Apparent Similarity of Mechanisms of Platelet Adhesion and Aggregation

A correlation between effects of a series of compounds on platelet adhesion, aggregation, and retraction of the clot, and their effects on platelet electrophoretic mobility, ecto-ATPase activities, and AChE activity has been sought. Compounds which inhibited aggregation induced by ADP or epinephrine also inhibited platelet adhesion to glass. Six compounds which inhibited adhesion and aggregation did not inhibit clot retraction. The data suggest that the effect of thrombin on platelet electrophoretic mobility and ecto-ATPase activities may have less influence on platelet function than was formerly believed. However, the effects of test compounds on platelet AChE activity suggest that this enzyme may play a role in aggregation and adhesion. Platelet adhesion and aggregation may operate by similar mechanisms.

Cardiac natriuretic peptides: hormones with anticancer effects that localize to nucleus, cytoplasm, endothelium, and fibroblasts of human cancers

Four cardiac peptide hormones, i.e., vessel dilator, long acting natriuretic peptide (LANP), kaliuretic peptide, and atrial natriuretic peptide (ANP) synthesized by the same gene decrease within 24 hours up to 97% the number of human breast, colon, pancreatic, and prostate adenocarcinoma cells as well as human small-cell and squamous carcinomas of the lung cells. These peptide hormones completely inhibit the growth of human pancreatic adenocarcinomas growing in athymic mice. Immunocytochemical investigations have revealed that LANP, vessel dilator, kaliuretic peptide and ANP localize to the nucleus and cytoplasm of human pancreatic adenocarcinomas, which is consistent with their ability to decrease DNA synthesis in the nucleus of this cancer mediated by the intracellular messenger cyclic GMP. These peptide hormones also localize to the endothelium of capillaries and fibroblasts within these cancers. These are the first growth-inhibiting peptide hormones ever demonstrated to localize to the nucleus. Their ability to decrease the activation of growth promoting substances such as Extracellular Receptor Kinase (ERK)-1/2 and Nuclear Factor Kappa Beta (NFkappaB) suggests that in addition to inhibiting DNA synthesis their ability to decrease the activation of growth promoting substances helps to mediate their ability to inhibit the growth of human cancers.

IL-1 and TNF independent pathways mediate ICAM-1/VCAM-1 up-regulation in ischemia reperfusion injury

In vitro studies have suggested that targeting interleukin (IL)-1 and tumor necrosis factor (TNF) can be used to regulate intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and potentially treat kidney inflammation. We therefore evaluated ICAM-1 and VCAM-1 regulation in knockout (KO) mice deficient in both IL-1 receptor 1 (R1) and TNF-R1 during renal ischemia reperfusion injury. ICAM-1 and VCAM-1 mRNA expression was measured with specific murine probes and Northern blotting (n =4/group). Protein expression was measured using immunohistochemistry. Serum creatinine (SCr), tubular histology, and neutrophil infiltration into postischemic kidneys were also quantified. ICAM-1 and VCAM-1 mRNA expression increased in both wild-type (WT) and KO mice at 2, 6, and 24 h. Protein expression of ICAM-1 and VCAM-1 was also increased at 24 h postischemia. SCr levels and tubular necrosis scores were comparable in WT and KO mice at 24 and 48 h. Neutrophil migration in KO mice was decreased at 24 h but comparable to WT at 48 h. These data demonstrate that IL-1 and TNF are not essential for postischemic increases in ICAM-1 and VCAM-1.

