Use of bare-mounted Palmaz-Schatz stents employing the stent saddle technique on the delivery balloon: a single center experience

The major limitations of the Palmaz-Schatz stent stem from the design of its stent delivery system (SDS). The SDS is bulky and has poor trackability in lesions with proximal tortuosity and/or vessel calcification. The use of bare-mounted Palmaz-Schatz stents on low profile balloons represents an alternate approach for lesions that are not accessible for stenting with the SDS. Thus we evaluated the indications, procedural success rate, and in-hospital complications of patients undergoing bare stenting at a single center between 1 October 1995 through 30 September 1996. A total of 363 coronary interventions were performed during this period, including coronary stenting in 194 vessels. In 18 of these 194 vessels, bare-mounted Palmaz-Schatz stents were used. The indications for bare stenting were: inability to deliver the Palmaz-Schatz stent on SDS for suboptimal angioplasty results or acute/threatened abrupt closure; use of half stents; stenting in vessels < 3.0 mm; intermediate disease in the proximal segment that would have precluded optimal visualization of stent placement; and use of guides 7 French or smaller. Bare stenting was successful in 15 of the 18 patients (vessels) in whom it was attempted. There were no deaths, myocardial infarctions, stent thrombosis, repeat interventions, or significant bleeding in patients with successful bare stent delivery. The stents were successfully retrieved in the three patients in whom the stent could not be advanced into the target coronary segment. One of these patients had a propagated spiral dissection prior to attempts at bare stenting and required emergent bypass surgery. The remaining two patients with failed deployment had suboptimal angioplasty results but had an uncomplicated hospital course. Thus bare stenting represents an alternate percutaneous approach to tackle suboptimal procedural results and/or complications in patients who have failed stent deployment with the standard sheathed stent delivery system currently available in the United States.

Zinc status of breastfed and formula-fed infants of different gestational ages

Zinc status in 186 full term and preterm infants was determined at birth, and 3, 6, 9, and 12 months of age along with determination of zinc levels in breast or formula milk to find out if routine zinc supplements are needed during infancy. The leukocyte and plasma zinc levels in all breastfed infants were high at birth and gradually declined reaching lowest values by 4-6 months of age, and improved to normal levels by 9 months following weaning. The preterm infants however, had significantly (P < 0.05) higher leukocyte zinc (213.6 +/- 46.91 micrograms/10(10) cells) at birth compared to term infants. Colostrum of all the mothers had higher zinc concentrations which declined to significantly lower levels in breastmilk by 4-6 months of lactation, corresponding to the age when the breastfed infants had lower zinc levels. The improvement of the levels to normal after weaning suggests that the fall in zinc status during early infancy could be a transient phenomenon which could be reversed by proper weaning, thus strengthening the plea for timely food supplements rather than the need for single nutrient supplements. Formula-fed full term infants had significantly lower leukocyte zinc levels (49.3 +/- 2.59 micrograms/10(10) cells) at 3 months of age compared to breastfed infants of the same age (92.8 +/- 14.04 micrograms/10(10) cells). Even these infants improved their zinc status after weaning on par with breastfed infants. The functional significance of their transient, but low zinc values during early infancy needs to be investigated.

High dose rate intracoronary radiation for inhibition of neointimal formation in the stented and balloon-injured porcine models of restenosis: angiographic, morphometric, and histopathologic analyses

PURPOSE

We examined the effects of intracoronary irradiation delivered at a high dose rate on neointimal hyperplasia after injury induced by two methods: balloon overstretch injury, and stent implantation in a porcine model of coronary restenosis.

METHODS AND MATERIALS

In 34 Hanford miniature swine, a segment of each coronary artery was targeted for injury and treatment. The artery segments were treated with 192Ir at doses of 10 Gy over 4 min (eight animals), 15 Gy over 6 min (nine animals), 25 Gy over 10 min (nine animals) or control (simulation wire only; eight animals). The treated segments were subjected to stent implantation (left anterior descending and right coronary artery) or balloon overstretch (circumflex) injury. Twenty-eight days later, repeat coronary angiography and sacrifice were done. Quantitative coronary angiography, morphometry, and extensive histopathologic analyses were carried out in a blinded fashion.

