Unstimulated polymorphonuclear neutrophils regulate proximal coronary arterial tone

Our objective is to clarify, by measuring the superoxide production as a marker of inactive state of polymorphonuclear neutrophils, whether unstimulated polymorphonuclear neutrophils would influence coronary arterial tone. We recorded the isometric tension of the porcine coronary arterial ring in a bath of oxygenated Krebs Ringer solution. Unstimulated porcine polymorphonuclear neutrophils that contained little superoxide were added to the bath. We also analyzed the prostaglandins produced in the bath. The isometric tension of arterial rings increased dose-dependently when polymorphonuclear neutrophils were added to the bath. The vasoconstriction induced by unstimulated polymorphonuclear neutrophils was inhibited by endothelial denudation, indomethacin, anti-CD11a/18-like antibody. Thromboxane A2 synthetase inhibitor and superoxide dismutase did not effect the vasoconstriction. Prostaglandin E2 predominated among the prostaglandins produced in the bath; its production was significantly inhibited by indomethacin (without vs. with indomethacin; 3898 +/- 1704 vs 1956 +/- 715 pg/ml, P < 0.05, n=6). Pretreatment of vascular rings with indomethacin blocked the interaction of the coronary artery with polymorphonuclear neutrophils. Results suggested that unstimulated polymorphonuclear neutrophils constrict the proximal coronary artery. Such vasoconstriction may be produced by cyclooxygenase products, especially prostaglandin E2 produced in the vascular wall via the interaction between the polymorphonuclear neutrophils and the endothelium. Polymorphonuclear neutrophils may regulate coronary arterial tone.

Therapeutic application of intravenous human natural immunoglobulin preparation

Human natural immunoglobulin (HunIg) preparation for intravenous use has been used in various diseases. The most typical application of this preparation is agammaglobulinemia. Currently, however, this preparation is being used in the therapy of many other disorders. These include thrombocytopenia, Kawasaki disease, systemic vasculitis, several other disorders of autoimmune origin and systemic inflammation such as sepsis. In some diseases, the clinical improvement following use of HunIg has been dramatic, while in others its effect is not striking. Due to rarity of the side effects, the range of application of HunIg has been recently broadened. Such side effects include transmission of several diseases such as hepatitis and retroviral infections. Before it is recommended for use, however, and primarily due to expense, the efficacy of this drug should be carefully evaluated. The mechanism of action of HunIg is not fully understood. However, it has been suggested that its action may involve blockade of Fc-receptor, an anti-cytokine effect, or inhibition of complement activation. In this review, the mechanism of action of HunIgG and its application in human diseases are discussed.

Differential effects of EMD-53998 on calcium-pressure relationship in normal and ischemic guinea pig heart

We investigated the effects of EMD-53998 and digoxin on Ca2+ transients and left ventricular (LV) function in indo 1-loaded Langendorff guinea pig hearts. EMD-53998 (10(-9) to 10(-5) M) and digoxin (10(-10) to 10(-6) M) increased +dP/dt and Ca2+ transients in normal hearts. The relative increase in Ca2+ transients by EMD-53998 was similar to digoxin. At 10(-5) M, EMD-53998 increased LV end-diastolic pressure. Low-flow ischemia decreased +dP/dt by 50%, while indo 1 ratio increased by 10-25%. EMD-53998 (10(-9) to 10(-6) M) effectively restored the depressed +dP/dt with little effect on indo 1 ratio, but at 10(-5) M, it markedly elevated LV end-diastolic pressure and the beneficial effect on contractile dysfunction disappeared. Digoxin (10(-10) to 10(-7) M) failed to improve LV function, but at 10(-6) M, it restored contractile dysfunction with a large increase in indo 1 ratio. The relation between indo 1 ratio and +dP/dt clearly showed that EMD-53998 restored contractile dysfunction by Ca2+ sensitization. These findings suggest that Ca2+ sensitization by EMD-53998 is an advantageous approach for ischemic contractile failure but impairs diastolic function.

