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Biomedical subjects

M Lee

Publications and source records attributed to M Lee.

1,242 records · Page 69Linked to original sources

A non-pharmacologic approach to the treatment of exercise-induced bronchospasm.

We investigated the effects of breathing air warmed and fully saturated to body temperature (AWS) before, during, and after exercise in asthmatic subjects. Airway responses to submaximal exercise on a cycloergometer were measured on four separate days in 14 asthmatic volunteers. On day 1 the subjects exercised breathing ambient air (AA). On the subsequent three days exercise was performed with the subjects breathing AWS, (1) for five minutes preceding, (2) during, and (3) for five minutes following exercise. We showed complete protection against EIB by AWS during exercise, but no protection by AWS before or after exercise. On two subsequent days we examined the effects of partially warming and humidifying the subjects' inspired air by having them wear a mask during exercise. We found that with such protection bronchospasm was significantly but not completely blunted. We conclude that the physiologic changes initiated during exercise can be prevented by breathing AWS during exercise, but are not by AWS inhaled before or after exercise. Furthermore, these studies demonstrate the possibility of using masks as a non-pharmacologic means of controlling EIB.

Adult↗

Sagittal plane rotation of the pelvis during lumbar posteroanterior loading.

OBJECTIVE: To determine the extent of sagittal plane rotation of the pelvis during lumbar spine posteroanterior loading. DESIGN: Quantitative study. SETTING: Biomechanics Laboratory, Faculty of Health Sciences, University of Sydney. PARTICIPANTS: Ten male and female subjects with no recent history of significant low back pain. INTERVENTION: A mechanical device was used to apply forces to the L3 spinous process. Data were collected during slow cyclical loading. MAIN OUTCOME MEASURE: The stiffness of the posteroanterior movement at the point of loading was measured, together with the sagittal plane rotation of the pelvis and the resistance to rotation provided by the bed on which the subject lay. RESULTS: Mean pelvic rotation was 2.1 degrees per 100 N applied force (SD 1.01 degrees/100 N). Mean posteroanterior stiffness was 13.4 N/mm (SD 3.13 N/mm) and resistance to pelvic rotation was 2.71 Nm/degree of pelvic rotation (SD 0.84 Nm/degree). CONCLUSION: During posteroanterior force application there is pelvic rotation of a magnitude that may be sufficient to have clinical significance. Abnormalities found during lumbar posteroanterior force application may originate in tissues caudad to the lumbar spine itself.

Adult↗

Topical diclofenac treatment prior to excimer laser photorefractive keratectomy in rabbits.

PURPOSE: This study sought to determine whether pre- and posttreatment with topical diclofenac sodium 0.1% eye drops suppresses corneal inflammation after 193-nanometer excimer laser corneal ablation more effectively than does posttreatment alone. METHODS: Eight rabbits were divided into four groups. Animals in group I were treated with topical diclofenac every half hour for 2 hours prior to photorefractive keratectomy; treatment was continued every hour for 3 hours after the ablation. Group II animals, used as controls, were treated with the diclofenac vehicle according to the same schedule. The third group (III) received diclofenac topically only after the excimer laser ablation. The fourth group (IV) consisted of normal corneas from these same animals. At 3 hours after ablation, prostaglandin E2 (PGE2) levels were measured in the corneas and leukocytes were quantified. RESULTS: Treatment with topical diclofenac significantly reduced levels of PGE2 compared to treatment with the vehicle (p = .024). Presurgical treatment with topical diclofenac did not result in greater suppression of PGE2 than did posttreatment alone (5.72 +/- 0.91 pg/mL versus 5.79 +/- 1.29 pg/mL). Similarly, there was a significant inhibition of leukocyte invasion in the diclofenac treated corneas (I vs II: p = .019, III vs II: p = .024), but no statistically significant difference between pretreatment and posttreatment alone groups (I vs III: p = .72). CONCLUSIONS: Topical administration of diclofenac reduces the release of PGE2 and the migration of polymorphonuclear leukocytes in the rabbit cornea 3 hours after 193-nanometer excimer laser ablation. However, pretreatment of the cornea, starting 2 hours prior to laser surgery, does not seem to offer advantages over postablation treatment in this animal model.

