Tritium partitioning and isotope effects in adenosylcobalamin-dependent glutamate mutase.

Tritiated adenosylcobalamin, labeled at the exchangeable position, has been used to investigate the partitioning of tritium between substrate and product in the reaction catalyzed by glutamate mutase. The isotope partitions between glutamate and methylaspartate in nearly 1:1 ratio, regardless of the direction in which the overall reaction is proceeding. This is consistent with a free-energy profile in which the interconversion of the intermediate glutamyl and methylaspartyl radicals is rapid relative to the transfer of tritium from 5'-deoxyadenosine to either substrate or product. Initial velocity measurements have been used to measure the tritium isotope effects for the transfer of tritium from adenosylcobalamin to product in each direction. The isotope effect is 21 for the formation of glutamate and 19 for the formation of methylasparate. The large magnitude of these isotope effects makes it likely that the rate-determining step may be altered by the substitution of tritium for hydrogen in the reaction. The results of these experiments are compared with previous isotope effect measurements made on other adenosylcobalamin-dependent enzymes.

Bullatacin, a potent antitumor annonaceous acetogenin, inhibits proliferation of human hepatocarcinoma cell line 2.2.15 by apoptosis induction.

Bullatacin, isolated from the fruit of Annona atemoya, is one of the most potentially effective antitumor annonaceous acetogenins. Bullatacin was studied here for its ability to inhibit the proliferation of 2.2.15 cells, hepatitis B virus (HBV) DNA transfected human hepatocarcinoma cell line. It was found that bullatacin induced cytotoxicity of 2.2.15 cells in a time- and dose-dependent manner. Fifty percent effective dose (ED50) on day 1 of exposure to bullatacin were 7.8 +/- 2.5 nM for 2.2.15 cells. [3H]-Thymidine incorporation assays showed almost the same results. Bullatacin-treatment also reduced concentrations of hepatitis B surface antigen (HBsAg) in the cultured medium released from 2.2.15 cells, coincident with the decrease in the cell proliferation. Analysis of mophological changes of bullatacin-treated 2.2.15 by inverted phase-contrast microscope and eletron microscopy revealed a possible model of action for bullatacin to inhibit proliferation of 2.2.15 cells by inducing apoptosis. Most of the bullatacin-induced cell death was found to be due to apoptosis, as determined by double staining with fluorescein-isothiocyanate (FITC)-labeled annexin V and propidium iodide (PI).

Dome corrective osteotomy for cubitus varus deformity.

Between 1994 and 1998, 15 patients had corrective dome-shaped osteotomy of the humerus for posttraumatic cubitus varus deformity. Thirteen patients had surgery before puberty and two patients had surgery after puberty. In the prepuberty group, all the osteotomies were done by a posterior approach with triceps muscle splitting, and cross pins were used to fix the osteotomy. In the postpuberty group, the osteotomies were done by a posterior approach with olecranon osteotomy, and reconstructive plates were used for fixation. The average followup was 2 years and 4 months. Preoperative carrying angle ranged from 19 degrees to 31 degrees varus (average, 26.2 degrees) and postoperative carrying angle ranged from 7 degrees to 15 degrees valgus (average, 10.7 degrees). No loss of correction was observed and all osteotomies united. The preoperative and postoperative differences of the lateral condylar prominence index ranged from -67% to +6% (average, -30.1%). After reviewing these cases, a dome-shaped osteotomy was found to have the following advantages for correction of cubitus varus deformity: the osteotomy site is more stable than a lateral closing wedge osteotomy for maintaining the correction obtained; the domed osteotomy avoids having the lateral condyle becoming prominent; and the posterior scar is more cosmetically acceptable than the lateral scar in the lateral closing wedge osteotomy.

The normal width of anterior hip synovial recess in children.

To establish the diagnostic criteria for hip joint effusion, the normal width of the anterior hip synovial recess in children and the difference between both hips of the same child were examined in this study. Eight kindergarten schools were randomly selected for study in Kaohsiung City. The width of anterior hip synovial recess of 1,568 hips in 784 children (421 boys, 363 girls) was measured by ultrasound scanner with 7.5-MHz linear probe. The age of children ranged from 2.5 to 6.6 years old. During measurement, the children were put in supine position with hips and knees in extension and patella facing up. The results revealed that the mean width of the anterior synovial recess was 7.29+/-1.15 mm. Linear correlation of the width of synovial recess to age and height was disclosed and expressed as follows: width (millimeters) equal to 6.52+0.013x age (months), or width (millimeters) equal to 3.97+0.030x height (centimeters). The mean difference between both hips of the same child was 0.611+/-0.523 mm, and the difference was independent from the factors of age, gender, height, or weight (p>0.05). Ninety-five percent of the differences should be < or =1.46 mm, so that if the difference between hips is >1.46 mm, hip joint effusion should be suspected.

The influence of the gap size on the interfacial union between the bone and the tendon.

An in-vivo model of New Zealand white rabbit was used to study the influence of gap size on the interfacial union between bone and tendon through histological observation and mechanical testing. In the model, the anterior cruciate ligament (ACL) was cut and reconstructed by autografted semitendinosus tendon (with average diameter of 1.48 mm +/- 0.12 mm). Mechanical testing of the interfacial healing tissue was done on the 15th post-operative day. At that time the mean maximal tensile strength was 2.511 +/- 0.293 kg to a bone tunnel size of 1.5 mm. The maximal tensile strength lowered to 1.853 +/- 0.563 kg to a bone tunnel size of 1.8 mm. The maximal tensile strength lowered to 1.302 +/- 0.657 kg to a bone tunnel size of 2.0 mm. Using a paired-t test, the gap size was found to have great influence on the tensile strength of the interfacial healing tissue (p < 0.05). The histological study showed that the interfacial gap was connected by the new growing collagen fibers. The healing tissue appeared much denser and much more maturated and organized in the smaller interfacial gap in comparison with specimens with a larger gap so that it can tolerate higher tensile strength. From this study, we concluded that the gap size really plays an important role in the process of maturation and organization of interfacial healing tissue. Furthermore, we recommend that in order to achieve greater anchoring strength of the grafted tendons, the bone tunnel should be made with approximately the same diameter of grafted tendon.

