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Biomedical subjects

S Saad

Publications and source records attributed to S Saad.

At least 37 records · Page 2Linked to original sources
PubMed1998

Polyethylene glycol 4000 attenuates adhesion formation in rats by suppression of peritoneal inflammation and collagen incorporation.

BACKGROUND: Postoperative separation of the peritoneal surfaces is a promising approach for the prevention of adhesion formation. Instillation of polyethylene glycol 4000 (PEG) was recommended as an appropriate method. METHODS: In a time-course study in rats, efficacy and mode of action of PEG was investigated. Adhesions were induced by crushing of the cecum. Sixty animals were randomly allocated to three control groups with intraperitoneal instillation of 5 mL 0.9% NaCl and to three therapy groups treated with 5 mL 20% PEG. After 3, 7, and 21 days, adhesion grade, intraperitoneal leukocytes, and collagen incorporation into the adhesion strands were evaluated. RESULTS: Administration of PEG resulted in a decrease of leukocytes by 43% (days 3 and 7), a reduction of the adhesion score by 85% (day 3), 77% (day 7), and 79% (day 21), and an impairment of collagen deposition by 54% (day 7) and 44% (day 21). CONCLUSIONS: Coating the peritoneal surfaces with PEG is a highly effective measure to suppress the fatal sequence of posttraumatic inflammation, formation of initial adhesions, and their subsequent organization to strong permanent adhesion strands.

Administration, Topical↗
PubMed1998

Portal vein reconstruction in pediatric liver transplantation from living donors.

OBJECTIVE: The authors analyze the surgical pattern and the underlying rationale for the use of different types of portal vein reconstruction in 110 pediatric patients who underwent partial liver transplantation from living parental donors. SUMMARY BACKGROUND DATA: In partial liver transplantation, standard end-to-end portal vein anastomosis is often difficult because of either size mismatch between the graft and the recipient portal vein or impaired vein quality of the recipient. Alternative surgical anastomosis techniques are necessary. METHODS: In 110 patients age 3 months to 17 years, four different types of portal vein reconstruction were performed. The portal vein of the liver graft was anastomosed end to end (type I); to the branch patch of the left and right portal vein of the recipient (type II); to the confluence of the recipient superior mesenteric vein and the splenic vein (type III); and to a vein graft interposed between the confluence and the liver graft (type IV). Reconstruction patterns were evaluated by their frequency of use among different age groups of recipients, postoperative portal vein blood flow, and postoperative complication rate. RESULTS: The portal vein of the liver graft was anastomosed by reconstruction type I in 32%, II in 24%, III in 14%, and IV 29% of the cases. In children <1 year of age, type I could be performed in only 17% of the cases, whereas 37% received type IV reconstruction. Postoperative Doppler ultrasound (mL/min/100 g liver) showed significantly (p < 0.05) lower portal blood flow after type II (76.6 +/- 8.4) versus type I (110 +/- 14.3), type III (88 +/- 18), and type IV (105 +/- 19.5). Portal vein thrombosis occurred in two cases after type II and in one case after type IV anastomosis. Portal stenosis was encountered in one case after type I reconstruction. Pathologic changes of the recipient native portal vein were found in 27 of 35 investigated cases. CONCLUSION: In living related partial liver transplantation, portal vein anastomosis to the confluence with or without the use of vein grafts is the optimal alternative to end-to-end reconstruction, especially in small children.

Adolescent↗
PubMed1998

[Revitalizing donor livers after cardiovascular arrest with venous oxygen persufflation].

The experimental study investigates the resuscitation of livers procured from non heart beating donors by venous systemic oxygen persufflation in a pig transplantation model. In group 1 livers were harvested from donor animals after 60 min of potassium induced cardiac arrest. Livers were then flushed and preserved in 4 degrees C cold University of Wisconsin solution for 4 hrs. Then liver transplantation was performed in recipient animals. Animals of group 2 received the same treatment, but during hypothermic storage we applied venous systemic oxygen gas persufflation (VSOP) via the supra-hepatic vena cava. Livers of group 3 were harvested without warm ischemia and without oxygen treatment during cold ischemic storage and were then transplanted. All recipient animals of group 2 and 3 survived the five day follow-up time. All recipient animals of group 1 died a few hours after liver reperfusion due to circulatory shock or liver failure. The liver quality of group 2 recipient animals was similar to group 3 livers, because serum transaminase levels and blood coagulation test showed no significantly different values between those groups. Our data suggest that livers procured from non heart beating donors after 1 hr of cardiac arrest can be resuscitated and successfully transplanted by therapeutic treatment with VSOP.

