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Biomedical subjects

E C Yang

Publications and source records attributed to E C Yang.

13 recordsLinked to original sources
PubMed2004

Quantum superposition of high spin states in the single molecule magnet Ni4.

Quantum tunneling of the magnetization in a single molecule magnet has been studied in experiments that combine microwave spectroscopy with high sensitivity magnetic measurements. By monitoring spin-state populations in the presence of microwave radiation, the energy splittings between low lying superpositions of high-spin states of single molecule magnet Ni4 (S=4) have been measured. Absorption linewidths give an upper bound on the rate of decoherence. Pulsed microwave experiments provide a measure of energy relaxation time, which is found to increase with frequency.

Journal Article↗
PubMed2001

Retinal regionalization and heterogeneity of butterfly eyes.

The regional characteristics of the eyes of butterflies from different families have been surveyed using epi-illumination microscopy, utilizing the eyeshine visible due to the tapetum situated proximally to the rhabdom. All butterflies studied have a high spatial acuity in the frontal region. The facet diameter varies slightly across the eye, and the interommatidial angle and the eye parameter p are especially large dorsally. Whereas the ommatidial lattice is generally highly regular, the eyeshine colours distinctly depend on the species. Sometimes the eyeshine is locally uniform, but often it is heterogeneous. It is hypothesized that the regional characteristics as well as the local heterogeneity are adaptations that optimize spectral discrimination.

Animals↗
PubMed2000

Initial treatment of traumatic hip dislocations in the adult.

The initial treatment of traumatic hip dislocations is critical to successful treatment of this injury. It generally is agreed that prompt reduction with the patient under anesthesia or sedation is required. Delay in reduction of posterior hip dislocations is associated with avascular necrosis of the hip. Occasionally the hip dislocation will be irreducible. Various methods to reduce hip dislocations have been described in the literature. The superiority of one particular technique has not been shown and the choice of reduction maneuver must be tailored to the condition of the patient. Traumatic hip dislocations often are associated with multiple injuries that may limit the options available for initial treatment of the hip dislocation. Adherence to general principles of skeletal reduction will increase the ease of reduction and decrease the risk of iatrogenic injury during reduction. Additional clinical and radiographic evaluation of the hip that was reduced often is necessary to determine whether subsequent open treatment is required.

Adult↗
PubMed1999

Glycosylation of fluoroquinolones through direct and oxygenated polymethylene linkages as a sugar-mediated active transport system for antimicrobials.

We report herein the synthesis and biological testing of several glycosylated derivatives of some fluoroquinolone antibiotics. In particular, we have prepared several glycosylated derivatives of ciprofloxacin (2) in which the carbohydrate units are linked to the free secondary amine of the piperazine unit by: (a) no linker (e.g., a glycosylamine), (b) a beta-oxyethyl linker, and (c) a gamma-oxypropyl linker. Both glucose and galactose were used as carbohydrates so that six compounds of this type were prepared, e.g., no linker 4a,b, oxyethyl linker 5a,b, and oxypropyl linker 6a,b. In addition the aryl glycosides of glucose and galactose (7a,b) were prepared from the active 1-(4-hydroxyphenyl)fluoroquinolone (3.) The syntheses of the glycosylamines 4a,b involved the direct condensation of glucose and galactose with the hydrochloride salt of ciprofloxacin (2). For the oxyalkyl-linked compounds, we first prepared the peracetylated omega-bromoalkyl glycopyranosides 14a,b and 15a,b and then coupled them to the allyl ester of ciprofloxacin (11) to give, after saponification to remove all of the esters, the desired fluoroquinolone carbohydrates 5a,b and 6a,b. The final series was prepared from 2,4,5-trifluorobenzoyl chloride (22) which gave 3 in four precedented steps. Coupling of 3 with the peracetylated glucosyl and galactosyl halides 12a,b and 26 afforded, after saponification, the desired aryl glycosides 7a,b. Six of these derivatives of ciprofloxacin-4a,b, 5a,b, and 6a,b-were subjected to microbiological screening. Of the six, compound 6a showed the highest activity. Since 6a would give the hydroxypropyl-substituted ciprofloxacin on hydrolysis and its activity is approximately 4-8 times less than that of ciprofloxacin (2), this implies that compound 6a is probably being actively transported. Thus preliminary results suggest that some of the compounds are stable in culture conditions and may be differentially transported by multiple resistant organisms. In some cases, the addition of a linker and a carbohydrate to ciprofloxacin lessens, but does not eliminate, antimicrobial activity.