Clinical application of ultrasonography for detection of septic arthritis in children.

For early detection of the effusion of infected joint, 40 children were examined by ultrasound scanner for suspected septic arthritis. Thirty-one patients were found with joint effusion, and the needle aspirations of these 31 joints confirmed septic arthritis in 22 patients. In 3 patients, in addition to the joint effusion, the joint surrounding subperiosteal abscess and cortical erosion also were found on sonography, resulting in a diagnosis of concurrent osteomyelitis. In two patients, sonography confirmed only soft tissue swelling and abscess formation on the buttock, but without hip joint effusion. These findings excluded the diagnosis of septic arthritis and helped us obviate the unnecessary attempts at joint aspiration. In one patient, sonography revealed only flexor tenosynovitis without wrist joint effusion. This case was later treated by tenosynovectomy rather than wrist arthrotomy and the pathological examination showed to be a tuberculous tenosynovitis. From the preliminary results, we find ultrasonography has the following advantages for the diagnosis of septic arthritis: 1.) ultrasonography is very sensitive in detecting the joint effusion of septic arthritis; 2.) ultrasonography can clearly define the pathological extent of septic arthritis and help clinicians to treat the concurrent osteomyelitis by appropriate surgical debridement; and 3.) ultrasonography can differentiate soft tissue abscess or tenosynovitis from septic arthritis and help clinicians obviate unnecessary needle joint aspiration.

Pre-steady-state kinetic investigation of intermediates in the reaction catalyzed by adenosylcobalamin-dependent glutamate mutase.

Glutamate mutase catalyzes the reversible isomerization of L-glutamate to L-threo-3-methylaspartate. Rapid quench experiments have been performed to measure apparent rate constants for several chemical steps in the reaction. The formation of substrate radicals when the enzyme was reacted with either glutamate or methylaspartate was examined by measuring the rate at which 5'-deoxyadenosine was formed, and shown to be sufficiently fast for this step to be kinetically competent. Furthermore, the apparent rate constant for 5'-deoxyadenosine formation was very similar to that measured previously for cleavage of the cobalt-carbon bond of adenosylcobalamin by the enzyme, providing further support for a mechanism in which homolysis of the coenzyme is coupled to hydrogen abstraction from the substrate. The pre-steady-state rates of methylaspartate and glutamate formation were also investigated. No burst phase was observed with either substrate, indicating that product release does not limit the rate of catalysis in either direction. For the conversion of glutamate to methylaspartate, a single chemical step appeared to dominate the overall rate, whereas in the reverse direction a lag phase was observed, suggesting the accumulation of an intermediate, tentatively ascribed to glycyl radical and acrylate. The rates of formation and decay of this intermediate were also sufficiently rapid for it to be kinetically competent. When combined with information from previous mechanistic studies, these results allow a qualitative free energy profile to constructed for the reaction catalyzed by glutamate mutase.

[A study of multiple factors related to Enterobius vermicularis infection among pre-school children in Ta-Liao district of Kaohsiung County].

In order to study the factors related to Enterobius vermicularis infection among pre-school children in Ta-Liao District of Kaohsiung County, a questionnaire was designed to interview parents of preschool children selected by random sampling from 7 kindergartens in Ta-Liao District. Enterobius infections in the children were then examined by using two-consecutive-day adhesive cellophane paper perianal swabs. The effective sample numbered 555 children. Variables causing the infection among infected and non-infected children were analyzed by chi-square test and point-biserial correlation. The results indicated that there were significant relationship between infection and the follow items: having snacks; sucking fingers; size of house; ways of cleaning house; place of activities; parent's cognizing that anus is the polluted source of eggs; recognition of the cause-and-effect relationship between eating in the bedroom and being reinfected with Enterobius; recognition of preventing reinfection of Enterobius by taking a shower; and educational background of father. Through logistic regression analysis with backward selection, the authors constructed a predicting model which can predict the infection rate of E. vermicularis among pre-school children according to the habit of having snacks, the habit of sucking fingers, size of house, parent's recognizing that taking a shower can prevent people from reinfection, and the educational background of father.

Anti-inflammatory activity of Taiwan folk medicine "ham-hong-chho" in rats.

"Ham-Hong-Chho" is a folk medicine in Taiwan, derived from the entire plants of Bidens pilosa L. var. minor (Blume) Sherff (Compositae), B. pilosa L. and B. chilensis DC. The anti-inflammatory effect of aqueous extracts of the three plants against paw edema induced by carrageenan and chronic arthritis induced by complete Freund's adjuvant were determined in rats. The results indicated that paw edema induced by carrageenan was significantly decreased by treatment with aqueous extracts (150 or 300 mg/kg) of all three plants (p < 0.05) and that the effect of Bidens pilosa var. minor was the most potent. However, only extracts (500 mg/kg) of B. pilosa L. var. minor and B. pilosa L. significantly decreased the paw edema induced by complete Freund's adjuvant (p < 0.05).