Animals↗
PubMed1997

Influence of polyethylene glycol 4000 and dextran 70 on adhesion formation in rats.

Studies on the prevention of peritoneal adhesions often address the impairment of adhesion formation by a special drug without any attempts to elucidate the working principles. In the present study PEG 4000 was compared with dextran 70 with respect to the influence on adhesion formation, inflammatory reaction, and collagen deposition. Adhesions were created in 30 rats by standardized crushing of the cecum. The animals were randomly allocated to 3 experimental groups receiving an intraabdominal instillation of 5 ml 20% PEG, dextran 70, or 0.9% NaCl. On Day 7 the adhesions were scored; additionally, the amount of leukocytes in the peritoneal cavity and the incorporation of collagen into the adhesion strands were determined. Administration of PEG resulted in a significant reduction of the adhesion score from 10.3 (NaCl) to 2.3, whereas dextran had no effect (score 11.0). This finding correlated with the leukocyte number which was reduced by 44% after PEG but was not affected by dextran. The collagen content of the adhesion strands was significantly decreased by PEG as well as by dextran when compared to the NaCl controls. In our model PEG was highly effective in the impairment of adhesion formation. The positive effect was mediated by a reduction of the inflammatory reaction which resulted in a decreased deposition of collagen into the adhesion strands.

Animals↗
PubMed1996

Ischemic preconditioning of the liver in rats: implications of heat shock protein induction to increase tolerance of ischemia-reperfusion injury.

It has been reported that ischemic preconditioning of the heart or brain has a possible relevance to heat shock protein (HSP). It is still unknown, however, whether HSP induced by means of ischemic preconditioning of the liver is a direct factor in the acquisition of tolerance to succeeding ischemia-reperfusion injury. In the present study we used ischemic preconditioning of the liver to verify the effects of induced HSP72 in the liver on the subsequent longer warm ischemia and reperfusion. Rats preconditioned with short-term (15-minute) ischemia were compared with rats preconditioned by heat exposure or with control rats. After a 48-hour recovery from the sublethal stress for preconditioning, all rats were exposed to longer (30-minute) warm ischemia and reperfusion. Forty-eight hours after ischemic preconditioning, HSP72 was clearly induced in the liver, as well as in the liver preconditioned with heat shock, but not in the kidney or heart. This ischemic preconditioning also attenuated the liver damage in the subsequent ischemia-reperfusion injury, improving the restoration of hepatic function during reperfusion and resulting in higher postischemic rat survival. According to the proposed model of tolerance acquisition for ischemia-reperfusion injury by stress preconditioning, these observations support the speculation that the induced HSP72 plays some beneficial role in this protection mechanism.

Adaptation, Physiological↗
PubMed1995

Ultrarapid mutation detection by multiplex, solid-phase chemical cleavage.

The chemical cleavage of mismatches in heteroduplexes formed by probe and test DNA detects and locates any sequence change in long DNA segments (approximately 1.8 kb), and its efficiency has been well tested in the analysis of both average (e.g., coagulation factor IX) and large, complex genes (e.g., coagulation factor VIII and dystrophin). In the latter application RT/PCR products allow the examination of all essential sequences of the gene in a minimum number of reactions. We use two specific chemical reactants (hydroxylamine and osmium tetroxide) and piperidine cleavage of the above procedure to develop a very fast mutation screening method. This is based on: (1) 5' or internal fluorescent labeling to allow concurrent screening of three to four DNA fragments and (2) solid-phase chemistry to use a microtiter format and reduce the time required for the procedure, from amplification of sequence to gel loading inclusive, to one person-working-day. We test the two variations of the method, one entailing 5' labeling of probe DNA and the other uniform labeling of both probe and target DNA, by detecting 114 known hemophilia B (coagulation factor IX) mutations and by analyzing 129 new patients. Uniform labeling of both probe and target DNA prior to formation of the heteroduplexes leads to almost two-fold redundancy in the ability to detect mutations. Alternatively, the latter procedure may offer very efficient though less than 100% screening for sequence changes with only hydroxylamine. The full method with two chemical reactions (hydroxylamine and osmium tetroxide) should allow one person to screen with virtually 100% accuracy more than 300 kb of sequence in three ABI 373 gels in 1 day.

