Autoantibodies directed against CD43 molecules with an altered glycosylation status on human immunodeficiency virus type 1 (HIV-1)- infected CEM cells are found in all HIV-1+ individuals

Autoantibodies to lymphocytes have been detected in sera from human immunodeficiency virus type 1 (HIV-1)-infected individuals, and several autoantigens have been described. Among them, hyposialylated CD43 has been shown to be a target for autoantibodies in up to 47% of HIV+ individuals. However, the corresponding autoantigen (ie, the incompletely sialylated CD43) has not been isolated from blood cells of HIV-1-infected individuals. Recently, we have observed in vitro that HIV-1 productively or latently infected CEM cells (CEMLAI/NP) express CD43 molecules with modified glycosylation (mogly CD43). Using CEMLAI/NP cells, which do not express any structural viral antigen, we show now that all of the tested HIV+ sera from asymptomatic individuals, and up to 86% of those from subjects at the acquired immunodeficiency syndrome stage contain antibodies (mainly IgM and, to a lesser degree, IgG) that recognize the surface of CEMLAI/NP cells, and precipitate mogly CD43 molecules from the cells lysates. Taken together with our previous demonstration of altered glycosylation of CD43 from HIV-1-infected CEM cells in vitro, the constant antimogly CD43 autoimmune response observed from asymptomatic HIV-1+ subjects is likely to illustrate the occurrence of an altered glycosylation in vivo of the major lymphocyte surface CD43 glycoprotein, associated with HIV- 1 infection.     

Retention of glycoprotein Ib/IX receptors on external surfaces of thrombin-activated platelets in suspension

The present study has evaluated the hypothesis stating that glycoprotein (GP) Ib/IX, the receptor for von Willebrand factor (vWF), is downregulated and cleared from exposed surfaces to channels of the open canalicular system (OCS) on platelets activated by thrombin in suspension. Cryosections of resting and thrombin-activated platelets fixed at intervals of 1 to 30 minutes after stimulation by thrombin and stained with antiglycocalicin antibody and protein A gold showed no decrease in the density of GPIb/IX receptors on the platelet surface or increase on linings of the OCS at any interval after stimulation by thrombin. Thin sections of platelets exposed to thrombin in suspension followed by settling onto a plastic chamber for intervals of 1 to 30 minutes revealed retention of GPIb/IX receptors on exposed surfaces detected by vWF, anti-vWF, and protein A gold throughout the 30-minute period of study. Results of this investigation indicate that GPIb/IX receptors remain on the surface of platelets activated by thrombin in suspension, are not cleared to the OCS, and retain the ability to bind vWF for at least 30 minutes.     

A truncation mutation in TBC1D4 in a family with acanthosis nigricans and postprandial hyperinsulinemia

Tre-2, BUB2, CDC16, 1 domain family member 4 (TBC1D4) (AS160) is a Rab-GTPase activating protein implicated in insulin-stimulated glucose transporter 4 (GLUT4) translocation in adipocytes and myotubes. To determine whether loss-of-function mutations in TBC1D4 might impair GLUT4 translocation and cause insulin resistance in humans, we screened the coding regions of this gene in 156 severely insulin-resistant patients. A female presenting at age 11 years with acanthosis nigricans and extreme postprandial hyperinsulinemia was heterozygous for a premature stop mutation (R363X) in TBC1D4. After demonstrating reduced expression of wild-type TBC1D4 protein and expression of the truncated protein in lymphocytes from the proband, we further characterized the biological effects of the truncated protein in 3T3L1 adipocytes. Prematurely truncated TBC1D4 protein tended to increase basal cell membrane GLUT4 levels (P = 0.053) and significantly reduced insulin-stimulated GLUT4 cell membrane translocation (P < 0.05). When coexpressed with wild-type TBC1D4, the truncated protein dimerized with full-length TBC1D4, suggesting that the heterozygous truncated variant might interfere with its wild-type counterpart in a dominant negative fashion. Two overweight family members with the mutation also manifested normal fasting glucose and insulin levels but disproportionately elevated insulin levels following an oral glucose challenge. This family provides unique genetic evidence of TBC1D4 involvement in human insulin action.     

