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A Sohrabi

Publications and source records attributed to A Sohrabi.

15 recordsLinked to original sources
PubMed2001

TgM2AP participates in Toxoplasma gondii invasion of host cells and is tightly associated with the adhesive protein TgMIC2.

Like other members of the medically important phylum Apicomplexa, Toxoplasma gondii is an obligate intracellular parasite that secretes several classes of proteins involved in the active invasion of target host cells. Proteins in apical secretory organelles known as micronemes have been strongly implicated in parasite attachment to host cells. TgMIC2 is a microneme protein with multiple adhesive domains that bind target cells and is mobilized onto the parasite surface during parasite attachment. Here, we describe a novel parasite protein, TgM2AP, which is physically associated with TgMIC2. TgM2AP complexes with TgMIC2 within 15 min of synthesis and remains associated with TgMIC2 in the micronemes, on the parasite surface during invasion and in the culture medium after release from the parasite plasma membrane. TgM2AP is proteolytically processed initially when its propeptide is removed during transit through the golgi and later while it occupies the parasite surface after discharge from the micronemes. We show that TgM2AP is a member of a protein family expressed by coccidian parasites including Neospora caninum and Eimeria tenella. This phylogenic conservation and association with a key adhesive protein suggest that TgM2AP is a fundamental component of the T. gondii invasion machinery.

Amino Acid Sequence↗
PubMed2000

Chitosan supports the expression of extracellular matrix proteins in human osteoblasts and chondrocytes.

The search for biocompatible materials that can support the growth and phenotypic expression of osteoblasts and chondrocytes is a major challenge in the application of tissue engineering techniques for the repair of bone and cartilage defects. Chitosan, a copolymer of glucosamine and N-acetylglucosamine, may provide an answer to this search. Chitosan is the deacetylated product of chitin, a ubiquitous biopolymer found in the exoskeleton of insects and marine invertebrates. Little is known about the utility of chitosan in propagating human osteoblasts and chondrocytes. In this study, we test the hypothesis that chitosan promotes the survival and function of osteoblasts and chondrocytes. Chitosan (4%, w/v in 2% HAc) was coated onto plastic coverslips that had been fitted into 24-well plates. Human osteoblasts and articular chondrocytes were seeded on either uncoated or chitosan-coated coverslips at 1 x 10(5)/cells per well. Cultures were incubated at 37 degrees C, 5% CO(2) for a period of 7 days. Cell viability was assessed at that time using a fluorescent molecular probe. The phenotypic expression of osteoblasts and chondrocytes was analyzed by reverse transcriptase-polymerase chain reaction and immunocytochemistry. Osteoblasts and chondrocytes appeared spherical and refractile on chitosan-coated coverslips. In contrast, greater than 90% of cells on plastic coverslips were elongated and spindle shaped after 7 days of culture. Similar to cells propagated on uncoated control wells, greater than 90% of human osteoblasts and chondrocytes propagated on chitosan remained viable. Human osteoblasts propagated on chitosan films continued to express collagen type I whereas chondrocytes expressed collagen type II and aggrecan, as shown by reverse transcriptase-polymerase chain reaction analysis and immunostaining. The present in vitro work demonstrates the biocompatibility of chitosan as a substrate for the growth and continued function of human osteoblasts and chondrocytes. Chitosan may have potential use as a tissue engineering tool for the repair of osseous and chondral defects.

Aggrecans↗
PubMed2000

Proinflammatory cytokine expression of IL-1beta and TNF-alpha by human osteoblast-like MG-63 cells upon exposure to silicon nitride in vitro.

