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Biomedical subjects

S M Alaish

Publications and source records attributed to S M Alaish.

6 recordsLinked to original sources
PubMed1998

Diagnostic laparoscopy.

Laparoscopy has been shown to be a safe and effective method to establish or rule out a diagnosis in difficult clinical situations and, in selected cases, provide minimally invasive access for therapeutic procedures. Relevant indications for diagnostic laparoscopy in the pediatric population include evaluation of a contralateral patent processus vaginalis in a child with a known unilateral inguinal hernia, an impalpable testis, acute and chronic abdominal pain, staging in cancer, and evaluation of traumatic injuries. Selected articles concerning these and other uses of diagnostic laparoscopy published between December 1996 and November 1997 are the subject of this review.

Abdominal Injuries↗
PubMed1995

Long-term venous access using endogenous splenic tissue: the 'spleen-o-port'.

The authors sought to determine whether endogenous splenic tissue placed in a subcutaneous pouch ("spleen-o-port") could function as a viable alternative to central venous catheters/ports for long-term venous access. A small transverse incision was made in the left upper quadrant of each puppy (n = 6) under general anesthesia. Using a stapler, the authors divided the splenic parenchyma. The superior portion was returned to its native location, and a subcutaneous pocket was created to house the inferior pole with its attached vascular supply. The fascial and muscular layers were closed with care to avoid compressing the blood supply to the spleen-o-port. Postoperatively the dogs resumed normal activity. There have been no deaths, infectious complications, splenic ruptures, or thromboses over a 6-month period. Under fluoroscopy, the dogs were imaged from postoperative day (POD) 10 to 177. Contrast agent entering the splenic parenchyma was promptly visualized in the splenic vein and then filled the portal vein. Electrolyte measurements from spleen-o-port blood samples were identical to those from peripheral venous samples. After gentamicin (mixed in a crystalloid solution) was infused through the spleen-o-port, the peak serum level corresponded to the therapeutic levels observed after standard intravenous administration. The spleen-o-port permits rapid infusion of drugs and crystalloid, and allows repetitive blood sampling while eliminating the foreign body that can promote septicemia in the immunocompromised patient.

Animals↗
PubMed1995

Hyaluronic acid metabolism in keloid fibroblasts.

Hyaluronic acid (HA), an important component of the tissue extracellular matrix, is a ubiquitous glycosaminoglycan (GAG) that forms a pericellular coat on the surface of cells. It has been speculated that this pericellular HA boundary may localize cytokines, such as transforming growth factor-beta 1, which is known to stimulate collagen production. The purpose of this study was to examine the role of HA and its cell surface receptor (CD44), an active participant in HA degradation, as they relate to keloid formation. Dermal excisions from both normal patients (n = 13) and keloid patients (n = 13) were analyzed for HA content using an alcian blue staining technique. Fibroblast cell cultures were used to quantitate HA synthesis and CD44 receptor density. Histological analyses showed a greater HA content in keloid tissue compared with normal dermal tissue. In agreement with this observation, keloid fibroblasts were found to synthesize significantly more HA than normal dermal fibroblasts (2469 +/- 483 cpm versus 1122 +/- 256 cpm, P = .02). Treatment of keloid fibroblasts with triamcinolone acetonide reduced the level of HA synthesis to that of normal fibroblasts (1560 +/- 477 cpm versus 1293 +/- 264 cpm, P = .6). However, there was no significant difference in HA receptor density on keloid cells compared with normal skin fibroblasts. Therefore, the increased HA deposits found in keloids are attributable to increased synthesis rather than to decreased degradation mediated by the CD44 receptor.

Adolescent↗
PubMed1995

Aggregatory characteristics and expression of the collagen adhesion receptor in fetal porcine platelets.

Fetal wound healing differs significantly from that of the adult by its rapidity, the paucity of an inflammatory response, and the lack of scarring. In the adult, activation and aggregation of platelets at the site of injury result in the release of cytokines and inflammatory mediators that stimulate wound healing by initiating an acute inflammatory response. The aim of this study was to characterize the activity of midtrimester (day 60) and third-trimester (day 95) fetal porcine platelets (full term, 114 days) compared with that of adults in an attempt to understand the lack of inflammation in fetal wounds. The aggregatory capabilities of adult and fetal platelets were analyzed after exposure to adenosine diphosphate (ADP) concentrations of 10 mumol/L and 40 mumol/L concentrations, collagen of 0.19 mg/mL, and arachidonic acid of 0.5 mg/mL. Expression of the alpha 2 subunit of the collagen receptor (alpha 2 beta 1) was evaluated by Western blot analysis. The aggregation of day-60 fetal platelets when exposed to ADP (10 mumol/L and 40mumol/L) and collagen was significantly lower than that of the adult. The aggregation of third-trimester platelets to 10 mumol/L of ADP was similar to that of the adult and significantly greater than that of midtrimester fetuses at higher concentrations (40 mumol/L). Both fetal groups responded suboptimally to collagen, and the response was significantly less than that of adults. In contrast, arachidonic acid caused rapid and complete aggregation of both fetal platelet groups, suggesting that both mid- and late-trimester fetal platelets possessed the ability to fully aggregate with the appropriate stimulus. The different aggregatory responses to collagen could not be explained by differences in collagen receptor expression, because these were found to be similar in adults and midtrimester fetuses. It is concluded that although fetal platelets have the potential to aggregate effectively, they aggregate poorly to collagen and exhibit improved aggregation to ADP with increasing maturity. There is a transition to "adultlike" platelet aggregatory activity in the third trimester, which correlates with the period of transition to adultlike wound healing in utero. Similar expression of the alpha 2 beta 1 collagen receptor in the fetus and adult cannot explain the differences observed in their responses to collagen.

Animals↗
PubMed1994

Biology of fetal wound healing: hyaluronate receptor expression in fetal fibroblasts.

Fetal tissue repair is rapid, relatively scarless, and proceeds in an environment rich in hyaluronic acid. Understanding the interaction of hyaluronic acid (HA) with the reparative cells may provide important insight into the remarkable process of fetal wound healing. Therefore, the purpose of this study was to characterize the HA receptor (a member of the CD44 family of cell surface glycoproteins) and its density on the cell surface of fetal fibroblasts. HA receptor expression on both adult and fetal fibroblasts was first studied by Western blot analysis. Autoradiographs of the blots were assessed by densitometry to quantitate the relative amounts of the HA receptor. It appears that the HA receptor expressed on both adult and fetal rabbit dermal fibroblasts is a 56-kd protein. After normalizing for total protein concentration using the Bradford protein assay, the fetal HA receptor density was found to be approximately four-fold greater than that of the adult. The same adult and fetal fibroblasts were then studied by flow cytometry, using a fluorescence-activated cell sorter (FACS). Relative fluorescence was representative of HA receptor density. Corroborating the authors' earlier result with the Western blot analysis, the FACS analysis showed that the fetal fibroblasts had 2.5 times the fluorescence of the adult cells. It is concluded that, in comparison to adult fibroblasts, fetal fibroblasts have an increased density of cell-surface HA receptor.

Animals↗