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Biomedical subjects

R Fresco

Publications and source records attributed to R Fresco.

At least 19 recordsLinked to original sources
PubMed2000

Human mesothelial cells are unusually susceptible to simian virus 40-mediated transformation and asbestos cocarcinogenicity.

Mesothelioma, a malignancy associated with asbestos, has been recently linked to simian virus 40 (SV40). We found that infection of human mesothelial cells by SV40 is very different from the semipermissive infection thought to be characteristic of human cells. Mesothelial cells are uniformly infected but not lysed by SV40, a mechanism related to p53, and undergo cell transformation at an extremely high rate. Exposure of mesothelial cells to asbestos complemented SV40 mutants in transformation. Our data provide a mechanistic explanation for the ability of SV40 to transform mesothelial cells preferentially and indicate that asbestos and SV40 may be cocarcinogens.

Asbestos↗
PubMed1996

The effect of fluoxetine on anxiety and depression symptoms in cancer patients.

Little has been done to study the effectiveness of antidepressants in controlling anxiety/depression in a population of cancer patients. A double-blind placebo-controlled study was therefore designed to assess the effectiveness of 20 mg fluoxetine. Of 115 cancer patients who fulfilled entry criteria for levels of distress, 45 patients were randomized to a fluoxetine treatment group (FA) and 46 patients to a placebo group (PA) after a 1-week placebo period designed to exclude placebo responders. The Montgomery and Asberg Depression Scale (MADRS), the Hamilton Anxiety Scale (HAS), the Hospital Anxiety and Depression Scale (HADS), the Revised Symptom Checklist (SCL90-R) and the Spitzer Quality of Life Index (SQOLI) were used to assess the efficacy of fluoxetine. The response rate, defined by a HADS score lower than 8 after 5 weeks of treatment, was not significantly higher in the FA group (11%) compared to the PA group (7%). Compared to the PA group, patients in the FA group showed a significantly greater decrease in SCL90-R mean total score after 5 weeks, but not a greater decrease in HADS mean score. No difference between the two groups was found in observer-reported assessments (MADRS, HAS and SQOLI). Significantly more drop-outs were observed in the FA group (n = 15) than in the PA group (n = 7), although the frequencies of side-effects were not significantly different.

Adult↗
PubMed1994

Microencapsulation of hemoglobin in liposomes using a double emulsion, film dehydration/rehydration approach.

A double emulsion, film dehydration/rehydration approach was developed for encapsulation of hemoglobin (Hb) at high concentration in liposomes. The liposome-encapsulated Hb (LEH) membrane was formulated to contain either phosphatidylinositol (PI) or polyethyleneglycol phosphatidylethanolamine (PEG-PE) along with partially hydrogenated egg-PC, cholesterol, and alpha-tocopherol in a molar ratio of 0.1:1:1:0.02, respectively. The methods introduced in this study followed a multi-step procedure. First, a primary emulsion of Hb in organic solvent containing dissolved lipids was formed. Next, the emulsion was dispersed into an aqueous continuous phase to form a water-in-oil-in-water type double emulsion. Other than the lipids noted above, no surfactants were used in this system. The double emulsion was then converted to LEH by the following steps: evaporating the organic solvent; dehydrating the water to form a dry, thin Hb-lipid film; rehydrating the film in Hb solution to form the LEH; reducing the size of the LEH using 'microfluidization' i.e., high pressure/hydrodynamic shear; and lastly washing the down-sized LEH in buffer. Physico-chemical properties of the model LEH were measured, including oxygen content, encapsulated Hb concentration, oxygen affinity and cooperativity, vesicular size distribution, viscosity, and stability. The suitability of LEH prepared in this manner as a red blood cell substitute was shown using continuous isovolemic exchange transfusion techniques in a small animal model: clearance, efficacy and acute toxicity were evaluated.

Animals↗
PubMed1992

Liposome-encapsulated hemoglobin processing methods.