Prevention of pancreatic cancer and strategies for management of familial pancreatic cancer

At the current time, pancreatic cancer remains a difficult and typically fatal disease. A number of case reports and case-control epidemiologic studies have suggested that familial aggregation plays a role in as many as 10% of all pancreatic cancers. During the last several years, genetic alterations responsible for syndromes linked with pancreatic cancer have been identified. These genes include BRCA2, p16, PRSS1, STK11, and various mismatch repair genes. Unfortunately, most kindreds with a familial aggregation cannot be explained by one of these known genetic syndromes. Recent data from the National Familial Pancreas Tumor Registry at Johns Hopkins have estimated the prospective risk of pancreatic cancer among first-degree relatives of pancreatic cancer patients. The risk was estimated by comparing observed new cases of pancreatic cancer to expected numbers. In families where three first-degree relatives had been diagnosed with pancreatic cancer, the risk of another individual developing pancreatic cancer rose to a 57-fold increase over the basal risk. This article reviews the data concerning familial pancreatic cancer. Additionally, this article reviews the data concerning the histological precursors of invasive ductal adenocarcinoma of the pancreas: pancreatic intraepithelial neoplasias. Further, the current Johns Hopkins methodology used to screen for early pancreatic neoplasia in familial pancreatic cancer patients and in patients with familial Peutz-Jeghers syndrome is discussed. In summary, the notable advances in the field of molecular genetics have allowed for a better definition of the genetics of pancreatic cancer. With this knowledge has evolved a better understanding of several high-risk clinical syndromes associated with pancreatic cancer, familial pancreatic cancer, and the evolution of strategies to screen high-risk families for early pancreatic neoplasia.     

Structural order of membranes and composition of phospholipids in fish brain cells during thermal acclimatization.

A comparison of the structural orders of membranes of a mixed brain-cell population isolated from Cyprinus carpio L. acclimated to either summer (23-25 degrees C) or winter (5 degrees C) revealed a high degree of compensation (80%) for temperature, as assayed by electron spin resonance spectroscopy. The cells rapidly forget their thermal history and adjust the physical properties of the membranes when shifted to the other extreme of temperature either in vivo or in vitro. Phospholipids separated from both types of animals exhibit only around 10% compensation. Arachidonic and docosahexaenoic acids are the major polyunsaturated fatty acids in the brains, but the fatty acid composition of the brain total phospholipids does not vary with adaptation to temperature. Separation of phosphatidylcholines and phosphatidylethanolamines into molecular species revealed a 2- to 3-fold accumulation of 18:1/22:6, 18:1/20:4, and 18:1/18:1 species in the latter; 18:0/22:6 showed an opposite tendency. Molecular species composition of phosphatidylcholines did not vary with the temperature. The same trends of changes were seen with brains of freshwater fish from subtropical (Catla catla L.) or boreal (Acerina cernua) regions. It is concluded that the gross amount of docosahexaenoic acid (22:6) plays only a minor role in adjusting the membrane physical properties to temperature. Factors other than lipids might be involved in the adaptation processes. Due to their specific molecular architecture, molecules such as 18:1/22:6, 18:1/20:4, or 18:1/18:1 phosphatidylethanolamine might prevent the contraction of membranes in the cold and may provide an environment for some other components involved in the temperature regulation of physical properties of nerve cell membranes.     

Burmese Russell's viper venom causes hormone release from rat pituitary cells in vitro

Acute and chronic hypopituitarism is associated with severe envenoming by the Burmese Russell's viper. We have demonstrated that in vitro, Burmese Russell's viper venom (0.1-10 micrograms/ml) causes a dose-dependent release of GH, TSH and ACTH from dispersed rat anterior pituitary cells in culture. At 10 micrograms/ml, venom causes a significant increase in the release of GH (344%, P less than 0.001), TSH (168%, P less than 0.005) and ACTH (greater than 700%, P less than 0.001). We have also shown that the component (or components) responsible for this stimulatory effect is stable to heat (60 degrees C, 1 h) and mild trypsinization. Repeated addition of venom (1 microgram/ml) to pituitary cells in a perifusion column system demonstrated attenuation of GH release. This reduced response was not due to depletion of the GH pool since the pituitary cells were subsequently able to respond to both GH-releasing factor (GRF) stimulation and KCl depolarization. Somatostatin in a dose which abolished GRF-stimulated GH release failed to affect venom-stimulated GH release, implying that venom acts in a cyclic AMP-independent manner. We conclude that Burmese Russell's viper venom has direct effects on pituitary hormone release in vitro. Whether these effects contribute to its known actions in vivo on the function of the pituitary remains to be established.     

