In vitro properties and in vivo behavior of technetium-99m labeled fibrinogens

Fibrinogen was labeled with Tc-99m by two methods and in vitro stability and the in vivo behavior in mice were studied. The Tc-99m labeling was performed by mixing an unreduced fibrinogen (UnFib) or a reduced fibrinogen (ReFib) with Tc-99m pertechnetate in the presence of stannous chloride. In both of them, chelation with Tc-99m resulted in a single radiochemical product. For the in vitro stability studies, Tc-99m labeled fibrinogen (Tc-99m UnFib) was prepared with UnFib, and transchelation with cysteine solution was easy to produce compared to Tc-99m labeled fibrinogen (Tc-99m ReFib) prepared with ReFib. The radioactivity bound to clottable protein for Tc-99m UnFib and Tc-99m ReFib was about 70% and about 69%, respectively. The in vivo behavior of these labeled fibrinogens was studied, and their efficiencies for imaging an abscess and Ehrlich tumor in mice were determined with a gamma camera. Technetium-99m UnFib underwent a rapid partial exchange of the Tc-99m with compounds of the blood buffer system in vivo, resulting in early biologically active and would be incorporated into the abscess and tumor. The uptake in the abscess increased slightly over time with Tc-99m ReFib, but the abscess to blood and abscess to muscle ratios were 0.09 and 2.6 at 5 hr, respectively. Clearly delineated images of abscess were obtained beginning at about 5 hr after injection. The tumor to blood and tumor to muscle ratios were 0.05 and 1.4 at 5 hr, respectively. The Ehrlich tumor image in mice was slightly visible at 10 hr. The short half-life of Tc-99m was inappropriate for fibrinogen with a low pharmacokinetic value, because it was necessary for imaging of the abscess and tumor to take a long time.

Angiotensin II action in isolated microperfused rabbit afferent arterioles is modulated by flow

We have recently presented evidence that endogenous nitric oxide (NO) and prostaglandins (PGs) modulate angiotensin II (Ang II) action in microperfused afferent arterioles (Af-Arts). Because flow may be a physiological stimulus of endothelial release of NO and PGs, we tested the hypothesis that flow through the lumen of the Af-Art stimulates the endothelium to produce NO and PGs, which in turn modulate the action of Ang II. We microdissected the terminal segment of an interlobular artery together with two Af-Arts, their glomeruli and efferent arterioles (Ef-Art). The two Af-Arts were perfused simultaneously from the interlobular artery, while one Ef-Art was occluded. Since the arteriolar perfusate contained 5% albumin, oncotic pressure built up in the glomerulus with the occluded Ef-Art and opposed the force of filtration, resulting in little or no flow through the corresponding Af-Art. Thus this preparation allowed us to observe Ang II action in free-flow and non-flow Af-Arts simultaneously. Ang II-induced constriction was weaker in free-flow than non-flow Af-Arts, with the luminal diameter decreasing by 8 +/- 2% and 23 +/- 3% at 10(-9) M, respectively (P < 0.013 free-flow vs. non-flow; N = 9). Disrupting the endothelium augmented Ang II action in free-flow (33 +/- 5.1%; P < 0.01 vs. intact endothelium) but not non-flow Af-Arts (31 +/- 5.3%), thus abolishing the differences between them (N = 8). Pretreatment with an inhibitor of either NO synthase (N-nitro-L-arginine methyl ester) or cyclooxygenase (indomethacin) augmented Ang II action more in free-flow than non-flow Af-Arts, likewise abolishing the differences between them. These results suggest that intraluminal flow modulates the vasoconstrictor action of Ang II in Af-Arts via endothelium-derived NO and PGs. Thus flow may be important in the fine control of glomerular hemodynamics.