Pathophysiological role of T lymphocytes in renal ischemia-reperfusion injury in mice

Mononuclear cell infiltrates are found in human renal ischemia-reperfusion injury (IRI), and peritubular T lymphocytes have been identified in experimental IRI. However, the role of T cells in the pathogenesis of renal IRI is unknown. We hypothesized that T cells are one of the important mediators of renal IRI. To test this hypothesis, we used an established mouse model of renal IRI, and evaluated mice with genetically engineered deficiency of both CD4+ and CD8+ T cells. At 48 h postischemia, CD4/CD8-knockout (KO) mice had marked improvement in renal function compared with control C57BL/6 mice (serum creatinine: 0.7 +/- 0.4 vs. 2.5 +/- 0.3 mg/dl, respectively; P < 0.05). Neutrophil infiltration into postischemic kidney was reduced in CD4/CD8 KO mice, compared with control mice, at both 24 h [polymorphonuclear neutrophils (PMNs)/10 high power fields: 714 +/- 354 vs. 3,514 +/- 660, respectively; P < 0.05] and 48 h (88 +/- 32 vs. 1,979 +/- 209, respectively; P < 0.05). Tubular necrosis score in CD4/CD8 KO mice, compared with control mice, was significantly less at 48 h (0.4 +/- 0.1 vs. 2.4 +/- 0.2, respectively; P < 0.05). Because adhesion between T cells and renal tubular epithelial cells (RTECs) may underlie the pathophysiological role of T cells in renal IRI, we also measured T cell adhesion to primary murine RTECs in vitro. Exposure of RTECs to 2 h of hypoxia followed by 1 h of reoxygenation increased T cell adhesion more than twofold. Phorbol ester treatment, which activates integrins, increased T cell adhesion threefold. These data suggest that T lymphocytes can mediate experimental renal IRI. Moreover, adhesion of infiltrating T cells to renal tubular cells may provide a potential mechanism underlying postischemic tubular dysfunction.

Amelioration with vessel dilator of acute tubular necrosis and renal failure established for 2 days

Seventeen Sprague-Dawley rats had ischemic nonoliguric acute renal failure (ARF) induced by vascular clamping resulting in their preischemic blood urea nitrogen (BUN) and creatinine levels of 16 +/- 1 and 0.56 +/- 0.05 mg/dl to increase to 162 +/- 4 and 8.17 +/- 0.5 mg/dl, P < 0.001, respectively, at day 4 of postischemia. Vessel dilator, a 37-amino-acid cardiac peptide hormone (0.3 microg x kg(-1) x min(-1) ip), decreased the BUN and creatinine levels to 53 +/- 17 mg/dl and 0.98 +/- 0.12 mg/dl (P < 0.001) in another seven animals where ARF had been established for 2 days. Water excretion doubled with ARF and was further augmented by vessel dilator. Transthoracic echocardiography revealed left ventricular dilation as a probable cause of the increase in vessel dilator in the circulation with ARF, and vessel dilator infusion reversed this dilation. At day 6 of ARF, mortality decreased to 14% with vessel dilator from 88% without vessel dilator. Acute tubular necrosis was <5% in the vessel dilator-treated rats compared with 25% to >75% in the placebo-treated ARF animals. We conclude that vessel dilator improves acute tubular necrosis and renal function in established ARF.

Acute renal failure from multiple myeloma precipitated by ACE inhibitors

Renal failure in multiple myeloma can be precipitated during hemodynamic perturbances of renal blood flow, as seen secondary to volume depletion, radiocontrast dye, and nonsteroidal anti-inflammatory agents. We report two cases of acute renal failure that developed suddenly after initiation of angiotensin-converting enzyme (ACE) inhibitor, both with biopsy-proven cast nephropathy. ACE inhibitors may contribute to the intratubular light chain cast formation and acute "myeloma kidney" in susceptible patients.

