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Biomedical subjects

I W Sherman

Publications and source records attributed to I W Sherman.

At least 19 recordsLinked to original sources
PubMed2005

Selection of peptides recognized by human antibodies against the surface of Plasmodium falciparum-infected erythrocytes.

In an attempt to identify mimotopes of the surface antigens of P. falciparum-infected erythrocytes (iRBC), antibodies were eluted from iRBC that had been treated with a pool of sera from malaria-infected individuals (IHS), and were used to screen a phage display library (PDL). After repeated panning of the PDL on immobilized antibodies, phage that selectively bound to IHS were accumulated. Of 23 randomly chosen clones that were sequenced, 13 individual sequences were detected at varying frequencies and 3 of the 13 sequences had homology with membrane proteins known to exist on iRBC. The majority of phage clones (7 out of 8 clones) selected after the 4th panning bound selectively to IgG in IHS. Specific binding of the selected phage to IgG in IHS was also confirmed using 24 IHS and 11 sera from uninfected individuals. One phage clone was the most frequently found in the sequenced clones after the 4th panning, and the binding of this clone to IgG in all IHS was greater than in any serum from uninfected individuals. A rabbit antiserum against the peptide expressed on the clone specifically recognized the surface of iRBC and resulted in iRBC haemolysis.

Amino Acid Sequence↗
PubMed2005

Conservative management of epistaxis: are we putting patients at risk of developing venous thromboembolic complications?

A retrospective study of 1585 patients, admitted with epistaxis to a busy District General Hospital in the United Kingdom between 1990 and 2000, was undertaken in order to identify the relationship between hospital admission for epistaxis and the development of a venous thromboembolic event. Only one person (0.06%) developed pulmonary embolus (PE) within 6 weeks of hospital admission. No one developed a deep vein thrombosis (DVT). This compares with the incidence of DVT and fatal PE in the general population. In our study population, the incidence of both PE and DVT was found to be no greater than that seen within the community and certainly less than the incidence seen within a group of high risk hospitalised patients. We conclude that hospital admission for epistaxis does not place the patient at increased risk of thromboembolic disease.

Adult↗
PubMed2004

Erythrocyte aging and malaria.

The human malaria parasite, Plasmodium falciparum, ages the red blood cell during its intracellular development. During this process of erythrocyte senescence the parasitized cell becomes less dense and deformable, its biconcave disc shape becomes more spherical and is covered with microscopic protuberances (knobs); the amounts of membrane cholesterol and phospholipids are altered and phosphatidylserine (PS) is externalized. The malaria-infected cell is osmotically fragile, more permeable to a wide variety of molecules via new permeation pathways (NPP), and there is surface deposition of immunoglobulins and complement. There are declines in sialic acid, reduced glutathione, tocopherol and ATP. Hemichromes are deposited on the inner surface of the red cell membrane and there is clustering of the anion transporter, band 3 protein, as well as exposure of neoantigens which contribute to antigenic variation and adhesivity of the parasitized erythrocyte. These time-dependent changes result from oxidative assault and a combination of factors, including a decline in levels of anti-oxidants and ATP coupled with an enhanced flux of ions especially calcium. Despite these parasite-induced age effects P. falciparum is able to avoid destruction by splenic removal through microvessel sequestration in the deep tissues via PS, clustered band 3 protein and adhesive neoantigens.

Erythrocyte Aging↗
PubMed2000

Pars tensa retraction pockets in children: treatment by excision and ventilation tube insertion.

Tympanic membrane retraction pockets involving the pars tensa are not uncommon in clinical practice. Recurrent infections, ossicular erosion and cholesteatoma are the recognized sequelae. The management options include surveillance, medical treatment and surgery. The surgical procedures range from grommet insertion to extensive tympanoplasty procedures. We report our experience with simple excision and grommet insertion, performed in 31 ears in 26 patients as day cases. The follow-up ranged from 8 to 34 months with a mean of 16 months. The procedure was successful in 23 ears (success rate of 74%). Recurrence of retraction occurred in seven ears and in one ear there was a persistent perforation. Age, previous grommet insertion and severity of retraction did not have a statistically significant influence on the final outcome. We conclude that excision and grommet insertion is a simple, safe and efficient procedure for the management of tympanic membrane retraction pockets and can be considered in preference to extensive tympanoplasty.