Detection of different quasispecies of hepatitis C virus core region in cancerous and noncancerous lesions

The quasispecies of hepatitis C virus (HCV) core region in non-cancerous and cancerous hepatocellular carcinoma (HCC) lesions, respectively, of 7 patients with hepatocellular carcinoma were studied. Multiple fluorescence based-polymerase chain reaction (PCR)-single strand conformation polymorphism exhibited a different set and a larger number of quasispecies in cancerous portions than those in non-cancerous portions. DNA sequencing of PCR-amplified core region substantiated an accumulation of nucleotide substitutions, and a greater number of quasispecies in cancerous portions than those in non-cancerous portions. The deduced amino acid sequences disclosed that at the peptide position 45, Ser is dominant in non-cancerous lesions, and Gly in cancerous lesions, respectively. Thus, HCV in hepatocellular carcinoma includes a large number of specific quasispecies presumably due to their vigorous proliferation. A different set of quasispecies with the amino acid change is presumed to be related to the hepatocarcinogenesis.

Excretion of fluoxetine and its metabolite, norfluoxetine, in human breast milk

A study was conducted to measure breast milk concentrations of fluoxetine and its active metabolite, norfluoxetine, excreted in breast milk in a cohort of nursing women using fluoxetine, and to estimate infant dose from nursing. The study included 10 women nursing 11 infants (median age, 185 days). The mean fluoxetine dose was 0.39 mg/kg/day. Each patient manually collected 3 to 6 milk samples throughout a dosing interval. Concentrations of fluoxetine and norfluoxetine in milk were measured by gas-liquid chromatography. Mothers reported whether they observed adverse effects in their infants. The average infant doses of fluoxetine and norfluoxetine, as estimated for an exclusively breast-fed infant ingesting 1000 mL of milk per day, were 0.077 mg (SD = 0.054 mg) and 0.084 mg (SD = 0.043 mg), respectively. The total dose of fluoxetine and norfluoxetine (expressed as fluoxetine equivalents) was 0.165 mg (SD = 0.092 mg), which was equivalent to 10.8% (SD = 2.2%) of the maternal dose, adjusted on a mg/kg basis in a 4-kg infant. No adverse events were reported by mothers in their infants. Approximately one tenth of the adult therapeutic dose of fluoxetine is excreted in breast milk. Although short-term adverse effects in the infant from exposure through nursing were not reported in this cohort, future studies that assess the potential long-term consequences are needed.

Influence of superimposed optokinetic stimulus on smooth pursuit eye movements elicited by sinusoidal spot target oscillation

In 6 healthy subjects, smooth pursuit eye movements (SPEMs), elicited by sinusoidal spot target oscillation, were measured against three different backgrounds: dark, stationary texture (texture), and texture background movement in-phase with the spot target (coupled). Spot-target oscillation frequencies ranging between 0.2 to 1.6 Hz and peak velocities ranging between 19 to 75 degrees/s were employed. SPEM gain did not differ significantly among the three backgrounds below 0.8 Hz. However when at 1.6 Hz it responded to a peak velocity of 75 degrees/s, the gain for the "coupled" background condition was greater than that for the "dark" condition, which in turn was greater than the gain for "texture". However, SPEM phase delays were found to be similar for the three background conditions. Since the responses during "coupled" and "texture" backgrounds are most likely elicited by rapid-rise optokinetic reflex (OKR) interaction it can be concluded that SPEMs and the rapid-rise OKR system have the same latency (response) time.

[Evaluation of myocardial sympathetic nerve function in patients with mitral valve prolapse using iodine-123-metaiodobenzylguanidine myocardial scintigraphy]

