Assessing the coking properties of concentrates in terms of the strength of the nonvolatile residue

The coking properties of coal concentrates are assessed on the basis of the strength of the nonvolatile residue.     

Evaluation of two dextrose-based directly compressible excipients

The objectives of this research were to evaluate the physical properties and compaction behavior of two dextrose-based directly compressed excipients. Anhydrous theophylline (10% w/w) was used as a drug model, Emdex and or Maltrin M510 (89.5% w/w) were used as diluent, and magnesium stearate (0.5% w/w) was used as lubricant. Direct compression and wet granulation methods were used for preparing the compacts. In general, the wet granulation method reduced the density of the mixture and consequently its flow rate compared to the mixture prepared only by solid-solid mixing. All formulations were compressed at four different compressional forces and at a target weight of 450 mg +/- 5%. Tablets obtained were different in physical properties and mechanical strength based on type of excipient used and methods of tablet preparation (direct compression versus wet granulation). Compacts prepared from Maltrin M510 had a longer disintegration time and slower drug release than compacts of the same composition but prepared with Emdex. Disintegration time and drug dissolution from tablets containing Maltrin M510 as diluent and prepared by wet granulation appeared to be controlled by a "gel" layer formation around the tablets and not by the tablets porosity. This study demonstrates that full characterization of excipients is needed because a different manufacturing process for the same excipients may produce differences in the pharmaceutical products.     

Microbiological examination of bandage soft contact lenses used in laser refractive surgery

BACKGROUND: Disposable soft contact lenses are known to be colonized by bacteria and play a key role in bacterial keratitis pathogenesis. Such lenses, commonly used after laser refractive surgery procedures in which postoperative corneal infiltrations are sometimes observed, are potentially a substrate for bacterial inoculation. This study evaluates the extent of such a contamination. METHODS: Sixty disposable lenses collected from 60 eyes of patients who underwent photorefractive keratectomy (PRK), photoastigmatic refractive keratectomy (PARK), or laser in situ keratomileusis (LASIK) for the treatment of myopia or hyperopia were collected under sterile conditions over 4 months and cultured in various media. Results were statistically analyzed and the correlation with clinical and epidemiological data was examined. RESULTS: Eleven (18.3%) of the examined lenses were contaminated with Staphylococcus epidermidis. No other bacteria or fungi were found. Contamination was significantly more common among female patients (P = .036). Correlation with the other clinical or operative parameters examined was statistically insignificant. CONCLUSIONS: Contamination was independent of the surgical procedure and females who were frequent users of eyelid cosmetics displayed higher contamination frequencies, suggesting that bacteria possibly originate from eyelid flora. The isolation of Staphylococcus epidermidis requires close postoperative surveillance, since it is a known cause of keratitis. Prophylactic postoperative treatment with tobramycin, gentamycin, or sulphonamides could be indicated.     

Reduction of thyroid hormone may participate in the modulation of cytochromes P450 2C11 and 3A2 by retinol

Both hypothyroidism and retinol supplementation in rats induce CYP 3A2 and suppress CYP 2C11. Therefore studies were performed to evaluate the role of thyroid hormones in the modulation of P450 expression by retinol. Adult male Sprague-Dawley rats were given retinol as a single oral dose of 75 mg/kg. Rats were killed and hepatic microsomes prepared at 24, 48, 72, and 96 hr following treatment. The catalytic activity of 2C11 was reduced maximally by retinol at 48 hr (by 30%) whereas 3A2 activity was elevated maximally at 24 hr (by 30%). The serum concentration of testosterone was not altered at any time point. However, retinol produced a decline in the concentration of thyroxine by 35% and 43% at 24 and 48 hr, respectively. These data suggest that administration of large doses of retinol may alter hepatic microsomal enzyme expression by perturbation of plasma thyroid hormone levels.     

Reaction of the type III iodothyronine deiodinase with the affinity label N-bromoacetyl-triiodothyronine

The type III iodothyronine deiodinase (ID-III) catalyzes the inner ring deiodination and, thus, the inactivation of the thyroid hormones T4 and T3. ID-III activity in rat brain, rat placenta and embryonic chicken liver is inhibited by the affinity label N-bromoacetyl-T3 (BrAcT3) with an affinity similar to that of T3. Reaction of rat brain and placenta microsomes with BrAc[125I]T3 resulted in the extensive labeling of a 32 kDa protein (p32). However, p32 was also prominently labeled in fetal rat liver microsomes which have no ID-III activity. Labeling of p32 was not influenced by 100 microM substrate analogs or inhibitors of ID-III, some of which completely inhibit ID-III activity at 1 microM. BrAc[125I]T3 labeling of embryonic chicken liver microsomes did not reveal p32 or another protein possibly related to ID-III. In contrast to previous suggestions, it is unlikely that p32 represents ID-III or a subunit thereof.     

Teenagers' perceptions of barriers to prenatal care

A structured interview conducted during the postpartum hospitalization of 184 patients aged 17 years or younger was used to study teenagers' perceptions of barriers to prenatal care. The interview consisted of more than 100 questions on demographic characteristics, family and social support, desire for the pregnancy, perceptions of the importance of prenatal care, practical obstacles to access to health care (such as lack of transportation, day care, etc), financial problems related to care, problems finding time to obtain health care, knowledge of available prenatal care resources, and perceptions of ease or difficulty in the use of existing clinics. Multiple regression analysis using the Kessner index as the criterion variable showed that major factors related to the adequacy of prenatal care received by these teenagers were perceptions of cost barriers, the gestational age at which the teenager discovered she was pregnant, school enrollment status (those in school received poorer care than those who had dropped out), and the degree of social support experienced by the teenager. These findings suggest that specific changes in the health care system are needed to make prenatal care more accessible for pregnant teenagers. These changes would include enhancing community awareness that Medicaid pays for prenatal care, establishing links between prenatal clinics and school health systems, and scheduling prenatal clinics at times more convenient for teenagers.     

New Product Theorems for Queueing Networks

New product theorems for open and closed queueing networks are proved. The theorems give precise analytical formulas for the computation of stationary distributions of queueing networks with a certain structure and principle of operation. The subject touched upon in the paper is developed in three directions, each of them being closely connected with mobile phone network systems.__________Translated from Problemy Peredachi Informatsii, No. 2, 2005, pp. 111–122.Original Russian Text Copyright © 2005 by Tsitsiashvili, Osipova.     

Ileal endometriosis masquerading as Crohn's ileitis

Endometriosis is usually confined to the pelvis but may involve distant organs. When the small bowel is affected, endometriosis has a propensity to develop in the distal ileum, which may lead to fibrosis and stricture formation that can be confused with Crohn's disease. Here were describe two women, one with antecedent Crohn's colitis in whom ileal endometriosis mimicked obstructing Crohn's disease of the terminal ileum. These reports illustrate that ileal endometriosis must be considered in the differential diagnosis of Crohn's disease of the ileum, even in the presence of Crohn's disease elsewhere in the gastrointestinal tract.