An effective and safe red blood cell substitute is being developed based on double emulsion/evaporation techniques followed by high pressure homogenization to form liposome-encapsulated hemoglobin (LEH). Formulations are made up of hydrogenated phosphatidylcholine (PC, soy or egg), cholesterol, phosphatidylinositol (PI), and alpha-tocopherol in a molar ratio of 1:1:0.2:0.02, respectively. Resulting LEH-encapsulated hemoglobin (Hb) concentrations are greater than 80% of precursor Hb solutions. Met-Hb generation accompanying LEH processing appears to be small with only a 3% increase for encapsulated over precursor. These results correspond to an oxygen content for an LEH suspension sample (50% by volume LEH) of 15 volume% oxygen. Oxygen affinity and cooperativity values for LEH suspensions appear to be near the normal values expected for whole blood. The viscosity of LEH suspension samples (50% by volume LEH in phosphate-buffered saline containing 7.5 wt% albumin) were slightly higher than that of whole blood. The effect of shear rate on leakage of encapsulated Hb from LEH was small, i.e. 0.5% or less. Nearly total isovolemic exchange transfusion using a cannulated rat model demonstrates efficacy of LEH suspension samples. There appears to be no difference in rat internal organ weights between rats exchanged with control compared to rats exchanged with LEH. Circulation half-life following 50% isovolemic exchange-transfusion is about 15 to 18 hours.

Animals↗
PubMed1991

The effect of chronic renal insufficiency on cyclosporine nephrotoxicity.

Despite cyclosporine's efficacy in preventing rejection, its use has been hampered by nephrotoxicity. Questions remain concerning its application in patients with decreased renal function. The purpose of this study was to 1) establish a reliable animal model with chronic renal insufficiency (CRI) to study cyclosporine (CyA) nephrotoxicity, and 2) compare the long-term (50 day) severity of CyA nephrotoxicity in CRI versus normal animals. Fischer 344 rats were divided into six groups (15 to 22 each). In three groups, CRI was induced by a 5/6th nephrectomy (three groups were sham operated). After three wks., daily i.p. injections of olive oil, CyA at five mg./kg., or CyA at 30 mg./kg. daily were administered. Serum and urine were collected at 10 day intervals for the determination of biochemical indices of renal function. Animals were sacrificed after 50 days of treatment and renal histology was evaluated by light and electron microscopy. Chronic CyA treatment was well tolerated by both intact and CRI rats, suggesting that this is a reliable model for long-term CyA toxicity studies. CyA decreased renal function at day 50 in both CRI and intact animals. CRI of mild to moderate degree had little effect on the biochemical and histological indices of CyA induced nephrotoxicity. CRI does appear to potentiate the metabolic toxicity that occurs after chronic treatment with high dose CyA.

Acetylglucosaminidase↗
PubMed1991

Failure to confirm the presence of a retrovirus in cultured lymphocytes from patients with Kawasaki syndrome.

We and others previously reported DNA polymerase activity in culture supernatants of peripheral blood mononuclear cells from patients with acute Kawasaki syndrome (KS). In the present study, we further characterized the previously detected polymerase activity and attempted to confirm its presence in cultured peripheral blood mononuclear cells from additional patients with KS. Characterization experiments indicated that the polymerase activity was typical of a DNA-dependent DNA polymerase rather than viral reverse transcriptase. Peripheral blood mononuclear cell cultures from 17 additional KS patients were negative for reverse transcriptase activity in three laboratories. Our findings do not provide support for a retroviral etiology of KS. Further studies should continue to focus on infectious agents in efforts to elucidate the etiology of KS.

Cells, Cultured↗
PubMed1989

Successful revascularization of an occluded renal artery after prolonged anuria.

Renal atherosclerosis and fibromuscular dysplasia are the most common causes of curable human renovascular hypertension and renal failure. Vascular reconstruction often preserves renal function, but renal failure is rarely reversed, especially after days of anuria. We report a case of a 23-year-old woman who as a child underwent a nephrectomy for congenital hydroureter and renal hypoplasia. She later experienced fibromuscular dysplasia of the remaining renal artery, which ultimately progressed to a complete occlusion and 31 days of total anuria. The patient was revascularized, and within 2 months renal function returned with a blood urea nitrogen and creatinine of 9.0 and 1.0 mg/dl, respectively. After a follow-up of 6 months the patient's blood pressure remained 120/80 to 130/80 mm Hg without administration of hypertension medication. In this report we emphasize that under selected circumstances a kidney can survive prolonged ischemia and that delayed revascularization may reestablish renal function.

Adult↗
PubMed1988

Neonatal and maternal platelets: activation at time of birth.