This study was designed to determine the effect of Si(3)N(4) disks and particulates on human osteoblast-like MG-63 cells in vitro. The MG-63 (10(5)/mL) cells were plated onto 24-well polystyrene plates fitted with either sintered reaction-bonded (SRBSN) or reaction-bonded (RBSN) 15-mm disks. Controls consisted of wells without Si(3)N(4) disks. Cells propagated at 37 degrees C, 5% CO(2) for 48 h on Si(3)N(4) disks and control polystyrene surfaces exhibited similar proliferative capacities (7000 and 4000 cpm/10(5) cells, respectively, p > 0.05). Cells incubated with 1, 10, or 100 microgram/ml of Si(3)N(4) particles (<1.00 to 5.00 micrometer) for 24 h did not exhibit a decrease in DNA synthetic activity: 12 +/- 1.3 x 10(4), 10.5 +/- 1.5 x 10(4), and 11.0 +/- 1.7 x 10(4) cpm, respectively, compared to 11.6 +/- 2.6 x 10(4) cpm/10(5) for the control cells, as indicated by (3)H-thymidine uptake. Cells propagated on RBSN displayed increased expression of cytokines IL-1beta and TNF-alpha compared to the control cells, as shown by reverse transcriptase-polymerase chain reaction (RT-PCR). In contrast, cells propagated on SRBSN surfaces expressed the same level of IL-1beta and TNF-alpha as that of control cells. Incubation of MG-63 cells with 1-10 microgram/mL of particles did not increase IL-1beta expression. However, at 100 microgram/mL, TNF-alpha expression was greater than that of the control cells. Silicon nitride, evaluated here as disks or as particulates (1-10 microgram/mL), is biocompatible and does not hinder the proliferation or induce proinflammatory cytokine expression of human osteoblast-like MG-63 cells in vitro.

Cell Culture Techniques↗
PubMed1999

Enhanced proliferation and osteocalcin production by human osteoblast-like MG63 cells on silicon nitride ceramic discs.

The biocompatibility of silicon nitride (Si3N4) was assessed in an in vitro model using the human osteoblast-like MG-63 cell line. Cells were propagated on the surface of: reaction-bonded silicon nitride discs, sintered after reaction-bonded silicon nitride discs or control polystyrene surface for 48 h. Compared to cells propagated on polystyrene surface, cells grown on the surface of unpolished silicon nitride discs had significantly lower cell yield and decreased osteocalcin production. In contrast, cells on the surface of polished silicon nitride discs showed similar proliferative capacity to control cells propagated on polystyrene surface. Cells propagated on polished discs also produced higher levels of osteocalcin than cells on unpolished discs. SEM analysis showed cells with well-delineated morphology and cytoplasmic extensions when propagated on polished sintered after reaction-bonded discs. Cells appeared more spherical, when grown on polished reaction-bonded discs. The results of this study suggest that silicon nitride is a non-toxic, biocompatible ceramic surface for the propagation of functional human bone cells in vitro. Its high wear resistance and ability to support bone cell growth and metabolism make silicone nitride an attractive candidate for clinical application. Further studies are needed to explore the feasibility of using silicon nitride clinically as an orthopedic biomaterial.

Cell Culture Techniques↗
PubMed1996

Human chondrocytes proliferate and produce matrix components in microcarrier suspension culture.

Chondrocytes propagated in monolayer culture proliferate and change into 'fibroblastoid'-like cells. This change is characterized by a shift in production of collagen type II to I and from high- to low-molecular-weight proteoglycans. When propagated in three-dimensional culture, chondrocytes have limited ability to divide but re-express their original characteristics. The goal of the present study was to determine whether a microcarrier suspension culture system would support chondrocyte proliferation and phenotype expression. Our experiments indicate that a collagen type I microcarrier (cellagen) best supported chondrocyte proliferation and phenotype expression. Cells in cellagen microcarriers multiplied at least twentyfold within 2 weeks and had doubling times of 2 to 3 d. Viable and metabolically active cells were retrieved with ease. The harvested chondrocytes had no detectable staining for collagen type I and stained intensely for collagen type II. Our studies demonstrate that the microcarrier suspension culture system supports growth and enhances expression of the 'chondrocytic' phenotype. Attachment to a constrained surface and the fluid shear forces on the microcarriers during suspension culture may have helped chondrocytes to reacquire their rounded shape and produce cartilage matrix components.

Biocompatible Materials↗
PubMed1993

Primary adenocarcinoma arising in an ileostomy.

Two cases are added to the world literature of patients in whom an adenocarcinoma developed at the ileostomy site after total proctocolectomy for ulcerative colitis. Fourteen additional cases have been reported in the world literature; of these, 12 cases have been in patients with ulcerative colitis, and four cases have been in patients with familial adenomatous polyposis. Adenocarcinoma of an ileostomy is not common. However, in the analysis of the reported cases, patients with long-standing ileostomies appear to be at a greater risk. With an aging ileostomy population, an increase in the number of cases may be seen. Three hypotheses are discussed as potential causative pathways to this entity. Continued analysis of these cases may yield information on the pathophysiology involved.