RESULTS

The change in minimal lumen diameter from postinjury to presacrifice in the stent-injured left anterior descending was -0.79 +/- 0.34 (mean: +/- SD) mm in the control group, compared to -0.43 +/- 0.35 mm in the 15 Gy (p = 0.04) and -0.21 +/- 0.50 mm in the 25 Gy (p = 0.01) groups; and in the balloon-injured circumflex was -0.31 +/- 0.22 mm in the control group compared to -0.03 +/- 0.18 mm in the 10 Gy (p = 0.05) and 0.00 +/- 0.33 in the 15 Gy (p = 0.01) groups. Percent area stenosis in the left anterior descending was 36 +/- 9% in the control group compared to 18 +/- 12% in the 15 Gy (p = 0.003) and 11 +/- 11% in the 25 Gy (p < 0.001) groups; and in the circumflex was 16 +/- 10% in the control groups, compared to 5 +/- 5% in the 15 Gy (p = 0.02) and 2 +/- 2% in the 25 Gy (p = 0.009) groups. Histopathology showed a striking reduction in the amount of neointima in the irradiated arteries compared with control vessels. Other radiation effects were stromal fibrin exudate, thinning of the media, and adventitial fibrosis and leukocyte infiltration in the radiated arterial segments.

CONCLUSIONS

High dose rate intracoronary irradiation with 192Ir effectively inhibits intimal proliferation after stent-induced as well as balloon-overstretch injury. This shorter treatment time (4 to 10 min) may provide a clinically practical approach to the prevention of restenosis after angioplasty.

Effect of factor Xa inhibitors on thrombin formation and complement and neutrophil activation during in vitro extracorporeal circulation

BACKGROUND

Even when large doses of heparin are administered during cardiopulmonary bypass, thrombin is produced. Thrombin is a powerful protease that is associated with the thrombotic and bleeding complications of open heart surgery and is produced by cleavage of prothrombin by factor Xa. This study assessed the ability of a specific inhibitor of factor Xa, recombinant tick anticoagulant peptide (rTAP), alone or in combination with standard heparin and a low-molecular-weight heparin, enoxaparin, to suppress thrombin formation and activity during in vitro extracorporeal circulation.

METHODS AND RESULTS

Fresh, anticoagulated human blood was recirculated for 2 hours in an extracorporeal membrane oxygenator perfusion circuit at 37 degrees C. Four anticoagulant protocols were evaluated; porcine heparin (3.75 U/mL); enoxaparin (17.5 U/mL); rTAP (4 mumol/L); and porcine heparin plus rTAP (2 mumol/L). Blood samples were obtained for analysis from the donor, after anticoagulation, and after 5, 30, 60, and 120 minutes of recirculation. There were no significant differences between groups in platelet count, response to adenosine diphosphate, or prothrombin fragment (F1.2) production. rTAP plus heparin reduced beta-thromboglobulin release; fibrinopeptide A concentrations were significantly higher with rTAP alone. Enoxaparin strongly and significantly inhibited complement C5b9 production and neutrophil elastase release and was associated with significantly increased concentrations of C1-C1 inhibitor and kallikrein-C1 inhibitor complexes.

CONCLUSIONS

rTAP does not reduce thrombin formation or activity during in vitro extracorporeal circulation. Enoxaparin markedly inhibits formation of the complement membrane attack complex and neutrophil elastase release, possibly by accelerating C1 inhibitor activity.

Further evidence of bradykinin involvement in septic shock: reduction of kinin production in vivo and improved survival in rats by use of polymer tailored SBTI with longer t1/2