Role of IL-1 in renal ischemic reperfusion injury

Interleukin-1 (IL-1) is a central component of many acute inflammatory processes. Blocking IL-1 receptor (IL-1R) with IL-1R antagonist (IL-1Ra) has attenuated ischemic reperfusion injury in brain, heart, and liver models. However, the role of IL-1 in renal ischemic reperfusion injury (IRI) is not known. Therefore, the role of IL-1 in renal IRI was evaluated using the complementary approaches of IL-1R blockade in wild-type mice in addition to the study of renal IRI in IL-1R knockout (KO) mice. Ischemia was induced by bilateral renal pedicle clamping for 30 min. IL-1Ra was administered at 10 mg/kg every 4 h, high doses that have been protective in previous organ injury models in mice. IL-1R KO animals, previously characterized as insensitive to IL-1, had the absence of IL-1R1 confirmed by DNA blots. IL-1Ra, IL-1R KO, and control groups had similar elevations of blood urea nitrogen (114 +/- 13, 133 +/- 11, and 120 +/- 11 mg/dl) and serum creatinine (1.7 +/- 0.3, 2.1 +/- 0.2, and 1.6 +/- 0.3 mg/dl) 24 h after ischemia. Furthermore, acute tubular necrosis scores were also similar in IL-1Ra-treated mice (3.0 +/- 0.3), IL-1R KO mice (2.7 +/- 0.3), and control mice (3.1 +/- 0.2). However, both IL-1Ra and IL-1R KO groups, compared with control animals, developed significantly less infiltration of polymorphonuclear leukocytes per 10 high-power fields in postischemic renal tissue (1111 +/- 228 and 967 +/- 198 versus 1820 +/- 190, P < 0.05). In contrast to the comparable renal functions at 24 h, recovery of renal function was significantly accelerated in the IL-1R KO group compared with control at both 48 (P < 0.05) and 72 (P < 0.05) h. Recovery in the IL-1Ra group was similar to that in the control animals. These data demonstrate that IL-1 is unlikely to be beneficial in the recovery of renal function after ischemia and may play a deleterious role.

Renal ischemic-reperfusion injury in L-selectin-deficient mice

L-selectin on leukocyte surfaces mediates cell rolling on endothelium. L-selectin blockade with antibodies attenuated ischemic-reperfusion injury (IRI) in heart and skeletal muscle, but its role in renal IRI is unknown. We evaluated the role of L-selectin in renal IRI using L-selectin-deficient mice. Neutrophil migration to chemically inflamed peritoneum was reduced by 47% (P < 0.01) in L-selectin-deficient mice. Ischemia was induced by bilateral renal pedicle clamping for 30 min. Control and L-selectin groups had similar elevations of serum creatinine (1.8 +/- 0.3 vs. 1.7 +/- 0.2 mg/dl) and blood urea nitrogen (111 +/- 17 vs. 128 +/- 12 mg/dl) 24 h postischemia. Pathological assessment showed comparable degrees of tubular necrosis at 24 h. The postischemic increase in peritubular neutrophils per 10 high-power field was similar in control and L-selectin-deficient groups at 4 (28 +/- 10 vs. 22 +/- 5), 12 (245 +/- 80 vs. 236 +/- 78), and 24 h (130 +/- 12 vs. 156 +/- 18). These data argue against a significant role for L-selectin in renal IRI. Patho-physiological roles of L-selectin in vivo appear to be more complex than in vitro data would suggest.

Antibodies to ICAM-1 protect kidneys in severe ischemic reperfusion injury

ICAM-1 has been implicated in the pathophysiology of ischemic-reperfusion injury in a number of organs, but its role in mediating severe ischemic-reperfusion injury in the kidney has not been extensively studied. Uninephrectomized Sprague Dawley rats were pretreated with either control monoclonal antibody (mAb) or mAb to ICAM-1 and subjected to 60 min of renal artery occlusion. The serum creatinine, complete blood count and kidney histo-pathological damage scores (PDS) (Scale:0-4) were assessed prior to and 24 hours after ischemia. Mean serum creatinine (mg/dl) 24 hours after ischemia was significantly decreased in the anti-ICAM-1 group (1.38 +/- 0.23, p < 0.001) compared to control (2.87 +/- 0.34). PDS was also reduced in anti-ICAM-1 (2.55 +/- 0.20, p < 0.05) group compared to control (3.35 +/- 0.30). These data demonstrate that blocking ICAM-1 significantly mitigates severe ischemic acute renal failure, findings which may lead to improved therapy for this condition.