Determination of the plasma concentrations of beta-thromboglobulin (BTG), thromboxane B2 (TxB2) and platelet factor 4 (PF4) were made at the time of birth in 18 newborns and their respective mothers. Both groups show significant elevation of all these molecular markers, suggesting marked platelet activation. The elevated TxB2 levels in the newborn group, 25 +/- 8 pg/ml, are compatible with a normally functioning and activated platelet prostaglandin pathway. Mode of delivery, vaginal or caesarean section, does not significantly influence the degree of activation in either group. Ultrastructural platelet examination did not reveal any morphologic differences between maternal and newborn platelets. There appears to be marked activation of the newborn and maternal platelet systems at the time of birth, and we postulate that this may explain in part the transient platelet dysfunction observed in newborns.

Blood Platelets↗
PubMed1988

Tumor of the tongue containing heterotopic brain tissue.

A polypoid tumor containing astrocytic glia and ependyma was excised from the base of the tongue of a 3-month-old infant. Neuroid elements were identified immunocytochemically and by means of electron microscopy. We attribute this rare anomaly to displacement of brain tissue in early embryogenesis before closure of the palate.

Astrocytes↗
PubMed1988

Definition of the pulmonary antibody response to ovalbumin following local challenge in systemically immunized rats.

The in vivo pulmonary immune response of rats to local stimulation with antigen was assessed by measuring antigen-specific antibody and antibody-secreting cells utilizing enzyme-immunoassay technology. Sprague-Dawley rats were immunized subcutaneously with ovalbumin (OA) emulsified in Freund's incomplete adjuvant, challenged with OA intratracheally on Day 19 and sacrificed 1, 2, 3, or 4 days later. Specific antibody-secreting cells in the lung-associated lymph nodes were enumerated with the ELISA-SPOT assay and antibody concentration in the pulmonary lavage fluids and sera was assessed with the ELISA. The greatest response for each parameter was on Day 2. Cellular infiltration of the lung was minimal. Cellular infiltrates consisted mainly of polymorphonuclear leukocytes and were most numerous in the lavage fluid on Days 1 and 2 and in the lung parenchyma on Day 2 after challenge. Local production versus serum transudation of antibody was evaluated by comparing the levels of OA-specific antibody to albumin in the lavage fluid and serum. The data showed that antibody in the lungs was primarily produced locally.

Animals↗
PubMed1987

Occurrence of renal tubular dysfunction in lupus nephritis.

We prospectively evaluated 30 patients who presented with active systemic lupus erythematosus (SLE) for the presence of tubular abnormalities. All patients fulfilled the American Rheumatology Association criteria for SLE. When appropriate, a renal biopsy was performed. Of the 30 patients studied, 12 had no abnormal tubular study results, whereas 18 patients had some form of defect in the handling of potassium, sodium, or hydrogen ions. Eight patients had distal renal tubular acidosis (dRTA) due to an isolated proton secretory defect. Five had dRTA of the gradient or acid back-leak type. Two had an unresponsive voltage-dependent form of dRTA; one had a responsive voltage-dependent form of dRTA. One individual had hyporeninemic hypoaldosteronism and one had dRTA plus hypoaldosteronism. Clinically, patients with the abnormal tubular study results more often presented with nephritis or nephrotic sediment, peripheral edema, or anemia. Renal biopsies failed to demonstrate any difference in glomerular histologic findings and calculated activity, chronicity, or interstitial indexes. We conclude that SLE may be associated with a variety of tubular defects.

Acidosis, Renal Tubular↗
PubMed1986

Pseudo-Chediak-Higashi anomaly in a child with a hepatic vascular malformation.

A case of a congenital hepatic vascular malformation in a child complicated by disseminated intravascular coagulation and hemolytic anemia is presented. Examination of the peripheral blood disclosed the presence in the leukocytes of giant intracytoplasmic inclusions resembling those of the Chediak-Higashi anomaly. Ultrastructural analysis characterized those inclusions as phagocytosed red cell debris, a result of mechanical destruction of the red cells.

Anemia, Hemolytic↗
PubMed1986

Systemic lupus erythematosus presenting with hyporeninemic hypoaldosteronism in a 10-year-old girl.

Hyperkalemia has been noted to occur spontaneously in patients with long-standing systemic lupus erythematosus who did not have advanced renal insufficiency. The patients previously described all had relatively normal renin-aldosterone systems, and the hyperkalemia was thus presumed to be secondary to a primary defect in renal tubular potassium secretion. We describe at 10-year-old girl with lupus nephritis, without significant renal insufficiency, who had hyperkalemia from hyporeninemic hypoaldosteronism postulated to be due to vasculitis involving the afferent/efferent arterioles and juxtaglomerular apparatus.

Aldosterone↗