Propranolol, a beta-adrenergic antagonist, retards response to MSH in skin of Anolis carolinensis

Lacking sympathetic innervation, the skin of A. carolinensis, an iguanid lizard, darkens within minutes in response to circulating melanocyte stimulating hormone (MSH) or beta adrenergic agonists such as epinephrine (EPI). This change is produced by dispersion of melanin from a perinculear position within dermal melanophores into superficial dendritic processes. These melanophores possess alpha-2 and beta-2 adrenergic as well as MSH receptors except in a patch of skin behind the eye, the eyespot, which lacks alpha receptors. Activation of beta or MSH receptors leads to stimulation of adenyl cyclase whereas alpha stimulation inhibits the enzyme to override the others. In a series of trials, injection of saline or propranolol was followed after 30 minutes by saline, EPI, or MSH. Propranolol inhibited chromatophore response to EPI. It also, unexpectedly, retarded the response to MSH, increasing latency to eyespot formation and body color change as well as the duration of darkening for both. Alteration of MSH response by a beta blocker could be explained by linkage of both adrenergic receptors and the MSH receptor to a common adenyl cyclase molecule to form a functional unit in the membrane of the melanophore.     

A role for hyaluronan in macrophage accumulation and collagen deposition after bleomycin-induced lung injury

Elevated concentrations of hyaluronan (HA) are associated with the accumulation of macrophages in the lung after injury. We have investigated the role of HA in the inflammatory and fibrotic responses to lung injury using the intratracheal instillation of bleomycin in rats as a model. After bleomycin-induced lung injury, both HA content in bronchoalveolar lavage (BAL) and staining for HA in macrophages accumulating in injured areas of the lung were maximal at 4 d. Increased HA in BAL correlated with increased locomotion of isolated alveolar macrophages. HA-binding peptide was able to specifically block macrophage motility in vitro. Importantly, systemic administration of HA-binding peptide to rats before injury not only decreased alveolar macrophage motility and accumulation in the lung, but also reduced lung collagen alpha (I) messenger RNA and hydroxyproline contents. We propose a model in which HA plays a critical role in the inflammatory response and fibrotic consequences of acute lung injury.     

Heterogeneity of VP4 neutralization epitopes among serotype P1A human rotavirus strains.

We have used serotype-specific VP4 and VP7 neutralizing monoclonal antibodies (Nt-MAbs), as well as subgroup (SG)-specific MAbs, to characterize by enzyme immunoassay rotavirus strains isolated from diarrheic infants in the city of Monterrey, Mexico, from July 1993 to March 1994. Of a total of 465 children studied, 140 were rotavirus positive, including 3 patients infected with non-group A rotaviruses. The SG and VP7 (G) serotype specificities could be determined for 118 (84%) of the 140 rotavirus-positive stool specimens; 4 rotavirus strains were serotype G1 and SGII; 1 strain was serotype G2 and SGI+II; 112 strains were serotype G3 and SGII; 1 strain was serotype G3 and SGI; and none of the strains was serotype G4. Fifty-eight specimens, representing the 13 different group A rotavirus electropherotypes detected, were chosen for VP4 (P) serotyping. Of these, 48 (83%) strains reacted with the P1A serotype-specific Nt-MAb 1A10. None of the strains reacted with the serotype P2-specific Nt-MAbs tested. Not all viruses that reacted with Nt-MAb 1A10 were recognized by Nt-MAbs 2A3 and 2G1, which also recognize P1A strains, indicating heterogeneity of neutralization epitopes among serotype P1A human rotaviruses. This heterogeneity could be relevant for the specificity of the VP4-mediated neutralizing antibody immune response and indicates the need for antigenic characterization, in addition to genomic typing, of the VP4 proteins of circulating human rotavirus field strains.     

The effect of calcium ions on the activated partial thromboplastin time of heparinized plasma

