Compressed Donut-Shaped Tablets with Zero-Order Release Kinetics

Purpose. Simple uncoated compressed tablets with a central hole (donut-shape) are proposed to provide a constant drug release over a long period of time (>20 hrs). The effect of hole size and drug solubility on the release kinetics is investigated. Methods. The donut-shaped polyethylene oxide (PEO, Mw = 4 × l0⁶) tablets (600 mg and 12 mm diameter) are bored with a drill bit (3/32, 7/64, 1/8, and 5/32). Results. The release of theophylline from the donut-shaped tablets is zero order (80 – 90% release) before rapidly decreasing. As the hole size is increased from 7/64 to 5/32, the release rate increases and the release time is shortened. However, the release of theophylline from the donut-shaped tablet with a hole size of 3/32 follows the same anomalous release profile from a tablet without a hole. As drug solubility increases, the duration of linear drug release is shortened to 65 – 70% release followed by a severe tailing at the later stage of the release. Conclusions. Donut-shaped PEO tablets with a hole provide zero-order release kinetics because the effect of the releasing surface area on the release kinetics is reduced.     

Varus deformity of the distal end of the femur secondary to a focal fibrous lesion

Severe unilateral varus deformity of the distal end of the femur secondary to a focal fibrous lesion is reported. It is a malformative process rare at this level, this being the first report of it in the radiological literature. The conventional radiograph is pathognomonic and CT is useful in the confirmation of the fibrous tissue. Osteotomy is indicated only if the deformity progresses or the angle of varus is severe.     

Recent trends of age-specific pneumoconiosis mortality rates in the United States, 1985-1996: coal workers' pneumoconiosis, asbestosis, and silicosis

The authors examined the temporal trends of age-specific pneumoconiosis mortality from coal worker's pneumoconiosis (CWP), asbestosis, and silicosis in the United States in 1985-1996. Mortality data were derived from the National Center for Health Statistics multiple causes of death files for the period. Age-specific mortality rates were computed for three age groups (15-44, 45-64, and > or = 65 years) among decedents with mention of CWP, asbestosis, or silicosis. Linear regression analysis was performed to examine the annual changes in age-specific mortality rates, by age group, with each specific condition. The CWP mortality rates declined significantly (p = 0.0001) in the groups 45 years old and older, but not in the age group 15-44. Asbestosis mortality rates declined significantly (p = 0.005) for the age group 45-64, while increasing (p = 0.0001) for those aged 65 years and older. However, in the younger age group 15-44, the rates showed no significant trend. Silicosis mortality rates declined significantly (p = 0.0001) for all groups. The continued occurrence of deaths from CWP, asbestosis, and silicosis among young adults may be the result of high levels of exposure to occupational risks. These results suggest that pneumoconiosis surveillance may help to evaluate the temporal pneumoconiosis mortality patterns in the United States.     

Heel pain in children. Diagnosis and treatment

Heel pain in children is common, and its evaluation is challenging. Medical history and physical examination may be unrevealing owing to children's limited communication skills. Often, advanced laboratory and imaging studies are required to make an accurate diagnosis. The most common causes of heel pain in children are apophysitis, enthesopathy, and overuse syndromes such as tendinitis. Juvenile rheumatoid arthritis is relatively uncommon. In very active children, occult fractures must also be evaluated. Pain unrelated to activity may indicate tumors, infection, or congenital problems. In general, heel pain in children is treated nonoperatively. For fractures in particular, children are less likely than adults to receive surgical treatment.     

Epidemiology of rotavirus diarrhea in Egyptian children and implications for disease control.

Reliable epidemiologic data are essential for formulating effective policy to control rotavirus disease through immunization. The objective of this study was to describe the epidemiology of rotavirus diarrhea in a population-based cohort of children under 3 years of age residing in Abu Homos, Egypt, in 1995-1996. Rotavirus diarrhea incidence rates (episodes per person-year) were 0.13 for infants aged <6 months, 0.61 for those aged 6-11 months, 0.17 for those aged 12-23 months, and 0.15 for those aged 24-35 months. Fifty-six percent of children with rotavirus diarrhea had clinical dehydration; 90% of rotavirus diarrheal episodes occurred between July and November. In infants under 1 year of age, receipt of breast milk was associated with a lower incidence of rotavirus diarrhea. No other sociodemographic or environmental factor was found to be significantly associated with rotavirus diarrhea. Of 46 rotavirus isolates with strains identified, 41 (89%) were G serotypes 1 and 2. Rotavirus diarrhea was a major cause of morbidity in this cohort. Promotion of breastfeeding may exert a protective effect in young infants in this setting, but improvements in water and sanitation are unlikely to be effective preventive measures. The use of effective immunization against rotavirus in early infancy should be considered a public health priority.     

