Melatonin reduces the increase in 8-hydroxy-deoxyguanosine levels in the brain and liver of kainic acid-treated rats

In the present study, the effect of melatonin on oxidative DNA damage induced by kainic acid (KA) treatment was investigated. 8-hydroxy-deoxyguanosine (8-OH-dG) is a main product of oxidatively damaged DNA and was used as the endpoint in these studies. The levels of 8-OH-dG were found to be elevated in the hippocampus and frontal cortex of rats treated with KA. These elevated levels were significantly reduced in animals that were co-treated with melatonin. Thus, there was no difference in 8-OH-dG levels in the brain of control rats compared to those treated with KA (10 mg/kg) plus melatonin (10 mg/kg). The levels of 8-OH-dG also increased in the liver of rats treated with KA. This rise in oxidatively damaged DNA was also prevented by melatonin administration. Melatonin's ability to reduce KA-induced increases in neural and hepatic 8-OH-dG levels presumably relates to its direct free radical scavenging ability and possibly to other antioxidative actions of melatonin.

Cataractogenesis and lipid peroxidation in newborn rats treated with buthionine sulfoximine: preventive actions of melatonin

The purpose of this study was to examine the influence of exogenously administered melatonin on cataract formation and lipid peroxidation in newborn rats treated with buthionine sulfoximine (BSO), a drug which inhibits the rate-limiting enzyme in glutathione (GSH) synthesis, gamma-glutamylcysteine synthase, thereby depleting animals of their stores of the important intracellular antioxidant, GSH. BSO (3 mmol/kg BW) was given for three consecutive days beginning on postnatal day 2; melatonin (4 mg/kg) was injected daily beginning on postnatal day 2 and continuing until the animals were killed (either day 9 or day 17 after birth). None of the control animals (rats treated with neither BSO nor with melatonin) developed lenticular opacification during the observation period. In the BSO-treated rats, 16 of 18 animals (89%) had observable cataracts when they were examined. In rats that received both BSO and melatonin, the incidence of cataracts was highly significantly decreased, i.e., only 3 of 18 rats (7%) had observable cataracts. In addition to cataracts, the level of lipid peroxidation products (malondialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)) was examined in the lens, brain, liver, lung, and kidney of control and experimental animals. In BSO-treated rats, the lens, kidney, and lung exhibited increased levels of MDA plus 4-HDA relative to those measured in the control rats; these increases were reversed in the BSO-treated rats who were injected with melatonin daily. While BSO administration did not increase basal levels of MDA plus 4-HDA in either the brain or liver, melatonin reduced levels of lipid peroxidation products below those measured in the control rats (at 17 days after birth). The changes induced by melatonin are consistent with the free-radical scavenging and antioxidative properties of this indole.

An expert system for performance-based direct delivery of published clinical evidence

OBJECTIVE

To develop a system for clinical performance improvement through rule-based analysis of medical practice patterns and individualized distribution of published scientific evidence.

METHODS

The Quality Feedback Expert System (QFES) was developed by applying a Level-5 expert system shell to generate clinical direct reports for performance improvement. The system comprises three data and knowledge bases: 1) a knowledge base of measurable clinical practice parameters; 2) a practice pattern database of provider-specific numbers of patients and clinical activities; and 3) a management rule base comprising "redline rules" that identify providers whose practice styles vary significantly. Clinical direct reports consist of a table of practice data highlighting individual utilization vs recommendation and selected pertinent statements from medical literature.

RESULTS

The QFES supports integration of recommendations from several guidelines into a comprehensive and measurable quality improvement plan, analysis of actual practice patterns and comparison with accepted recommendations, and generation of a confidential individualized direct report to those who significantly deviate from clinical recommendations. The feasibility of the practice pattern analysis by the QFES was demonstrated in a sample of 182 urinary tract infection cases from a primary care clinic. In a set of clinical activities, four questions/procedures were associated with significant (p < 0.001) and unexplained variation.

