Expression of receptors for plasminogen activators on endothelial cell surface depends on their origin

Summary.  Receptors for plasminogen activators present on endothelial cell (EC) surface regulate local plasmin activity. Plasmin generation by human ECs, derived from cerebral cortex, skin and lung, iliac artery, iliac vein, aorta and coronary artery, was studied. The respective ECs were treated with recombinant tissue plasminogen activator (rt-PA) or with recombinant urokinase-type plasminogen activator (ru-PA), washed, plasminogen added and the plasmin generated then assayed. The largest amounts of plasmin were generated by cerebral ECs, under baseline conditions or after exposure to rt-PA or ru-PA ( P  < 0.0001). Exposure to rt-PA also resulted in more plasmin generation than ru-PA in the cerebral ECs ( P  < 0.0001) but not in the other ECs. Heparin enhanced plasmin generation by both rt-PA and ru-PA. Specific antibody against annexin II, a t-PA receptor, blocked plasmin generation by rt-PA. Western blotting showed higher amounts of annexin II on the cell membrane in cerebral ECs. This suggests that expression of annexin II in ECs depends on their location, being greatest in cerebral ECs. In contrast, expression of u-PA receptor was the same for all ECs. This has implications for higher risk of intracranial bleeding during thrombolytic therapy, and for a role of t-PA in neurological development and function.     

D2-40 immunohistochemistry in the differential diagnosis of seminoma and embryonal carcinoma: a comparative immunohistochemical study with KIT (CD117) and CD30.

The distinction between seminoma and embryonal carcinoma based on morphology alone can sometimes be problematic, requiring the use of immunohistochemistry to facilitate diagnosis. D2-40 is a monoclonal antibody that reacts with an oncofetal antigen expressed by fetal germ cells and testicular germ cell tumors. The diagnostic value of D2-40 immunohistochemistry in distinguishing seminoma from embryonal carcinoma has not been determined. D2-40 immunoreactivity was evaluated in a series of testicular germ cell tumors and compared with that of KIT (CD117) and CD30, to assess the relative utility of this marker in discriminating between seminoma and embryonal carcinoma. Forty testicular germ cell neoplasms were examined, which included 19 seminomas, three embryonal carcinomas, three teratomas, one yolk sac tumor, and 14 mixed germ cell tumors. The 14 cases of mixed germ cell tumors contained components of seminoma (n=7), embryonal carcinoma (n=11), teratoma (n=10), yolk sac tumor (n=2), and choriocarcinoma (n=1). All cases of pure seminoma and the seminomatous components of mixed germ cell tumors exhibited positive immunoreactivity for D2-40. Focal positivity for D2-40 was also observed in 29% of the embryonal carcinoma samples. D2-40 immunoreactivity in seminomas was characterized by diffuse membrane staining, whereas for embryonal carcinomas, staining was focal and distributed along the apical surfaces of the neoplastic cells. Immunohistochemical staining for KIT was observed in 92% of the seminoma samples and in none of the embryonal carcinomas. Conversely, CD30 expression was identified in 93% of the embryonal carcinoma samples and in none of the seminomas. Other germ cell components showed no immunoreactivity for D2-40, KIT, or CD30. KIT and CD30 are effective immunohistochemical markers in separating seminoma from embryonal carcinoma. Although a highly sensitive marker for seminomas, D2-40 positivity was also observed in a subset of embryonal carcinomas, thus limiting the utility of this antibody for discriminating between these two malignancies.     

