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Biomedical subjects

M F Lee

Publications and source records attributed to M F Lee.

33 records · Page 2Linked to original sources
PubMed1993

Isolation and in vitro translation of messenger RNA from the American cockroach.

Total RNA was extracted from the whole body of American cockroach (Periplaneta americana) using chaotropic salt guanidine isothiocyanate in the presence of 2-mercaptoethanol (2-ME). Polyadenylated mRNA was isolated by oligothymidylic acid-cellulose chromatography and mRNA was translated using a rabbit reticulocyte lysate system. The translation, as judged by the incorporation of 35S-methionine, was obtained with poly(A)+ RNA, where an approximately 9.5-fold increase in label incorporation over control was achieved. Analysis of translation products by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) in combination with autoradiography showed that many proteins with apparent molecular weights ranging from 12 to 200 kD were synthesized, and no labelled proteins were found with negative RNA control and poly(A)- RNA. Immunoprecipitation studies performed using polyclonal and monoclonal antibodies revealed that synthesized proteins of MW 90, 78, 72, 49, 45, and 26 kD corresponded with previously identified principal and major allergens of American cockroach from our laboratory. In addition, the allergenicity of the translation mixtures was also confirmed by fluoroallergosorbent test (FAST) inhibition studies with IgE antibodies of human reaginic serum pool.

Allergens↗
PubMed1990

Etiology and treatment of post-cesarean-section endometritis after cephalosporin prophylaxis.

To describe the microbiologic etiology of post-cesarean endometritis developing after perioperative cephalosporin prophylaxis, endometrial samples were obtained from 27 women with a triple-lumen catheter. The women were assigned in a double-blind, randomized fashion to receive either ticarcillin/clavulanate, 3.1 g, or cefoxitin, 2 g, administered every six hours, until the clinical signs of infection resolved. A total of 149 microorganisms (84 facultative and 65 obligate anaerobes) were recovered from 26 women, for a mean of 5.5 isolates per specimen. One endometrial specimen was sterile. Bacteroides and Peptostreptococcus species were the most frequent isolates, followed by Gardnerella vaginalis, Enterococcus, facultative gram-negative rods and Mycoplasma hominis. Each of the isolates was tested for beta-lactamase activity. At least one beta-lactamase-producing isolate was recovered from 56% of the specimens. Susceptibility testing of endometrial isolates demonstrated that 96% of 118 potential pathogens (Gardnerella, Bacteroides, Peptostreptococcus, enterococci and streptococci) were susceptible to ticarcillin/clavulanate. By comparison, 86% of these isolates were susceptible to cefoxitin in vitro. Women who were treated with ticarcillin/clavulanate were less likely to have a temperature greater than 38 degrees C for two or more days (8% vs. 57%, P = .01). Also, there was a trend toward a decreased duration of uterine tenderness in the ticarcillin/clavulanate group, but it did not attain statistical significance (60% vs. 86%, P = .4). However, the overall clinical success rate with these single-agent treatments was not different for the two groups (77% vs. 79%, P = 1.0).(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Infections↗
PubMed1989

Ca2+-mediated activation of human erythrocyte membrane Ca2+-ATPase.

Ca2+-ATPase of human erythrocyte membranes, after being washed to remove Ca2+ after incubation with the ion, was found to be activated. Stimulation of the ATPase was related neither to fluidity change nor to cytoskeletal degradation of the membranes mediated by Ca2+. Activation of the transport enzyme was also unaffected by detergent treatment of the membrane, but was suppressed when leupeptin was included during incubation of the membranes with Ca2+. Stimulation of the ATPase by a membrane-associated Ca2+-dependent proteinase was thus suggested. Much less 138 kDa Ca2+-ATPase protein could be harvested from a Triton extract of membranes incubated with Ca2+ than without Ca2+. Activity of the activated enzyme could not be further elevated by exogenous calpain, even after treatment of the membranes with glycodeoxycholate. There was also an overlap in the effect of calmodulin and the Ca2+-mediated stimulation of membrane Ca2+-ATPase. While Km(ATP) of the stimulated ATPase remained unchanged, a significant drop in the free-Ca2+ concentration for half-maximal activation of the enzyme was observed.

Calcium↗
PubMed1986

A comparison of CNS angiotensin II binding in the hypothalamus-thalamus-septum-midbrain region of developing spontaneously hypertensive and normotensive rats.

