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Biomedical subjects

R L Wolf

Publications and source records attributed to R L Wolf.

At least 19 recordsLinked to original sources
PubMed1992

Blood flow imaging through detection of temporal variations in magnetization.

Two hypotheses were tested: (a) that view-to-view variations in bulk phase and modulus of magnetization in vascular volume elements can indicate the presence of disordered blood flow, and (b) that a substantial loss of signal intensity on magnetic resonance (MR) angiograms of poststenotic regions is due to view-to-view changes in magnetization. To test these hypotheses, a technique was developed in which view-to-view variations in transverse magnetization were used to create angiographic projection images, which showed only disordered flow (disordered flow maps) in vitro and in vivo. In phantom studies, this technique recovered signal intensity downstream from stenoses. A combination of disordered flow maps with morphologic images improved visualization of stenotic regions and provided information on characteristics of local flow. These results show that view-to-view variations in transverse magnetization occur in regions of disordered flow and are an important cause of loss of signal intensity. This technique can provide information about dynamic blood flow and improve depiction of anatomic structures on MR angiograms.

Blood Circulation↗
PubMed1988

Human placental cells that regulate lymphocyte function.

We examined normal human placenta for an immunologic function by measuring the release of soluble inhibitory factor (SIF). SIF is a product of normal T lymphocytes and of the JEG-3 choriocarcinoma cell line, and blocks proliferative and antibody-producing responses of mononuclear cells. SIF can be further characterized by a noncovalently linked subcomponent, lipid suppressor substance. The villous surfaces of six normal human placentae were digested with collagenase to obtain a population of predominantly multinucleated giant cells. These cells were maintained in standard culture for 5 days after which the cell-free conditioned culture medium was assayed for SIF content by measuring suppression of [3H]thymidine incorporation into lymphocytes stimulated by low-dose phytohemagglutinin. Undiluted placental SIF induced 88% inhibition of this response (p less than 0.001). The placental SIF was found to contain lipid suppressor substance, as does SIF from mononuclear cells. We determined this by thin-layer chromatography where a peak of suppressive activity occurred at Rf 0.32 [( 3H]thymidine incorporation reduced from 21810 +/- 308 to 4121 +/- 214 cpm); this is the position on thin-layer chromatography to which mononuclear cell lipid suppressor substance migrates. Ion exchange chromatography comparing the elution patterns of lymphocyte-SIF and placental-SIF indicated that both eluted in the fraction of 40-50 mM PO4 means buffer, further suggesting identity between these two substances. SIF from placental and lymphocyte sources functioned by inducing the presence of suppressor cells in culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed1987

Unusual arteritis causing myocardial infarction in a child.

A 5-year-old girl presented with a diffuse inflammatory disease that consisted of fever, lymphadenopathy, splenomegaly, and anterior uveitis. A chest x-ray film indicated an apparently nodular infiltrate. Her condition deteriorated abruptly, and she died of acute myocardial infarction. Autopsy revealed an extensive vasculitis that involved the aorta, pulmonary arteries, and coronary vessels. An aneurysm of the left coronary artery was noted. We present and discuss this case as an unusual arteritis in childhood, closely resembling Takayasu's disease. The presence of extensive erythrophagocytosis in sinus histiocytes hinted at a viral or immunologic origin for this child's disease.

Aortic Diseases↗
PubMed1986

In vitro biological activities of Escherichia coli-derived bovine interferons-alpha, -beta, and -gamma.

The infectious yields of several bovine viruses were inhibited in bovine cells treated with purified preparations of E. coli-derived bovine interferons (BoIFNs)-alpha, -beta, and -gamma. BoIFN-beta 2, encoded by one member of the BoIFN-multigene family, had more potent antiviral and antiproliferative activities than the product of one member of the class-I IFN-alpha gene family (BoIFN-alpha I1). BoIFN-beta 2 also completed more effectively than BoIFN-alpha I1 with HuIFN-alpha I2 for cell-surface receptors on bovine cells. Despite these differences, the kinetics of maximal antiviral activity were similar for BoIFN-alpha I1, BoIFN-beta 2, and HuIFN-alpha I2. In comparison to BoIFN-alpha I1 and BoIFN-beta 2, BoIFN-gamma had the least in vitro antiviral activity and required the longest contact with cells to achieve maximal protection against virus infection, but had a dramatically greater antiproliferative activity.

Animals↗
PubMed1983

Characterization of an immune suppressor from transformed human trophoblastic JEG-3 cells.

Cultured human choriocarcinoma JEG-3 cells secrete an immunosuppressor that inhibits lymphocyte proliferation stimulated by either an antigen or a mitogen. In this study, the immunosuppressive factor was characterized by three methods: ion-exchange and exclusion chromatography, partition in organic solvents, and thin-layer chromatography on silicic acid. This JEG-3 cell factor appeared to be a protein complex of about 150,000-200,000 Da that contained an immunologically active polar lipid. The structural and functional characteristics of JEG-3 cell immunosuppressor are similar if not identical to those of SIF, a suppressor lymphokine derived from T cells. These secretions from transformed trophoblastic cells may correspond to normal placental products or represent a function of malignant cells.