Administration, Topical↗

Retrospective analysis of iatrogenic Mallory-Weiss tears occurring during upper gastrointestinal endoscopy.

BACKGROUND/AIMS: This study was made to determine the incidence and natural history of iatrogenic Mallory-Weiss tears. PATIENTS AND METHODS: We retrospectively analyzed twelve cases of iatrogenic Mallory-Weiss tears identified from 2,461 consecutive upper gastrointestinal endoscopies performed at our institution over a period of twenty-two months. RESULTS: In all cases, bleeding stopped spontaneously without the need of blood transfusions, endoscopic hemostasis therapy or any other interventions. Eight patients (67%) had retching or struggling during the procedure. Hiatus hernias were noted in three patients (25%). CONCLUSIONS: Iatrogenic Mallory-Weiss tears are rare and generally have a benign course. They tend to occur mostly in patients who have experienced excessive retching or struggling during endoscopy.

Adult↗

Phosphatidylethanolamine methylation and hepatoma cell growth.

Phosphatidylethanolamine is converted to phosphatidylcholine in hepatocytes via the enzyme phosphatidylethanolamine N-methyltransferase (PEMT). An isoform, PEMT2 has been cloned, expressed and localized to a mitochondria-associated membrane in rat liver. Expression of PEMT2 caused a decreased rate of cell division of cultured rat hepatoma cells. Mechanistic studies suggest that the slower growth of transfected hepatoma cells may be due to down regulation of CTP: phosphocholine cytidylyltransferase and the CDP-choline pathway for phosphatidylcholine biosynthesis. A role for PEMT2 in the regulation of hepatocyte cell division is also indicated by PEMT2 down-regulation in regenerating rat liver.

Animals↗

An investigation of the relationship between low back pain and lumbar posteroanterior stiffness.

OBJECTIVE: To investigate the relationship between low back pain (LBP) and lumbar posteroanterior (PA) stiffness. DESIGN: A repeated-measures design was used to measure lumbar posteroanterior stiffness on two occasions in subjects with and without LBP. SUBJECTS: Twenty-five subjects with acute or subacute LBP and twenty-five pain-free subjects participated. Pain subjects reported pain on the application of a manual PA force to the lumbar spine and had no contraindication to PA stiffness testing. Pain-free subjects reported no history of LBP requiring treatment, and obtained a score of 0 on the McGill Pain Questionnaire. METHODS: PA stiffness was measured in subjects with LBP when (a) they first presented with pain and (b) when pain had resolved by more than 80%. Pain-free subjects, matched with pain subjects on gender, age, vertebral level to be tested and time between tests, were also measured on two occasions, to control for the effects of repeated stiffness testing and the passing of time. RESULTS: In subjects with low back pain stiffness decreased by 1.21 N/mm between test 1 and test 2. A paired t test found a significant difference between the tests (t = 3.04, df = 24, p = .006). In subjects without pain, there was an increase in stiffness of 0.74 N/mm between test 1 and test 2; a paired t test found no significant difference between the tests (t = -1.673, df = 24, p = .107). CONCLUSIONS: Subjects with LBP showed increased PA stiffness compared with when they had little or no pain, whereas pain-free subjects showed unchanged PA stiffness over time.

Adult↗

Normal response to large posteroanterior lumbar loads--a case study approach.

