Iranian Journal of Basic Medical Sciences
Year:2002 | Volume:5 | Issue:1 (13)|Papers Count:8

Longitudinal study is an important part of epidemiological, clinical, and social science studies. In these kinds of studies every individual is observed frequently for a period of time. The statistical analysis of longitudinal presents special opportunities and challenges. Repeated outcomes for one individual tend to be correlated among themselves. Also one of the problems that we face in longitudinal studies is the missing data. These two issues are taken into account in this article. By using the probit link function, designed for longitudinal data, we introduce a mixed model, and then we present the evaluation of variance components by Bayesian methods. The applied method exploits the nonconjugate priors. The conjugate priors, however, are easier to deal with. Finally an application of the model in a clinical experiment, (the effect of lidocaine and lidocaine /morphine on pain after the root canal therapy) is presented.      

It was shown that the aqueous solubility of acetaminophen in presence of PVP increased. The solubility at 25°C increased from 14.3 mg ml-1 in absence of PVP, to 19.7mg ml-1  in presence of 4% w/v PVP, and to 26.7 mg ml-1  in presence of 8% w/v PVP. Dialysis studies indicated that there is a potential of binding between PVP and acetaminophen in their aqueous solution. Dialysis studies also revealed that the nature of interaction between PVP and acetaminophen is physical and reversible, and there was no strong binding between PVP and acetaminophen in their solutions. Infrared spectroscopy of acetaminophen /PVP co-precipitate indicated that the mechanism of interaction between PVP and acetaminophen is via hydrogen bonding. Therefore the increase in solubility of acetaminophen in presence of PVP is attributed to its ability to form water soluble complex with PVP.      

Due to soil bio-diversity, many research projects are undertaken by research laboratories affiliated by large international pharmaceutical companies to identify new medicines as well as new antibiotics. Though few of these new compounds find their way into clinics, this search is still valuable and greatly benefits the owners of those companies. In this project, different stages of a screening method have been carried out. Soil samples from eleven different places in Mashhad, Iran, were taken and their representative microorganisms were isolated. Screening for organisms producing anti-microbial agents resulted in identification of 111 potential isolates. Further studies on the isolation and purification of those agents as well as their cytotoxicity as potential anti-tumor agents are underway.      

Acetaminophen is an effective antipyretic and analgesic with rare and usually mild side effects. Over dosage with acetaminophen can result in severe liver damage and sometimes-acute renal tubular necrosis. In order to assess the risk of liver damage it is very important to measure the plasma acetaminophen concentration. In this study a new and simple visible spectrophotometric method for analysis of acetaminophen in plasma is introduced. There are several different methods using various instrumental analyses for measurement of acetaminophen in plasma e.g. visible spectrophotometry and high performance liquid chromatography (HPLC) methods. Since visible spectroscopy is a simple, cheap, and available method in nearly every laboratory, in this study a new and simple visible spectrophotometric method for analysis of acetaminophen in plasma is introduced. In this method only 200 µl of plasma is needed. After quick hydrolysis, and formation of a complex, the absorption is measured at 635 nm: The possible interference of 84 different drugs was studied. In order to compare it with HPLC method 23 standard plasma samples with known amount of acetaminophen and 12 plasma samples from different subjects, after acetaminophen tablet administration, were analyzed by these two methods. Statistical analysis showed no significant differences between the two methods. Considering these results and their comparison, it can be suggested that the purposed visible spectrophotometric method is simple, cheap, quick and a suitable method for analysis of acetaminophen in plasma. It is comparable with the tested HPLC method. Therefore it is recommended for die analysis of acetaminophen in plasma, in overdose patient and in TDM where more sensitive methods are not available      

In an open and cross over trial, the antidiabetic effect of the leaves of Morus nigra was studied. Fifty patients with the non insulin dependent diabetes mellitus (NIDDM) (38 women and 12 men) between 25 and 60 years old were studied. The fasting blood sugars (FBS) were between 150 mg/dl to 250 mg/dl. Microbial control tests were done for the extracts. Three groups of patients (10 people in each group) took decoction extracts (5, 10 and 15 percent) once a day. The treatments lasted for one week. Before and after treatment, the following parameters were determined: FBS, blood pressure and weight. At each visit (before and after treatment) a questionnaire about side effects and associated symptoms were completed. The extracts did not reduce FBS after 7 days administration. Glibenclamide (2.5 mg/day) reduced FBS after 7 days. Adding the extract to glibenclamide group, did not increase the antidiabetic effect of this drug. In this study neuropathy and symptoms of diabetes were improved by the extracts. It is possible these extracts act like biguanides in reduction diabetic symptoms and eleminate neuropathy like analgesic or anesthetic drugs.      

Two questions about food center of circadian clock are: 1) where is the food center of circadian clock? 2) What is the relationship of food center and light center of circadian clock? This study has described fasting induced changes at dawn and dusk on locomotor activity and investigated the possible role of suprachiasmatic nucleus (SCN) and feeding center of circadian clock in these changes and tries to answer to these questions. Experiment was done in the following order: (1) Effect of light-dark cycle with food adlibitum (only light center of circadian clock is active) and in this situation locomotor activity in the first hour of night was more than the last hour of night. (2) Effect of light-dark cycle with restricted feeding (both light and food center of circadian clock is active). In our experiment, locomotor activity has no difference in the last hour of night and first hour of night (3) Effect of SCN lesions with restricted feeding (only food center of circadian clock is active). In this situation locomotor activity in the last hour of night was more significant than the first hour of night. We concluded: 1) the food center is separated from SCN 2) Food center is more potent than light center. 3) Food center receives light information and food center of circadian clock do not receive this information directly from SCN. 4) The power of food center in the last hour of night is more than the first hour of night but the action of light center of circadian clock in the fIrst hour of night is more prominent than the last hour of night. 5) Circadian clock can integrate photic and non-photic cues.6) Death from surgery was more in the last hour of night than first hour of night probably due to action of circadian clock.      

Introduction: The morphogenesis of the paraventricular choroid plexus (PCP) was studied during different life periods in mice (balb/c) by histochemical methods. Methods: Fetal and postnatal brain mice, fixed in formalin 10%, provided coronal and horizontal serial sections and stained for light microscopic study. Results and Discussion: Based on this investigation, PCP in mice appears on post conception day (PCD) 11 with the formation of a horizontal crest in the roof of the interventricular foramen and apical portion of the fourth ventricle. During these changes the epithelial cells differentiate and stratify to form the choroid plaque. From PCD 11 the developing choroid plexus (CP) expands into the ventricular cavity taking with it mesenchyme and vessels. Light microsopic studies show that differential epithelial cells are more cylindrical and their nuclei become more elongated. These cells in microscopic view exhibit prolongations into the ventricular cavities. Apical ends of the epithelial cells show numerous elevations into the choroid lakes. During these morphogenical changes other cells appear in neighboring areas of these formations, named epiplexus cells. Morphological studies in old mice show atrophy and flattening of the CP epithelial cell layer. Other morphological changes in old CP was irregularity of the epithelial basement membrane but previous changes do not show in fetal and early postnatal groups.