The effect of calcium chloride (CaCl2) on the activated partial thromboplastin time (aPTT) of heparinized plasma was studied. The aPTT ratio (heparinized plasma:control plasma) increased as the CaCl2 concentration to recalcify the plasma was increased from 15 to 35 mmol/L CaCl2. Platelet-poor plasma from patients receiving intravenous heparin, and in vitro heparinized plasmas from either coumarinized patients or plasma depleted of the vitamin K-dependent factors, displayed the calcium-dependent increase in the aPTT ratio. The magnitude of the calcium-dependent change in the aPTT ratio was similar for the three partial thromboplastins studied. Heparinized blood collected in 3.2% and 3.8% citrate demonstrated the calcium-dependent increase in the aPTT ratio. The authors have also studied the effect of the divalent cations (Ca+2, Mg+2, Zn+2, and Sr+2) on the anti-Factor Xa activity of heparin to determine whether the calcium-dependent increase in the aPTT was due to an increase in the anti-Factor Xa activity. The anti-Factor Xa activity of heparin was measured using chromogenic substrate S-2251, purified Factor Xa, and excess antithrombin III. The anti-Factor Xa activity of heparinized plasma increased 2.4-2.8-fold as the divalent cation concentration was increased from 0-5 mmol/L. Similar results were obtained using purified bovine Factor Xa, antithrombin III, and heparin in the absence of plasma. These results suggest that divalent cations play an important role in modulating heparin's anticoagulant activity in vitro. In addition, the CaCl2 concentration used to recalcify plasma is an important variable that modifies heparin sensitivity of the aPTT. Furthermore, divalent cations play an important role in regulating the anti-Factor Xa activity of heparin in vitro.     

Potential uses of interleukin 2 in cancer therapy

Interleukin 2 (IL 2) has several potential uses in cancer therapy including: the augmentation of specific T cell mediated anti-tumor immunity and the activation of non-specific cytolytic effector cells, termed lymphokine-activated killer (LAK) cells. The current review will present data from our laboratory demonstrating in animal models the feasibility of both potential approaches. Studies to be reviewed show that: IL 2 can induce the proliferation and expansion in number of tumor-reactive T cells in vitro; T cells grown in culture in IL 2 can be effective reagents in vivo for specific tumor therapy; the administration of exogenous IL 2 can induce the growth and augment the function of cultured T cells in vivo; however, as a corollary, T cells cultured long-term in vivo with IL 2 are functionally limited in vivo without the administration of exogenous IL 2 in vivo; by contrast, T cells grown in vitro with specific antigen, as opposed to IL 2, as the major stimulus for proliferation are able to proliferate rapidly in vivo, distribute widely in host lymphoid organs, and mediate therapy of disseminated murine leukemia; importantly, such antigen-driven long-term cultured T cells can survive long-term in vivo and provide specific immunologic memory, and, the administration of low-dose IL 2 in vivo can induce the growth of antigen-driven long-term cultured T cells in vivo and thereby increase the number of functional memory T cells; the culture of lymphoid cells in high concentrations of IL 2 can induce LAK cells in vitro capable of lysing leukemia in vitro; LAK cells generated in vitro can mediate a small but detectable anti-tumor effect in vivo against disseminated leukemia as an adjunct to chemotherapy; and, high-dose IL 2 administered in vivo can activate LAK cells in vivo and cure disseminated murine leukemia. Therefore, it is highly likely that IL 2 can become an effective reagent for the therapy of human cancer.     

Familial Miller-Dieker syndrome associated with pericentric inversion of chromosome 17

Recently it has been shown that most cases of the Miller-Dieker syndrome (MDS) are caused by deletion 17p13.3. All familial cases have been associated with a balanced reciprocal translocation in a carrier parent and unbalanced translocations in their affected offspring. We report a new case of familial MDS in whom the mother carries a pericentric inversion of chromosome 17. She has had two children with MDS, one of whom was shown to carry a recombinant 17 consisting of dup(17q) and del(17p). The high frequency of familial MDS and its consistent association with balanced chromosomal rearrangements in one of the parents makes it important to do high-resolution chromosome analysis on all patients with MDS and possibly all patients with lissencephaly. Finding a familial balanced rearrangement makes prenatal diagnosis of this condition feasible.     

Serotypic and genotypic characterization of human serotype 10 rotaviruses from asymptomatic neonates.

Human rotaviruses were isolated from asymptomatic neonates at various hospitals and clinics in the city of Bangalore, India, and were found to be subgroup I specific and possess long RNA patterns (M. Sukumaran, K. Gowda, P. P. Maiya, T. P. Srinivas, M. S. Kumar, S. Aijaz, R. R. Reddy, L. Padilla, H. B. Greenberg, and C. D. Rao, Arch. Virol. 126:239-251, 1992). Three of these strains were adapted to tissue culture and found by serotype analysis and neutralization assays to be of serotype 10, a serotype commonly found in cattle but infrequently found in humans and not previously identified in neonates. By RNA-RNA hybridization, a high level of relatedness to a serotype 10 bovine rotavirus strain and a low-to-medium level of relatedness to a human rotavirus strain were observed. Since this human isolate shares a genogroup with bovine rotavirus, it is likely that it originated by interspecies transmission. A human rotavirus strain isolated from asymptomatic neonates and similar to bovine rotavirus might represent a good vaccine candidate.     