Mitral valve prolapse (MVP) is closely related to myocardial sympathetic nerve function. This study evaluated the presence of impaired myocardial sympathetic nerve function by Iodine-123-metaiodobenzylguanidine (MIBG) scintigraphy in nine patients with MVP. For comparison, 15 healthy subjects without heart disease were investigated (control group). Single photon emission computed tomography (SPECT) and anterior planar myocardial scintigraphy were performed 15 min (initial images) and 3 hours (delayed images) after injection of MIBG (111 MBq). The location and degrees of reduced tracer uptake were evaluated. Myocardial MIBG uptake was quantified by uptake ratio of the heart (H) to upper mediastinum (M) on the anterior planar images (H/M). Percentage washout of MIBG in nine sectors of all oblique slices along the short-axis was calculated. The washout rates were higher at the inferoposterior and septal segments in patients with anterior leaflet prolapse, and at inferoposterior and lateral segments in patients with posterior leaflet prolapse. The bull's eye map showed increased washout rate in the apical and posteroseptal basal segments. There was no significant difference in the H/M ratio between MVP patients and the control group. These results indicate that MIBG can be used to evaluate localized myocardial sympathetic nerve function in MVP.

High-density lipoprotein inhibits the synthesis of platelet-activating factor in human vascular endothelial cells

The regulation of platelet-activating factor (PAF) synthesis by serum lipoproteins was investigated in human umbilical vein endothelial cells. High-density lipoprotein (HDL) inhibited PAF synthesis in agonist (thrombin, histamine, and A23187)-stimulated endothelial cells, that was determined by incorporation of [3H]acetate into PAF and by bioassay. The inhibition by HDL was increased in a concentration-dependent manner, but was reversed as the concentration of thrombin increased. HDL did not affect the time course of PAF production. HDL lipids suppressed the PAF production to a lesser extent than HDL. The reduction of PAF accumulation in HDL, did not result from degradation of PAF but inhibition of PAF synthesis, which was mainly mediated via the blockade of acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase activation. HDL did not prevent the release of [3H]arachidonic acid in thrombin-stimulated endothelial cells. The binding of 125I-HDL to endothelial cells and its uptake were not enhanced by thrombin stimulation. These results demonstrate that HDL may inhibit the activation of acetyltransferase by thrombin at the cell surface. This observation may explain a part of mechanism of HDL action.

The treatment of chronic hemodialysis vascular access by directional atherectomy

Directional atherectomy (DA) was developed as a new therapeutic modality for coronary artery disease. For the past 3 years, we have applied DA intervention to vascular access failure with either poor blood flow rate or high venous pressure. DA intervention was performed on 27 lesions of 16 hemodialyzed patients. A reduction of stenosis to less than 20% of that before treatment was judged a technical success, and the rate of technical success was 84%. All patients showed adequate blood flow rates after DA intervention, indicating initial success. Although restenotic events occurred frequently, repeated DA interventions could be performed successfully. The patency rate at 1 month after DA intervention was 100%, at 3 months 93%, at 6 months 92% and at 12 months 75%. The short-term patency rate of DA was more satisfactory than the results of percutaneous transluminal angioplasty as reported by several investigators. Regarding the site of stenosis, restenotic events were relatively fewer in the lesions occurring at the native vein compared to those at graft-venous anastomotic sites. Eccentric-type stenosis was also associated with fewer restenotic events than circumferential-type stenosis. These results suggest that eccentric-type stenosis at the native vein is the most suitable lesion for the application of DA intervention in terms of long-term patency. As no severe complications occurred after DA intervention, this would appear to be a useful therapeutic modality for the correction of vascular access failure.

[Interleukin-3 therapy in patients with aplastic anemia refractory to prior therapies]

A therapeutic trial of interleukin-3 (IL-3) was carried out in four patients with aplastic anemia refractory to the prior therapies. Daily subcutaneous doses of 2.5, 5.0 or 7.5 micrograms/kg was given for 7 or 14 days. In a patient who had co- and immediate boost-administration of granulocyte colony-stimulating factor (G-CSF) and/or erythropoietin (Epo) and another who had sequential administration of G-CSF and Epo two weeks after IL-3, definite hematological response was obtained during the course after IL-3. In one patient, moderate to severe side effects consisting of facial edema, conjunctival bleeding, chills and fever, were observed after two days' administration of IL-3. Co- or sequential administration of other hemopoietic factor(s) may be essential in IL-3 therapy for aplastic anemia.