Role of CD11a and CD11b in ischemic acute renal failure in rats

Leukocytes, particularly neutrophils, have been implicated in ischemic-reperfusion organ injury (IRI). However, their role in kidney IRI is controversial. Leukocytes express the adhesion molecules CD11/CD18 on their surface, which mediate many functions that can lead to tissue damage. To determine the role of CD11a and CD11b in IRI in the kidney, uninephrectomized Sprague-Dawley rats were pretreated with monoclonal antibodies (MAbs) directed against CD11a and CD11b or control MAbs. The serum creatinine (SCr), complete blood count, and kidney histopathological damage scores (PDS) (scale: 0-4) were assessed prior to and 24 h after 60 min of ischemia. Mean SCr 24 h after ischemia was significantly decreased in the anti-CD11a- and -CD11b-treated group compared with the control MAb-treated group (2.5 +/- 0.3 mg/dl vs. 3.4 +/- 0.2 mg/dl, P < 0.05). PDS were also reduced in the CD11a and CD11b group compared with controls (2.7 +/- 0.2 vs. 3.5 +/- 0.1, P < 0.001). These data show that the CD11/CD18 leukocyte adhesion pathway plays a role in mediating ischemic acute renal failure in rats.

Immunocytochemical localization of ProANF 1-30, ProANF 31-67, atrial natriuretic factor and urodilatin in the human kidney

Whether ProANF 1-30 [first 30 amino acids (a.a.) of the 126-a.a. atrial natriuretic factor (ANF) prohormone] and ProANF 31-67 (a.a. 31-67 of this prohormone) with their natriuretic and diuretic properties are present within the human kidney is unknown. In the present investigation, ProANFs 1-30 and 31-67 as well as ANF (a.a. 99-126) of the ANF prohormone localized to the subbrush border of the pars convoluta and pars recta of the proximal tubules of the human kidney with immunoperoxidase staining. Immunofluorescent studies revealed that each of these peptides had a strong inclination for the perinuclear region in the proximal and distal tubules. ProANFs 1-30, 31-67 and 99-126 (i.e. ANF) also localized with both immunoperoxidase and immunofluorescent staining to the coritcal collecting ducts, glomeruli, and peritubular and interstitial blood vessels. ANF immunoperoxidase staining was particularly striking in the endothelium of interstitial arteries and vasa recta. In the glomeruli, prominent staining was noted in the peripheral glomerular capillary wall and in some of the visceral epithelial cells. In contrast, urodilatin (i.e. a.a. 95-126 of the ANF prohormone) was not found in the proximal tubules, but weak staining was found in the distal tubules and interstitial vessels with some but not all glomeruli, peritubular vessels, cortical collecting tubules and outer medullary nephrons weakly staining by immunoperoxidase and immunofluorescent methods. The whole prohormone being present in the kidney was suggested by immunological recognition of both the N- and C-termini of the ANF prohormone by radioimmunoassays.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical localization of proANF 1-30, proANF 31-67 and atrial natriuretic factor in the kidney

ProANF [1-30 first 30 amino acids (a.a) of the 126 a.a atrial natriuretic factor (ANF) prohormone], ProANF 31-67 (a.a 31-67) as well as atrial natriuretic factor (a.a 99-126), of the ANF prohormone localized to the sub-brush border of the pars convoluta and pars rectus of the proximal tubules of hydrated and dehydrated rat kidneys with immunoperoxidase staining. Immunofluorescent studies revealed that each of these peptides and especially ProANF 31-67 had a strong predilection for the perinuclear region in the proximal and distal tubules. ProANFs 1-30, 31-67, and 99-126 (that is, ANF) also localized with both immunoperoxidase and immunofluorescent staining to the cortical collecting ducts, glomeruli, peritubular, and interstitial blood vessels. ProANF 31-67 immunoperoxidase staining was particularly striking in the elastica of the small and large interstitial arteries. The whole prohormone being present was suggested by immunological recognition in the rat kidney of both the N-terminus and C-terminus of the ANF prohormone by radioimmunoassays. The concentration of the N-terminus in the kidney was 1.0 +/- 0.03 ng/g of kidney weight, while the C-terminus of the ANF prohormone concentration was 0.4 +/- 0.01 ng/g of kidney tissue. These findings of a sub-brush border and perinuclear location of the N-terminal and C-terminal ANF prohormone peptides suggest that the atrial natriuretic factor prohormone may be synthesized in and/or the respective peptides are captured by the proximal tubules, but also to a lesser extent by the distal tubules of the kidney.