Involvement of bradykinin in septic shock and its therapeutic endeavor using soybean trypsin inhibitor (SBTI, Kunitz type) were investigated in an in vivo model of septic shock induced by pseudomonal elastase. Pseudomonal elastase injection at 0.5 mg/kg i.v. to guinea pigs resulted in elevation level of bradykinin in the blood from < 1 ng/ml to 25 ng/ml which was accompanied by a drop of mean arterial blood pressure (MABP) (about 45 mmHg). When native soybean trypsin inhibitor (SBTI, Kunitz type, 20 kDa) was injected, into this model, induction of bradykinin generation and hypotension by the bacterial protease treatment was completely obliterated as judged by the both levels of bradykinin and MABP. Specifically, by the treatment with SBTI, bradykinin levels did not increase and the drop of the blood pressure was minimal (< 10 mmHg) in this time frame (< 30 min). We designed and prepared succinylated gelatin-conjugated SBTI (suc-gel SBTI) with enlarged molecular mass (M(r) approximately 110,000) and higher area under the curve of the plasma concentration, which exhibits about 6 times longer plasma half-life (t1/2) and about 4 times larger area under the curve of plasma concentration. Suc-gel-SBTI suppressed the pseudomonal protease-induced shock much more effectively than native SBTI, the conjugate exhibited its effect for more than 3 h, while the native SBTI showed the effect only within 2 h after i.v. injection.

Neutrophil adhesion on surfaces preadsorbed with high molecular weight kininogen under well-defined flow conditions

The adhesion of neutrophils and other leukocytes to biomaterial surfaces is an important phenomenon in the host response to biomaterials because the number of adherent leukocytes is often related to the inflammatory response after implantation. After adhering to biomaterial surfaces, other leukocyte reactions, such as phagocytosis, respiratory burst, and protease release, may occur and result in the deterioration of the implanted biomaterial and injury to peripheral tissue. This study of neutrophil adhesion quantitatively characterizes neutrophil adhesion under well-defined laminar flow conditions using a radial flow chamber. In this rheologically well-defined system, the fluid shear rate on the surface varies continuously with radial position. This allows the study of shear-dependent behavior of neutrophil adhesion. Exploiting the variable shear rate in the radial flow chamber, the kinetics of neutrophil adhesion was obtained using automated video microscopy and image analysis to recursively acquire cell counts from multiple fields in different radial positions, and to quantify the surface density of neutrophil as a function of time. Neutrophil adhesion was studied on glass preadsorbed with fibrinogen and high-molecular-weight kininogen (HK). At a shear rate of 20 s-1, the number of adherent cells on the preadsorbed fibrinogen surface was similar to that on bare glass, and the number of adherent cells on the HK surface was less than 10% of that on the bare glass. We conclude that surfaces preadsorbed with HK are anti-adhesive to neutrophils.

Parasuicide in Pakistan: experience at a university hospital

There have been few reports of parasuicide from Pakistan, where the act is considered to be a criminal offence and the Islamic religion strongly disapproves of it. In order to address the problem, a retrospective case report analysis of all index cases of parasuicide presenting over a period of 3.5 years to a university hospital in Karachi, Pakistan, was undertaken. Our results showed that most of the subjects were young adults, with married women representing the single largest group. Self-poisoning with medication was the most common method, and benzodiazepines the most frequently used drug. Interpersonal conflict with the opposite sex was the most common precipitating cause. In Pakistani culture, marriage appears to be a significant source of stress for women. Reports based on official police records do not reflect the true picture of the problem in Pakistan.

Phosphodiesterase inhibitors suppress proliferation of peripheral blood mononuclear cells and interleukin-4 and -5 secretion by human T-helper type 2 cells

It has been suggested that interleukin-4 and -5 (IL-4 and IL-5) are instrumental in the control of allergic disease. Elevated levels of IL-4 messenger RNA (mRNA) have been detected in numerous foci of atopic activity, including bronchoalveolar lavage (BAL) fluid from atopic asthmatics and skin of atopic dermatitis patients. IL-5 is important in eosinophil activation, which is a common feature of atopic disease. IL-5 mRNA has been detected in BAL fluid from both atopic and non-atopic asthmatics, indicating that IL-5 may be a common feature of the two disease states. Production of IL-4 and IL-5 by T cells appears to be associated with a high affinity cyclic AMP (cAMP) phosphodiesterase (PDE). This study was designed to compare the effects of PDE inhibitors Ro20-1724 and theophylline on (1) the mitogenic response of peripheral blood mononuclear cells from atopic and non-atopic individuals and (2) secretion of IL-4 and IL-5 by TH(2) cells after activation with PMA and anti-CD3. Both Ro20-1724 and theophylline inhibited proliferation of PBMC in a dose-dependent manner. There was no significant difference between proliferation of PBMC from atopic versus non-atopic donors, but Ro20-1724, a specific PDE IV inhibitor, was more potent at a concentration of 10(-5)M than theophylline in suppressing lymphocyte proliferation. Similarly, both PDE inhibitors suppressed secretion of IL-4 and IL-5 from TH(2)-like cell lines in a dose-dependent manner. In conclusion, as Ro20-1724 and theophylline inhibit proliferation of PBMC and secretion of IL-4 and IL-5 from human TH(2) cell lines, the development of a selective cyclic nucleotide PDE IV inhibitor may provide a promising new approach for asthma prophylaxis.

