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Biomedical subjects

W C Allen

Publications and source records attributed to W C Allen.

At least 19 recordsLinked to original sources
PubMed2003

Does batch operation enhance oxidation in subsurface constructed wetlands?

Two side-by-side experimental sub-surface flow systems allowed direct comparison of wetland performance under batch and continuous-flow operation. One system consisted of microcosm "columns" operated in 20-day batch mode while the second consisted of continuous-flow "cells" operated at a five-day residence time. Both systems treated identical synthetic domestic wastewater for two years and then treated identical synthetic mine-impacted water for one year. Each system had replicates planted with Typha latifolia, Scirpus acutus and unplanted controls. Temperature was cycled annually between 4 to 24 degrees C. Results indicated that plant species, season, and mode of operation interacted strongly in controlling dynamics of COD, nitrogen species, phosphate, sulfate, and redox potentials. In batch-loaded columns, between-species differences in oxidation and COD removal were large in winter, during plant dormancy, but absent in summer; COD removal, sulfate concentration, and redox potentials were closely correlated, suggesting that variation in root-zone oxygenation due to seasonal plant growth patterns and temperature-dependent plant and microbial respiration may explain observed differences. In the continuous-flow cells, species and seasonal differences were minimal or non-existent, indicating that under continuous-flow operation plants either did not influence root zone oxidation or that this influence had no effect on wetland performance for COD and nutrient removal or sulfate reduction.

Ecosystem↗
PubMed1997

Polycaprolactone/glass bioabsorbable implant in a rabbit humerus fracture model.

Research in improved materials and methods for internal fixation has centered on internal fixators made of bioabsorbable materials such as polylactic acid, polyglycolic acid, and polyparadioxanone. These materials have two problems: the first is a postoperative complication related to a delayed inflammatory response; and the second is low strength characteristics. An alternative material developed to alleviate these problems is a composite of phosphate glass fibers embedded in the polymer polycaprolactone, referred to as PCL. In this study, intramedullary pins made of PCL were compared to stainless steel pins in a rabbit humerus osteotomy model. Specimens were harvested at 0, 6, and 12 weeks postoperatively, radiographs and mechanical testing to failure were performed at each time interval, and tissue was examined microscopically at 6 and 12 weeks. Histologic results showed PCL pins to be well tolerated with minimal inflammation around the pin. Mechanical testing revealed the PCL fixation to be weaker initially than the stainless steel fixation. There was significant stress shielding of stainless-steel-healed rabbit humeri when compared to the PCL/bone humeri. All osteotomies immobilized with PCL healed with abundant periosteal callus production.

Absorption↗
PubMed1997

Endometrial carcinoma presenting with an isolated osseous metastasis: a case report and review of the literature.

Endometrial carcinoma, the fourth most common cancer in women, is primarily a disease afflicting postmenopausal women and usually presents with vaginal bleeding or vaginal discharge. A slender, athletic 44-year-old woman was diagnosed with endometrial carcinoma after presenting with an isolated, solitary femoral bone metastasis. She had no symptoms except for progressive left knee pain. An open biopsy of the lesion in the proximal left femur revealed metastatic adenocarcinoma compatible with an endometrial primary. An endometrial biopsy subsequently revealed moderately differentiated endometrioid adenocarcinoma. The patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy, and adjuvant chemotherapy. An aggressive metastatic workup revealed no other sites of metastatic disease. The femoral metastasis was treated with radiation. On chronic progestin therapy, the patient is clinically free of disease 2 years following diagnosis. Patients with endometrial carcinoma (with otherwise early stage disease) who present with an isolated skeletal lesion may represent an unusual group with perhaps a better prognosis. This patient received aggressive multi-disciplinary therapy and has had a two year progression-free interval.

Adenocarcinoma↗
PubMed1995

Closed reduction and percutaneous stabilization of tibial plateau fractures.

Twenty-eight patients with tibial plateau fractures treated by closed reduction using forceful traction and percutaneous stabilization with pins or screws were reviewed. For six bicondylar fractures, transfixion pins with an external fixation device were used. In six cases, an arthroscopic exam was also done. For 21 patients, external support was used postoperatively. Twenty-one patients were followed an average of 26 months. All fractures healed. Functional ratings were: 14 excellent, 6 good, and 1 poor. Radiographic ratings were: 11 excellent, 9 good, and 1 fair. For fractures with large fragments without excessive comminution or severe central depression, this technique yields good results with minimal surgical morbidity.