[Hepatic blood flow decreases during laparoscopic cholecystectomy]

Changes of median hepatic venous blood flow (MHVBF) and left portal venous blood flow (Lt. PVBF) were measured continuously in 31 patients undergoing elective laparoscopic cholecystectomy (LC) by using transesophageal echocardiography (TEE). The patients were anesthetized with inhalation and epidural anesthesia. MHVBF and Lt. PVBF decreased from preoperative level of 317 +/- 61 ml.min-1, 522 +/- 86 ml.min-1 to 73 +/- 22 ml.min-1, 98 +/- 28 ml.min-1 after inflation with high pneumoperitoneum pressure and they recovered by deflation. These findings suggest that hepatic blood flow decreases by increased intraperitoneal pressure.

Preceding PTGBD decreases complications of laparoscopic cholecystectomy for patients with acute suppurative cholecystitis

Laparoscopic cholecystectomy (LC) has become one of the options for the treatment of acute cholecystitis as surgeons gain facility with this procedure. However, acute suppurative cholecystitis is still a severe condition, because a high mortality rate still exists. In the early years (1991 to 1992), 4 patients were operated on without a preceding percutaneous transhepatic gallbladder drainage (PTGBD) at our hospital, however, one patient died of septic shock after a laparoscopic cholecystectomy. Conversion to open surgery was performed on two patients. However, in later years (1992 to 1995), 14 patients were operated on with preceding PTGBDs safely. Here, we report the safeness and significance of the combination therapy of PTGBD and LC for patients with severe acute suppurative cholecystitis.

G2 arrest following fractionated irradiation in the mouse jejunal crypt

A G2 block is a well-known response to irradiation, showing a delay time that depends on the given single dose. Our question was whether the division delay time is the same after multiple doses as after a single dose. We therefore studied mitosis in the mouse jejunal crypt using a quantitative approach. Three radiation schedules with a fraction size of 2 Gy were compared: a single dose and twice-daily irradiation at a 4-h interval, for 1 or 3 days. With the single dose, mitotic figures disappeared at 0.5 h and reappeared after 2 h. At the end of each multiple-dose regimen, significant numbers of mitoses could be observed at 0.5 and 1 h but a trough was seen at 2 h, with numbers then increasing again. Calculated average division delays after the single dose and repeated doses for 1 and 3 days were 1.5, 1.3 and 1.7 h respectively. In summary, most crypt cells treated with multiple fractions remain susceptible to G2 arrest, showing the same delay time as with the single dose.

The cytokines NAP-1 (IL-8), MCP-1, IL-1 beta, and GRO in rabbit inflammatory skin lesions produced by the chemical irritant sulfur mustard

Developing and healing dermal inflammatory lesions were produced in rabbits by the topical application of dilute sulfur mustard (SM), the military vesicant. In tissue sections of such lesions, cells containing the mRNA of important cytokines were identified with in situ hybridization techniques. These cytokines were neutrophil attractant/activation protein-1 (NAP-1 (also called IL-8), monocyte chemoattractant (activating) protein 1 (MCP-1), interleukin 1 (beta) (IL-1 (beta)), and GRO (a growth factor and chemokine). Mononuclear cells (mainly macrophages and activated fibroblasts) contained the mRNA of all four of these cytokines. A higher percentage of cytokine-producing mononuclear cells (macrophages and activated fibroblasts) was present in lesions at 2 days (their peak size) than at 6 days, when they were almost healed. Granulocytes emigrated from the bloodstream, passed through the lesions, and were the major constituent of the protective crust. This sequence correlated with the distribution of cells able to produce NAP-1: At 2 days and 6 days, the mononuclears that contained messenger RNA for this granulocyte chemoattractant were found mainly in the upper part of the dermis. At 2 days and 6 days, cells containing the mRNA of IL-1, a primary cytokine, were also found predominantly in the upper dermis, i.e., nearest the site of injury. In contrast, mononuclears containing the mRNA of MCP-1 (a monocyte chemoattractant), and the mRNA of GRO (a granulocyte chemoattractant) were more equally distributed throughout the dermis. SM stimulated hair follicle epithelial cells to up-regulate GRO mRNA and, to a lesser degree, NAP-1 mRNA. Apparently, the irritation produced by SM directly or indirectly induces such epithelial cells to manufacture these growth factors. In the rabbit, hair follicles are known to be the main source of new epithelial cells after the covering epithelium has been destroyed. Therefore, GRO is probably a major autocrine-paracrine stimulus for such repair. A brief review of the role of cytokines in dermal inflammation is presented.