Inhibition of tissue plasminogen activator activity by aspirin in vivo and its relationship to levels of tissue plasminogen activator inhibitor antigen, plasminogen activator and their complexes

The observation that aspirin inhibits the increment in tissue plasminogen activator (t-PA) activity induced by venous occlusion of the forearm became controversial with the publication of several nonconfirmatory studies. The current study was performed to confirm the original observation and determine the mechanism by which aspirin suppresses the incremental t-PA activity induced by venous occlusion. Aspirin (650 mg/d X 2) caused no change in resting levels of t-PA antigen (t-PA:Ag) or activity, plasminogen activator inhibitor 1 antigen (PAI-1:Ag), or activity or t-PA-PAI-1 complexes. In contrast, aspirin reduced the increments induced by venous occlusion as follows: t-PA:Ag by 45% (P = .001); t-PA activity (euglobulin lysis time, ELT) by 43% (P = .006); and t-PA activity (alpha 2-plasmin inhibitor-plasmin complexes, PIPC) by 41% (P = .003). The inhibition of incremental t-PA activity measured as ELT or PIPC was linearly correlated with the inhibition of incremental t-PA:Ag (respectively, r = .75, P less than .02; r = .67, P less than .05). Aspirin had no effect on the increment in PAI-1:Ag induced by venous occlusion, but similar to the effect on t- PA:Ag, aspirin induced a 51% inhibition of the increment in t-PA-PAI-1 complex formation. Aspirin did not alter the ability of alpha 2-plasmin inhibitor to bind plasmin, nor the ability of plasma to support the fibrin-catalyzed generation of plasmin by t-PA, nor the subsequent formation of PIPC. Aspirin inhibits the t-PA activity induced by venous occlusion primarily by inhibiting the release of t-PA antigen.     

Primary squamous cell carcinoma in the chest wall mimicking abscess

We report a case of squamous cell carcinoma (SCC) presenting a painful cystic mass which originated from the chest wall with bony destructions. The patient underwent complete excision with chest wall reconstruction. Although the imaging characteristics of chest wall tumor can be variable, SCC should be considered in differential diagnosis in the case of symptomatic cystic mass in elderly patients.     

Apoptosis in rheumatoid arthritis synovium.

RA synovial tissue (ST) was studied to determine if and where apoptosis occurs in situ. Genomic DNA was extracted from 5 RA and 1 osteoarthritis ST samples. Agarose gel electrophoresis demonstrated DNA ladders characteristic for apoptosis from each tissue. In situ and labeling (ISEL) was used to identify DNA strand breaks consistent with apoptosis in frozen sections. 12 RA and 4 osteoarthritis ST were studied by ISEL and all were positive, but only 2 of 4 normal tissues were positive. The primary location of apopotic cells was the synovial lining. Some sublining cells were also positive, but lymphoid aggregate staining was conspicuously absent. Immunohistochemistry and ISEL were combined and showed that the lining cells with DNA strand breaks were mainly macrophages, although some fibroblastlike cells were also labeled. Sublining cells with fragmented DNA included macrophages and fibroblasts, but T cells in lymphoid aggregates, which expressed large amounts of bcl-2, were spared. DNA strand breaks in cultured fibroblastlike synoviocytes was assessed using ISEL. Apoptosis could be induced by actinomycin D, anti-fas antibody, IL-1, and TNF-alpha but not by IFN-gamma. Fas expression was also detected on fibroblast-like synoviocytes using flow cytometry. Therefore, DNA strand breaks occur in synovium of patients with arthritis. Cytokines regulate this process, and the cytokine profile in RA (high IL-1/TNF; low IFN-gamma) along with local oxidant injury might favor induction of apoptosis.     

Upstream promoter mutation associated with a modest elevation of fetal hemoglobin expression in human adults

In hereditary persistence of fetal hemoglobin, Hb F (alpha 2 gamma 2) is elevated after birth. Screening of sickle cell patients has revealed a family with elevated Hb F and high A gamma values. The propositus was a sickle cell patient with approximately 25% Hb F and 68.4% A gamma. He was heterozygous for the Benin (#19) and Mor beta S haplotypes. Five AS relatives with the Mor haplotype had 2.5% +/- 0.9% fetal hemoglobin and 92.8% +/- 2.8% A gamma, whereas two with the Benin haplotype had normal fetal hemoglobin (0.5%). The Mor haplotype is thus associated with the elevated Hb F in this family. The 13-kilobase (kb) Bg/II fragment containing the G gamma and A gamma genes of the Mor haplotype was cloned, and the G gamma and A gamma promoters sequenced from -383 to beyond the Cap sites. The Mor G gamma gene was normal, but the A gamma gene had a unique C----T mutation at -202. A different mutation at -202 of G gamma (C----G) was previously detected by other researchers in association with considerably higher Hb F in AS cases (15% to 25%). These data suggest either that -202 mutations affect the G gamma and A gamma promoters differently or that different nucleotide substitutions at -202 have divergent effects. Alternatively, additional unknown mutations could cause the differences in gene expression.