Spontaneous platelet aggregation in type IIB Tampa von Willebrand disease is inhibited by the 52/48-kDa fragment of normal von Willebrand factor, which contains the GPIb binding domain

The association of Type IIB von Willebrand disease (vWD) with chronic persistent thrombocytopenia and spontaneous platelet aggregation has recently been recognized. It has been shown that IIB von Willebrand factor (vWF) can initiate platelet aggregation by binding to the platelet glycoprotein (GP) lb receptor and inducing exposure of the GpIIb/IIIa fibrinogen receptor. In this study we demonstrate the increased binding of Type IIB Tampa vWF with normal platelets when compared with nonthrombocytopenic Type IIB vWF. Studies further demonstrate that spontaneous platelet aggregation initiated by IIB Tampa vWF can be blocked by a 52/48-kDa fragment of normal vWF, which contains the binding domain.

Occupational exposure to organic solvents causing chronic tubulointerstitial nephritis

We describe a patient with a history of ulcerative colitis and long-standing occupational exposure to organic solvents. Over a follow-up period of almost four years he had progression of tubulointerstitial damage documented by two kidney biopsies. We propose that long-term exposure to organic solvents can lead to the development of chronic tubulointerstitial nephritis. We describe experimental evidence that supports our conclusion.

Proteinuria in hypertension

It had been previously thought that protein excretion in hypertensive nephrosclerosis was less than 0.5 to 1.0 g/24 h. Furthermore, it was believed that proteinuria in the nephrotic range associated with hypertension was probably due to primary renal disease, malignant hypertension, renal artery stenosis, or pheochromocytoma. We report eight patients with biopsy-proven hypertensive nephropathy and heavy proteinuria in the absence of malignant hypertension or renal artery stenosis. The 24-hour protein excretion ranged from 2.7 to 4.3 g. All patients had renal insufficiency, with serum creatinine ranging from 2.0 (176.8) to 7.8 mg/dL (689.5 mumol/L). Renal function worsened in most patients during the follow-up period despite adequate control of the hypertension, and three patients had to be started on hemodialysis. Three patients died during the follow-up period. We conclude that hypertensive nephrosclerosis must be included in the differential diagnosis of marked proteinuria in patients with essential hypertension and that heavy proteinuria, along with renal insufficiency, are poor prognostic indicators in such patients.

Hypocomplementemic vasculitis and renal involvement

Hypocomplementic urticarial vasculitis is a disorder that not only affects the skin, but other organs as well. We are describing a patient with this rare disorder and serious renal involvement that was treated with immunosuppressive therapy with good response and stabilization of the renal function. We emphasize the fact that renal involvement can occur with this disease and that the renal involvement is of the immune-mediate type and cannot be considered as benign as thought in the past.

Hypernephroma associated with multiple endocrine neoplasia type I: a case report

We report a case of multiple endocrine neoplasia type I and hypernephroma. Parathyroid hyperplasia, adrenocortical hyperplasia, a nodular goiter, multiple lipomas, a chromophobe adenoma of the pituitary and hypernephroma had all been diagnosed previously. All but the last are features consistent with the diagnosis of multiple endocrine neoplasia type I (Wermer's syndrome). The association of multiple endocrine neoplasia type I and hypernephroma may represent a new manifestation of this pleiotropic syndrome.

Antiheparin activity in human endothelial cells

Human endothelial cells possess antiheparin activity that neutralizes the anticoagulant action of heparin as measured by different tests of the clotting system. The antiheparin activity appears to be associated with an acid-soluble basic protein present in the particulate fraction of the endothelial cell cytoplasm. This finding might have some relevance in the maintenance of hemostasis. Furthermore, it might also have a pharmacological role in terms of resistance to exogenously infused heparin in patients with thromboembolic disorders.

