Conscious minipig model for evaluating the lower urinary tract

An animal model using minipigs to study urodynamic pressure flow relationships in the conscious animal is described. Port-catheters were implanted subcutaneously in the backs of 22 minipigs with access to the bladder (to measure intravesical pressure Pves) and to the peritoneal cavity (to measure abdominal pressure Pabd). The subtracted pressure (Pdet = Pves = Pabd) was recorded during the storage phase following Furosemide diuresis. Simultaneously, measurement of urinary flow (Q) during voiding was also recorded. Urodynamic studies were performed satisfactorily in all animals, and normal urodynamic profiles in minipigs were established. The minipig model allows reliable and reproducible measurement of pressure-flow parameters in a conscious state and in the natural posture.

Regulation of coenzyme Q biosynthesis

The side-chain moiety of coenzyme Q is synthesized by a trans-prenyltransferase present in microsomes. Condensation of this moiety with the precursor ring takes place in the Golgi system. The enzymes involved, as well as the cytosolic geranylgeranyl-PP synthase, are regulated in an independent fashion. When the size of the farnesyl-PP pool is decreased or increased by employing appropriate inhibitors, the rate of CoQ synthesis is modified accordingly, indicating the dependence of trans-prenyltransferase activity on the level of intracellular substrate concentrations. Administration of peroxisome proliferators elevates CoQ concentrations not only in blood, but also in various tissues. Thus, it may be possible in the future to selectively increase CoQ concentrations in certain organs, without increasing the level of cholesterol.

Remeasurement of electrosprayed proteins in the trapped ion cell of a Fourier transform ion cyclotron resonance mass spectrometer

A single population of multiply charged protein ions formed by electrospray ionization (ESI) is subjected to multiple Fourier transform ion cyclotron resonance (FTICR) excitation and detection events without promoting ion loss from the trapped ion cell. This nondestructive approach to mass spectrometric detection will allow detection limits to be significantly reduced by averaging the repetitive time-domain response that follows each excitation event. Under appropriate conditions, unit remeasurement efficiency is observed for large proteins; for example, 250 consecutive remeasurements of a single population of bovine albumin dimer ions (MW 132,532) yield the expected 16-fold improvement in signal-to-noise ratio compared to a single measurement. Examples presented include a 14-fmol sample of horse myoglobin (MW 16,951), which yields a 15:1 S/N for 50 remeasurements compared to a single scan S/N of 2:1 and a 30-fmol sample of bovine albumin dimer which exhibits a S/N of 25:1 for 50 remeasurements compared to a single scan S/N of 3:1. Of both practical and theoretical interest is the observation of a rapid collision-mediated homogeneous relaxation process that can return these large ions to the center of the cell within a few hundred milliseconds after excitation.

Concentric tube vacuum chamber for high magnetic field, high-pressure ionization in a fourier transform ion cyclotron resonance mass spectrometer

A new differential pumping design for external source Fourier transform ion cyclotron resonance mass spectrometry is described. A network of concentric tubes of increasing diameter terminates at a series of conductance limits across which a pressure from atmosphere to low-10(-8) torr is achieved. This design permits high-pressure sources to be positioned within the solenoidal superconducting magnet less than 20 cm from the analyzer trapped ion cell. Ionization at high magnetic field offers the advantage of radial ion confinement and consequently delivers enhanced ion current to the trapped ion cell. Ion injection utilizing this vacuum chamber design is simpler than previously reported serial pumping stage designs because elaborate focusing optics to overcome the magnetic mirror effect are unnecessary. Two probe-mounted atmospheric pressure sources are described as evidence of the general applicability of the concentric tube vacuum chamber. An electrospray source that delivers several hundred picoamperes of ion current to the cell yields high-sensitivity spectra of proteins beyond 100 kDa. Improved pumping compared with a prototype concentric tube network configuration now permits mass resolution in excess of 20,000 for the [M + 4H](4+) ion of melittin. The resolution is sufficient to distinguish isotope peaks within a single charge state. A probe-mounted, pulsed-laser ablation source that permits cluster formation in the strong magnetic field is also demonstrated.

