Activation of Classical Complement Pathway by Naturally Occurring Heteroantibodies in Normal Rabbit Serum. Effect on Subpopulations of Human Lymphoid Cells

Heteroantibodies present in normal rabbit serum (NRS) are toxic to human B lymphocytes, T lymphocytes, and monocytes. Even NRS, which exhibits little back ground cytotoxicity for human lymphoid cells in conventional HLA or B-cell lymphocytotoxic assays, can be shown to contain considerable activity by making two modifications in usual procedures: by washing cells in saline or balanced salt solutions devoid of protein or sugar substances, and by increasing incubation time for 1 h to 3--4 h. Using such modifications, the cytotoxic activity of NRS towards human lymphoid cells was investigated and was found to involve activation of the classical complement pathway rather than activation of the alternate complement pathway. Residual unwanted background cytotoxicity of NRS toward human lymphoid cells can be decreased without loss of desired complement activity either by heating NRS for 15 min at 50 degrees C or by mixing NRS with small amounts of normal human serum.     

In vitro effects of ascorbate and Trolox on the biocompatibility of dental restorative materials

Previous in vitro studies on the cytotoxicity of eight dental restorative materials including composites, compomers, resin-modified glass ionomer cements and glass ionomer cements have demonstrated a depletion of intracellular glutathione in gingival fibroblasts incubated with eluates of these materials and a protective effect of N-acetylcysteine. In the present study, we investigate the effects of two other antioxidants: ascorbate and Trolox. It was found that Trolox reduced the cytotoxicity induced by resin-based biomaterial eluates. In contrast, ascorbate increased in a dose-dependent manner the toxic effect of all eluates except for Z100 MP and Tetric flow (composites). The effect of D-mannitol was studied for GC FUJI II and was found to neutralize the additional toxic effect of ascorbate. Ascorbate increased the depletion of intracellular glutathione of these dental material eluates (between 17% and 24%, depending on the material). Quantification of metal ions in the dental material eluates showed the presence of significant amounts of aluminum and iron in GC FUJI II > photac fil > GC FUJI II LC > F2000. The mechanism of this increased cytotoxicity could be explained by the Fenton reaction resulting from the pro-oxidant effect of ascorbate in the presence of iron (transition metal ions) and/or aluminum.     

“Porcupine” polymers and double-star polymers

Anionic block copolymerization of styrene and divinylbenzene is known to lead to the formation of star-shaped macromolecules. This “arm-first” method has been widely used and studied. The present paper is devoted to two special aspects of this method: The first is concerned with the efficiency of the protection exerted by the arms on the crosslinked core, preventing gelation of the reaction medium. A number of “porcupine” polymers involving bulky cores, fitted with a large number of arms, were synthesized and characterized. The second deals with the possibility of using the “living” carbanionic sites present in the cores, either for purpose of functionalization, or to grow new branches from the core. The presence of remaining unsaturations in the core was evidenced. This is a drawback, since the possibility for “transverse” bonds to be formed results in couplings, inducing gelation.     

Unsteady simulation of distal blood flow in an end-to-side anastomosed coronary bypass graft with stenosis

In this paper, we report on the unsteady state modeling of blood flow in an end-to-side anastomosed bypass graft, which has a stenosis upstream from the junction. In coronary artery bypass grafting/surgery (CABG), new arteries are created in order to provide blood to the heart using other blood vessels as conduits to bypass the blocked section in the patient's coronary arteries. The failure of coronary artery bypass procedures has been attributed to both intimal hyperplasia (IH) and atherosclerosis. It is believed that these two phenomena are, in turn, related to the local hemodynamic factors. In this work, a three-dimensional computational fluid dynamics analysis is used to simulate the physiological blood flow through a model of a stenosed coronary bypass graft with the realistic assumption of non-Newtonian flow for human blood. For different flow repartitions and at different times of the cycle, both the recirculating areas and wall shear stress (WSS) are studied. Based on the different distribution of flow rates in the bypass graft and the host artery, the flow features are investigated and the influence of non-Newtonian behavior is discussed in terms of separation points, reattachment points, and the wall shear stresses. Various differences are observed based on the assumption of non-Newtonian behavior of blood, which have not been reported before when a simplified Newtonian approach is utilized.     

Prognostic implication of histopathological, immunohistochemical and clinical features of oligodendrogliomas: a study of 89 cases