Surface-bound heparin fails to reduce thrombin formation during clinical cardiopulmonary bypass

The hypothesis that heparin-coated perfusion circuits reduce thrombin formation and activity; fibrinolysis; and platelet, complement, and neutrophil activation was tested in 20 consecutive, randomized adults who had cardiopulmonary bypass. Twenty identical perfusion systems were used; in 10, all blood-contacting surfaces were coated with partially degraded heparin (Carmeda process; Medtronic Cardiopulmonary, Anaheim, Calif.). All patients received a 300 U/kg dose of heparin. Activated clotting times were maintained longer than 400 seconds. Cardiopulmonary bypass lasted 36 to 244 minutes. Blood samples for platelet count, platelet response to adenosine diphosphate, plasma beta-thromboglobulin, inactivated complement 3b, neutrophil elastase, fibrinopeptide A, prothrombin fragment F1.2, thrombin-antithrombin complex, tissue plasminogen activator, plasminogen activator inhibitor-1, plasmin alpha 2-antiplasmin complex, and D-dimer were obtained at these times: after heparin was given, 5 and 30 minutes after cardiopulmonary bypass was started, within 5 minutes after bypass was stopped, and 15 minutes after protamine was given. After cardiopulmonary bypass, tubing segments were analyzed for surface-adsorbed anti-thrombin, fibrinogen, factor XII, and von Willebrand factor by radioimmunoassay. Heparin-coated circuits significantly (p < 0.001) reduced platelet adhesion and maintained platelet sensitivity to adenosine diphosphate (p = 0.015), but did not reduce release of beta-thromboglobulin. There were no significant differences between groups at any time for fibrinopeptide A, prothrombin fragment F1.2, or thrombin-antithrombin complex or in the markers for fibrinolysis: D-dimer, tissue plasminogen activator, plasminogen activator inhibitor-1, and alpha 2-antiplasmin complex. In both groups, concentrations of prothrombin fragment F1.2 and thrombin-antithrombin complex increased progressively and significantly during cardiopulmonary bypass and after protamine was given. Concentrations of D-dimer, alpha 2-antiplasmin complex, and plasminogen activator inhibitor-1 also increased significantly during bypass in both groups. Fibrinopeptide A levels did not increase during bypass but in both groups increased significantly after protamine was given. No significant differences were observed between groups for levels of inactivated complement 3b or neutrophil elastase. Radioimmunoassay showed a significant increase in surface-adsorbed antithrombin on coated circuits but no significant differences between groups for other proteins. We conclude that heparin-coated circuits used with standard doses of systemic heparin reduce platelet adhesion and improve platelet function but do not produce a meaningful anticoagulant effect during clinical cardiopulmonary bypass. The data do not support the practice of reducing systemic heparin doses during cardiac operations with heparin-coated extracorporeal perfusion circuitry.

Primary corneal graft failure. A national reporting system. Medical Advisory Board of the Eye Bank Association of America

OBJECTIVES

To describe a national eye banking registry and to assess the effects of donor age, cause of donor death, time from death to procurement, storage time, and distance between the points of recovery and transplantation on the reported occurrence of primary corneal graft failure.

DESIGN

We performed a retrospective case-control study to estimate the odds ratios of five donor factors for cases of primary graft failure voluntarily reported to a national registry using controls from selected eye banks. We also performed a nested case-control cohort study to compare cases of primary graft failure that occurred in both corneas from the same donor with those of nonmated corneas in which primary graft failure was reported to assess odds ratios for the same donor factors.

