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At least 685 records · Page 38Linked to original sources
PubMed1990

[Defects in the prostaglandin system. IX. Lipoxygenase defect of thrombocytes in a patient with polycythemia vera].

Patients with the myeloproliferative syndrome (MPS) often show morphological and functional platelet abnormalities and an increased incidence of lowered cyclooxygenase- and/or lipoxygenase activity. We present the case history of a 68-year-old male patient with polycythaemia vera in whom an absolute absence of platelet lipoxygenase activity has been detected for the first time in the literature.

Aged↗
PubMed1989

Defective insulin-mediated splanchnic glucose regulation and glucose clearance: early glucose homeostatic defects in nondiabetic, young offspring of patients with noninsulin-dependent diabetes mellitus.

Nondiabetic, young offspring of noninsulin-dependent diabetic (NIDDM) patients manifest insulin insensitivity. The pathophysiologic implications of the insulin insensitivity are uncertain since such subjects are usually normoglycemic. We have, therefore, studied isotopically the glucose turnover fluxes (D(3-3H) glucose technique) during postabsorptive state and after a physiological solid mixed meal ingestion for 240 min in 13 nondiabetic offspring and eight age-, sex- and weight-matched controls. Mean fasting serum glucose (84 +/- 3 vs. 78 +/- 2 mg/dl) and insulin (13.9 +/- 1.5 vs. 5.3 +/- 0.8 microU/ml) were significantly (p less than 0.05) greater in the offspring vs. controls. After the mixed meal ingestion, both serum glucose and insulin levels rose to significantly higher levels throughout the study period in the offspring vs. controls. Basal (2.04 +/- 0.73 vs. 1.84 +/- 0.76 ng/ml) and peak (5.72 +/- 0.65 vs. 6.47 +/- 0.40 ng/ml) serum c-peptide levels were not significantly different between the offspring and controls, respectively. Mean basal hepatic glucose output was significantly (p less than 0.05) higher in the offspring vs. controls (79 +/- 6 vs. 66 +/- 6 mg/m2.min). Following the mixed meal ingestion, the total splanchnic glucose appearance was significantly greater and qualitatively different in the offspring vs. controls. This occurred in the presence of identical intestinal carbohydrate absorption rates in both groups as assessed by simultaneous D-xylose test. Despite higher serum insulin levels, basal and post-meal metabolic clearance rates of glucose were similar in the two groups. We conclude that in nondiabetic offspring, greater basal and post-meal serum glucose and insulin levels occur.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Immune defects in chronic renal impairment: evidence for defective regulation of lymphocyte response by macrophages from patients with chronic renal impairment on haemodialysis.

Cellular mechanisms contributing to impaired lymphocyte proliferative responses in chronic renal impairment (CRI) were investigated using peripheral blood mononuclear cells (PBMC) from 25 patients receiving haemodialysis. Impaired T cell proliferative responses to phytohaemagglutinin were demonstrated. The hyporeactive PBMC from patients with CRI suppressed the responses of PBMC from normals to a greater degree than did control PBMC. This immunosuppression was reversed significantly by depleting adherent monocytes (M phi). To further determine if these impairments might be critically dependent on cell-cell contact, M phi from an additional 10 patients on haemodialysis were examined for ability to support B and T cell colony formation in semi-solid cultures stimulated by Staphylococcus protein A (SpA). When compared to normal controls, significantly fewer B and T cell colonies were observed with M phi from CRI patients than when autologous M phi were used. Also, T cells from patients were significantly less effective than controls in supporting B cell colony growth. Decreased T and B cell colony responses in patients were not due to a primary abnormality of these cells, since allogeneic mixing experiments showed that B and T cells from patients were able to form a sufficient number of colonies when control M phi or T cells from normals were used as accessory and helper cells. These findings suggest that although M phi-mediated suppressor activity is an important mechanism contributing to impaired lymphocyte responsiveness in patients with chronic renal impairment on haemodialysis, additional or related abnormalities in M phi 'accessory' function may also exist.

Adult↗
PubMed1988

[Defects in the prostaglandin system. VI. Acquired plasma factor defect].

A 44 year-old male was admitted to hospital in October 1984 presenting with enzymatic and electrocardiographic signs of posterior wall myocardial infarction. At this time 2 separate examinations revealed normal plasma factor activity. At the 1 year follow-up (November 1985) plasma factor activity was still present. However, in February 1987 for the first time, the patient's plasma failed to enhance PGI2 synthesis from vascular tissue in vitro. 3 further follow-up examinations within the next 6 weeks again revealed an acquired absence of plasma factor activity of unknown cause. No deterioration in clinical condition occurred. All relatives tested showed normal plasma factor activity.

Adult↗
PubMed1988

The effect of cryosurgery and polymethylmethacrylate in dogs with experimental bone defects comparable to tumor defects.