Histopathological, immunohistochemical and clinical parameters were correlated with survival in 89 cases of oligodendroglioma (65 patients with grade II and 24 patients with grade III of the WHO classification). Median survival time and 5-year survival rate were 3.5 years and 76% for patients with oligodendroglioma grade II and 0.875 years and 23% for patients with oligodendroglioma grade III. The tumor biopsy specimens were immunohistochemically analyzed for Ki 67 (MIB-1), vimentin, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE) and synaptophysin. MIB-1 nuclear labeling index ranged from 0.0% to 33.4%; vimentin-immunoreactive tumor cells were found in 25 cases. MIB-1 nuclear labeling index and vimentin immunoreaction showed a significant statistical correlation to the 5-year survival rate of the patients. Tumors with vimentin expression (n = 25) and/ or high MIB-1 labeling index (n = 26) had a poorer prognosis than tumors lacking vimentin expression (n = 57) and/or displaying a low MIB-1 labeling index (n = 56). The expression of immunoreactivity for GFAP (n = 53), NSE (n = 23) and synaptophysin (n = 15) appeared to be of no prognostic relevance. Patients with gross total tumor resection (n = 47) had a median survival time and 5-year survival rate of 3.3 years and 84% compared to 1.2 years and 42% for patients with subtotal resection (n = 41). The comparison between patients who underwent surgery alone (n = 53) and those who had surgery plus postoperative radiation therapy showed no significant survival benefit from postoperative radiation therapy. In conclusion, tumor grade, MIB-1 labeling index, expression of vimentin and the extent of surgery are shown to be of prognostic relevance for patients with oligodendroglioma. Received: 29 July 1997 /Revised: 14 October 1997, 4 December 1997 / Accepted: 14 December 1997     

Rat liver adenyl cyclase activity in various thyroid states

Thyroidectomized and euthyroid rats were injected with three doses of triiodothyronine (T(3)) or of the diluent over a 6 day period, and liver homogenates were assayed for basal, epinephrine-stimulated, and NaF-stimulated adenyl cyclase activity. Based on NaF-stimulated levels, total adenyl cyclase activity, expressed per milligram of liver protein, was increased after thyroidectomy. Administration of T(3) to either hypothyroid or euthyroid rats, however, had no effect on the NaF-stimulated levels. Basal and epinephrine-stimulated enzyme activities were the same in hypothyroid, euthyroid, and hyperthyroid (euthyroid + T(3)) liver homogenates. In contrast, injections of T(3) in hypothyroid rats increased the activities of basal and epinephrine-stimulated adenyl cyclase. In view of the findings in euthyroid and hyperthyroid liver, it is possible that this effect is transient. In general, no correlation was found between the effects of thyroid hormone on respiration and on adenyl cyclase activity of the rat liver. These results imply that the hepatic thermogenic response to thyroid hormone is not mediated by stimulation of adenyl cyclase activity with the possible exception of the early effects of T(3) in the athyroid rat.     

NOD2 exonic variations in Iranian Crohn's disease patients

Purpose

The NOD2 gene is known to have a strong association with Crohn??s disease, but different trends were reported in occurrence of NOD2 variants in distinct ethnicities. The aim of this study was to assess all exonic sequences of the NOD2 gene in Iranian Crohn's disease patients and healthy controls to identify any existing variation and evaluate their association with Crohn's disease.

Methods

A total of 90 non-related Crohn's disease patients and 120 sex- and age-matched healthy controls of Iranian origin were enrolled in this study. The participants were referred to a tertiary center in a 2-year period (2006?C2008). The exonic regions of the NOD2 gene were amplified by polymerase chain reaction and evaluated by direct sequencing.

Results

A total of 21 sequence variations were identified among all exonic regions of the NOD2 gene, of which eight had an allele frequency of more than 5%. Eight new mutations (one in exon 2 and seven in exon 4) were observed. The three main variants (R702W, G908R, and 1007fs) showed allele frequencies of 13.3%, 2.2%, and 1.7%, respectively. Three new variations (P371T, A794P, and Q908H) and R702W mutation were significantly more frequent in Crohn's disease patients compared to controls.

Conclusions

Eight novel mutations were identified in the NOD2 exons, but the pathophysiological importance of these variants remains unclear. Iranian patients with their different genetic reservoirs may demonstrate some novel characteristics for disease susceptibility.     

Factors influencing the quality of medical documentation when a paper-based medical records system is replaced with an electronic medical records system: an Iranian case study

OBJECTIVES: Information technology is a rapidly expanding branch of science which has affected other sciences. One example of using information technology in medicine is the Electronic Medical Records system. One medical university in Iran decided to introduce such system in its hospital. This study was designed to identify the factors which influence the quality of medical documentation when paper-based records are replaced with electronic records. METHODS: A set of 300 electronic medical records was randomly selected and evaluated against eleven checklists in terms of documentation of medical information, availability, accuracy and ease of use. To get the opinion of the care-providers on the electronic medical records system, ten physicians and ten nurses were interviewed by using of semi-structured guidelines. The results were also compared with a prior study with 300 paper-based medical records. RESULTS: The quality of documentation of the medical records was improved in areas where nurses were involved, but those parts which needed physicians' involvement were actually worse. High workloads, shortage of bedside hardware and lack of software features were prominent influential factors in the quality of documentation. The results also indicate that the retrieval of information from the electronic medical records is easier and faster, especially in emergency situations. CONCLUSIONS: The electronic medical records system can be a good substitute for the paper-based medical records system. However, according to this study, some factors such as low physician acceptance of the electronic medical record system, lack of administrative mechanisms (for instance supervision, neglecting physicians and/or nurses in the development and implementation phases and also continuous training), availability of hardware as well as lack of specific software features can negatively affect transition from a paper-based system to an electronic system.