PATIENTS

One hundred forty-seven patients developed primary graft failure in penetrating keratoplasty transplantations performed between January 1, 1991, and December 31, 1993. These cases were reported to the Adverse Reaction Registry of the Eye Bank Association of America, Washington, DC. Controls included 7240 donor corneas distributed by nine eye banks during 1992.

RESULTS

Of the 147 donor corneas that developed primary graft failure, 17 (12%) were obtained from donors who were aged 70 years and older, 39 (27%) came from donors who died of trauma, 13 (9%) had a cadaver time longer than 12 hours, 10 (7%) had a storage time longer than 7 days, and 38 (26%) were distributed outside the eye bank's region. Compared with controls, these donor corneas were more likely to have a storage time longer than 7 days (odds ratio, 2.4; 95% confidence limits, 1.2 and 4.6) and to come from donors aged 70 years and older (odds ratio, 2.4; 95% confidence limits, 1.4 and 4.0). The 22 corneas (15%) in which primary graft failure occurred in both recipients from the same donor were 8.5 times (95% confidence limits, 1.1 and 51.5) more likely to be preserved beyond 1 week than were nonmated corneas with primary failure but were not from significantly older donors. Logistic regression analysis showed that the association between prolonged storage time and primary graft failure in mated corneas remained significant even when the analysis was controlled for other donor factors.

CONCLUSIONS

No clearly defined donor or eye banking factor accounted for most cases of primary graft failure, although prolonged corneal storage and advanced donor age may increase its risk. Ophthalmologists are urged to report to their eye bank all cases of primary graft failure and other adverse events that might be attributable to donor eye tissue.

An eye banking program for selecting donor corneas for surgical distribution

Since fewer donated corneas have become available for surgery, we sought to chart the reasons to exclude them for surgical use over time. Those excluded from surgical use (1991-1994) were plotted using an algorithm based on the reasons for exclusion. Four general categories (universal contraindications [UC], national/local medical criteria [NLMC], serology, and morphology) yielded 13 possible areas. UC and NLMC exclusions for 1993-1994 were higher compared with 1991 and 1992 (p < 0.001). The proportion of corneas excluded for serological reasons decreased (p < 0.001) from 1991 to 1994. Exclusions due to morphology remained the same for all 4 years (p = NS). NLMC eliminate older donors but also exclude younger donors before the tissue reaches the eye bank (p > 0.001). Three of four of the youngest tissues ( < 30 years) are used for surgery, whereas one of five of the oldest ( > 70 years) is used. A quality control algorithm provides a heuristic and logical paradigm for noting changes from year to year. Heightened regulation has counteracted many gains in corneal donation fostered by favorable laws.

Recurrent myocardial infarction with angina and normal coronary arteries

Although it is well recognised that patients with ischemic heart disease can have normal coronary arteries on coronary angiography, most such patients have angina pectoris, whilst a minority have had a previous myocardial infarction. There are few reports of patients with recurrent myocardial infarctions and angina, but with normal coronary arteries on coronary angiography. We describe six patients who had more than one myocardial infarction, confirmed by raised cardiac enzymes and changes on the electrocardiogram. They subsequently developed classical angina and subsequent coronary angiography demonstrated no atherosclerotic coronary artery disease. Coronary artery spasm and diminished coronary reserve may have been contributory factors in these patients.

Capillary perfusion--a study in two groups of radiated patients for cancer of head and neck

Laser Doppler velocitometry is novel non-invasive technique to assess cutaneous microcirculation. Patients undergoing radiation therapy for head and neck cancer with convention and accelerated fraction action were evaluated under normal condition before and after radiation. A total of 70 sites in group A (conventional fractionation) and 35 sites in group B (accelerated fractionation were evaluated. Increase in perfusion was noted in patients undergoing radiation with accelerated fractionation.