Base Sequence↗
PubMed1995

Protective effect of heat shock pretreatment with heat shock protein induction before hepatic warm ischemic injury caused by Pringle's maneuver.

BACKGROUND: Induction of heat shock proteins is thought to have a > cytoprotective effect against environmental stress and to result in a better ischemic tolerance. The protective ability of heat exposure and heat shock protein 72 (HSP 72) induction before warm ischemia caused by Pringle's maneuver was evaluated in rats. METHODS: Heat exposed rats (HS) were compared with control animals (C). The gene expression (messenger RNA) of HSP 72 and HSP 72 were detected by Northern and Western blot analyses. During 40 minutes of in situ reperfusion, liver energy metabolism and levels of standard liver enzymes were evaluated. The survival rate was determined after postoperative day 7. RESULTS: After heat exposure and recovery, messenger RNA of HSP 72 and HSP 72 can be detected strongly in HS group but not in C group. During reperfusion HS group exhibited a significantly (p < 0.01) improved energy metabolism, and the release of liver enzymes was significantly (p < 0.001) reduced compared with C group. Seven-day survival rate was 100% in HS group but at 50% was significantly impaired (p < 0.05) in C group. CONCLUSIONS: Heat exposure associated with HSP induction has a significant protective effect against warm ischemic liver injury, which results in a relevant improvement of survival rate.

Adenosine Triphosphate↗
PubMed1995

Rapid determination of the membrane potential of mitochondria in small biopsy specimens of the liver.

In liver transplantation, graft viability is ideally to be determined before implantation. Integrity of mitochondria may be a prerequisite to a viable graft. A new method is presented, which allows for the determination of the membrane potential of mitochondria (MPM; mV) in state 4 respiration within 50 min in 40-mg specimens, employing rhodamine 123 as a probe. Normal control showed a MPM of 239.2 mV. Storage in saline at 37 degrees C yielded an impaired MPM of 153.5 mV within 3 h. The cold storage at 1 degree C could preserve MPM at quasi-normal after 3 h but reduced it significantly after 24 h to 222.2 mV in saline (p < 0.005 vs. control) and 231.0 mV in UW solution (p < 0.05 vs. control): the difference between the 24-hour values was significant (p < 0.05).

Animals↗
PubMed1994

First report on UK database of haemophilia B mutations and pedigrees. UK Haemophilia Centres.

In order to obtain complete success in the carrier and prenatal diagnoses required for genetic counselling in haemophilia B a new strategy is being implemented in the UK. This entails the construction of a national confidential database of mutations, pedigrees and haematological data. This will allow the inefficient indirect tests based on the analysis of DNA polymorphisms to be abandoned and direct detection of the gene defect to be used instead. After two and a half years of nationwide collaboration, 702 samples have been collected from 313 families, representing more than half of the UK haemophilia B families, and 217 mutations have been characterised. The 141 diagnostic tests so far performed have clearly indicated that the new strategy not only allows virtually 100% diagnostic success, but also rapid results. This work on haemophilia B may represent a model for other diseases with high mutational heterogeneity.

Databases, Factual↗
PubMed1993

The effects of allopurinol and SOD on lipid peroxidation and energy metabolism in the liver after ischemia in an aerobic/anaerobic persufflation.

This study was aimed at examining the vulnerability of the liver to oxygen-free radicals upon reoxygenation after prolonged ischemia. Livers from male Wistar rats were first flushed with Ringer's and Euro-Collins solutions. After ischemic storage in Krebs-Henseleit solution at 37 degrees C for 60 min and in Euro-Collins solution at 4 degrees C for another 60 min, they were then persufflated with either gaseous O2 or N2 for 30 min at 37 degrees C, and rinsed again with Ringer's solution. Enzyme concentrations and calcium ion activities were measured in the effluent rinsing solution after passage through the liver. Treatment with superoxide dismutase (SOD) or allopurinol resulted in a significant reduction of tissue injury, determined by the enzyme loss, calcium uptake, and lipid peroxidation upon persufflation with O2. Allopurinol also improved the tissue levels of ATP and the sum of adenine nucleotides after aerobic persufflation, whereas SOD did not. Notwithstanding, neither treatment had any effect on anoxic persufflation with N2. Thus, we conclude that the postischemic liver is susceptible to oxygen-induced free radical injury and that allopurinol and SOD promote specific antioxidative protection of the liver, with the exclusion of side effects related to substrates or perfusion modalities.