Cell Line↗
PubMed1979

Role of lipids in the immune response. I. Localization to a lipid-containing fraction of the active moiety of an inhibitor (SIF) of lymphocyte proliferation.

By further study, a previously described inhibitor of lymphocyte proliferation and immunoglobulin synthesis, soluble inhibitory factor (SIF), has been shown to comprise two moieties; a nondialyzable protein, apparently inert with regard to inhibition of proliferation, and a polar lipid bound to the protein fraction, presumably by hydrophobic interaction. The lipid contained the activity responsible for inhibition of PHA-induced DNA synthesis. It was tentatively identified as a lipid with an as yet unidentified polar group, on the basis of mobility on thin layer chromatographic plates and behavior on silicic acid.

Amino Acids↗
PubMed1979

Role of lipids in the immune response. II. An enhancer of antibody production (APS) that is a lipid closely associated with lymphocyte mitogenic factor (LMF).

Lymphocyte mitogenic factor (LMF) is a lymphokine produced by dividing T cells. An activity coeluting with LMF from a Sephadex resin is extractable from LMF with chloroform-methanol. It enhances but does not initiate antibody formation measured by generation of plaque-forming cells (PFC). It does not cause proliferation of B cells. This activity elutes from a silicic acid column and produces a pattern on thin layer chromatography that suggests that the compound(s) responsible for the activity is a polar lipid.

Antibody Formation↗
PubMed1977

An inhibitor of lymphocyte proliferation and lymphokine production released by unstimulated foetal monocytes.

Supernatants obtained from 3-day cultures of cord blood monocytes inhibited normal lymphocyte activation by either PHA or in a two-way MLC. Both lymphocyte transformation and lymphokine production was significantly inhibited by these supernatants but not by those derived from adult mononuclear cell cultures. The inhibitory material produced by foetal monocytes was dialysable and was non-cytotoxic to target cells. It is postulated that this factor contributes to the depressed maternal cell-mediated immune response observed in pregnancy.

Female↗
PubMed1976

An unusual experience of neonatal necrotising enterocolitis.

Fifty-three patients with neonatal necrotising enterocolitis, who were seen over a 1-year period, were reviewed with regard to weight, gestational age, type of feed and incidence of exchange transfusion. These babies were larger and more mature than those in whom this disease is usually described. A significantly smaller number of babies with necrotising enterocolitis than control babies were breast-fed. A high positive association with exchange transfusion was noted.

Enterocolitis, Pseudomembranous↗
PubMed1976

Production of leucocyte migration inhibitory factor by neonatal lymphocytes.

Lymphocytes (mononuclear cells) from cord blood of 10 normal placentas and from 10 normal adults were assessed for production of leucocyte migration inhibiting factor (LIF) after phytohaemagglutinin (PHA) stimulation, as a measure of cell-mediated immunity. Mononuclear cells from both adult and cord blood produced adequate quantities of LIF, indicating that neonatal lymphocytes have the ability to manufacture normal amounts of lymphokines.

Adult↗
PubMed1976

Prolonged rupture of fetal membranes and neonatal infections.

Fifty-one babies with prolonged rupture of fetal membranes (longer than 24 hours) were studied for evidence of latent infection. Cord blood was taken from all babies for a full blood count and blood culture. Gastric aspirates were collected and vernix swabs were taken immediately after delivery. Microscopy, culture and antibiotic sensitivity tests were done on the appropriate specimens. Each baby had a thorough medical examination immediately after birth, and 3 and 7 days afterwards. After the initial investigation they were allocated to a treatment (penicillin 50 000 U/kg/d and kanamycin 10 mg/kg/d) or a non-treatment group by randomised card selection. Six patients became infected, as was shown by a positive blood culture, while 4 of the 6 had clinical signs of infection as well. These infants were treated with penicillin and kanamycin, and all did well. None of the remaining babies showed any signs of infection. There were no deaths. Blood culture was found to correlate well with clinical infections, and many be used as a guide to latent infection and treatment.

Bacterial Infections↗
PubMed1975

Phaeochromocytoma in childhood. A case report.

The clinical features of a 9-year-old boy with an extra-adrenal phaeochromocytoma, complicated by malignant hypertension, are described. The value of urinary and blood catecholamine assays and specialised radiological investigations in the accurate localisation of the tumour, is emphasised. Successful removal of the tumour was facilitated by pre-operative control of the hypertension with a combination of alpha and beta-adrenergic blockade (phenoxybenzamine and practolol). Intra-operative control of fluctuations in blood pressure was simplified by the use of Ethrane (enflurane compound 347) as one of the anaesthetic agents. As a result, sodium nitroprusside was infrequently used.

Anesthesia, General↗