Mechanisms through which gangliosides inhibit PDGF-stimulated mitogenesis in intact Swiss 3T3 cells: receptor tyrosine phosphorylation, intracellular calcium, and receptor binding

Several potential mechanisms through which gangliosides could modulate PDGF-stimulated events in Swiss 3T3 cells were studied using intact cells. Of the gangliosides studied, at low micromolar concentrations GM2 was the only one that inhibited PDGF-stimulated DNA synthesis, but GT1b was the most potent between 25 and 100 microM; GM1 was generally the least effective, and GD1a and GM3 had intermediate effects. All gangliosides tested inhibited the PDGF-stimulated increases in free intracellular calcium concentrations ([Ca2+]i) with the rank order of potency being GM1 > or = GT1b > GM2 > GM3. PDGF stimulated phosphorylation on tyrosine of a protein with apparent M(r) = 170 kDa which was immunoprecipitated by an anti-PDGF receptor (beta) antibody, indicating that it is a PDGF receptor. Preincubating the cells with specific gangliosides inhibited tyrosine phosphorylation of this protein in a dose-responsive fashion with the following rank order of potency GD1a = GT1b > GM1 > GM2 > GM3. Autoradiography showed that this was due to a decrease in the proportion of cells synthesizing DNA, and a time study showed that ganglioside did not delay entry of the cells into S phase. These effects were not due to gangliosides interfering with PDGF binding to its receptor because results of competitive binding studies showed that none of the gangliosides studied had an effect on either receptor number or affinity, and did not bind to PDGF in solution. These results show that gangliosides affect several specific components of the complex responses to PDGF in intact cells. The relative effectiveness of individual gangliosides, however, varied among the different cellular and molecular responses. This is interpreted to mean that specific gangliosides modulate to different degrees several molecular mechanisms which converge on the common biological response of mitogenesis, and suggests that gangliosides as a family of molecules may function as coordinators of different molecular events involved in complex cellular processes.

Gangliosides inhibit platelet-derived growth-factor-stimulated increases in intracellular calcium in Swiss 3T3 cells

Individual Swiss 3T3 cells stimulated by platelet-derived growth factor delivered by means of a picopump device respond with a brisk, large, and sustained increase in intracellular calcium concentration ([Ca2+]i). Preincubation of cells with either GM1 or GT1b gangliosides inhibited the proportion of responding cells and caused a dose-related diminution in the magnitude of the increase in [Ca2+]i. This effect of ganglioside is probably part of the mechanism through which gangliosides exert their biological effects, including inhibition of platelet-derived growth-factor-induced mitogenesis.

Synthesis of Fluoropolymers in Supercritical Carbon Dioxide

Fluoropolymers are used in many technologically demanding applications because of their balance of high-performance properties. A significant impediment to the synthesis of variants of commercially available amorphous fluoropolymers is their general insolubility in most solvents except chlorofluorocarbons (CFCs). The environmental concerns about CFCs can be circumvented by preparing these technologically important materials in supercritical fluids. The homogeneous solution polymerization of highly fluorinated acrylic monomers can be achieved in supercritical carbon dioxide by using free radical methods. In addition, detailed decomposition rates and efficiency factors were measured for azobisisobutyronitrile in supercritical carbon dioxide and were compared to those obtained with conventional liquid solvents.

Activation of the phosphatidylinositol pathway in the primate corpus luteum by prostaglandin F2 alpha

The current study was designed to investigate the ability of prostaglandin F2 alpha (PGF2 alpha) to activate a second messenger system (phosphatidylinositol pathway) in corpora lutea (CL) of rhesus monkeys. Activation of this pathway was assessed by monitoring the hydrolysis of phosphatidylinositol to inositol phosphates. Since inositol triphosphate mobilizes intracellular Ca2+, intracellular free calcium concentrations ([Ca2+]i) were also assessed in individual cells by fura-2 fluorescence photometry. These responses to PGF2 alpha were measured in luteal cells collected from nonpregnant rhesus monkeys. CL were collected during the early (days 4-5 after estimated LH surge; n = 4), mid (days 8-9; n = 4), and late (days 13-14; n = 5) luteal phase and 1 day after in vivo hCG treatment (15 IU/dose, morning and evening), which began during the midluteal phase (n = 5). PGF2 alpha significantly increased the accumulation of inositol phosphates in all groups (P less than 0.05), except the midluteal phase (P = 0.07). The luteal sensitivity to PGF2 alpha, judged by phosphatidylinositol hydrolysis, was low in the early to midluteal phase compared to that in the late luteal phase and after in vivo hCG treatment. PGF2 alpha also caused a rapid, yet transient, increase in [Ca2+]i in a large proportion of primate luteal cells. The proportion of luteal cells that responded to PGF2 alpha with an increase in [Ca2+]i was smaller (P less than 0.05) in CL collected during the early luteal phase than in the other groups. Luteal progesterone production was inhibited by PGF2 alpha in CL collected after in vivo hCG. CL treated in vivo with hCG also displayed in vitro the largest increases in phosphatidylinositol hydrolysis and [Ca2+]i in response to PGF2 alpha. Therefore, this study demonstrates that PGF2 alpha is a potent activator of the phosphatidylinositol pathway in the primate CL. This activation is augmented as the luteal phase progresses and is influenced by in vivo hCG treatment. This study also provides evidence that the inhibitory effects of PGF2 alpha on progesterone production are associated with the activation of the phosphatidylinositol pathway.