Epidemiology of smallpox in west Pakistan. III. Outbreak detection and interlocality transmission. 1971

During one year, 121 outbreaks of variola major were detected in 99 of the 1717 localities within a rural area of West Pakistan with a total population of approximately 1.2 million. Only 19% of the outbreaks, representing 36% of the 1040 investigated cases, were officially reported, although potential strengths in the government surveillance system were also identified. Persistence of smallpox within the area depended on introductions from the outside, and more than one-half of all outbreaks of known source could be ultimately traced to cities. Within the study area, outbreaks with the largest numbers of cases and those in the larger communities were the ones from which smallpox was most frequently transported. The frequency with which variola was introduced into localities was directly related to population size and to the presence of medical care facilities. Trips between localities by infected individuals were extremely rare events. They were made most often during the late fall and winter, primarily during the incubation period of the disease, and did not differ in purpose, means or destination from journeys unassociated with smallpox. Individuals at relatively high risk of becoming introducers included the unvaccinated (primarily children under five), the unschooled and those not native to the area. Vaccination priorities based on these findings could increase the efficiency of smallpox eradication efforts.

Role of alpha-2-macroglobulin and bacterial elastase in guinea-pig pseudomonal septic shock

An essential role of alpha-2-macroglobulin (alpha 2M) was revealed in the prevention of septic shock induced in guinea-pigs by an elastase producing strain (IFO-3455) of Pseudomonas aeruginosa. When bacterial peritonitis was induced by inoculating fibrin-thrombin clot containing viable bacteria at a dose of 10(9) c.f.u./kg body weight, the guinea-pigs (n = 6) died within 7-8 hours due to septic shock. Prior to the shock, consumption of two-thirds of the circulating alpha 2M was observed. When circulating alpha 2M was depleted 4 hours after the bacterial inoculation, the guinea-pigs immediately developed shock and died within one hour. This shock was prevented either with a specific elastase inhibitor, HONHCOCH(CH2C6H5)CO-Ala-Gly-NH2, zincov (6 microM), or with human alpha 2M. Simultaneous depletion of circulating Hageman factor also prevented shock in the alpha 2M-depleted animals. These results indicate that septic shock was induced through activation of the Hageman factor dependent system by the bacteria-produced elastase which survived alpha 2M in the circulation.

Differential effects of histamine on T helper type 2 (TH2) lymphocytes

Histamine inhibits IL-4 secretion from T helper type 2 cells but enhances IL-5 secretion from the same cells. Both of these effects are mediated by H2 receptors. Not all cyclic AMP-elevating agents affect IL-4 and IL-5 secretion. The observations suggest a selective effect of histamine on TH2 lymphocytes. Furthermore, Cl- channels may be involved in histamine-mediated regulation of cytokine secretion. The data suggest that histamine-induced elevation of cyclicAMP may be an important, but probably not the sole, mechanism underlying the selective effects of histamine on cytokine production.

Esophageal countershock: anthropometric determinants of impedance

OBJECTIVE

To examine the use of a novel esophageal electrode system for countershock of atrial and ventricular tachyarrhythmias, with particular regard to the measurement of transesophageal and transthoracic impedances and their association with anthropometric variables.

METHODS

Transesophageal cardioversion was attempted during 131 episodes of arrhythmia in 105 patients (including 109 episodes of atrial fibrillation). The esophageal system also used in 29 patients undergoing electrophysiologic studies for investigation of ventricular tachyarrhythmias. Transesophageal and transthoracic impedances were estimated during passage of a high-frequency, low-amplitude current between the respective electrodes. Impedance estimates were associated with anthropometric measurements using linear regression (least-squares method).

RESULTS

In the group of patients undergoing attempted transesophageal cardioversion, the mean estimated transesophageal impedance of 52.6 +/- 11.7 omega was significantly lower than the mean estimated transthoracic impedance of 63.1 +/- 16.4 omega (n = 104, p < 0.01). For all the patients, transesophageal impedance was associated with weight, body mass index, and chest circumference (all r > or = 0.65, p < 0.01). Transthoracic impedance was associated with the same factors (all r > or = 0.55, p < 0.01).

CONCLUSION

This esophageal electrode system results in lower impedance values for countershock between the esophagus and the cutaneous cardiac apex in comparison with standard transthoracic cutaneous electrode placement. Both techniques are dependent on anthropometric factors.