Situation of monomethoxypolyethylene glycol covalently attached to lysozyme

We selectively introduced monomethoxypolyethylene glycol (mPEG) 5000, 2000, and 550 into Asp119 in lysozyme. To examine how the mPEGs were present on the surface of the modified lysozyme, the activities, binding abilities to the Fab fragment of anti-lysozyme monoclonal antibody, net charges and nuclear magnetic resonance (NMR) spectra of mPEG lysozymes were examined. With the increase in molecular weight of mPEG, the activities and binding abilities to the Fab of mPEG lysozyme decreased. However, introduced mPEG5000 did not cause complete inhibition of the activities and binding abilities to the Fab, while the maximum length of mPEG5000 was so great that it largely covered the surface of the lysozyme molecule. Analyses of the net charges and NMR suggested that the introduced mPEG preferentially assumed a folded conformation on the surface rather than spread all over the surface. Based on the structure of mPEG lysozyme, the mechanism of the reduced immunogenicity of mPEG lysozyme was discussed.

The effect of combination splenectomy and low-dose FK506 therapy on graft survival after liver allograft transplantation in rats

The effect of splenectomy on allograft survival was investigated using orthotopic liver transplantation in a rat experimental model (ACI rat liver grafted to LEW rat). Control rats without any immunosuppressive treatment died, on average, 10.4 +/- 1.4 days after operation. Splenectomy alone somewhat prolonged the survival (13.4 +/- 2.0 days), and low-dose FK506 therapy moderately prolonged it (22.7 +/- 7 days). The graft survival period was significantly prolonged (39.7 +/- 6.3 days) when them two treatments were combined. The elevation of cytotoxic antiallograft antibodies was suppressed by splenectomy but not by low-dose FK506 therapy. The development of jaundice was moderately suppressed by FK506 but not by splenectomy. There was no difference between the pattern of body weight decline in either of them two groups and that in control rats. When these two treatments were combined at the same time, the elevation of cytotoxic antibodies, development of jaundice and decline of body weight were suppressed. These data indicate that B cells play an important role in the acute rejection of the rat liver allograft at least partially via production of cytotoxic antiallograft antibody. Splenectomy or other immunosuppressive methods affecting B cells can be a supplement for immunosuppression when using reduced-dose FK506.

Microwave coagulation therapy for hepatocellular carcinoma

BACKGROUND & AIMS

Surgical resection is not always feasible in patients with hepatocellular carcinoma. Microwave coagulation therapy has been used as an alternative to resection, and its efficacy has been evaluated.

METHODS

Nineteen patients with unresectable hepatocellular carcinoma underwent microwave coagulation therapy through laparotomy (n = 12), laparoscopy (n = 5), or thoracotomy (n = 2) because of advanced liver cirrhosis and/or intrahepatic metastases. One nodule was treated in 13 patients, tumor size ranged from 5 to 90 mm. Patient outcomes were studied.