Coagulation and immunology

One of the most vital functions of the vertebrates is to maintain hemostasis through coagulation and fibrinolysis. This is achieved by the interaction of vascular walls with blood components such as cells and proteins (coagulation factors, immunoglobulins, and complement). Deficiency of coagulation factors results in bleeding disorders. The immune system, in response to foreign proteins or defective self proteins, produces antibodies triggering an Ag-Ab interaction with the related host of different reactions including abnormal coagulation leading to hemorrhagic diathesis.

Heparin-mediated neutralization of platelet antiaggregatory activity of prostacyclin (PGI2): studies on mechanism

Prostacyclin (PGI2) is a well-known potent inhibitor of platelet aggregation. Its role has been implicated in physiological and pathological states of hemostasis. Heparin blocks the prostacyclin-mediated antiaggregatory activity on platelets. Prior treatment of heparin with heparinase as well as with protamine destroyed heparin's ability to neutralize PGI2. Studies on the mechanism of heparin blocking of PGI2 activity suggested that heparin interacted directly with PGI2, as shown by the loss of PGI2 mobility on thin layer chromatography concomitant with the loss of PGI2-mediated inhibition of platelet aggregation. PGI2 in this combination with heparin, nevertheless, retained its time-dependent ability to be hydrolyzed to 6-keto-PGF1 alpha. Findings of these studies may have implications in thrombosis and hemostasis, particularly in heparin-mediated abnormalities of circulating platelets.

Type IIB Tampa: a variant of von Willebrand disease with chronic thrombocytopenia, circulating platelet aggregates, and spontaneous platelet aggregation

Type IIB von Willebrand disease is characterized by enhanced ristocetin-induced platelet aggregation and absence of large von Willebrand factor multimers from plasma. An alteration of the von Willebrand factor molecule resulting in increased reactivity with platelets appears to be the basis for these abnormalities. We have now identified a new variant of type IIB von Willebrand disease in a family in which the four affected members also have chronic thrombocytopenia, in vivo platelet aggregate formation, and spontaneous platelet aggregation in vitro. In spite of repeatedly prolonged bleeding times and persistent thrombocytopenia, their bleeding diathesis is only moderate.

Ankylosing spondylitis and glomerulonephritis. Study of a case

Ankylosing spondylitis is a seronegative spondyloartropathy associated with IgA glomerulonephritis. We described a case not associated with IgA immunoglobulin deposition in the glomerulus, but with C3 complement deposition. At the same time circulating immune complexed of the IgG type were found. The possible association of glomerulonephritis and seronegative spondyloartropathies are discussed.

Ultrastructural and immunohistochemical studies of bronchiolo-alveolar carcinoma

A detailed ultrastructural study was made of seven cases of bronchiolo-alveolar carcinoma, and the findings were correlated with histochemical and immunohistochemical data. By electron microscopic examination all seven tumors displayed glandular differentiation, manifested by the presence of microvilli and intercellular junctions, with or without mucin production. Variable proportions of tumor cells retained ultrastructural characteristics of alveolar type II cells and Clara cells. In addition, some tumor cells revealed desmosomes and tonofilaments consistent with squamous differentiation. Immunohistochemical evaluation was carried out using a peroxidase-antiperoxidase technique and specific antibodies against surfactant high molecular weight glycoproteins, keratin proteins, IgA + secretory piece, carcinoembryonic antigen (CEA), human chorionic gonadotropin (HCG), and alpha-fetoprotein (AFP). Four tumors with type II cell-like differentiation stained with anti-surfactant glycoprotein sera. All seven tumors stained focally with anti-keratin and IgA + anti-secretory piece antibodies, and diffusely with CEA. These tumors failed to stain with antisera against HCG and AFP. It is concluded that bronciolo-alveolar carcinomas are primarily composed of cells with alveolar and bronchiolar cell differentiation. Adequate criteria were established for ultrastructural identification of tumor cells with differentiation to type II alveolar cell or Clara cell. Moreover, the findings of this study indicate that the surfactant glycoprotein marker, when present in a given tumor either diffusely or focally, is diagnostic of bronchiolo-alveolar carcinoma.