Adenine Nucleotides↗
PubMed1992

Removal of intrauterine devices with missing tails during early pregnancy.

During a 70-month period, CO2 hysteroscopy was carried out on 52 pregnant women wearing IUDs with retracted tails. Ultrasonography was done prior to hysteroscopy to determine the size of the gestational sac and the site of the device. Successful removal of the device occurred in 46 cases. The technique, the findings of the study, and the limitations of the procedure are described.

Abortion, Spontaneous↗
PubMed1992

Evaluation of antioxidant treatment with superoxide dismutase in rat liver transplantation after warm ischemia.

In order to investigate the effects of the exogenously administered radical scavenger superoxide dismutase (SOD) on the orthotopic liver graft, livers from male Wistar rats were transplanted after subjection to 40 min of warm ischemia and 30 min of storage at 4 degrees C. SOD was given at the onset of ischemia and before reperfusion as a supplement (6,000 IU) to the washout solutions. 30,000 IU were infused into the recipient. SOD reduced tissue levels of thiobarbituric acid-reacting substances at the end of ischemia (737 vs. 956 nmol/g; p < 0.01) and 60 min after the onset of reperfusion (629 vs. 947 nmol/g; p < 0.001) and preserved total adenine nucleotides after reperfusion (11.69 vs. 10.40 mumol/g; p < 0.01). Survival 2 weeks after transplantation was 18% (2/11) in the SOD group versus 10% (1/10; nonsignificant) in untreated animals. It is concluded that SOD protects the ischemically altered liver from radical mediated peroxidation and preserves hepatic energy stores upon reperfusion. However, in our model no major improvement in organ viability could by achieved.

Adenine Nucleotides↗
PubMed1991

[Mediators and their antagonists in shock therapy].

The list of shock mediators currently comprises more than 150 candidates. A careful analysis using the criteria of Koch-Dale together with decision trees for exclusion of bias revealed that only histamine, C5a, beta-endorphin, tumor necrosis factor (TNF) thromboxane B2, platelet-activating factor (PAF), and oxygen free radicals are shown to be causally associated with shock symptoms. Although experimental studies with inhibitors of these mediators were convincing, there is still a lack of evidence under clinical conditions (exception histamine: anaphylactic shock). Combinations of antagonists against different causal mediators are the most promising future approaches.

Acute-Phase Proteins↗
PubMed1991

Involvement of oxygen in harvesting injury of the liver. An experimental study including substrate free organ persufflation to evaluate a specific therapeutic approach.

The present study was undertaken to assess the role of oxygen free radicals relating to cell damage upon reoxygenation of the ischemically altered isolated rat liver. Livers were excised and flushed via the portal vein with Ringer's solution and Euro-Collins solution, to which superoxide dismutase (SOD) was added in the experimental group. After warm ischemia at 37 degrees C and cold storage at 4 degrees C, the livers were reperfused via the portal vein with carbogen-saturated Krebs-Henseleit solution. Other livers were subjected to a retrograde persufflation via the infrahepatic caval vein with either oxygen or nitrogen and then rinsed with Ringer's solution. During reperfusion, SOD-treated livers showed markedly reduced vascular resistance, lower enzyme release and enhanced VO2 accordingly, energy charge at the end of reperfusion was significantly higher in the treated group. With reference to the tissue content of malondialdehyde, SOD-treated livers showed significantly less damage than the corroboration for these data. Enzyme activities in the eluate were significantly reduced under anoxic conditions as well as in the presence of SOD. We conclude from these data that oxygen free radicals do exert a detrimental impact on the reoxygenated liver, which could be specifically suppressed by application of exogenous SOD.

Adenosine Triphosphate↗