RESULTS

Microwave coagulation therapy created a reproducible regional necrosis. Fourteen patients underwent potentially curative treatment; the remaining 5 patients underwent palliative treatment (n = 4) or incomplete tumor coagulation (n = 1). Of the 31 nodules treated, 28 underwent complete tumor ablation. Only 2 patients undergoing laparoscopic microwave coagulation therapy developed local recurrence. The coagulated area subsequently shrank. Patients showed rapid recovery without hepatic dysfunction. Thirteen patients, including 2 long-term survivors, are alive either without tumor (n = 10; 14-64 months) or with tumor (n = 3; 17-22 months). Six patients died of hepatocellular carcinoma (n = 4) or liver insufficiency (n = 2).

CONCLUSIONS

This preliminary study suggests the efficacy of microwave coagulation therapy, including safety and potential curability, in patients with hepatocellular carcinoma with advanced liver cirrhosis and multifocal or central tumors.

Strange hemodynamic attractor parameter with 1/R total artificial heart automatic control algorithm

To evaluate the automatic control algorithm of the total artificial heart (TAH) as an entity, and not just as parts, a non-linear mathematical analyzing technique including chaos theory was utilized. Chronic experiments on the biventricular bypass type artificial heart implantation were performed in healthy adult goats after the natural ventricles were removed. Hemodynamic time series data were recorded under the awake standing condition with TAH 1/R and fixed driving. Time series data were recorded on a magnetic tape and analyzed on a personal computer system with an A-D converter. Using the nonlinear mathematical technique, the time series data were embedded into the phase space and the Lyapunov numerical method was carried out for the quantitative evaluation of the sensitive dependence on the initial condition of the reconstructed attractor. Calculation of the largest Lyapunov exponents suggested that the reconstructed attractor of the left pump output during TAH 1/R control was a larger dimensional strange attractor, a characteristic pattern of deterministic chaos. A total system indicating chaotic dynamics was thought to be a flexible and intelligent control system. Thus, our results suggest that 1/R TAH control may be suitable for the biventricular assist type total artificial heart.

Therapeutic efficacy of an antineutrophil monoclonal antibody, Urge-8, against acute necrotizing pancreatitis in rats

BACKGROUND

Although they have critical roles in the defense mechanism against invading microorganisms, neutrophils may facilitate exacerbation of critical conditions associated with acute necrotizing pancreatitis by a discharge of granule contents into the organ tissues. Because of this constitution of neutrophils, the therapeutic efficacy of Urge-8, a mouse monoclonal antibody to neutrophils, on the survival of rats with experimentally induced acute necrotizing pancreatitis was investigated in vivo.

METHODS

Acute pancreatitis was induced by injection of trypsin mixed with sodium chenodeoxycholic acid into pancreatic ducts. Urge-8 was infused intravenously 30 minutes after pancreatitis was induced, a series of vital signs was taken, and plasma amylase level was estimated.

RESULTS

Hemorrhagic necrosis of the pancreas and intraabdominal bleeding were observed 1 hour after the pancreatitis-inducing drugs were injected, and death occurred at 240.9 +/- 24.6 minutes (mean +/- SD)in the control group. With Urge-8 administration, however, the survival time was significantly prolonged to 395.2 +/- 64.4 minutes (p = 6.0 x 10-(10) versus control). Failure in the vital signs (mean arterial pressure, heart rate, and body temperature) was significantly ameliorated by injection of Urge-8. The plasma amylase level was elevated after pancreatitis was induced and peaked at 3 hours (4915 +/- 1966 IU/L in mean +/- SD). This level was suppressed during the first 3 hours by injection of Urge-8 (3372 +/- 1223 IU/L); however, the amylase level increased thereafter, becoming comparable with the peak in the control group, and then death occurred. Arterial blood gas and plasma electrolyte analyses showed that pH, base excess, and plasma potassium levels in the group treated with monoclonal antibody were significantly improved.

CONCLUSIONS

It was suggested that neutrophils play some critical role in the exacerbation of acute necrotizing pancreatitis and its related symptoms. Although not capable of preventing death in our model, treatment with the antineutrophil monoclonal antibody Urge-8 after the onset of acute pancreatitis prolonged the survival time significantly.