Adult↗
PubMed1994

High-performance liquid chromatographic analysis of glycoamines in serum.

This report describes the development of an HPLC-UV method for studies of glycoamines and glycoamine-like compounds in normal human serum and osteosarcoma patients serum as potential biological markers of cancer. The glycoamines, a newly recognized class of endogenous, low-molecular-mass biopolymers, are conjugates of amino acids and sugar units, containing 5 to 29 amino acid and 1 to 17 sugar units. After ultrafiltration of serum samples, reversed-phase HPLC separation with diode-array detection was used to obtain standard profiles of serum ultrafiltrates below M(r) 10,000 in healthy subjects. These highly reproducible profiles utilized two-dimensional peak identification and were used to develop a statistical profile of the major glycoamine peaks in normal serum. This newly developed analytical method was subsequently used to address a key question: whether or not there is a single tumor-specific glycoamine or a family of tumor-specific glycoamines in cancer patient serum. Preliminary results suggest that this method can separate and detect glycoamines and glycoamine-like compounds in various types of cancer patients serum with a high degree of reproducibility on the basis of comparative two-dimensional identification of natural compounds and a panel of synthetic glycoamine analogs. Moreover, the method is useful for following the relative changes in the amount of a given glycoamine over an extended clinical time course. Initial results suggest that a glycoamine or glycoamine-like compound, GA-4.63, may have clinical utility in human osteosarcoma studies.

Biomarkers, Tumor↗
PubMed1992

Fractures of the femur treated by intramedullary nailing using the fluted rod. A report of 193 consecutive cases.

One hundred ninety-three of 196 acute nonpathologic femoral shaft fractures were treated consecutively with intramedullary nailing using the fluted rod. Closed intramedullary nailing was used in 126 fractures, and an open technique was used in 67. This series includes 58 open fractures and 104 comminuted fractures. All fractures treated with the fluted rod united. Complications included three superficial infections (1.5%). Malrotation greater than 20 degrees was noted in six patients (3.1%). Significant shortening (5 cm), which required treatment, occurred in one patient. After initial resuscitation and evaluation, routine treatment included preoperative traction and a first-generation cephalosporin followed by accurate reduction and nailing of the fracture. The results of this series suggest that the fluted rod may be ideal for the treatment of most femoral shaft fractures.

Adolescent↗
PubMed1991

A bone biopsy procedure for neonatal pigs.

Neonatal pigs were used to develop a surgical biopsy procedure to remove bone tissue from the ilium of small animals, with potential application for infants and small children. While the neonatal pig was under general anaesthesia, a scalpel was used to make a punch incision down to the ilium. Then a Craig Biopsy Trephine was used to remove a core sample of the bone. The samples ranged from 5 to 15 mm in length and 2 to 3 mm in diameter, with an average dry weight of 34.4 mg. The samples were adequate for mineral (calcium and zinc) analysis in our laboratory and may be equally suitable for histological or biochemical analyses. Surgical trauma was minimal, which permitted each pig to be biopsied every 7 days for 5 weeks without adverse consequences.

Animals↗
PubMed1990

A comparison of transfusion requirements after total knee arthroplasty using the Solcotrans autotransfusion system.

Twenty-five consecutive total knee arthroplasties were performed with the Solcotrans unit for scavenging postoperative drainage (study group) and were compared with the previous 25 arthroplasties performed without the Solcotrans unit (control group). Mean preoperative hematocrits, estimated blood loss, and fluid replacement for both control and study groups were nearly identical. When the autotransfusion system was not used, 10 patients in the control group required transfusion of a total of 20 units of packed red blood cells, while only two patients utilizing the Solcotrans unit required transfusion of five units of packed red blood cells (P less than .01). The total amount autotransfused in the study group averaged 607.9 mm, and the hematocrit of the scavenged drainage was 29.3%. Samples from all autotransfusions were sent to the microbiology lab for routine culture and were finalized as no growth after 14 days. Serial postoperative hematocrits, platelet counts, prothrombin, partial thromboplastin, blood urea nitrogen, and creatinine values were compared between the two groups. No significant differences were found, and no evidence of coagulopathy, thrombocytopenia or renal dysfunction was found in the study group.

Aged↗
PubMed1990

The relationship between residency programs and fellowships in the educational setting.