Changes of brain response induced by simulated weightlessness

The characteristics change of brain response was studied during 15 degrees head-down tilt (HDT) comparing with 45 degrees head-up tilt (HUT). The brain responses evaluated included the EEG power spectra change at rest and during mental arithmetic, and the event-related potentials (ERPs) of somatosensory, selective attention and mental arithmetic activities. The prominent feature of brain response change during HDT revealed that the brain function was inhibited to some extent. Such inhibition included that the significant increment of "40Hz" activity during HUT arithmetic almost disappeared during HDT arithmetic, and that the positive-potential effect induced by HDT presented in all kinds of ERPs measured, but the slow negative wave reflecting mental arithmetic and memory process was elongated. These data suggest that the brain function be affected profoundly by the simulated weightlessness, therefore, the brain function change during space flight should be studied systematically.

[Convergence insufficiency and asthenopia]

22 cases with convergence insufficiency (CI) were presented here. It is found that there was an important relationship between CI and asthenopia. The causes clinical findings, diagnostic criteria, treatment of CI and relation with asthenopia were discussed.

The effects of elevation and depletion of intracellular free calcium on progesterone and prostaglandin production by the primate corpus luteum

The role of the phosphatidylinositol second messenger system in luteal regulation has not been extensively studied, particularly in the primate. The objectives of this study were (1) to further characterize the response of the primate CL to the calcium ionophore A23187, in terms of intracellular free calcium concentrations ([Ca2+]i) and progesterone (P) production; and (2) to assess the effects of depleting, as well as elevating, available calcium on luteal P and prostaglandin (PG) production. The response to A23187, in terms of [Ca2+]i, was measured by fura-2 fluorescence microscopy of single small and large luteal cells. A23187 significantly increased [Ca2+]i in both cell types (p less than 0.01). P production (basal and hCG-stimulated) by dispersed primate luteal cells incubated for various times (1-8 h) with and without A23187 was measured. Treatment with A23187 rapidly (within 1-2 h) attenuated (p less than 0.05) the time-dependent increase in basal and hCG-stimulated P production. Luteal P and PG production following treatment with the calcium ionophore, ionomycin, alone or in combination with additional CaCl2, was also monitored. Treatment with ionomycin (p less than 0.01) and CaCl2 (p less than 0.01) inhibited luteal P production. In contrast, treatment with ionomycin stimulated (p less than 0.01) luteal PG production. To determine the effects of Ca2+ depletion on luteal function, P and PG production by cells incubated for 2 and 8 h in the absence and presence of the Ca(2+)-chelator EGTA was measured. Luteal production of both P and PG was inhibited by 8-h treatment with EGTA.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hemostatic agents in canine gastric serosal blood vessels

The efficacy of various sclerotherapeutic agents in the control of acute bleeding, via subserosal injection, was assessed in 10 dogs. Blood flow rate (BFR) from severed gastric serosal vessels (diameter, 1.6 to 2.2 mm) was measured for 3 min (ml/min) for a control group and the agent used. The agents tested were 5 ml of normal saline (NS), 5 ml of 3% hypertonic saline (HS), 5 ml of 1:10,000 epinephrine in NS, 5 ml of 1:10,000 epinephrine/HS, 5 ml of 1:20,000 epinephrine/HS, 2 ml of old thrombin "cocktail" (thrombin, cephapirin + 1% tetradecyl), and 2 ml of fresh thrombin cocktail (total seven). One agent was tested per dog; there were one to two dogs in each subgroup. All of the agents showed significant reduction in BFR (except old thrombin) when compared with BFR of control vessels. The reduction ranged from 30% to more than 75% after 1:10 epinephrine/HS. Complete hemostasis was achieved in up to 47% of vessels using 1:20 epinephrine/HS. Overall, the epinephrine solutions achieved the best results. No systemic effects were observed with the use of any of the agents. Histological studies showed that epinephrine caused mild tissue damage, whereas the cocktail caused significant tissue necrosis. This serosal vessel model permits comparison of the effectiveness of each agent; however, clinical extrapolation to mucosal vessels in a patient and the long-term histological changes are not known.