Development of a conductivity-based immunosensor for sensitive detection of methamphetamine (stimulant drug) in human urine

A simple immunosensor based on a conductivity method was developed for determination of methamphetamine (MA, a stimulant drug) in urine. Anti-MA antibody was immobilized onto the surface of a pair of platinum electrodes. The reaction of MA with the antibody causes a decrease in the conductivity of the anti-MA immobilized layer between the electrodes. A linear relationship was obtained between the conductivity and MA concentration in the range of 1-10 micrograms/ml. The method requires the sample to be rinsed with water on the electrodes after the immunoreaction. This detection system was applied to the determination of MA in urine and proved to be a useful and a simple detection technique of MA in forensic science in comparison with a gas chromatography-mass spectrometry method.

Platelet-activating factor dilates efferent arterioles through glomerulus-derived nitric oxide

Despite evidence that platelet-activating factor (PAF) is produced by the glomerulus, its direct action on the glomerular microcirculation is poorly understood. It was recently reported that at picomolar concentrations, PAF dilates isolated microperfused afferent arterioles (Af-Art) via nitric oxide (NO). The present study tested the hypothesis that PAF acts on the glomerulus to release NO, which in turn controls the resistance of the efferent arteriole (Ef-Art). Rabbit Ef-Art were perfused from the distal end (retrograde perfusion [RP]) to eliminate the influence of the glomerulus, or through the glomerulus from the end of the Af-Art (orthograde perfusion [OP]) to maintain the influence of the glomerulus. Ef-Art were preconstricted by approximately 40% with norepinephrine and increasing doses of PAF were added to both the arteriolar perfusate and bath. Only with OP did PAF at picomolar concentrations cause significant dilation: at 400 pmol, the diameter increased by 64 +/- 11% from the preconstricted level (N = 6, P < 0.01). This dilation was completely abolished by pretreatment with an NO-synthesis inhibitor. To study its possible constrictor action, PAF was added to nonpreconstricted Ef-Art. At nanomolar concentrations, PAF constricted Ef-Art similarly in both RP and OP: at 40 nM, the diameter decreased by 24 +/- 4% (N = 6, P < 0.01) and 20 +/- 2% (N = 6, P < 0.01), respectively. This constriction was attenuated by pretreatment with indomethacin (Indo) in both RP (14 +/- 2%, N = 7; P < 0.02 versus without Indo) and OP (10 +/- 2%, N = 6; P < 0.02 versus without Indo).

IN CONCLUSION

(1) at picomolar concentrations, PAF stimulates the glomerulus to release NO, which in turn dilates the Ef-Art; and (2) at nanomolar concentrations, PAF constricts the Ef-Art partly through release of cyclooxygenase metabolites. Thus, PAF may play a role in glomerular hemodynamics under various physiological and pathological conditions.

Morphological and histochemical study of nonhemiplegic muscle in acute stroke patients manifesting respiratory failure

There is little information on skeletal muscle changes in patients with acute stroke. We performed morphological and histochemical examinations of nonhemiplegic sternothyroid muscles biopsied at the time of tracheostomy from 13 patients with acute stroke manifesting acute respiratory failure. Degenerating and regenerating fibers were observed in all 13 specimens. Following characteristic myopathic changes suggestive of mitochondrial abnormalities were also demonstrated in a majority of patients. Namely, ragged-red fibers, focal increase in NADH-TR activity in subsarcolemmal areas and increases in acid phosphate activity were found. The changes were similar but extremely slight in control patients with acute respiratory failure due to causes other than stroke and were absent in the other control patients with adenomatous thyroid tumor. The severity and extent of the histopathological changes in the muscle fibers in patients with acute stroke were closely correlated with the duration of hypoxemia but not with such items as type of stroke, site of cerebral lesion, consciousness level, days of biopsy after the stroke, clinical outcome, levels of serum creatine kinase, myoglobin and PaO2. This acute nonhemiplegic muscle involvement was considered to be a very common complication in severe stroke patients.

