukong elements. Elements of these three families are associated with 7 of 16 fully or partially sequenced Ae. aegypti genes. Characteristics of these mosquito elements indicate strong similarities to the miniature inverted-repeat transposable elements (MITEs) recently found to be associated with plant genes. MITE-like elements have also been reported in two species of Xenopus and in Homo sapiens. This characterization of multiple families of highly repetitive MITE-like elements in an invertebrate extends the range of these elements in eukaryotic genomes. A hypothesis is presented relating genome size and organization to the presence of highly reiterated MITE families. The association of MITE-like elements with Ae. aegypti genes shows the same bias toward noncoding regions as in plants. This association has potentially important implications for the evolution of gene regulation.

Aedes↗