OBJECTIVE: Characterization of the responses to spinal posteroanterior loading has involved measuring the gradient of the linear region of the force-displacement relationship between 30 N and 100 N of applied force. However, forces applied during manual assessment of stiffness may reach 300 N. This study investigated whether the force-displacement relation remains linear above 100 N. DESIGN: A single-case-study design with replication was used. SUBJECTS: Two male subjects, with no history of low back pain requiring treatment over the preceding twelve months, participated in this study. METHODS: Posteroanterior loads of 275 N were applied to the 1.3 vertebra of both subjects using a mechanical device. The force-displacement responses in these subjects were measured and analyzed to examine the linearity of the data. RESULTS: The responses from the two subjects were similar. In both cases, the responses were approximately linear at all levels of load up to 275 N. Because of the small degree of nonlinearity, there was a tendency for the stiffness to show moderate increases as the load increased. Stiffness was approximately 25% greater when calculated between 30 N and 275 N than when calculated between 30 N and 100 N. CONCLUSION: In these two subjects, the force-displacement relation was approximately linear for all three force intervals considered, although there was some increasing stiffness with increasing force.

Adult↗

The effects of high and low loading forces on measured values of lumbar stiffness.

OBJECTIVE: One explanation for the poor reliability of manual judgments of posteroanterior (PA) stiffness may be that if manual therapists use different forces when testing, different stiffness is perceived. This study was conducted to examine measurements of lumbar PA stiffness obtained using a device programmed to generate different loading forces. SUBJECTS: Twenty-five subjects with no history of low back pain and a mean age of 23.5 yr were measured. METHODS: Measures of lumbar PA stiffness were obtained using a mechanical device that applied a testing force of 200 N to the skin overlying the L3 spinous process. Six stiffness coefficients were determined from the force/displacement curve obtained from each subject by performing linear regressions from 30-80 N, 30-150 N, 30-200 N, and from 30-83.3 N, 83.3-136.7 N, and 136.7-200 N. Intraclass correlation coefficients and repeated measures analysis of variance were used to analyze the data. RESULTS: Although moderate reliability [ICC 2,1 = 0.67] was found for stiffness measures arising from increasingly wide force-interval regressions (30-80 N, 30-150 N, 300-200 N), poor reliability [ICC (2,1) = 0.39] was found for stiffness measures arising from same-width, higher force regressions (30-83.3 N, 83-137 N, 137-200 N). In both cases there were significant differences between the obtained K stiffness values corresponding to different force intervals. CONCLUSION: These results show that if therapists push harder, different stiffnesses will be felt. Studies using instrumental measurement of spinal stiffness to obtain 'K' values should report the force intervals used. Also, revised protocols for manually judging PA stiffness should ensure that stiffness is assessed by sampling specified force intervals rather than the raters determining their own force limits.

Adult↗

Momordins inhibit both AP-1 function and cell proliferation.

The activation of Jun/Fos is a crucial factor in transmitting the tumor promoting signal from the extracellular environment to nuclear transcription machinery. One of the final steps in signal transduction is the binding of Jun/Fos to the AP-1 site in order to express gene transcription. Utilizing this concept, we screened about 100 extracts of natural plants to search for a Jun-Fos function inhibitor. The methanol extract of Ampelopsis radix reduced Jun/Foc retardation remarkably. The active principles of the extract were isolated and purified by repeated column chromatography and their structures were identified as oleanolic acid glycosides known as momordin I, Id, and Ie. These compounds reduced the Jun/Fos-DNA interaction and their activities were quantitated with liquid scintillation counting of corresponding bands. Among them, momordin I had the strongest inhibitory activity, with an IC50 value of 22.8 micrograms/ml. The methanol extract and momordin I, Id and Ie also showed cell cytotoxicity against human cancer cell lines. As expected from a gel shift assay, momordin I showed the strongest cytotoxicity and its IC50 value was from 7.280 micrograms/ml to 16.05 micrograms/ml depending on the cell line. With these data, it may be concluded that the mechanism of anticancer activity of momordin I comes from its inhibitory effect on the protein-DNA interaction. The in vivo test was done only with the methanol extract. The extract showed measurable anticancer activity against murine colon cancer. The wet tumor weight reduction rate was 17.73% at 90 mg/kg dose. We suggest that the Jun/Fos-DNA interaction results in cell cytotoxicity.

Cell Division↗