Persistent Organochlorines in the Effluents from a Chlorine-Bleached Kraft Integrated Pulp and Paper Mill in Southeast Asia

A bleached sulfate integrated pulp and paper mill producing printing and writing paper from mixed tropical hardwood and bamboo was studied. The mill uses a “conventional bleaching sequence,” C-E-H1-H2, with an average molecular chlorine consumption of 50 kg per ton of air-dried pulp (ADP). The content of polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs) in the bleaching filtrate in terms of the nordic toxicity equivalent (N-TEQ) was 33.5, 1.15, 0.56, and 0.014 pg/L for the E, C, H1, and H2 bleaching stages, respectively. The corresponding PCDFs and PCDDs loads in ng/t ADP were in the same ranking, i.e., 670, 69, 11.2, and 0.28, respectively. The congener and isomeric pattern of PCDFs and PCDDs of the bleaching filtrate and the bleached pulp was found to be typical for the chlorine bleaching plant effluent. The obtained dioxin load formed in the mill is in agreement with Western studies for the given multiple chlorine of 0.21–0.23. The load is, however, lower than reported discharges from Scandinavian mills using 1980s bleaching technologies, but substantially higher than the discharges from mills with modern bleaching technologies. Modifications in the bleaching plant to reduce molecular chlorine use are necessary to reduce dioxin formation. Received: 15 July 1998/Accepted: 17 March 1999     

High-voltage-activated calcium channel messenger RNA expression in the 140-3 neuroblastoma-glioma cell line

Expression of calcium channel alpha1 subunits in oocytes or cell lines has proven to be a powerful method in the analysis of structure-function relations, but these experimental systems are of limited value in the examination of neuron-specific functions such as transmitter release. Cell lines derived from neurons are often capable of these functions, but their intrinsic calcium channel alpha1 subunits are complicating factors in experimental design. We have examined the biophysical and molecular properties of calcium channels in a little studied neuroblastoma-glioma hybrid cell line, 140-3, a close relative of the NG108-15 cell line, to test whether this cell line might serve a role as an expression system for neural mechanisms. This cell was selected as it contains an intact transmitter release mechanism yet secretes little in response to depolarization. Patch-clamp recording revealed only a prominent low-threshold, rapidly inactivating calcium current with a single-channel conductance of approximately 7 pS that was identified as T type. A search for calcium channel alpha1 subunit messenger RNA in the 140-3 cells with three different tests only revealed alpha1C, whereas alpha1A-alpha1C were present in the parent NG108-15 line. We made a particular effort to search for alpha1E, since this subunit has been associated with a low-voltage-activated current. Our findings suggest that, since the principal nerve terminal-associated calcium channels (alpha1A, alpha1B, alpha1E) are absent in the 140-3 cell, this cell line may prove a particularly useful model for the analysis of the role of high-voltage-activated calcium channels in complex functions of neuronal cells.     

Technical evolution of arthoscopic knee surgery

The widespread growth of arthroscopic techniques and their use has dramatically changed the practice of orthopaedic surgery. A high degree of clinical accuracy and minimally invasive procedure with a low surgical morbidity have encouraged the use of arthroscopy to assist in diagnosis, to determine prognosis and to provide treatment. In particular, the knee is the proper joint in which arthroscopy has its diagnostic and intraarticular surgical application. The rapid advancement of arthroscopic techniques has demonstrated a variety of surgical techniques in procedures such as meniscectomy, meniscal repair and cruciate ligament reconstruction during the last decade. This article reviews the past history of arthroscopy and technical evolution of arthroscopy in knee surgery in our department.