Degradation of tissue-type plasminogen activator by human monocyte- derived macrophages is mediated by the mannose receptor and by the low- density lipoprotein receptor-related protein

The balance of tissue-type plasminogen activator (t-PA) production and degradation determines its concentration in blood and tissues. Disturbance of this balance may result in either increased or decreased proteolysis. In the present study, we identified the receptor systems involved in the degradation of t-PA by human monocytes/macrophages in culture. Monocytes were cultured and became macrophages within 2 days. At 4 degrees C, 125I-t-PA bound to macrophages with high (apparent dissociation constant [kd], 1 to 5 nmol/L) and low affinity (kd > 350 nmol/L). At 37 degrees C, the cells internalized and degraded t-PA via the high affinity binding sites, which were partially inhibited by mannan. The low affinity binding sites were 6-aminohexanoic acid- inhibitable and not involved in t-PA degradation. Degradation of t-PA was upregulated during differentiation of monocytes to macrophages. Dexamethasone further upregulated the mannan-inhibitable t-PA degradation. Lipopolysaccharide downregulated both mannan-inhibitable and non-mannan-inhibitable t-PA degradation. Non-mannan-inhibitable degradation was completely blocked by recombinant 39-kD receptor- associated protein (RAP, inhibitor of lipoprotein receptor-related protein [LRP]), whereas mannan-inhibitable degradation was blocked by the addition of a monoclonal antibody against the mannose receptor. No differences between the degradation of t-PA and functionally inactivated t-PA were observed. We conclude that human monocyte-derived macrophages are able to bind, internalize, and degrade t-PA. Degradation of t-PA does not require complex formation with plasminogen activator inhibitors. The macrophages use two independently regulated receptors, namely, the mannose receptor and LRP, for the uptake and degradation of t-PA.     

A comparison of manual and mechanical ventilation during pediatric transport.

OBJECTIVE: To compare the amount of variability in ventilation during intrahospital transport of intubated pediatric patients ventilated either manually or with a transport ventilator. DESIGN: Prospective, randomized study. SETTING: Tertiary, multidisciplinary, pediatric intensive care unit. PATIENTS: Forty-nine pediatric postoperative heart patients who required transport while still intubated. INTERVENTIONS: Patients were randomized to receive either manual ventilation during transport or ventilation by a portable mechanical ventilator. Baseline ventilatory and hemodynamic parameters were recorded before and during transport. Before and after arterial blood gases were also obtained. All other aspects of care were identical. MEASUREMENTS AND MAIN RESULTS: There was a statistically significant greater amount of variation in ventilation during transport with manual technique as opposed to the mechanical ventilator. A Student's t-test on pre- to post-blood gas differences showed a significantly lower PetCO2 (p = .02) in the manually ventilated patients when compared with the mechanically ventilated patients. Values for PCO2 were higher, but only marginally significant (p = .08). Repeated measures analysis of variance using these same pre- and post blood gas values confirmed the significant decrease in PetCO2 (p = .05). Minute to minute variation in PetCO2 during transport was greater and the mean values significantly lower in the manually ventilated group (p < .05). Hemodynamic data were remarkably stable when examined both before and after transport and on a minute to minute basis during transport. CONCLUSIONS: Manual ventilation during intrahospital transport results in greater fluctuation of ventilatory parameters from an established baseline than does use of a transport ventilator. No clinically significant changes in status occurred during the brief period of transport studied.     

The distribution of infectivity in blood components and plasma derivatives in experimental models of transmissible spongiform encephalopathy

BACKGROUND: The administration of blood components from donors who subsequently develop Creutzfeldt-Jakob disease has raised the issue of blood as a possible vehicle for iatrogenic disease. STUDY DESIGN AND METHODS: We examined infectivity in blood components and Cohn plasma fractions in normal human blood that had been "spiked" with trypsinized cells from a scrapie-infected hamster brain, and in blood of clinically ill mice that had been inoculated with a mouse-adapted strain of human transmissible spongiform encephalopathy. Infectivity was assayed by intracerebral inoculation of the blood specimens into healthy animals. RESULTS: Most of the infectivity in spiked human blood was associated with cellular blood components; the smaller amount present in plasma, when fractionated, was found mainly in cryoprecipitate (the source of factor VIII) and fraction I+II+III (the source of fibrinogen and immunoglobulin); almost none was recovered in fraction IV (the source of vitamin-K-dependent proteins) and fraction V (the source of albumin). Mice infected with the human strain of spongiform encephalopathy had very low levels of endogenous infectivity in buffy coat, plasma, cryoprecipitate, and fraction I+II+III, and no detectable infectivity in fractions IV or V. CONCLUSION: Convergent results from exogenous spiking and endogenous infectivity experiments, in which decreasing levels of infectivity occurred in cellular blood components, plasma, and plasma fractions, suggest a potential but minimal risk of acquiring Creutzfeldt-Jakob disease from the administration of human plasma protein concentrates.     