Effect of heparin on platelet aggregation

The effect of heparin on platelet aggregation was systematically examined on platelets in plasma (PRP), as well as on gel-filtered, washed, and formaldehyde-fixed platelets. Results indicate that, although heparin causes a mild potentiation of platelet aggregation in the PRP systems, a significant inhibitory activity is observed when heparin is added to isolated platelets. This inhibitory activity appears to be specific and not related to the impurities in the heparin preparations, as heparinase, as well as protamine, effectively neutralizes the heparin-mediated inhibitory activity on platelet aggregation. Although heparin-mediated inhibitory activity can be demonstrated in the presence of a number of different agonists (ADP, arachidonic acid, thrombin, Ionophore A23187, epinephrine, and ristocetin), the most pronounced inhibition is seen in the presence of ristocetin. Further studies show that heparin enhances thromboxane generation in isolated platelets. Platelets pretreated with heparin, however, fail to respond to preformed thromboxane. These findings suggest that, in addition to the potentiation of thromboxane production in platelets, heparin may also attribute some change(s) to the platelet(s)/platelet membrane, which interferes with their ability to respond to the agonists of platelet aggregation. This antiaggregatory activity of heparin was found to be inhibited by a factor(s) present in plasma but not in serum.

Hemolytic uremic syndrome after Campylobacter-induced diarrhea in an adult

Campylobacter fetus subspecies jejuni is a recognized pathogen of the gastrointestinal (GI) tract resulting in a spectrum of illness from mild gastroenteritis to severe colitis with bloody diarrhea. Campylobacter is also being recognized as capable of producing systemic illness. Furthermore, antibody response, hypocomplementemia, and bacteremia with enterotoxic organisms have been described. Many of the clinical features, both local (le, in the GI tract) and systemic, parallel those of Shigella. Since the hemolytic uremic syndrome (HUS) may be produced by the effect of endotoxins or the immunocomplex on vascular endothelium in susceptible patients, it is expected that this syndrome may follow Campylobacter enteritis as it does Shigella enteritis. We, therefore, believe Campylobacter jejuni enteritis should be considered as one of the causative agents capable of inducing the HUS.

Endotoxin-mediated inhibition of human platelet aggregation

A variety of endotoxins, when added to human platelet-rich plasma (PRP) or to suspensions of washed platelets (WP), demonstrated an inhibitory effect on platelet aggregation induced by various aggregating agents. Endotoxin blocked the release of 14C serotonin from platelets but had no influence on cyclic AMP production. Endotoxin did not interfere with thromboxane generation by platelets. However, endotoxin-treated platelets failed to respond to added thromboxane. The inhibitory effect of endotoxin on platelet aggregation was more pronounced in the presence of ionophore A23187 as compared to other aggregating agents and was effectively reversed by calcium but not by magnesium, another divalent cation. Furthermore, endotoxin failed to inhibit the ristocetin-induced agglutination of formaldehyde-fixed platelets; a non-calcium dependent phenomenon. These findings appear to suggest that endotoxin-mediated inhibitory activity of platelet aggregation is related to the interference in the role of calcium. The antiaggregatory activity of endotoxin appears to be due to a direct and rapid action on platelets and not due to a non-specific binding, as the effect was not abolished by washing the endotoxin-incubated platelets. Endotoxin-mediated alteration of platelet function may contribute to bleeding diathesis in septecemic and endotoxemic patients.

Carcinomas of the lung: an ultrastructural and immunocytochemical study

Fifty-two primary carcinomas of the lung were studied by electron microscopy and by an immunoperoxidase method, using an anti-human keratin antiserum. The results were compared with light microscopic observations. One-third of the carcinomas of the lung showed ultrastructural evidence of both glandular and squamous differentiation. The group of small cell carcinomas was found to be particularly heterogenous ultrastructurally with only three out of eight tumors showing neurosecretory-type granules. Indirect immunoperoxidase staining revealed presence of a keratin-type protein in the vast majority of carcinomas, including foci of small cell carcinomas. Our studies emphasize the heterogeneity and frequent intermixing of the four major categories of lung carcinomas: squamous cell carcinomas, adenocarcinomas, small cell carcinomas, and large cell carcinomas. It is suggested that all these tumors might be derived from pluripotential "reserve" bronchial or bronchioalveolar cells. The segregation of small cell carcinomas from other groups continues to be justified on pragmatic grounds because these carcinomas constitute a group of predominantly small fast-replicating cells amenable to chemotherapy.