CONCLUSION

The QFES provides a flexible tool for the implementation of clinical practice guidelines in diverse and changing clinical areas without the need for special program development. Preliminary studies indicate utility in the analysis of clinical practice variation and deviations. Using data obtained through a retrospective chart audit, the QFES was able to detect overutilization, and to identify nonrandom differences in practice patterns.

Multipurpose practice guideline modules for clinical decision analysis and quality improvement

This study aimed to measure the loss of information in communication between clinical researchers and information system developers, to design a tool for sharing clinical practice guidelines, and to test the feasibility of this tool in knowledge base development. The analysis of a sample of 101 randomized controlled clinical trials indicated that exact numeric results were published in only 64 percent of the trials. While structured abstracts were associated with improved total quality scores (p0.001), there was no significant improvement in reporting numeric results (p=0.31). Based on the documented loss of information and the needs of various parties involved, the concept of a multipurpose knowledge module was developed for sharing clinical practice recommendations. Such clinical practice guideline modules were applied in developing the knowledge base of a quality feedback expert system (QFES).

Differential binding of nuclear c-ets-1 protein to an intron I fragment of the c-myb gene in growth versus differentiation

For growth, ML-1 human myeloblastic leukemia cells require insulin-like growth factor 1 together with transferrin, whereas for differentiation they depend upon transforming growth factor beta in combination with transferrin. As shown in this study, growth stimulation is accompanied by c-myb expression, whereas initiation of differentiation results in the cessation of c-myb expression through premature termination of transcription in the first intron of the myb gene. Growth factor-stimulated c-myb elongation was found to correlate with an elevated level of nuclear c-ets-1 protein and with increased binding of this protein to an 18-base pair sequence in intron 1 of the c-myb gene containing the putative regulatory element PEA 3. In contrast, differentiation factor-initiated ML-1 cell maturation was accompanied by a very low level of nuclear c-ets-1 protein, by the inability to detect binding of the protein to the 18-base pair sequence, and by the cessation of c-myb expression. These results show a correlation to exist between c-ets-1 binding to intron 1 of the c-myb gene and c-myb expression. The mechanism underlying this correlation is under further study.

Down-regulation of c-myc gene expression with induction of high molecular weight DNA fragments by fluorodeoxyuridine

5-Fluoro-2'-deoxyuridine (FdUrd), a potent inhibitor of thymidylate synthase, induces extensive bulk DNA damage at drug concentrations that produce significant in vitro growth inhibition of human ileocecal carcinoma (HCT-8) cells. Constant- and pulsed-field gel electrophoresis (CFGE and PFGE), to detect size distribution of DNA double-strand breaks and repair kinetics, in parallel with northern and western blot analyses, to quantitate c-myc gene and protein expression, were utilized to analyze drug effects. At 24-hr post in vitro drug treatment, when maximum bulk DNA damage was detected, FdUrd produced a broad range of high molecular weight DNA fragments, clustering between 0.1 and 5.7 megabases in size, and resulted in a decrease in the level of c-myc transcripts and protein with no significant effect on the level of v-myc and H-ras. These effects preceded the observed cellular growth inhibition. Addition of the reduced folate leucovorin potentiated the effects induced by FdUrd, indicating that thymidylate synthase inhibition is an important initial step in drug effect followed by DNA fragmentation and suppression of c-myc expression. Changes in the integrity of the genetic materials and regulatory genes occurred prior to the observed cell growth inhibition by FdUrd, suggesting that these molecular alterations by FdUrd may be associated with subsequent FdUrd-induced cell growth inhibition.