Anti-Infective Agents↗
PubMed1997

Treatment of type II and type III open tibia fractures in children.

OBJECTIVES: To determine whether severe open tibial fractures in children behave like similar fractures in adults. DESIGN AND SETTING: A combined retrospective and prospective review evaluated treatment protocol for type II and type III open tibial fractures in children over a ten-year period from 1984 to 1993. PATIENTS: Twenty-three fractures were studied in children aged 3.5 to 14.5 (18 boys and 5 girls). There were six type II, eight type IIIA, and nine type IIIB fractures. Type I fractures were not included. Seven fractures were comminuted with significant butterfly fragments or segmental patterns. INTERVENTION: Treatment consisted of adequate debridement of soft tissues, closure of dead space, and stabilization with external fixation. Bone debridement only included contaminated devitalized bone or devitalized bone without soft tissue coverage. Bone that could be covered despite periosteal stripping was preserved. MAIN OUTCOME MEASUREMENTS: Clinical and roentgenographic examinations were used to determine time to union. RESULTS: All fractures in this series healed between eight and twenty-six weeks. Wound coverage included two flaps, three skin grafts, and two delayed primary closures. No bone grafts were required. There were no deep infections, growth arrests, or malunions. Follow-up has ranged from six months to four years. CONCLUSIONS: Open tibia fractures in children differ from similar fractures in adults in the following ways: soft tissues have excellent healing capacity, devitalized bone that is not contaminated or exposed can be saved and will become incorporated, and external fixation can be maintained until the fracture has healed. Periosteum in young children can form bone even in the face of bone loss.

Child↗
PubMed1996

The use of an anterior incision of the meniscus for exposure of tibial plateau fractures requiring open reduction and internal fixation.

The purpose of this study was to examine the use of an anterior incision of the meniscus for exposure of tibial plateau fractures. We studied 27 fractures of the proximal tibia treated with open reduction and internal fixation (ORIF). There were nine unicondylar fractures (five A-O B2; four A-O B3) fixed with plates and screws and 18 bicondylar fractures (seven A-O C1; five A-O C2; six A-O C3) fixed with combination internal and external fixation. Length of follow-up averaged 26 months. All patients were treated with an anterior incision of the meniscus and retraction with the condyle. Of the 18 bicondylar fractures, nine severely displaced fractures were found to have peripherally detached menisci. Unicondylar fractures did not display this finding. After fixation, menisci were repaired at the periphery and sewn to the original anterior insertion. The repair begins posteriorly and advances the cartilage to ensure anatomic placement. There were four medial and 23 lateral menisci in this series. Ten patients underwent knee arthroscopy 6 months to 2 years post-ORIF as a routine procedure during hardware removal. All menisci were found to be healed to the periphery and were stable. There were no gross tears. In one patient, the anterior meniscal incision could be visualized. No patients developed mechanical symptoms either in postoperative rehabilitation or postoperative follow-up at a maximum of 6 years. All patients had > 125 degrees of motion. Less motion when compared with the normal knee was felt to be related to more complex fracture patterns. In conclusion, the anterior meniscal incision allows for excellent exposure of severe proximal tibia fractures. This technique allows for anatomic meniscal repair and early rehabilitation. Arthroscopic examination confirms peripheral meniscal healing. No patient experienced clinical symptoms of meniscal pathology.