Isolation of alkaline phosphatase-positive gingival fibroblasts from patients with chronic inflammatory periodontal disease

We have reported recently that increased expression of membrane alkaline phosphatase (ALP) activity is a phenotypical characteristic of gingival fibroblasts located in chronic inflammatory periodontal lesions. To understand the cellular properties of these cells, we isolated ALP-positive gingival fibroblasts from patients with adult periodontitis and evaluated their proliferative potential. Using an enzymatic digestion procedure, we prepared gingival cell suspensions containing ALP-positive fibroblasts without affecting their ALP activities. These cell suspensions were then subjected to 1 g sedimentation, followed by allowing cells to adhere to substrata. Using this procedure, 71.9% of isolated cells were ALP-positive. Dissociation of ALP-positive fibroblasts and contamination by non-fibroblastic cells were examined by cytochemical and immunocytochemical analyses. The proliferative capacity of ALP-positive fibroblasts in culture was assessed by monitoring the proportion of ALP-positive cells after repeated subculture passages and by labelling DNA-synthesizing cells with bromodeoxyuridine (BrdU). The proportion of ALP-positive fibroblasts decreased during cell culture passages without an apparent change in the ALP-positive phenotype. The percentage of BrdU-positive cells was significantly lower among ALP-positive than among ALP-negative fibroblasts. These results indicate that ALP-positive fibroblasts in chronic inflammatory periodontal lesions have low growth potential. We suggest that their reduced capacity to grow in vitro reflects a more differentiated state induced under inflammatory conditions in vivo.

Spontaneous antibody-secreting cells in the stomach of gastric cancer patients

The gastric mucosa has been regarded as an active site of humoral immunity since the discovery of Helicobacter pylori. The present study was conducted to determine the in vivo activity of gastric B cells in 53 gastric cancer patients. B-cell activity was measured by protein-A plaque assay, in which IgA-, IgM-, and IgG-plaque-forming cells (PFC) were counted. The number of PFC was associated with the stage of cancer, but the response of lymphocytes in a non-tumorous area (NML) and tumor-infiltrating lymphocytes (TIL) differed. PFC in both sites were decreased compared to n0 cancer in n1 lymph node metastasis-positive cancer, while only NML showed raised PFC in n2 + (P < 0.05, vs TIL). Cancer cells penetrating the submucosa caused the PFC of TIL (but not of NML) to decrease. Invasion of the intratumor capillary (V) or lymphatic (Ly) vessels also caused PFC to change, showing differences of Ig class; there was a decrease of PFC in V2 (IgG- and IgM-PFC) and in Ly2 (all Ig-PFC). IgA-PFC in Ly1 differed in TIL (decrease of PFC) and NML (increase). PFC also differed in TIL and NML in cancer cells, as follows: TIL < NML in tubular and poorly differentiated adenocarcinoma and TIL > NML in papillary and signet ring cell adenocarcinoma. Changes in lymph node (LNL) and blood lymphocytes were similar to those in gastric PFC whose IgA value was 10 times as much as that of LNL. The 5-year survival rate was significantly better in patients with lower rather than higher PFC such as 89% vs 68%. Gastric B cells thus appear to be active and to reflect gastric mucosal immunity.

[Changes in the working status of pulmonary tuberculosis patients after the admission]

We reported changes in the working status of pulmonary tuberculosis patients after the admission to our hospital. The age of patients ranged from 20 to 69 years old, and they were admitted to the 18th ward of our hospital from April 1991 to March 1993. We sent out the questionnaire to 198 patients, and the reply was sent back from 116 patients (Male 74, Female 42). Out of the 116 patients, we excluded the unemployed, the government employees, and self-employed workers. The remaining 76 patients were examined about their working status after admission, and the results were as follows: 2 patients lost their work, 11 patients retired from the work, 2 patients faced the drop of their position, and 3 patients had their salary reduced.