A comparative ultrastructural study of the parotid gland acinar cells of nine wild ruminant species (mammalia, artiodactyla)

The ultrastructural similarities and differences of the parotid gland acinar cells of nine wild ruminants (roe deer, nyala, tahr, Eld's deer, red deer, Pere David's deer, European mouflon, African buffalo, sable antelope) representing three feeding types i.e. concentrate selectors (CS), grass and roughage eaters (GR) and intermediate feeders (IM) were compared. The parotid acinar cells of the CS contained more granular endoplasmic reticulum, Golgi-complexes and secretory granules than those of the GR. The acinar cells of the latter were characterized by numerous mitochondria, folded plasma membranes and intercellular secretory canaliculi. The ultrastructure of the secretory granules varied in different species but their morphology was not related to feeding type. An unusual feature of the parotid acinar cells of all feeding types was the evidence of an apocrine-like mode of secretion. A typical morphological change of some parotid acinar cells was the compression of the nucleus by large vacuoles. No distinctive differences were found in the ultrastructure of the parotid gland of wild and captive ruminants.

Modulation of calcium current by ATP in guinea-pig adrenal chromaffin cells

The effects of extracellular adenosine 5'-triphosphate (ATP) on voltage-dependent Ca2+ currents were examined using the whole-cell voltage-clamp technique in guinea-pig isolated adrenal chromaffin cells. ATP (500 microM) reversibly suppressed Ca2+ currents in the presence of 5mM Ca2+ in the extracellular solution. The inhibitory effect of ATP on Ca2+ currents tended to increase with increases in the peak amplitude of ATP-evoked current when the intracellular solution contained 0.1 or 1 mM ethylenebis(oxonitrilo)tetraacetate(EGTA). Using the intracellular solution containing 10mM EGTA, on the other hand, the inhibitory effect did not change regardless of the amplitude of current responses to ATP. In the presence of 10 mM Ba2+, ATP (100 microM) reduced Ba2+ currents in a manner similar to Ca2+ currents. This reduction was decreased by dialysis of cells with the internal solution containing guanosine 5'-O-(2-thiodiphosphate) (GDP [beta-S]; 1 mM) or guanosine 5'-O-(3-thiotriphosphate) (GTP [gamma-S]; 100 microM). A depolarizing prepulse to + 100 mV partly relieved ATP-induced reduction of Ba2+ currents. ADP, AMP and adenosine also reduced Ba2+ currents and the effect of adenosine was the most potent. Adenosine (0.5 and 1 mM) significantly inhibited adrenaline secretion induced by nicotine (50 microM). These results suggest that Ca2+ entry through ATP-activated non-selective cation channels results in the inactivation of voltage-dependent Ca2+ channels. In addition, ATP seems to modulate Ca2+ channels via the pathway related to G-protein. Adenine nucleotides and adenosine may play a role in controlling secretory activity in guinea-pig adrenal chromaffin cells.

Changes in left ventricular inflow and pulmonary venous flow velocities during preload alteration in dilated heart

The aim of the present study was to assess the changes of left ventricular inflow (LVIF) and pulmonary venous flow (PVF) velocities during preload alteration in 30 patients with dilated heart (LV end-diastolic dimension > or = 6.0 cm) and impaired LV systolic function (% fractional shortening of the LV < or = 25%). We performed transesophageal pulsed Doppler echocardiography during lower body negative (LBNP, -40 mmHg) and positive pressure (LBPP, +40 mmHg) in 10 patients with dilated cardiomyopathy, in 20 with old myocardial infarction, and in 22 healthy controls. Eight of the patients showed a pseudonormalization (compliance failure) pattern, and 22 showed a decreased early diastolic wave and compensatorily increased atrial systolic wave (relaxation failure) pattern of LVIF in the control state. Mean pulmonary capillary wedge pressure (PCWP) was greater in the compliance failure group than in the relaxation failure group in the control state. LVIF in 6 of the 22 patients with the relaxation failure pattern changed to the compliance failure pattern during LBPP, and that in 3 of 8 patients in the compliance failure group changed to the relaxation failure pattern during LBNP. The 6 patients with a change from the relaxation failure to the compliance failure pattern showed significantly higher peak diastolic and atrial systolic PVFs during LBPP than in the control state, and significantly higher PCWPs in the control state than the 16 patients with no change in LVIF. These findings suggest that the compliance failure and relaxation failure patterns of LVIF are readily interchangeable in various hemodynamic conditions, and that pattern analysis of LVIF and PVF during preload alteration is useful for understanding the hemodynamic severity and for evaluating preload reduction therapy in the dilated heart.

