The pattern of cardiovascular alterations induced by infusion of platelet-activating factor in rabbit is modified by pretreatment with H1-H2 receptor antagonists but not by cyclooxygenase inhibition

The intravenous infusion of platelet activating factor (PAF) (0.8 g/kg b.w.) induced ECG and hemodynamic alterations characterized by the following sequential three phases. Phase I (15 sec) consisted of a transient bradycardia with reduction in left ventricular pressure (LVPs), mean arterial pressure (MAP) and cardiac output (CO). Phase II developed within 30 sec and consisted of a rise in cardiac frequency, increase in LVPs, MAP and total peripheral resistances (TPR), which were associated with a decrease in CO. Finally, phase III, that occurred about 90 sec after PAF infusion, was characterized by marked ECG changes (ST segment depression and conduction arrhythmias), a decrease in LVPs and MAP, as well as a rise in TPR and in right atrial pressure (RAP). All these alterations were reversible within 30–60 min. Pretreatment with promethazine and cimetidine, as H₁ and H₂ histamine receptor antagonists, markedly prevented the development of phase II, namely the rise in cardiac frequency, LVPs, MAP and TPR, but did not significantly modify phase I and III. In contrast, pretreatment with indomethacin, an inhibitor of cyclooxygenase, moderatively attenuated, but did not abolish, the three phases of cardiovascular changes induced by PAF infusion.     

Monoclonal antibodies against transferrin. Precipitating mixtures and lack of inter-species cross-reactivity

Five stable hybridoma lines were prepared using the myeloma cell line P3-X63-Ag.653 and spleen cells of mice hyperimmunized by pig transferrin. All hybridomas grew well in mouse peritoneal cavity and produced antibodies of the IgG₁ subclass. Antibody preparations obtained from ascitic fluids tested for their capacity of antigen precipitation. No precipitation was obtained with single antibodies and with pairs of antibodies. Three out of 10 possible triads gave clear and sharp precipitation zones and rings in immunodiffusion tests performed in agar gel. All 5 antibodies were shown by quantitative enzyme-immunoassay to be specific for pig transferrin: no cross-reaction was obtained with mouse, human, horse and sheep transferrins.     

Distinct pathways for constitutive endocytosis of fully conformed and non-conformed L(d) molecules

PROBLEM: To characterize the constitutive internalization of major histocompatibility complex (MHC) class I molecules, we have studied the expression of completely conformed (full) and unconformed (empty) L(d) molecules on non-polarized murine P815 cells. METHODS OF STUDY: Spontaneous endocytosis of L(d) molecules was induced by cycloheximide, an inhibitor of protein synthesis, and their disappearance from the cell surface was determined by flow cytometry. In order to investigate the mechanism of internalization, a palette of inhibitors of endocytosis and vesicular transport was used. RESULTS: Inhibitors of clathrine endocytosis did not influence the internalization of L(d) molecules. Inhibitors of caveolar endocytosis and inhibitors of endolysosomal degradation prevented down-regulation of empty, but not of full L(d) molecules. CONCLUSIONS: Empty L(d) molecules are internalized mostly by caveolar endocytosis and full L(d) molecules use a different pathway, neither clathrine-mediated nor caveolar. After internalization, full L(d) molecules are probably degraded and empty L(d) molecules recycle between endosomal compartment and the cell surface before they enter into the degradation compartment.     

Differential histochemical peanut agglutinin stain in benign and malignant human prostate tumors: Relationship with prostatic specific antigen immunostain and nuclear DNA content

The histochemical binding pattern of the peanut (Arachis hypogaea) lectin (PNA) was quantitatively described by means of computer-assisted microscope analysis in 28 benign prostatic hyperplasias (BPH), 15 prostatic intraepithelial neoplasias (PIN), and 119 prostatic adenocarcinomas. PNA exhibits noninunune but selective binding to glycoproteins with β-D-galactosyl(1,3)-N-acetyl-D-galactosamine residues. We also investigated whether a relationship existed between the number of histochemical-related PNA acceptors and the histochemical prostate-specific antigen (PSA) stain intensity, and between the number of PNA receptors and DNA ploidy level. The results show that neoplastic prostate tissues and high-grade intraepithelial prostatic neoplasias (PIN2_3) exhibit a significantly higher number of PNA acceptors than benign prostatic hyperplasias and low (PIN1) grade prostatic intraepithelial neoplasias. A statistically significant correlation was observed between the number of histochemically related PNA acceptors and PSA immunostain intensity. Lastly, diploid prostatic tumors, whether benign or malignant, exhibited a significantly higher number of PNA acceptors than aneuploid ones. These results suggest that PNA acceptors play an important role in the biology of prostate tumors.     