Levels of soluble cell adhesion molecules in patients with dyslipidemia

BACKGROUND

Increased expression of cell adhesion molecules (CAMs) on the vascular endothelium has been postulated to play an important role in atherogenesis. Both in vitro and in vivo studies have suggested that dyslipidemia may increase expression of CAMs.

METHODS AND RESULTS

To determine whether dyslipidemia is associated with increased expression of CAMs, we examined the levels of soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), and soluble E-selectin (sE-selectin) in individuals with either hypercholesterolemia or hypertriglyceridemia and in control subjects matched for age and sex. Patients with hypertriglyceridemia had significantly higher levels of sVCAM-1 (739 +/- 69 ng/mL) compared with patients with hypercholesterolemia (552 +/- 63 ng/mL) and control subjects (480 +/- 56 ng/mL). Levels of sICAM-1 were significantly increased in both the hypercholesterolemic and hypertriglyceridemic groups (298 +/- 29 and 342 +/- 31 ng/mL, respectively) compared with the control group (198 +/- 14 ng/mL). Levels of sE-selectin were significantly increased in hypercholesterolemic patients (74 +/- 9 ng/mL) compared with control subjects (48 +/- 5 ng/mL). Ten hypercholesterolemic patients were treated aggressively with atorvastatin alone or a combination of colestipol and either atorvastatin or simvastatin for a mean of 42 weeks and had an average LDL cholesterol reduction of 51%. Comparison of soluble CAMs before and after treatment showed a significant reduction only in sE-selectin (77 +/- 11 versus 56 +/- 6 ng/mL, P < or = .03) but not for sVCAM-1 or sICAM-1.

CONCLUSIONS

Although severe hyperlipidemia is associated with increased levels of soluble CAMs, aggressive lipid-lowering treatment had only limited effects on the levels. Increased levels of soluble CAMs in patients with hyperlipidemia may be a marker for atherosclerosis.

Purification of a novel UV-damaged-DNA binding protein highly specific for (6-4) photoproduct

UV damage-specific binding proteins are considered to play important roles in early responses of cells irradiated with UV, including damage recognition in the DNA repair process. We have surveyed nuclear and cytoplasmic proteins which bind selectively to UV-irradiated DNA using an electrophoretic mobility shift assay. We detected four distinct binding activities with different mobilities in fractions separated from HeLa cells by heparin chromatography. Three of them were found in nuclear extracts and one in cytoplasmic extracts. We purified one of the binding factors from nuclear extracts to homogeneity, which was designated NF-10 (the 10th fraction of nuclear extract on heparin chromatography). It migrated as a 40 kDa polypeptide in SDS-PAGE, and bound to UV-irradiated double- stranded DNA but not to unirradiated DNA. The binding pattern of the NF-10 protein to DNA irradiated with UV corresponded to the induction kinetics of (6-4) photoproduct. Removal of (6-4) photoproducts from UV- irradiated DNA by (6-4) photoproduct-specific photolyase diminished the binding of NF-10 protein. These results suggest that the NF-10 protein binds to UV-damaged DNA through (6-4) photoproduct. Immunoblot analysis using a monoclonal antibody revealed that the NF-10 protein was expressed in cell lines from all complementation groups of xeroderma pigmentosum, indicating that the NF-10 protein is a novel UV-damaged-DNA binding protein.