Facilitating the decrease in fibromyalgic pain during metabolic rehabilitation: an essential role for soft tissue therapies

Recent evidence indicates that fibromyalgia (FMS) is a manifestation of impaired metabolism. In most cases, the cause is primarily inadequate thyroid hormone regulation of cell function. The measurable features of FMS can be improved or relieved in most patients through therapy that is best termed ‘metabolic rehabilitation’. For many patients undergoing metabolic rehabilitation, however, FMS pain scores normalize only after soft tissue treatment controls or eliminates noxious neural input from the musculoskeletal system to the central nervous system. Our studies and clinical experiences convince us that effective soft tissue therapy can expedite the typical patient's improvement or recovery. Neglecting to use such therapy can hinder recovery, even when the patient undergoes expertly conducted metabolic rehabilitation. This paper describes the probable mechanisms by which musculoskeletal lesions can sustain FMS pain, and gives guidelines for treating the FMS patient's soft tissues to facilitate the reduction of pain during metabolic rehabilitation.     

Acquired immunodeficiency syndrome-associated non-Hodgkin's lymphomas and other malignancies in patients with hemophilia

Non-Hodgkin's lymphoma (NHL) is the most common human immunodeficiency virus (HIV)-associated malignancy in hemophiliacs. We studied the incidence and clinicopathologic features of NHL in 3,041 hemophiliacs followed at 18 US Hemophilia Centers between 1978 and 1989. Of the 1,295 (56.6%) who were HIV(+), 253 (19.5%) developed acquired immunodeficiency syndrome (AIDS), of whom 14 (5.5%) developed NHL. Three NHL occurred in HIV(-) hemophiliacs, for a 36.5-fold greater risk in HIV(+) than HIV(-) hemophiliacs (P < .001). The NHL incidence rate was 29-fold greater than in the US population by Surveillance, Epidemiology, and End Results (SEER) estimates (P < .001). Between 0 and 4 lymphomas have been observed per year between 1978 and 1989. At presentation 13 (92.9%) of the HIV(+) NHL were extranodal. Ten were stage IV, 1 stage II, and 3 stage IE. Ten (71.4%) were high-grade, 3 (21.4%) intermediate-grade, and 1 (7.1%) was a low-grade B-cell lymphoma. Epstein-Barr virus (EBV) DNA was detected in 36% by in situ hybridization, including one central nervous system (CNS) lymphoma. The mean CD4 cell count at NHL diagnosis was 64/mm3, the mean latency from initial HIV infection was estimated to be 59 months, and the median survival was 7 months. The incidence of basal cell carcinoma in HIV(+) hemophiliacs was 18.3-fold greater than in HIV(-) hemophiliacs (P < .001) and 11.4-fold greater than in the US population (P < .001). In conclusion, incidence rates of NHL and basal cell carcinoma in HIV(+) hemophiliacs are significantly increased over rates in HIV(-) hemophiliacs and over rates in the US population. Clinicopathologic presentation of NHL in HIV(+) hemophiliacs is similar to that in HIV(+) homosexual men.     

Peripheral arterial disease is only the tip of the atherosclerotic "iceberg".

The peripheral vascular system makes up the largest single "organ system" and holds many biological secrets that, when unlocked, can open doors for new treatments for all vascular beds, including those of the coronary and cerebral arteries. The coronary and noncoronary circulations are inseparable and interdependent. Cardiologists as well as primary care physicians should have a global view in the management of patients with PAD. The treatment of atherosclerosis in any of the arterial beds is a multifactorial problem. PAD is underrecognized. Antiplatelet and lipid-lowering therapy is underutilized in patients with PAD. Clopidogrel, an antiplatelet drug, has proven to prevent adverse cardiovascular events in patients with PAD. Therapeutic angiogenesis has been reported to improve severe claudication.     

Allogeneic marrow transplantation for refractory anemia: a comparison of two preparative regimens and analysis of prognostic factors

From 1990 to 1993 we performed a prospective study of busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) in 30 patients with refractory anemia (RA) undergoing related (n = 17) or unrelated (n = 13) donor marrow transplantation. Nineteen patients survive disease free (63% 3- year actuarial disease-free survival [DFS]) and no patient relapsed. These results were compared to those of 38 historical controls with RA treated with cyclophosphamide and total body irradiation, of whom 22 are disease-free survivors and 1 relapsed. After correcting for significant variables between the two treatment groups, we found no statistically significant difference in outcome based on preparative regimen. Combining data from these 68 patients plus 2 additional patients with RA treated before 1993 with busulfan and cyclophosphamide, we identified four variables independently associated with improved survival: younger age, shorter disease duration, lower neutrophil count pretransplant, and lower hematocrit pretransplant. We also found that 15 patients 40 to 55 years of age had a 46% 3-year actuarial DFS and 26 patients receiving unrelated or mismatched related donor marrow had a 50% 3-year actuarial DFS. We conclude that there does not appear to be any significant difference in outcome based on preparative regimen in this patient population. In addition, allogeneic bone marrow transplantation may be a reasonable approach to therapy of RA early after diagnosis. However, whether early intervention with transplantation prolongs survival over that expected without transplantation cannot be ascertained with certainty from available data.