Myxoid leiomyosarcoma of the ovary: Analysis of three cases

The first three cases of myxoid leiomyosarcoma occurring in the ovary are reported. Two cases in stage III were found in postmenopausal patients and a further case was found in stage I in a 32-year-old. All masses were large and gelatinous with cystic change, necrosis, and hemorrhage, but both uteri and ligaments and contralateral adnexa appeared normal. Microscopically, the tumors showed a predominantly reticular meshwork of elongated cells surrounded by abundant basophilic material. While electron microscopy proved inconclusive due to nondifferentiation, the use of monoclonal antibodies against smooth muscle actin demonstrated a smooth muscle type of differentiation. The differential diagnosis of this rare ovarian condition includes other myxoid ovarian lesions, such as ovarian edema, myxoma, endodermal sinus tumors, and the sarcomatous component of malignant mixed müllerian tumor and carcinosarcoma, as well as lymphovascular tumors. Since mitotic count due to decreased cellular density is unusually low in myxoid leiomyosarcoma, capsular rupture and clinical stage seem to be more reliable prognostic markers. The highly aggressive behavior of myxoid leiomyosarcoma parallels that of typical ovarian leiomyosarcoma. Two of the three patients in this series died of tumor at 13 and 24 months after diagnosis; the other patient is free of disease at 3 years after diagnosis.     

Long-term evaluation of usefulness of skin and incremental challenge tests in patients with history of adverse reaction to local anesthetics

A variety of adverse reactions to local anesthetics has been described, some of which are thought to be allergic. Different protocols of prick and intradermal skin tests as well as subcutaneous challenge tests are used to select a local anesthetic which can safely be used. Their long-term effectiveness has not yet been assessed. Twenty-eight patients with a history of adverse reaction to local anesthetics were evaluated over a 3-year period. Loss of consciousness occurred in eight patients, skin reaction in nine, and vagal symptoms in eight. Various reactions were recorded in the remaining three patients. Rapid spontaneous recovery was the rule, suggesting that immediate allergic reaction and, in particular, anaphylactic reaction were unlikely. Investigation allowed the selection of a tolerated anesthetic in all cases. Reexposure occurred in 19 patients 16–50 months after evaluation and 6.8 ± 5.5 years after the first reaction. No patient presented a second reaction. In conclusion, adverse reactions to local anesthetics seem to be, in most cases, not allergic in nature. Evaluation protocols are effective in selecting an agent susceptible to tolerance, but are time consuming. However, they probably contribute to an important reassurance effect that is likely to increase tolerance to subsequent local anesthetic administration. Simplification of the protocols and better patient selection are proposed.     

Estimating the relative frequency of leukodystrophies and recommendations for carrier screening in the era of next‐generation sequencing

Leukodystrophies are a heterogeneous group of heritable disorders characterized by abnormal brain white matter signal on magnetic resonance imaging (MRI) and primary involvement of the cellular components of myelin. Previous estimates suggest the incidence of leukodystrophies as a whole to be 1 in 7,000 individuals, however the frequency of specific diagnoses relative to others has not been described. Next generation sequencing approaches offer the opportunity to redefine our understanding of the relative frequency of different leukodystrophies. We assessed the relative frequency of all 30 leukodystrophies (associated with 55 genes) in more than 49,000 exomes. We identified a relatively high frequency of disorders previously thought of as very rare, including Aicardi Goutières Syndrome, TUBB4A‐related leukodystrophy, Peroxisomal biogenesis disorders, POLR3‐related Leukodystrophy, Vanishing White Matter, and Pelizaeus‐Merzbacher Disease. Despite the relative frequency of these conditions, carrier‐screening laboratories regularly test only 20 of the 55 leukodystrophy‐related genes, and do not test at all, or test only one or a few, genes for some of the higher frequency disorders. Relative frequency of leukodystrophies previously considered very rare suggests these disorders may benefit from expanded carrier screening.