Vasodilation induced by vasopressin V2 receptor stimulation in afferent arterioles

We have previously reported that vasopressin (AVP) V2 receptor stimulation increased renal blood flow in dogs anesthetized with pentobarbital. In this study, we examined the direct effects of AVP on afferent arterioles to clarify the role played by V2 receptors in regulating afferent arteriolar tone. We microdissected a superficial afferent arteriole with glomerulus from the kidney of a New Zealand White rabbit. Each afferent arteriole was cannulated with a pipette system and microperfused in vitro at 60 mm Hg. The effects of vasoactive substances were evaluated by changes in the lumen diameter of afferent arterioles. We found that AVP decreased the lumen diameter of microperfused afferent arterioles dose-dependently and that a V1 antagonist, OPC21268, inhibited the vasoconstrictor action of AVP. However, AVP 10(-8) M increased the lumen diameter of norepinephrine (NE)-constricted afferent arterioles pretreated with OPC21268 (OPC + NE, 8.2 +/- 0.7 microns; OPC + NE + AVP, 9.9 +/- 0.9 microns*; *P < 0.05, N = 13). This vasodilatory effect of AVP was abolished by pretreatment with a V2 antagonist, OPC31260. Desmopressin (dDAVP), a V2 agonist, increased the lumen diameter of the NE-constricted afferent arterioles (NE, 7.4 +/- 0.9 microns; NE + dDAVP, 10.1 +/- 0.7 microns*; *P < 0.05, N = 9). These results suggest that AVP V2 receptors are present in rabbit afferent arterioles and that V2 receptor stimulation induces vasodilation in rabbit afferent arterioles.

Advantage of in vivo chemosensitivity assay to detect vincristine-resistance in a human epidermoid carcinoma xenograft

We examined both in vitro and in vivo chemosensitivity of the human epidermoid carcinoma xenograft xeKB3-1-R which shows overexpression of the multidrug resistance gene (MDR1). XeKB3-1-R was sensitive to vincristine (VCR, 6%) and doxorubicin (DOX, 9%) in the adhesive tumor cell culture system in vitro. However, this xenograft showed decreased sensitivity to VCR (65%) and DOX (42%) in an in vivo chemosensitivity assay. The in vivo resistance of xeKB3-1-R to both VCR and DOX was reversed by coadministration of cyclosporin A (VCR 22%, DOX 11%). The xenograft xeKB3-1-R expressed significantly higher levels of MDR1 than xeKB3-1. The results confirmed that multidrug resistance in xeKB3-1-R was related to enhanced MDR1 expression in vivo. The observed discrepancies between in vitro and in vivo chemosensitivities suggest that the in vivo sensitivity assay more accurately reflects drug resistance as a result of low-level MDR1 overexpression in solid tumors.

[Amrinone (50 micrograms.kg-1.min-1) does not impair regional myocardial tissue metabolism during the 40%-decrease of left anterior descending coronary flow]

We investigated the effects of amrinone on metabolism of regional myocardial tissue during the 40%-decrease of left anterior descending coronary (LAD) flow in anesthetized dogs. Fourteen adult mongrel dogs weighing 15.4 +/- 5.1 kg were anesthetized with 0.5% isoflurane in 50% oxygen and ventilated mechanically to maintain normocapnia. After thoracotomy, regional myocardial tissue PO2 was measured using a monopolar polarographic needle electrode inserted in the myocardium. Electromagnetic blood flow probes were placed around LAD and circumflex artery. A 23-gauge catheter was inserted into a coronary vein which runs along LAD to obtain coronary venous blood for measuring oxygen content, lactate and pyruvate. A variable constrictor was placed distal to the flow-probe. After decreasing LAD flow for 40%, cardiac index (CI) decreased. Systemic venous resistance was decreased and CI was increased by amrinone (50 micrograms.kg-1.min-1) infusion. Myocardial tissue oxygen tension, venous lactate, lactate extraction, lactate-pyruvate ratio and excess lactate were all unchanged by amrinone. In conclusion, amrinone does not impair myocardial aerobic metabolism and increases CI under the stenosis of coronary artery.