Adolescent↗
PubMed2000

Surgical management of intractable epistaxis: audit of results.

We have audited our results after changing the management practice in patients with intractable epistaxis. These patients are offered trans-nasal endoscopic sphenopalatine artery diathermy with or without anterior ethmoid artery diathermy instead of conventional surgical procedures. During the first year after the change in practice, 145 patients were treated as inpatients for epistaxis. Ten patients (seven per cent) required a surgical procedure under general anaesthesia due to the recurrent nature of bleeding. All 10 patients had endoscopic sphenopalatine artery diathermy, whereas in four patients anterior ethmoid artery diathermy was also performed concurrently. The post-operative hospital stay ranged from one to three days (mean 2.1 days). The mean follow-up was 10 months. The epistaxis recurred in one patient and this was managed conservatively. There were no complications related to surgery. In the previous year, 132 patients were admitted for epistaxis and eight patients had surgical procedures, which included septoplasty, nasal packing and external carotid artery ligation. The post-operative stay ranged from three to six days (mean 3.9 days). Our audit shows that endoscopic sphenopalatine artery diathermy is a safe, successful and effective management option for patients with refractory epistaxis. The morbidity is reduced and the hospital stay is shortened. The sphenopalatine artery diathermy can be combined with anterior ethmoid surgery, when necessary.

Aged↗
PubMed1999

A high capacity in vitro assay for measuring the cytoadherence of Plasmodium falciparum-infected erythrocytes.

A simple, efficient, sensitive, reproducible and high throughput assay for measuring the cytoadhesion of Plasmodium falciparum-infected red blood cells (human malaria) is described. The assay format uses 96-well microplates, with the number of P. falciparum parasitized erythrocytes bound determined by measuring Plasmodium specific lactic dehydrogenase activity colorimetrically (absorbance at 655 nm) using the 3-acetylpyridine analog of nicotinamide adenine dinucleotide, nitro blue tetrazolium and diaphorase. The results of the described microplate assay were found to be comparable to those using microscopic analysis but much less time consuming.

Animals↗
PubMed1999

Inhibitory activity of human lactoferrin and its peptide on chondroitin sulfate A-, CD36-, and thrombospondin-mediated cytoadherence of plasmodium falciparum-infected erythrocytes.

Lactoferrin (LF), a human serum protein, strongly inhibited the adherence of Plasmodium falciparum-infected erythrocytes (PE) to immobilized chondroitin sulfate A (CSA)-conjugated albumin at a concentration of 100 microg/mL and blocked the PE binding to CD36-expressing Chinese hamster ovary (CHO) cells, as well as immobilized CD36 at concentrations of 5 microg/mL and 100 microg/mL, respectively. Biotinylated LF bound to CD36 in a saturable manner, and such binding was inhibited by unlabeled LF and the anti-CD36 monoclonal antibody, 8A6, suggesting specificity of binding. Additionally, LF inhibited PE binding to immobilized thrombospondin (TSP) at a concentration of 100 microg/mL, and specific binding of LF to TSP was confirmed using biotinylated LF. LF inhibited PE binding to C32 amelanotic melanoma cells in a dose-dependent manner. A peptide of LF, Arg-Asn-Met Arg-Lys-Val Arg-Gly-Pro-Pro-Val-Ser-Cys (amino acid residues 25-37 of LF), which has been suggested to contribute to LF binding to various materials, including CSA, inhibited PE binding to immobilized CSA-conjugated albumin, immobilized CD36, CD36-expressing CHO cells, immobilized TSP, and C32 amelanotic melanoma cells, as well as LF itself. These results suggest that LF peptide may provide the basis for developing agents that are able to inhibit CSA-, CD36-, and TSP-mediated cytoadherence of PE.

Animals↗
PubMed1999

Plasmodium falciparum-infected erythrocyte adhesion to the type 3 repeat domain of thrombospondin-1 is mediated by a modified band 3 protein.