Application of thermosensitive polymers as a new embolic material for intravascular neurosurgery

Application of thermosensitive polymers as an embolic material for intravascular neurosurgery was investigated. We intended to use thermosensitive polymers to occlude vessels by precipitation in response to body temperature. Copolymers of N-isopropylacrylamide (NIPAM) and N-n-propylacrylamide (NPAM) were selected as thermosensitive polymers. To determine the optimal lower critical soluble temperature (LCST) for the embolic material, we developed an in vitro flow model. In this study the copolymers with an LCST of 24-26 degrees C showed appropriate precipitation. To prove the occlusion of vessels in vivo, we injected the copolymers into a rabbit kidney through a microcatheter. The extent of embolization was judged by angiography and histological examination. An acute toxicity test of the copolymer of NIPAM and NPAM was performed in comparison with that of the NIPAM monomer. The copolymer used in this paper showed no acute toxicity in mice. Water solubility, non-adhesiveness, and non-toxicity are the advantages of the use of thermosensitive polymers as an embolic material. By changing the LCST, various embolic materials can be designed. Based on our results, we believe that the application of thermosensitive polymers as a new embolic material is very promising.

L-NAME, an inhibitor of nitric oxide synthase, blocks the established allodynia induced by intrathecal administration of prostaglandin E2

We recently reported that intrathecal (i.t.) administration of prostaglandin E2 (PGE2) to conscious mice induced allodynia, a state of discomfort and pain evoked by innocuous tactile stimuli. In the present study, we examined the effect of the PGE receptor EP1 subtype antagonist ONO-NT-012, the N-methyl-D-aspartate (NMDA) receptor antagonist MK-801, and the NO synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) on the allodynia. The PGE2-induced allodynia was blocked by simultaneous i.t. injection of ONO-NT-012, MK-801, or L-NAME. However, 5 min after i.t. injection of PGE2, the allodynia was significantly blocked by i.t. L-NAME, but not by i.t. ONO-NT-012 or MK-801. These results demonstrate that the PGE2-induced allodynia, once developed, does not require the continued agonist occupancy of EP1 and NMDA glutamate receptor sites.

Muscarinic receptor subtypes mediating catecholamine secretion and increase in intracellular Ca2+ concentration in adrenal chromaffin cells of the guinea pig

Muscarinic receptor subtypes mediating catecholamine secretion and increase in the intracellular concentration of Ca2+ ([Ca2+]i) were examined using muscarinic agonists and antagonists in dispersed adrenal chromaffin cells of the guinea pig. All muscarinic agonists (1-1,000 microM) tested caused increases in adrenaline secretion in a dose-dependent manner. Muscarine and methacholine were more effective than bethanechol, oxotremorine and pilocarpine. Muscarine and oxotremorine caused a small increase in adrenaline secretion even in the absence of extracellular Ca2+. Both 4-DAMP (0.1 microM) and pirenzepine (0.1 microM), but not methoctramine (0.1 microM), shifted the dose-response curve for muscarine-induced adrenaline secretion to the right. These muscarinic agonists also caused increase in [Ca2+]i in the presence of extracellular Ca2+. Muscarine-induced [Ca2+]i rises were reduced, but not abolished, by removal of extracellular Ca2+. These results suggest that catecholamine secretion induced by muscarinic agonists is mediated through M1, or M1 and M3 muscarinic receptor subtypes in adrenal chromaffin cells of the guinea pig.