A decision-support system for the analysis of clinical practice patterns

Several studies documented substantial variation in medical practice patterns, but physicians often do not have adequate information on the cumulative clinical and financial effects of their decisions. The purpose of developing an expert system for the analysis of clinical practice patterns was to assist providers in analyzing and improving the process and outcome of patient care. The developed QFES (Quality Feedback Expert System) helps users in the definition and evaluation of measurable quality improvement objectives. Based on objectives and actual clinical data, several measures can be calculated (utilization of procedures, annualized cost effect of using a particular procedure, and expected utilization based on peer-comparison and case-mix adjustment). The quality management rules help to detect important discrepancies among members of the selected provider group and compare performance with objectives. The system incorporates a variety of data and knowledge bases: (i) clinical data on actual practice patterns, (ii) frames of quality parameters derived from clinical practice guidelines, and (iii) rules of quality management for data analysis. An analysis of practice patterns of 12 family physicians in the management of urinary tract infections illustrates the use of the system.

Construction of a medical informatics thesaurus

Medical Informatics needs a specific terminology that reflects the multi-disciplinary nature of the field and can rapidly change as the discipline evolves. Using the four primary methods of thesaurus construction, a group at the University of Missouri-Columbia is developing a thesaurus that meets these criteria and includes both user and literary warrant. The steps in construction include using existing thesauri, medical informatics literature, and the terminology of experts to produce a thesaurus arranged within a hierarchical structure.

CT scanning of spinal injuries

Ninety-one patients with spinal injuries were studied by CT scanning. A comprehensive classification of spinal injuries was proposed according to the mechanism of trauma, the concept of three-column anatomical structure of the spine and the degree of spinal canal stenosis. CT scanning was advantageous in the diagnosis of spinal injuries such as clear detection of the three-column anatomical structure of the spine and spinal canal, demonstration of fracture lines in all 3 planes, determination of the amount of displacement of bony fragment into the spinal canal, assessment of spinal stability or instability, and restricted movement of the patient. The key points in general CT diagnosis, its role and limitation in the diagnosis of spinal injuries were discussed. The authors conclude that combined comprehensive classification of spine injuries is helpful in planning suitable treatment for the patient and predicting prognosis.

[Clinical and experimental studies on membranous pulp-capping agent with Chinese medicinal herbs]

A membranous pulp-capping agent of Chinese medicinal herbs was made by ourselves prescription, and was filled in capsules for medication. Direct pulp-capping and pulpotomy were performed on 102 permanent teeth. During the observation period of more than one year, the successful rate was 82.4%. Under light microscope, the artificial exposed sites of normal sheep teeth were fully sealed after capping for 45 days. There were calcification under the exposed sites. The inner lines were preparative dentins. Experiments on dogs' teeth revealed that the pulps were normal after two month's direct pulp-capping, and the new dentins appeared. The bacteria culture test was made before and after the pulp-capping agent was used on ten deep carious teeth. It revealed that the bacteria all converted negative after medication of two weeks. Clinical and experimental studies indicated that the pulp-capping agent is valuable in clinical treatment.

Interspinous process segmental instrumentation with bone-button-wire for correction of scoliosis

From May 1985 to May 1988, 55 patients with scoliosis were given interspinous process segmental spinal instrumentation with bone button-wire. The Harrington distraction rod and Luque's rod were placed separately in the concave and convex sides of the curvature fixed with bone button-wire. The fixations were subjected to biomechanical analysis, and the patients were followed up for an average of 18 months with satisfactory results. The curves were corrected from 69.4 degrees to 33.2 degrees, with a corrective rate of 47.8%. The merits of this procedure lie in (1) no injury to the spinal cord and minimal neurological complications, (2) strong fixation for correcting deformities, and (3) minimal blood loss and short time for operation.

[Comprehensive classification and surgical treatment of injury of the thoracolumbar spine]

Based on the theory of three-column of spine and in combination with the findings on CT scannings, particularly the status of the spinal canal, of 47 patients sustained trauma of thoracolumbar spine, a comprehensive classification has been proposed and described in the paper. 26 patients out of the 47, who had had signs of neurological damage and spinal instability, were operated upon and their spines were stabilized with Harrington-Luque instrumentation. 14 of the patients treated operatively enjoyed, at the time of follow-up, the satisfactory result. We have been convinced that this comprehensive classification serves as a very good guidance in selection the procedure of treatment, operation or conservatism, and in predicting prognosis.