Previously, the binding site for the Plasmodium falciparum-infected erythrocyte (PE) was determined to be the C-terminal 120 or 140 kDa region but not the N-terminal 25 kDa domain of thrombospondin (TSP). In this work, we have localized the TSP binding site for PE more precisely. PE adhered to glutathione-S-transferase-fusion proteins containing the type 3 repeat (T3) of TSP, but not to other functional domains of TSP (i.e. N-terminal domain, procollagen domain, type 1 and 2 repeat, and C-terminal domain). Soluble T3 inhibited PE binding to immobilized TSP. PE binding to immobilized T3 was inhibited by soluble TSP, a monoclonal antibody directed against the T3, glycine-arginine-glycine-aspartic acid-serine-proline (GRGDSP) peptide, and *cysteine-GRGDSP-cysteine*, where *cysteine and cysteine* form a disulfide linkage, suggesting involvement of an RGD-containing motif in the T3. In support of this, a fusion protein which excluded the RGD motif showed no PE binding activity. Earlier it was shown that the amino acid sequence of the band 3 protein, histidine-proline-leucine-glutamine-lysine-threonine-tyrosine (HPLQKTY), was exposed on PE and mediated PE binding to TSP. Monoclonal antibodies, which recognize HPLQKTY and inhibit PE binding to TSP, also inhibited PE binding to the T3. The involvement of the sequence was confirmed by the fact that an octamer of HPLQKTY-containing peptide bound to the T3 but not to the RGD motif-excluded fusion protein and the binding to T3 was inhibited by GRGDSP peptide. Thus, PE binding to the T3 domain of TSP is mediated by the peptidic sequence HPLQKTY of band 3 which is exposed on PE.

Animals↗
PubMed1998

Plasmodium falciparum: thrombospondin mediates parasitized erythrocyte band 3-related adhesin binding.

Plasmodium falciparum-parasitized red cells attach to endothelial cells through several receptor-adhesin pairs. One of the adhesins on the surface of malaria-infected red blood cell is the modified band 3 molecule. We tested a synthetic peptide (HPLQKTY) based on a peptidic sequence of human band 3 protein to determine whether CD36 or thrombospondin is a receptor for the band 3-related adhesin. Although both CD36 and thrombospondin can bind parasitized cells independently, the HPLQKTY peptide and a monoclonal antibody (3H3) that recognizes the HPLQKTY sequence blocked only the adhesion of parasitized red cells to thrombospondin. The binding of thrombospondin, but not CD36, to the immobilized multiple antigen peptide-conjugated HPLQKTY was dependent on the concentration of the immobilized peptide. It would appear therefore, that thrombospondin is a receptor for the band 3-related cytoadhesion of parasitized erythrocytes.

Animals↗
PubMed1998

Papillary endothelial hyperplasia (Masson's tumour) of the maxillary sinus.

In 1923, Masson described a neoplastic process consisting of papillary hyperplasia of the endothelial cells, with a consequent obliteration of the vascular lumen, followed later by degenerative changes. Masson coined the term vegetant intravascular haemangioendothelioma, however, these days it is more commonly known as papillary endothelial hyperplasia (PEH), or by the pseudonym, Masson's tumour. Although relatively rare, there are numerous accounts of PEH in the literature, describing its predilection for the head and neck region. Our case report describes the finding of a PEH within the paranasal sinuses, a site not previously mentioned even in the largest of series found on literature search. We will then discuss the relevant histological features of the lesion, and its natural history.

Aged↗
PubMed1998

The effects of chemical modification on the adhesion of Plasmodium falciparum-infected and uninfected erythrocytes.