A percutaneously accessible pulsatile left ventricular assist device: modified assist device type 5

To provide percutaneous access, a new circulatory assist system was developed. We call this newly developed system the modified assist device (MAD). The system is composed of a sac-type blood pump and cannula. Inflow and outflow valves are mounted in the apex and at the side wall 10 cm from the apex of the cannula, respectively. During systole, the blood is sucked from the left ventricle through the inflow valve of the cannula connected to the blood pump, and during diastole, the blood is ejected to the root of the aorta through the outflow valve. In vitro and in vivo evaluations of the pump performance were performed. The maximum flow rate of 1.9 L/min was obtained in the mock circulatory system. In our animal experiment, effective systolic unloading and diastolic augmentation were observed by activation of this system during regular sinus rhythm. In conclusion, the MAD-5 is thought to be percutaneously accessible and increases systemic and coronary flow.

Calcium sensitization in perfused beating guinea pig heart by a positive inotropic agent MCI-154

We investigated the effects of MCI-154, a positive inotropic agent that increases the myofilament response to Ca++, on Ca++ transients, left ventricular (LV) function and phosphodiesterase (PDE) III activity of guinea pig heart, and compared them with the effects of pimobendan and milrinone. In Langendorff guinea pig hearts loaded with a fluorescent Ca++ probe indo-1, LV pressure and Ca++ transient were measured simultaneously. MCI-154 (10(-10)-10(-6) M) increased LV developed pressure, +dP/dt and -dP/dt with a reduction of LV end-diastolic pressure, although it did not affect coronary flow. The positive inotropic activity of MCI-154 was more potent than that of pimobendan and milrinone; EC50 values (concentrations for increasing +dP/dt by 50% from base line) were 4.31, 41.5 and 294 x 10(-9) M, respectively. The positive inotropic effect of MCI-154 was accompanied by the increase in systolic, diastolic and amplitude of indo-1 fluorescence ratio. The relative increase in Ca++ transients against the increase in LV contractility produced by MCI-154, however, was significantly less than that by increasing perfusate [Ca++], pimobendan or milrinone. MCI-154 (3 x 10(-7)-10(-4) M) inhibited the activity of PDE III isolated from guinea pig LV tissues, but the inhibitory effect of MCI-154 was less than pimobendan and milrinone; IC50 values were 10.1, 3.5 and 2.4 x 10(-6) M, respectively. These findings suggest that MCI-154 exerts a positive inotropic effect mainly through Ca(++)-sensitizing action in intact beating whole hearts.

Feasibility of fluorine-18-fluorophenylalanine for tumor imaging compared with carbon-11-L-methionine

L-[methyl-11C]methionine (11C-Met) is a useful tracer for tumor imaging with PET. The drawbacks include a short half-life and high physiological accumulation in abdominal organs. To overcome these shortfalls, the feasible use of [18F]fluorophenylalanine (18F-Phe), which shares the same amino acid transport system with Met, for tumor imaging was examined.

METHODS

The time course of tissue distribution of 18F-Phe and the tumor uptake response to radiotherapy were compared with 14C-Met and [3H] thymidine (3H-Thd) in the rat AH109A tumor model. Intratumoral distribution of 18F-Phe was compared with 14C-Met and 14C-Thd using double-tracer macroautoradiography (ARG). We also evaluated whole-body ARG.

RESULTS

Tumor uptake of 18F-Phe peaked at 60 min postinjection and was higher than that of the liver, intestine and kidney but lower than the pancreas. Tumor uptake of 18F-Phe was similar to that of 14C-Met. Tumor-to-blood and tumor-to-muscle ratios were higher in 14C-Met compared with that of 18F-Phe because of the rapid blood clearance of 14C-Met. With whole-body ARG, the tumor was clearly visualized with high contrast. Radiotherapeutic response of tumor uptake of 18F-Phe was as rapid as that with 14C-Met and with 3H-Thd. Intratumoral distribution of 18F-Phe and 14C-Met were identical, and 18F-Phe and 14C-Thd were similar.

CONCLUSION

Fluorine-18-Phe seems to be a potentially useful amino acid tracer for tumor imaging with a longer half-life than 11C, with higher tumor contrast in the abdomen than Met and a similar sensitive response to radiotherapy.