Structural characterization of BPI-modulating 15 kDa proteins from rabbit polymorphonuclear leukocytes: Identification of a novel family of leukocyte proteins

We have previously described the isolation and initial characterization of 15 kDa protein isoforms (p15s) from rabbit polymorphonuclear leukocytes (PMN) that bind toEscherichia coli and modulate the antibacterial actions of other leukocyte proteins on this gram negative organism. We now report that the p15s differ in primary structure. The cloning and sequencing of two distinct p15 cDNAs from a rabbit bone marrow library reveal that two of the isoforms are closely similar in primary structure differing at only two amino acid positions. The p15 cDNAs encode putative signal sequences suggesting a granule-associated localization for these proteins. Analysis of the derived p15 primary structures reveals homology to two leukocyte proteins: CAP-18, an 18 kD lipopolysaccharide (LPS) binding protein from rabbit PMN and cathelin, an 11 kD cysteine protease inhibitor from porcine leukocytes. This structural similarity suggests the existence of a novel family of low molecular weight leukocyte proteins with potential roles in inflammation.     

Ethanol effects in an anxiety/defense test battery

Two tests, components of an Anxiety/Defense Test Battery, have been designed to measure risk assessment, inhibition of nondefensive behaviors, and movement arrest, all of which occur in the natural defense patterns of rats to threatening stimuli. In these tests, which used a nonpainful threat stimulus (a cat), ethanol (0.6 and 1.2 g/kg) increased two risk assessment behaviors on an initial test day, and produced a wider pattern of changes in all three patterns on a retest (no cat) day, 5 days later. The pattern of results obtained is compatible with a view that defensive behaviors occur in a fixed sequence with the decreasing intensity of threat an important factor in the transition from one defensive behavior to the next, and with ethanol at these doses producing a mild and relatively nonspecific anxiolytic effect. Comparison of male and female subjects on these tasks also suggested that females are more defensive than males, a finding which agrees with a variety of human anxiety studies but is at variance with previous rodent literature.     

Drug effects on an effortful operant: pentobarbital and amphetamine

The behavioral effects of amphetamine and pentobarbital depend upon the conditions maintaining behavior. For example, amphetamine usually decreases the rate of operant behavior maintained by fixed ratio schedules while pentobarbital either increases it or leaves it unaffected. However, when considerable exertion is required, as in situations that require endurance, amphetamine tends to enhance performance while barbiturates degrade it. These differences complicate predictions of the effects of these two drugs on effortful operants. The present experiment was designed to characterize effortful responding behaviorally and pharmacologically. Cebus monkeys were trained to operate a lever by flexing their arms and extending their legs; this response exerted a force approximating their body weight. This operant was maintained by a multiple fixed ratio fixed interval (Mult FR FI) schedule. The two schedules maintained dramatically different response patterns. The FR schedule maintained vigorous, high rate responding characterized by a narrow IRT distribution centered at 0.5 sec. The FI schedule maintained very low overall rates of responding characterized by a variable IRT distribution with a median of 1.5 to 2 sec. Despite very low rates of responding during the FI component, no consistent rate increases appeared after amphetamine, and 0.3 mg/kg eliminated responding altogether. Pentobarbital increased overall rate but also shifted the interresponse time (IRT) distribution toward longer IRTs. The increase in overall rate arose from an earlier onset of responding during the FI component and occurred simultaneously with response slowing. The present studies do not support suggestions of a generalized enhancement of effortful performance by amphetamine or a generalized degradation by pentobarbital.     

Postirradiation malignant fibrous histiocytoma expressing cytokeratin. Implications for the immunodiagnosis of sarcomas

A malignant fibrous histiocytoma of the sacrum complicating the course of radiation therapy for endometrial carcinoma is presented. Although the tumor fulfilled the clinical, radiologic, and histologic criteria for a postirradiation malignant fibrous histiocytoma of bone, it also expressed cytokeratin. That this immunoreactivity reflected keratin synthesis by the tumor and not an unusual pattern of cross-reactivity with another intermediate filament such as vimentin is strongly suggested by the reproducibility of the immunoreactivity utilizing both polyclonal and monoclonal antibodies and extinction of the immunoreactivity following absorption of the primary antiserum with keratin proteins. This is the first reported instance of keratin expression by a malignant fibrous histiocytoma; it indicates that sarcomas apart from synovial sarcoma and epithelioid sarcoma may sometimes express this protein.     