Regulation of IL-4 and IL-5 secretion by histamine and PGE2

This study was designed to study the effects of autacoids on IL-4 and IL-5 secretion. IL-4 and IL-5 are secreted by TH2 cells. TH2 cells were generated by the culture of peripheral blood lymphocytes from atopic individuals in the presence of ragweed or dustmite antigen. The cloned TH2 lymphocytes were then stimulated with PMA (10 ng/ml) and alpha-CD3 (50 ng/ml) in the presence and absence of histamine (10(-4) - 10(-8)M) and PGE2 (10(-6) - 10(-8)M) for 48 hours. Other cAMP elevating agents were used as control. The supernatants were then assayed for the presence of IL-4 and IL-5 by ELISA. Both histamine and PGE2 suppressed the secretion of IL-4 in a dose dependent manner. Other cAMP elevating agents did not affect IL-4 secretion. In contrast, histamine upregulated the secretion of IL-5, whereas the effects of PGE2 on IL-5 secretion were not conclusive. Chloride channels have been implicated in the secretory processes. The effects of a chloride channel blocker, DIDS, were studied on histamine-induced suppression of IL-4 secretion. DIDS (10(-7) - 10(-12)M) abrogated the inhibitory effects of histamine on IL-4 secretion. The observations suggest that histamine may inhibit IL-4 secretion via activation of chloride channels.

Alpha-2-macroglobulin as the major defence in acute pseudomonal septic shock in the guinea-pig model

An intravenous injection of 1.2 mg/kg of Pseudomonas aeruginosa elastase induces immediate lethal shock in guinea-pigs. In the present study, alpha-2-macroglobulin (alpha 2M) was shown to be the major factor in guinea-pig plasma that inhibits the enzymatic activity of elastase in vitro. Depletion of circulating alpha 2M by injecting anti-guinea-pig alpha 2M rabbit IgG F(ab')2 rendered the animals sensitive to a dose of elastase of 0.05 mg/kg. When the alpha 2M-depleted guinea-pigs were reconstituted with human alpha 2M, this sensitivity was reversed. Lethal shock did not occur in alpha 2M-depleted animals even at an elastase dose of 0.2 mg/kg when Hageman factor was simultaneously depleted, indicating that elastase induces shock through activation of the Hageman factor-dependent system. Similar results were obtained when the culture supernatants of an elastase-producing strain, IFO-3455, were used instead of the purified elastase, whereas no cardiovascular changes occurred, even in the alpha 2M-depleted guinea-pigs, when the culture supernatants were pretreated with an elastase specific inhibitor (zincov) or when the culture supernatants of an elastase non-producing strain, PA-103 were used.

Effects of lymphokines and mitogens on a histamine derivative-induced intracellular calcium mobilization and inositol phosphate production

Histamine trifluoromethyl-toluidine derivative (HTMT), a novel immunosuppressive agent, stimulates H1, H2 and HTMT receptors in lymphocytes. HTMT receptors are different from the classical H1, H2 or H3 receptors. Stimulation of HTMT receptors results in increased intracellular concentrations of calcium ([Ca2+]i) and inositol phosphate (IP) in human peripheral blood lymphocytes. In the present study, we investigated the effects of lymphokines [interleukin-4 (IL-4), interleukin-2 (IL-2)] and other pharmacologic agents [lipopolysaccharide (LPS), phorbol 12-myristate 13-acetate (PMA)] on HTMT-induced Ca2+ and IP responses in non-rosetted cells. HTMT caused enhanced [Ca2+]i and IP responses when the cells were pretreated with IL-4. The effects of IL-4 were concentration dependent and became maximal after the cells were incubated with IL-4 for 48 hr. Inhibitors of protein synthesis, but not of RNA synthesis, blocked the effects of IL-4 on HTMT-induced responses. LPS was more potent than IL-4 in augmenting CA2+ mobilization induced by HTMT. However, the effects of LPS were not altered by inhibitors of either protein synthesis or RNA transcription. This indicated that LPS may act differently than IL-4 on the HTMT response. IL-2 and PMA did not affect HTMT-induced [Ca2+]i and IP responses. The effects of IL-4 and LPS were agonist specific. They did not affect the Ca2+ mobilization induced by PAF. The data indicate that the response to HTMT can be regulated by IL-4 and LPS. Although the in vivo importance of these receptors is not yet clear, the receptor is likely a contributor to immune and/or inflammatory regulation.