Specific angiotensin II (ANG II) binding was studied in brain homogenates from the hypothalamus-thalamus-septum-midbrain (HTSM) region of age-matched 4-, 8-, 12- and 16-week spontaneously hypertensive rats (SHR) and their normotensive controls, Wistar-Kyoto (WKY) rats, using 125I-angiotensin II. Scatchard analysis revealed that the dissociation constants (Kd) ranged from 0.36 to 0.73 nmol/l, although these values were not significantly different at any given age period between the SHR and WKY rats. In contrast, a statistically significant increase in ANG II receptor binding was seen between the SHR and WKY rat at 4 weeks of age. However, this difference was not observed at older age periods. Furthermore, both the SHR and WKY rat showed a decrease in ANG II receptor levels during development, with the most marked reductions occurring between 12 and 16 weeks of age for both strains. These findings suggest that ANG II receptors in the HTSM region of both the SHR and WKY rat are down-regulated during development, that receptor loss is more significant in the SHR than in its normotensive control and that binding capacity differences between the two strains are only seen before the onset of measureable increases in the arterial pressure of the SHR. We conclude that there is a significant difference in the ANG II binding capacity during the development of hypertension in the SHR as compared with the WKY rat and therefore it may play a role in the pathogenesis of this disorder.

Angiotensin II↗
PubMed1985

Effects of guanyl nucleotides and ions on kappa opioid binding.

Displacement curve analyses demonstrated that GTP and its nonhydrolyzable analog, GPP(NH)P, inhibited the binding of [3H]dihydromorphine (mu agonist), [3H]D-Ala2-D-Leu5-enkephalin (delta agonist), and [3H]ethylketocyclazocine (general agonist) but not [3H]diprenorphine (general antagonist). Using a paradigm to block mu and delta sites with specific cold ligands, [3H]ethylketocyclazocine labeled kappa sites which were less GTP sensitive than sites labeled by mu and delta agonists. Further, Na+ and Mg++, important in inhibitory adenylate cyclase systems, also decreased both unblocked and mu-/delta-blocked [3H]ethylketocyclazocine binding. Scatchard analyses revealed that the inhibitory effects of GTP result in a decrease in affinity without a significant change in binding capacity, and that the kappa component of [3H]ethylketocyclazocine binding was less sensitive to the effects of GTP than binding sites labeled by mu or delta agonists. In comparison to the effects of GTP, Na+ decreased binding affinity but increased the binding capacity of the kappa component. These data also suggest that the inhibitory effects of Na+ and GTP on binding affinity are not additive. Association and dissociation plots revealed that although both components of binding may be involved in these affinity changes, the dissociation rate represents the more significant factor. These data suggest that [3H]ethylketocyclazocine binding to kappa sites is GTP and Na+ sensitive. However, it should be noted that [3H]ethylketocyclazocine binding to kappa sites is less sensitive to GTP than its binding to other opiate sites, and that this kappa binding is differentially affected by Na+. The significance of these characteristics with regard to the effect of kappa opiates on adenylate cyclase activity remains to be determined.

Animals↗
PubMedDate not supplied

Tarsal tunnel syndrome caused by talocalcaneal coalition.

Tarsal tunnel syndrome caused by talocalcaneal coalition is uncommon. We presented the ultrasonography (US) and magnetic resonance imaging findings of this disease. This is, to our knowledge, the first case report describing the US findings in tarsal tunnel syndrome caused by talocalcaneal coalition.

Female↗
PubMedDate not supplied

Comparison of polymerase chain reaction, monoclonal antibody based enzyme immunoassay, and cell culture for detection of Chlamydia trachomatis in genital specimens.

An enzyme immunoassay (EIA; AntigEnz Chlamydia; Northumbria Biologicals, Northumberland, United Kingdom) and a polymerase chain reaction (PCR) assay (Genemed Biotechnologies, San Francisco, CA) were evaluated for the detection of Chlamydia trachomatis in urogenital specimens. Of 324 specimens, 23 were positive by cycloheximide-treated McCoy's cell culture method. Of 23 culture-positive specimens, 20 and 22 were found to be positive by EIA and PCR, respectively. Among 301 culture-negative samples, 4 were found to be positive by both PCR and EIA, 2 were PCR-positive and EIA-negative, and 3 PCR-negative and culture-negative specimens were found to be positive by EIA. In comparing nonculture methods with cell culture technique, combined sensitivities of 87.0% (90.9% in men and 83.3% in women) and 95.6% (90.9% in men and 100% in women), and specificities of 97.7% (99.4% in men and 95.7% in women) and 98.0% (99.4% in men and 96.5% in women) are achieved by EIA and PCR, respectively. The PCR proved to be the more sensitive of these two nonculture methods, and it can be used for the rapid diagnosis of C. trachomatis urogenital infection.