A phase I clinical and pharmacokinetic study of the topoisomerase I inhibitor topotecan (SK&F 104864) given as an intravenous bolus every 21 days.

Topotecan (SK&F 104864) is a novel antitumor agent whose mechanism of action is inhibition of the DNA unwinding protein topoisomerase I. An analog of camptothecin, topotecan was designed to be more water soluble in an effort to decrease the severe and sporadic toxicities experienced during phase I/II trials of the parent compound. In this phase I clinical and pharmacological trial, topotecan was given as a bolus intravenous (i.v.) infusion over 30 min every 21 days. A total of 42 patients entered the study, receiving doses ranging from 2.5 to 22.5 mg/m2. The maximum tolerated dose (MTD) of topotecan given in this schedule was 22.5 mg/m2. Myelosuppression, primarily neutropenia, was dose-limiting. The extent of prior therapy did not predict for more severe neutropenia. Non-hematologic toxicities were mild and included low-grade to moderate fever, nausea, vomiting, alopecia, diarrhea and skin rashes. There were no objective partial or complete responses, although there was a suggestion of antitumor activity in three patients. Topotecan undergoes pH-dependent hydrolysis of the lactone ring; only the closed, lactone form is active. The lactone form predominated during infusion, with hydrolysis occurring rapidly following the end of infusion. There were linear relationships between dose administered and peak plasma lactone concentrations as well as AUC lactone to AUC total. The lactone was rapidly cleared from plasma with a total body clearance of 25.7 (+/- 6.7) l/h/m2. The plasma lactone concentration declined rapidly with a harmonic mean terminal half-life of 3.4 (+/- 1.1)h. Lactone hydrolysis and renal excretion were the major routes of elimination.(ABSTRACT TRUNCATED AT 250 WORDS)     

Group A Streptococcus invasive infections: a review

The incidence of group A Streptococcus (GAS) invasive infections has been increasing worldwide, and there is no obvious explanation for this phenomenon. In 1993, a working group on severe GAS infections was established to define accurately what constitutes an invasive infection. Three types of infection are particularly feared: necrotizing fasciitis, myositis and a newly defined entity, named streptococcal toxic shock syndrome (STSS) because of a certain analogy with its staphylococcal counterpart. GAS produces many toxins responsible for its clinical manifestations. Some of them, labelled streptococcal pyrogenic exotoxins, have been characterized as superantigens. These proteins play a key role in initiating the immune response to GAS and are mostly responsible for the precipitous course of invasive infections. Death rates are high in streptococcal invasive infections, ranging from about 20% for necrotizing fasciitis to almost 100% for myositis. Therapy consists mainly of high doses of antibiotic combinations, aggressive surgery, and intravenous administration of immunoglobulins for STSS.     

Insulin binding to erythrocytes of nonpregnant women: a reevaluation, underlining the importance of body weights even in nonobese subjects.

Insulin binding to erythrocytes was measured in 18 healthy, non-obese women in the follicular phase and in 6 women in the mid-luteal phase of the same menstrual cycle. The presence of 55 nM and 220 nM monoclonal anti-IGF I receptor antibody (alpha-IR3) reduced only the number of low affinity binding sites for insulin by 20% and 33%, respectively. Women with relative body weights 110-119% had a lower number of high affinity receptors and an increased high affinity compared to women with relative body weights 91-109%. In women with relative body weights greater than or equal to 100%, maximum specific binding and high affinity constants increased and the receptor numbers decreased from the follicular to the luteal phase, whereas in women with relative body weights less than 100% the parameter changes were reverted. The data indicate: (1) erythrocytes contain two different classes of binding sites for insulin, (2) IGF I receptors might contribute to low-affinity binding of insulin to erythrocytes and (3) the relative body weight must be considered even for 'non-obese' control groups used in insulin binding studies of various clinical conditions.