Binding of Plasmodium falciparum-infected erythrocytes (PE) to endothelial cells is mediated by the erythrocyte-membrane protein, band 3-related adhesin. To determine its role, the binding of infected cells treated with various chemical modifiers was investigated. Binding was inhibited by a lysine modifier (4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS)) known to specifically bind to band 3, another lysine modifier (trinitrobenzene sulfonic acid), a tyrosine modifier (sodium iodide in conjunction with lactoperoxidase, hydrogen peroxide) and oxidants (diamide, sodium periodate and ADP-chelated ferric ion), but binding was unaffected by the histidine modifier (diethylpyrocarbonate) and the arginine modifier (phenyl glyoxyl monohydrate). To artificially expose the band 3-related adhesin, uninfected erythrocytes were treated with acridine orange or loaded with calcium. These cells bound to C32 amelanotic melanoma cells, were immunostained with a monoclonal antibody that specifically binds to the band 3-related adhesin on PE, and the binding was inhibited by this monoclonal antibody. The binding of acridine orange-treated and calcium-loaded uninfected erythrocytes, could also be blocked by DIDS. In the case of acridine orange-treated erythrocytes, the patterns of the effects of the chemical modification on binding were consistent with that of PE except for tyrosine modification. These results demonstrate that the band 3-related adhesin, even in the absence of parasite-encoded proteins, contributes to PE adhesion.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1997

Band 3 peptides block the adherence of sickle cells to endothelial cells in vitro.

Malaria-parasitized erythrocytes have increased endothelial adherence due to exposure of previously buried intramembranous sites of band 3. Because sickle erythrocytes also show increased adhesiveness and because the membrane portion of band 3 is aggregated in both types of cells, we examined the role of band 3 in sickle cell adhesiveness. Synthetic peptides derived from the second and third exofacial, interhelical regions of band 3 completely inhibited the abnormal adherence of sickle cells to an endothelial monolayer in a static assay. This effect was observed independently of plasma factors, required micromolar levels of peptide, was sequence-specific, and was found with both L- and D-isomers. The active peptides also inhibited the increased adherence induced by low-dose calcium loading of normal red blood cells. Finally, a monoclonal antibody against an active peptide specifically immunostained a fraction of sickle cells. These findings implicate a role for band 3 in at least one type of sickle cell adhesiveness via the exposure of normally cryptic membrane sites.

Anemia, Sickle Cell↗
PubMed1996

Plasmodium falciparum: naturally occurring rabbit immunoglobulins recognize human band 3 peptide motifs and malaria-infected red cells.

The reactivity to overlapping decapeptides based on sequences of human band 3 protein was determined for 24 rabbit serum samples. A high percentage of the sera recognized sequences of amino acid 650-670, as well as several other sequences representing putative exofacial regions of the band 3 protein. When sera were used to stain immunofluorescently human erythrocytes, some of which were infected with P. falciparum, those samples that predominantly reacted with amino acids 650-670 stained P. falciparum-infected red cells, whereas those that reacted with other regions of band 3 stained all erythrocytes. A positive correlation was found between anti-band 3 reactivity and the capacity of a serum to inhibit the cytoadherence of P. falciparum-infected erythrocytes to C32 amelanotic melanoma cells. Also, some rabbit sera immunoprecipitated a high-molecular-weight protein from extracts of surface iodinated P. falciparum-infected red cells.

Amino Acid Sequence↗
PubMed1996

Studies of Plasmodium falciparum cytoadherence using immortalized human brain capillary endothelial cells.

The cytoadherence of Plasmodium falciparum-infected erythrocytes was studied using immortalized human brain capillary endothelial cells. The immortalized cells, denoted as BB19, derived from the human brain endothelium, were transformed with the E6E7 genes of human papilloma virus and retained their endothelial nature, i.e. tubule formation occurred with Matrigel as a substratum and the cells stained positive for Factor VIII-related antigen, or vonWillebrand's factor. Surface expression of ICAM-1, VCAM, E-selectin, and CD36 was demonstrated by immunofluorescence staining with monoclonal antibodies to these ligands. Exposure to cytokines (TNF, IFN gamma, IL-1 alpha, and IL-6) and lipopolysaccharide resulted in an increase in expression of ICAM-1, VCAM, E-selectin, and CD36. The BB19 cells bound P. falciparum-infected red blood cells with both the FCR-3 and the ITO4 strains. Antibodies to CD36 and ICAM-1 partially inhibited the binding of the FCR-3 and the ITO4 lines, respectively. These findings suggest that BB19 cells may be useful in the analysis of receptor-based cytoadherence and sequestration, as well as in the cell biology of microvessel formation.

Animals↗