Determination of Fura-2 dissociation constants following adjustment of the apparent Ca-EGTA association constant for temperature and ionic strength

The accurate calibration of Fura-2 fluorescence in living cells is dependent upon the apparent dissociation constant (Kd) of Fura-2 for Ca2+. If Ca-EGTA calibration buffers are used to construct an in vitro calibration curve, then the calculated value of the apparent Ca-EGTA association constant (K'CaEGTA) will have an important influence on the Kd of Fura-2 and thus the calculated free [Ca2+] in cells. In order to simulate experimental conditions, the individual proton and Ca2+ association constants for EGTA in these experiments were adjusted for both ionic strength and temperature using a semi-empirical form of the Debye-Huckel limiting law and the Van't Hoff isochore, respectively, as described by Harrison and Bers. The modified individual binding constants were then employed in the calculation of K'CaEGTA using the SPECS computer program of Fabatio. At pH = 7.05, ionic strength = 0.15 M, temp = 20 degrees C, K'CaEGTA = 3.232 x 10(6) M-1; at pH = 6.84, temp = 36 degrees C, K'CaEGTA = 1.652 x 10(6) M-1. These values differed substantially from those obtained with unadjusted individual association constants. Calibration buffers of varying [Ca2+] were prepared using the corrected values of K'CaEGTA, and Fura-2 fluorescence ratios were measured during superfusion of these buffers in the experimental chamber at both 20 degrees C and 37 degrees C. The Kd of Fura-2 for Ca2+ was determined to be 236 nM at 20 degrees C and 285 nM at 37 degrees C, utilizing the value of K'CaEGTA adjusted by the method of Harrison and Bers.(ABSTRACT TRUNCATED AT 250 WORDS)

[Obliterative peripheral retinal vascular disease in children]

Obliterative peripheral retinal vascular disease in children is a rare disease. Only 4 cases had been reported abroad. No case of this disease was reported in China before. This paper reported a 13-year-old girl suffering from this disease in both eyes. Neovascular glaucoma of her left eye has developed and that of her right eye was still in early stage. Fluorescein angiography changes, diagnosis and differential diagnosis, pathogenesis and treatment of the disease were discussed.

Hyperthyroid adult rat cardiomyocytes. II. Single cell electrophysiology and free calcium transients

The effects of hyperthyroidism on electrophysiological properties and intracellular free calcium transients in single adult rat cardiomyocytes were studied using conventional microelectrodes and time-resolved single cell fura-2 fluorescence microscopy. Under control conditions, resting membrane potentials and triggered action potentials were not different in euthyroid and hyperthyroid myocytes. Calcium transients produced by electrical stimulation, however, were markedly abbreviated in hyperthyroid myocytes. During a train of stimuli, the duration of the calcium transients at half peak amplitude (half time) was 124 +/- 14 ms at the fifth beat in hyperthyroid cells vs. 287 +/- 35 ms in euthyroid cells. Isoproterenol (1 microM) prolonged time to 50% repolarization (APD50) of the action potentials and increased the peak calcium transients in both euthyroid and hyperthyroid myocytes. It also shortened the half time of the calcium transients in euthyroid myocytes but had little effect on the half time in hyperthyroid cells. These data are consistent with the electrophysiology and mechanical performance in intact euthyroid and hyperthyroid cardiac tissues, and the intrinsic changes in hyperthyroid tissues can therefore be illustrated in single ventricular myocytes. Furthermore, the results suggest that alterations in intracellular calcium handling by sarcoplasmic reticulum may account for contractile changes of the heart induced by hyperthyroidism.

Acinetobacter calcoaceticus septicemia in patients with cancer

At our institution, 95 cases of Acinetobacter septicemia occurred over a ten-year period (1973 to 1982) in patients being treated for cancer. In 24 patients the infection was polymicrobial, while Acinetobacter ssp was the only offending pathogen in 71 patients. In 76 patients (80%), the infection was related to an indwelling central venous catheter (CVC). A sharp increase in the frequency of Acinetobacter septicemia was noticed in the years 1981 and 1982 and coincided with a marked increase in the number of indwelling CVCs in use. Acute leukemia and breast cancer were the malignancies most commonly associated with Acinetobacter septicemia. The isolates of Acinetobacter calcoaceticus from the patients in this study were highly susceptible to the aminoglycosides and moderately susceptible to trimethoprim-sulfamethoxazole (TMP-SMX), carbenicillin, and tetracycline. Seventy-nine patients recovered from their infection with removal of the CVC and antimicrobial chemotherapy. Acinetobacter sp was the cause of death in none of the 16 patients who died. A calcoaceticus is an important nosocomial pathogen causing infections predominantly in immune compromised patients and frequently associated with indwelling catheters.