"Undifferentiated" large cell malignancies: an ultrastructural and immunocytochemical study

One of the most difficult areas of surgical pathology is the classification of "undifferentiated" or "anaplastic" large cell malignant tumors. The differential diagnosis of these tumors includes poorly differentiated carcinomas, large cell malignant lymphomas, and amelanotic malignant melanomas. In this study of 56 such cases, the application of electron microscopy and, in selected instances, of indirect immunofluorescence and immunoperoxidase staining methods have helped us reach a precise histopathologic diagnosis in the majority of neoplasms that were considered to be "undifferentiated" by light microscopy.

In vitro cytotoxicity of human endothelial cells in polymyalgia rheumatica and giant cell arteritis

We studied sera from 20 patients with polymyalgia rheumatica (PMR)/giant cell arteritis (GCA), 15 patients with systemic lupus erythematosus (SLE), 15 patients with the CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, and telangietasia) and 33 age and sex matched controls for cytotoxicity against human endothelial cells using a 51Cr release assay. We observed increased levels of endothelial cytotoxic activity in the PMR/GCA sera compared with controls (P less than 0.001). This cytotoxicity was predominantly found in the GCA group, where 7 out of 10 patients (70%) demonstrated significant cytotoxicity. Sequential studies showed that the cytotoxic activity returned to normal when the disease was under control. Although 7 SLE and 3 CREST sera had significant cytotoxic activity, as a group they did not differ from controls (P less than 0.05). Pre-incubation with soybean trypsin inhibitor suppressed the cytotoxic activity in the positive sera suggesting the cytotoxicity is mediated via a protease mechanism. Our results demonstrate the presence of a cytotoxic factor in the serum of patients with PMR/GCA which may play an important role in the pathogenesis of the vascular lesions observed in these disorders.

Dual differentiation in small cell carcinoma (oat cell carcinoma) of the lung

Two cases of small cell "undifferentiated" carcinoma (oat cell carcinoma) of the lung with dual neurosecretory and squamous differentiation are reported. One was treated with various regimens of chemotherapy and radiotherapy; the other was untreated at the time of biopsy. By electron microscopy, the same tumor cells showed membrane-bound, dense-core, neurosecretory-type granules and bundles of tonofibrils denoting squamous differentiation. This dual differentiation underlies the difficulty of ascribing an exclusively neural histogenesis to small cell carcinomas with neurosecretory-type granules. It is possible that entoderm-associated neuroectodermal tumors develop features of autochthonous entodermal tumors as a result of microenvironmental influences. An alternative hypothesis would be that small cell tumors are derived from basal reserve bronchoepithelial cells with pluripotentialities.

Laryngeal tuberculosis

Tuberculosis involvement of the larynx is uncommon. However, it is a highly infectious disease and a hazard to both community and hospital staff. It should be considered in the differential diagnosis of patients presenting with chronic hoarseness. Two patients with laryngeal tuberculosis are the objective of the present report. The diagnosis was established by biopsy followed by isolation and identification of Mycobacterium tuberculosis from sputum.

Heparin neutralization of PGI2: effects upon platelets

Heparin neutralizes the inhibitory effect of prostacyclin (PGI2) on platelet aggregation. The PGI2-induced enhancement of platelet cyclic adenosine monophosphate levels is also inhibited. The mechanism appears to involve a direct interaction in which heparin neutralizes the inhibitory effects of PGI2 on platelet aggregation but, at the same time, does not lose its own anticoagulant activity. These findings may explain instances in which heparin infusions have been reported to produce hyperaggregation of platelets, thrombotic episodes, and thrombocytopenia in patients.

Platelet ATPase activities. II. ATPase activities of isolate platelet membrane fractions

Images