Damaged chromatin does not prevent the exit from metaphase I in fused mouse oocytes

The presence of checkpoint mechanisms which are able to recognize damaged chromatin and thereafter to prevent exit from metaphase I has been investigated in giant mouse oocytes produced by fusion of a normal metaphase I oocyte with an equivalent oocyte with damaged chromatin. The presence of damaged chromatin did not prevent the onset of anaphase I in both sets of chromatin in the fused cells. Interestingly, fused or unfused cells containing only damaged chromatin failed to enter anaphase and persisted instead in a metaphase-like state. These results demonstrate the fragility of checkpoint controls in mammalian female germ cells.      

The "hyperacute" extraaxial intracranial hematoma: computed tomographic findings and clinical significance

Thirteen patients with acute subdural and epidural hematomas were found to have fresh, unclotted blood at the time of surgical decompression several hours after injury. Computed tomographic (CT) scans of these patients demonstrated areas of hyperdensity, corresponding to clotted hematoma, admixed with areas of isodensity, corresponding to liquid blood. Active bleeding from identifiable loci was found in 11 patients, 4 of whom had massive hemorrhages. Clotting abnormalities ranging from slightly elevated laboratory test results to a full-blown clinical picture of disseminated intravascular coagulation occurred in 8 patients. We describe the CT pictures of these "hyperacute" lesions, and we postulate that such CT presentations indicate either the presence of ongoing active intracranial bleeding or the onset of a coagulopathy complicating the management of these lesions.     

Systemic and transcardiac platelet activity in acute myocardial infarction in man: resistance to prostacyclin

There is increasing evidence that platelets play an important role in the pathogenesis of acute ischemic heart disease. Therefore an understanding of factors that influence platelet performance is important. This study was undertaken (1) to characterize during evolving myocardial infarction platelet activity in the peripheral circulation and across the ischemic/infarcting myocardial compartment, the locus of presumed platelet hyperactivity, and (2) to evaluate the effects of prostacyclin (PGI2), a most potent antiplatelet agent and vasodilator. A total of 59 patients with evolving myocardial infarction were studied. Twenty-two patients were instrumented with arterial and coronary sinus catheters and received intravenous infusion of PGI2, 13 +/- 4.5 ng/kg/min (mean +/- SD), for 90 min. In 15 patients with anterior myocardial infarction, transcardiac platelet function and response to PGI2 were studied. Plasma levels of beta-thromboglobulin (beta-TG) and of thromboxane B2 (TxB2), in vivo measures of platelet activity, were elevated three- and 10-fold. 6-Keto-prostaglandin F 1 alpha, the stable end product of PGI2, was less than 10 pg/ml, reflecting a leftward shift of the TxB2/PGI2 ratio. Platelets circulating during evolving myocardial infarction ("ischemic platelets") were hyperaggregable in response to ADP and relatively resistant to PGI2, both in vivo and in vitro. Concentrations of platelet cyclic AMP and the cyclic AMP response to PGI2 were diminished. The platelet hyperreactivity, expressed by plasma beta-TG, platelet aggregation, and PGI2-induced inhibition of aggregation, was most intense early during infarct evolution and decreased with time. The increased platelet performance resulted in "platelet fatigue," indicated by decreased contents of beta-TG of the ischemic platelet and decreased TxA2 production in response to collagen. However, the ischemic platelet produced twice normal TxA2 in response to arachidonic acid (stimulus and substrate), demonstrating a heightened metabolic capacity. TxA2 was produced across the ischemic/infarcting compartment in 10 of 15 patients with anterior myocardial infarction. The antiplatelet effect of PGI2 was greatly diminished. In summary, the data define an abnormal pattern of platelet behavior during evolving myocardial infarction, characterized by a proaggregatory environment, heightened platelet reactivity in both the peripheral and coronary circulation, and relative resistance to PGI2. The clinical consequences of the data are that the patient in the acute phase of myocardial infarction may benefit from suppression of platelet function and requires significantly greater doses of PGI2 than normal subjects.(ABSTRACT TRUNCATED AT 400 WORDS)