Antibodies, Monoclonal↗
PubMedDate not supplied

Detection of human papillomavirus types in cervical lesions of patients from Taiwan by the polymerase chain reaction.

BACKGROUND AND OBJECTIVES: The association of human papillomavirus (HPV) infection with cervical carcinoma is well documented. The HPV types in cervical lesions of patients from Taiwan are analyzed by the polymerase chain reaction (PCR). STUDY DESIGN: DNA was extracted from paraffin-embedded, formalin-fixed tissues using a sonication method. PCR was performed using type-specific primers for the presence of HPV types 6, 11, 16, 18, 31, and 33 DNA. Amplified product was subjected to gel electrophoresis and Southern blot hybridization analysis. RESULTS: A total of 129 cervical lesions and normal cervical biopsies were examined. Histologic examination revealed a spectrum of lesions, which were classified as condyloma acuminata (AC), condyloma (CL), koilocytosis (KL), various grades of cervical intraepithelial neoplasia (CIN I, II, and III), carcinoma in situ (CIS), and invasive carcinoma (ICa). Of 114 cervical lesions, 65% (26 of 40) of AC; 61% (11 of 18) of CL; 20% (2 of 10) of KL; 25% (1 of 4) of CIN I; 69% (9 of 13) of CIN II; 80% (12 of 15) of CIN III; 83% (5 of 6) of CIS; and 100% (8 of 8) of ICa were positive for at least one type of HPV by the PCR. Among the 74 HPV-positive specimens, 19 (26%) were detected with multiple types. HPV DNA was detected in the cervical biopsies of 1 of 15 (6.7%) normal individuals. CONCLUSION: Excluding AC, HPV 6 and/or 11 (HPV 6/11), HPV 16 and/or 18 (HPV 16/18), and HPV 31 and/or 33 (HPV 31/33) were detected in 40% (19 of 48), 71% (34 of 48), and 12% (6 of 48) of neoplastic lesions of patients from Taiwan respectively. These findings are compatible with those reported by others worldwide.

Base Sequence↗
PubMedDate not supplied

Effect of lipid peroxidation on beating frequency of human sperm tail.

The tail beat frequency (TBF) of sperm was measured with a sperm-head fixation method which was based on the tendency of sperm to attach its head to the surface of a glass slide. Ferrous sulphate, a promotor of lipid peroxidation, inhibited TBF within 5 min of mixing with sperm. This inhibition can be reversed dose-dependently by superoxide dismutase, catalase, glutathione, and albumin. It was concluded that TBF could be a new pharmacological model for studying the effect of lipid peroxidation and antioxidant on sperm motility. Both enzymatic and non-enzymatic antioxidants can be screened with this method.

Catalase↗
PubMedDate not supplied

Practical considerations in acquiring biological signals from confocal microscope: solvent effect and temperature effect.

Fluorescence microscopic imaging (FMI) is one of the fastest growing and most powerful techniques to study cellular activities in a living single cell. FMI has been widely used to monitor the temporal and spatial changes of many important intracellular messengers such as Ca2+, H+ and cAMP. In the course of our study of cellular responses with confocal scanning fluorescence microscopy, we detected two sources of artifacts which may render experimental observations invalid. First, the water content of the DMSO used could affect the efficiency of loading of the fluorescence indicator into cells and also give rise to spurious fluorescence spots. Secondly, apparently spontaneous temperature-dependent oscillations of BCECF fluorescence and cellular pulsations were recorded in cells which might be misinterpreted as natural rhythmic behavior. These were later shown to be artifacts arising from changes in refractive indices of the immersion oil due to small fluctuations in temperature, which in turn leads to random shifts of the focal plane erroneously manifest as signal oscillations. Based on these observations, certain recommendations for the control and elimination of false images are presented.

Animals↗
PubMedDate not supplied

Tail beat frequency of human sperm: evaluated with sperm head fixation method and computer-assisted semen analysis.

Tail beat frequency (TBF) of individual sperm in 15 semen samples was evaluated with a sperm head fixation method (SHFM). Motility parameters of the semen samples were also measured with computer-assisted semen analysis (CASA). The TBF obtained from SHFM correlated best with beat cross-frequency obtained from CASA. The TBF measured soon after sperm head fixation also correlated well with total motility and rapid motility, but not with progress motility and critical motility measured with CASA. SHFM is a simple method for the study of tail beat frequency and the TBF of individual sperm is closely related to the overall motility in a semen sample.

Computers↗