The effects of liquid nitrogen (LN) and polymethylmethacrylate (PMMA) on normal bone, bone graft incorporation, and reossification were evaluated by simulating a tumor in dogs with experimental bone cavity. Ten skeletally mature mongrel dogs (20 femora) were divided into three groups: Group I, controls; Group II, LN (with and without bone graft); and Group III, PMMA (with and without LN). Roentgenograms, whole-mount histology, and tetracycline fluorescence studies were performed on the distal femur. Correlation of these studies showed that (1) marked trabecular and bone necrosis, extending 7-12 mm around the circumference of the cavity, developed by three and seven weeks after LN but no bony necrosis occurred after PMMA; (2) the pattern of reossification following cryosurgery was delayed and abnormal, demonstrating increased calcification and metaplastic bone formation; (3) cryosurgery decreased the rate of bone graft incorporation; (4) the cryonecrotic rim following cryosurgery correlated with an abortive attempt at peripheral reossification; and (5) cryosurgery had no effect on the articular cartilage. Cryosurgery is effective in causing bone necrosis, whereas PMMA is not, and the pattern of reossification is delayed and altered by freezing. This study suggests that microvascular thrombosis with subsequent ischemic infarction of bone is a major cause of bone necrosis following cryosurgery.

Animals↗
PubMed1988

Mechanism of defective natural killer cell activity in patients with AIDS is associated with defective distribution of tubulin.

Previous studies have demonstrated the importance of some cytoskeleton components in killing mechanisms. In fact, a microtubule and microfilament (MF) rearrangement in the lytic sequence of CTL and NK cells has been observed. In particular, MF seem to be related to the binding phase, because MF inhibitors suppress the binding of NK cells to the target, whereas microtubule inhibitors suppress only the killing phase. In this paper, the distribution of two cytoskeleton components, actin and alpha- and beta-tubulin, has been studied in PBL from AIDS patients, who maintain the capacity to bind to the target cell line K562 but are not able to kill it. PBL were labeled with mAb to these two cytoskeleton components, and then indirect immunofluorescence was used to visualize their distribution in the conjugates. A normal polarization of actin in the effector PBL was found, whereas no tubulin rearrangement was evident in the effector and target cells. On the contrary, in conjugates of PBL or large granular lymphocytes from normal donors and K562, a polarization of actin in the effector cell and a polarization of tubulin both in the effector and in the target cells, at the site of the attachment, was evident. These data suggest that a deficiency of tubulin rearrangement may underlie the inability of the NK cells from AIDS patients to kill their target.

Acquired Immunodeficiency Syndrome↗
PubMed1986

The genetic deficiency of leukocyte surface glycoprotein Mac-1, LFA-1, p150,95 in humans is associated with defective antibody-dependent cellular cytotoxicity in vitro and defective protection against herpes simplex virus infection in vivo.

The role of the Mac-1, LFA-1, p150,95 leukocyte glycoprotein family in mediating antiviral host defense was investigated by utilizing mononuclear cells (MC) obtained from eight patients with a genetic deficiency of Mac-1, LFA-1, and p150,95, and normal MC incubated with subunit-specific monoclonal antibodies (MAb) directed against these glycoproteins. As shown with an in vitro chromium-release cytotoxicity assay to herpes simplex virus (HSV)-infected Chang liver target cells, MC of these patients with the severe phenotype or normal MC preincubated with a combination of MAb against Mac-1 glycoprotein subunits were deficient in antibody-dependent cellular cytotoxicity (ADCC). When used individually, MAb directed at LFA-1-alpha or -beta also inhibited ADCC and natural killer cytotoxicity (NKC). In a single cell agarose assay, MC of Mac-1-deficient patients formed fewer effector-target cell conjugates in the presence of specific anti-HSV antibody. To investigate the in vitro contributions of these glycoproteins to cytotoxic host defense mechanisms, two in vivo adoptive transfer models were explored in which neonatal mice are protected against a lethal HSV challenge by normal human MC plus anti-HSV antibody (in vivo ADCC) or human interferon-alpha (NKC stimulated in vivo). In each model, MC from patients with "severe" or "moderate" phenotypes of Mac-1 deficiency, or normal MC incubated with a combination of anti-LFA-alpha, Mac-1-alpha, p150,95-alpha plus -beta MAb failed to protect neonatal mice against lethal HSV infection. These studies further indicate requirements for adhesion-dependent mechanisms in the mediation of MC-ADCC, and suggest that Mac-1-dependent cellular adhesive properties are necessary for normal cytotoxic functions in vivo in experimental models of human ADCC or interferon-stimulated NKC. These findings, in addition to the recognized occurrence of severe or even lethal viral infections in some Mac-1-deficient patients, suggest that glycoproteins of the Mac-1 family may be important determinants of antiviral host defense.

Adult↗