Adenocarcinoma↗
PubMed1990

Pulmonary coin lesions caused by Dirofilaria immitis.

The dog heartworm Dirofilaria immitis has been diagnosed by thoracotomy as the etiology of neoplastic-appearing nodules in two patients in the Peoria, Illinois area. This brings the total number of reported cases of human pulmonary dirofilariasis to approximately 81 in the United States. The major concern of this benign disease is that in making the diagnosis the patients undergo the risk of surgery because of the presumed preoperative diagnosis of cancer. Greater awareness of this disease is needed as the geographic distribution of human pulmonary dirofilariasis expands in this country.

Adult↗
PubMed1989

Free jejunal graft for repair of cervical esophagus.

We have operated upon six patients with cervical esophageal carcinoma and reconstructed these with free jejunal graft. The pathology of all six patients was squamous cell carcinoma, and no patient had apparent distant metastasis. The procedure was a two team approach. While the surgical oncology team resected the esophageal tumor, the microvascular team harvested the jejunal graft. The range of warm ischemia for the free jejunal graft was 1-2.5 hr, and no graft was lost because of recirculation failure. The range of operative time was 5-6.5 hr. There was no operative mortality. There were two minor cervical wound infections, both healed with conservative management. Hospital stay ranged from 10 to 15 days. The swallowing mechanism was satisfactory in all patients. We believe that the free jejunal graft is the procedure of choice for reconstruction of the cervical esophagus.

Adult↗
PubMed1980

Recurrence of breast cancer. Obesity, tumor size, and axillary lymph node metastases.

Substantially different conclusions have been reached by several studies about relationships between mammary cancer and obesity. We studied retrospectively 106 consecutive patients who underwent mastectomy for breast cancer. We found no association between obesity per se and the frequency or time of recurrence. Our sample did reaffirm that recurrence of breast cancer is related to tumor size and nodal status. Obesity was similarly related to tumor size and nodal status. However, we could not confirm prior findings that obese patients with pathologically similar breast tumors had a poor prognosis.

Axilla↗
PubMed1979

Cholate sodium infusion for retained common bile duct stones.

Eight patients with stones retained in the extrahepatic biliary tract underwent cholate sodium infusion for dissolution of the stones. In six patients, the stones disappeared. However, in two of the patients, the stones did not disappear, and they were removed with the ureteral basket. Infusion of cholate sodium was well tolerated by six patients, but was accompanied by nausea, vomiting, and abdominal pain in two patients. In one case, mucosal deformity of the common bile duct was noticed during the infusion, but it was not apparent on a subsequent cholangiogram. As a result of our experience, we conclude that cholate sodium infusion is a safe procedure for the attempted dissolution of retained common bile duct stones.

Adult↗
PubMed1978

Duplication of male urethra.

Male urethral duplication is an unusal anomaly with many variants including complete duplication from the bladder to the glans penis as well as incomplete and abortive forms. Two cases are presented of duplication of the male urethra of the epispadiac incomplete type. A chart has been constructed to facilitate categorization of the various forms of urethral duplication in the male.

Adult↗
PubMedDate not supplied

Follicular carcinoma of the thyroid.

Follicular carcinoma deserves a careful preoperative evaluation and multidisciplinary therapy planning. Needle aspiration may be of less value than for other thyroid lesions. If the surgeon is suspicious of a carcinoma, a total lobectomy of the involved side and frozen section may be indicated. Lobectomy with or without isthmusectomy seems to be the minimal treatment for tumors confined to the lobe without nodal metastases. Total thyroidectomy is reserved for patients at high risk by nature of age, large lesions, angioinvasion, capsular invasion, or known metastatic disease where subsequent I-131 therapy is considered likely. I-131 scanning for metastatic disease is indicated in these high-risk patients. I-131 therapy is very valuable for treatment of metastatic disease; and in patients presenting with metastatic disease, total thyroidectomy may be indicated to maximize the therapeutic benefit of the I-131. Judicious planning and care of these patients can result in a 50 to 70% total cure and as high as 85% long-term survival.

Adenocarcinoma↗