Anterior Cruciate Ligament Injuries↗
PubMed1995

Gunshot wounds to the forearm.

The rising incidence of civilian gunshot wounds has been well documented. Approximately 4% to 20% of these wounds consist of injuries to the forearm. An organized approach to the treatment of these injuries should be used to obtain an optimal result. Factors to be considered in treatment include the type of weapon and bullet involved, the neurovascular status of the patient, the possibility of compartment syndrome, the presence and type of fracture, and soft-tissue injury.

Algorithms↗
PubMed1995

Metaphyseal dissociation fractures of the proximal tibia. An analysis of treatment and complications.

A study was done of 44 metaphyseal dissociation fractures of the proximal tibia in 42 patients (27 men and 15 women, aged 22 to 77 years; mean, 42 years). Follow-up ranged from 6 months to 4 years. There were 2 study groups: a retrospective group (group 1, 22 fractures) given a variety of treatments ranging from casts to dual plates, and a prospective group (group 2, 22 fractures) treated by combining external fixation and optional minimal internal fixation. There were 12 comminuted fractures in group 1 and 20 in group 2 (P < 0.01). All fractures eventually healed, with an average healing time in group 1 of 3.8 months, and 5.3 months in group 2. There was one delayed union in group 2. Results were graded from poor to excellent, based on pain, range-of-motion, and malunion. There were 6 poor and 4 fair results in group 1, and no poor and 3 fair results in group 2. Complications included 6 deep infections, 5 in group 1 (1 requiring a free-flap procedure); and 1 pin-tract infection resulting in septic arthritis in group 2. There were 7 gastrocnemius flaps required in group 1, and 1 in group 2. The results of this study suggest that patients treated with external fixation had better results with less infection and soft-tissue complications than those treated with conventional internal fixation.

Adult↗
PubMed1994

Timing of internal fixation in low-velocity extremity gunshot fractures.

A ten-year retrospective review of extremity long bone gunshot fractures treated operatively at the Elmhurst City Hospital Center, New York, was performed to examine the operative outcomes with regard to immediate, intermediate, and delayed fixation. A total of 121 low-velocity gunshot fractures were evaluated in 107 patients. Cases were separated into three groups according to the actual timing of the internal fixation procedure. The results revealed a total deep infection rate of 2.6% (3/121) and a nonunion rate of 3.3% (4/121), with no significant differences among the three groups. Early internal fixation reduced comparative hospital stay length and overall costs for operative patients.

Adolescent↗
PubMed1992

The Thurstan-Holland fragment.

The Thurstan-Holland fragment, a small triangular piece of metaphyseal bone, may provide the only roentgenographic evidence of a prior epiphyseal separation that subsequently resolved.

Epiphyses↗
PubMed1992

Inserting distal screws into interlocking IM nails.

The use of interlocking IM nails is commonplace in major trauma centers. Currently, an accurate guide for inserting the distal screws is not available. Most centers use the "free-hand" technique. Every surgeon must be familiar with this method to insert the screws. We describe our protocol for inserting the distal screws into interlocking IM nails.

Bone Nails↗
PubMed1988

Pseudomonas aeruginosa as a causative agent of cervical osteomyelitis. Case report and review of the literature.

Pseudomonas aeruginosa osteomyelitis and epidural abscess of the cervical spine developed in a previously healthy, 73-year-old man who was not an intravenous drug abuser. In the recent literature, Pseudomonas cervical osteomyelitis has been reported only in intravenous drug abusers or in otherwise healthy individuals after a tooth extraction. In the literature of the past 30 years, isolated cases of cervical osteomyelitis were associated with urinary tract infections. The majority of these cases involved urinary tract instrumentation. The pathogenesis remains controversial. It appears that spontaneous cervical osteomyelitis in a non-intravenous drug abuser has not been previously reported.

Abscess↗