In 1981, the Advisory Council for Orthopaedic Education published a list of 175 orthopedic postgraduate fellowships. Since that time, several groups within orthopedics have discussed various methods for enhancing the educational nature of fellowships as they related to orthopedic residency programs. The orthopedic community as a whole has concurred about the concept of accrediting fellowships, ensuring a minimum standard educational quality, and keeping the growth of fellowships in some areas from adversely affecting the educational quality of a residency program. When fellowships are accredited, standards are created, such as the requirement that a fellowship must last at least one year, and depending on the area of specialization, include both research and clinical work. Certification and accreditation are separate issues. Certification is the process of credentialing individual physicians as specialists and is the responsibility of a specialty board. Accreditation is the process of identifying residency and fellowship programs that meet published educational standards and is the responsibility of the Accreditation Council for Graduate Medical Education and the corresponding Residency Review Committee. There is little question that the educational process that occurs during a fellowship can have a beneficial effect on the learning process of residents and vice versa.

Accreditation↗
PubMed1990

Disseminated intravascular coagulation complicating Ender's nailing of a pathologic fracture in prostatic carcinoma. A case report.

Disseminated intravascular coagulation (DIC) occurred after closed Ender's pinning of a pathologic fracture of the humerus in a 58-year-old man with metastatic prostatic carcinoma. A review of the oncologic and urologic literature revealed that coagulopathy can be associated with prostatic carcinoma. This association seems not to have been previously reported in the orthopedic literature.

Bone Nails↗
PubMed1987

Primary iliopsoas bursography in the diagnosis of disorders of the hip.

The iliopsoas bursa is a well-defined anatomic structure that has been involved in various diseases about the hip, including osteoarthritis, rheumatoid arthritis, pigmented villonodular synovitis, and synovial chondromatosis. Demonstration of the iliopsoas bursa using contrast material has been reported during hip arthrography and inadvertently during angiography, but no direct or primary methods of iliopsoas bursography have been reported. A technique of primary bursography under fluoroscopy is described wherein filling of the bursa with contrast material allowed the observation of movement of the iliopsoas musculotendinous unit across the front of the pelvis during motion of the hip. This technique, which was of significant benefit in determining the etiology of two cases of the snapping hip syndrome of the internal variety, is simple, easily reproducible, and has clinical application.

Adult↗
PubMed1978

Ligament repair in the knee with preservation of the meniscus.

In early surgical repair of forty acute ruptures of the medial ligament of the knee in patients sixteen to twenty-four years old, the meniscus was resutured when it was avulsed from the bone and was excised only when there was central disruption (three knees). Follow-up of one to six years in thirty-six patients whose menisci were preserved showed that thirty-three had no limitations due to knee impairment. Twenty-six patients were re-examined; sixteen had no medial instability and twenty-one had no anterior rotatory instability. We concluded that in the absence of significant advantage from meniscectomy, an intact meniscus should not be removed.

Adolescent↗
PubMed1978

A fluted femoral intramedullary rod. Biomechanical analysis and preliminary clinical results.

An intramedullary rod for the femur was designed and compared with rods commonly used. Its bending strength was increased 40 to 80 per cent and its torsional rigidity was increased 230 to 3,000 per cent compared with the other devices tested. In forty patients with traumatic and pathological fractures and osteotomies of the femur, excellent fixation was achieved and very early weight-bearing was possible. In all fresh fractures and non-infected non-unions, union occurred very promptly and bone-grafting was not required in most instances. The stregth and rigidity of the device made it exceptionally useful for non-unions, pathological fractures of the femur, and resection-fusions of the knee.

Adolescent↗
PubMed1975

Mechanical studies of the bone bioglass interfacial bond.

A series of squirrel monkeys received segmental femoral replacements in a study of the strength of the interface developed between the implant and bone. Implants were either made completely of bioglass-ceramic, or 316L stainless steel with a flame-sprayed coating of bioglass. Fracture torque, energy at fracture, and shear stress at failure were compared to values obtained from a control group of pairs of tibias. Femurs containing bulk bioglass-ceramic implants showed about a 25% difference in strength compared to the opposite bone, while femurs containing flame-sprayed implants exhibited extremely low structural strength. While the strength of the metal-glass bond was very low (less than 500 kgf/cm2), the bone-bioglass bond was found to be at least as strong as the bioglass-ceramic, and at least 3/4 as strong as the host bone.

Animals↗