Modeling the two stages of surfactant-aided soil washing

This paper provides new insights into modelling the distribution of hydrophobic compounds between soil and water phases in the presence of nonionic surfactant micelles. Experimental measurements were made of various systems comprising a non-ionic surfactant, five soils of different fractional organic carbon contents, and a hydrophobic (disperse) dye. Soil-washing performance was quantified using reciprocal surfactant-soil solubilization coefficients (1/Kd). Two stages of partitioning were identified. In stage 1, the dye concentration increased slightly with increasing surfactant dose until surfactant monomers saturated the bulk solution at the critical micelle concentration (cmc). The washing performance was 1:1 proportional to the surfactant monomer concentration. Most of the surfactant in this stage is sorbed. In stage 2, above the cmc, soil-washing performance increased linearly with increasing available surfactant micelles in the bulk solution. Reciprocal surfactant-soil solubilization coefficients (1/Kd), octanol-water partition coefficients (Kow), fractional organic carbon content of the soil (foc), and surfactant concentration were correlated for each stage in the soil-washing process using two simple equations.

Age-dependent resistance to Cryptosporidium muris (strain MCR) infection in golden hamsters and mice

An age-dependent aspect of resistance to Cryptosporidium muris (strain MCR) infection was monitored in Syrian golden hamsters, Mesocricetus auratus, at 1-, 5- and 10-week of age and in ICR mice. Mus musculus, at 3-, 12-, and 15-week of age orally inoculated with a single dose of 2 x 10(6) oocysts, respectively. The prepatent periods for both animals were similar, independent of age, but the patency was significantly longer in younger hamsters (P < 0.001) and a long tendency in younger mice. Hamsters infected at 1-week of age excreted about 10 times higher oocysts than those at 5- and 10-week of age. However, the total oocyst output was similar among mice of different ages. There was a good correlation between the length of the patency and the total oocyst output in hamsters (R = 0.9646), but not in mice (R = 0.4561). The immunogenicity of the parasite to homologous challenge infections was very strong in hamsters and relatively strong in mice. These results indicate that acquired resistance to C. muris infection is age-related and the innate resistance is independent of age of hamsters, and that both innate and acquired resistance, on the contrary, are irrespective of age of mice.

Multicenter trial of modified Gamma nail in East Asia

The mismatch of the standard Gamma nail in the Chinese femora led to the modification of its femoral shaft component based on the anthropometric study of 28 pairs of Chinese femora. A multicenter clinical trial was done in 6 countries and regions in East Asia. Three hundred forty-nine fractures were treated and studied. More than 60% of the fractures were unstable by Evans classification. The average age of the patients was 73.6 years. The male to female ratio was 2:3. The mean followup period was 11.7 months. The result of the trial showed that the intraoperative complication rate was 7.7%, and complications primarily were related to faulty operative technique. There were 7.2% postoperative complications related to the fractures that again decreased toward the later stage of the trial. Functionally, there was progressive improvement of the hip score within the followup period. The results show that the modified Gamma nail gave better results in the treatment of geriatric trochanteric fractures by minimizing reaming, thereby reducing complications related to the implants.

Iliopsoas haematoma in an adolescent Taekwondo player

A 16-year-old male Taekwondo player was admitted with a 1-day history of right groin pain and a palpable mass in the right lower abdominal quadrant following a Taekwondo training session. No history of direct trauma was given, but the pain followed a high inward-to-outward kick. The patient was not on any medication, and tumour and infection were excluded. A high-resolution real-time ultrasound scan identified a well-defined, hyperechoic, heterogeneous mass in the substance of the right iliopsoas muscle, compatible with a collection of partially clotted blood, confirming the clinical diagnosis of iliopsoas haematoma. After conservative treatment the patient resumed training and is now fully asymptomatic.

Percutaneous elongation of the Achilles tendon in children with cerebral palsy

From 1987 to 1990, 45 children with cerebral palsy underwent percutaneous elongation of the Achilles tendon (71 ankles); the mean age was 5.7 years. Most suffered from spastic diplegia or hemiplegia. A three-step cut technique was used, the limb immobilised in a long leg fiberglass cast and immediate weightbearing allowed. Follow up was from 2 to 5 years. Satisfactory results were obtained with significant improvement in walking in 89%.

Treatment of ipsilateral femoral shaft fractures and hip fractures

Ipsilateral femoral shaft fractures and hip fractures are difficult to treat. The treatment protocols are diversified. We report the results of treating 16 such fractures. The diaphyseal fractures are fixed with intramedullary locked nails and the hip fractures with cannulated lag screws. The average follow-up period is 21.8 months. The results show that all diaphyseal fractures healed, one proximal fracture had delayed union. Functionally, 14 (87.5 per cent) patients had good results and two (12.5 per cent) had fair results; additional procedures may be necessary if the treatment of fractures is delayed. It is concluded that the present treatment protocol gives predictable good results for these fractures. The use of the newly available long gamma nail is also discussed and illustrated.

Gamma nails and dynamic hip screws for peritrochanteric fractures. A randomised prospective study in elderly patients

The Gamma nail was introduced for the treatment of peritrochanteric fractures with the theoretical advantage of a load-sharing femoral component which could be implanted by a closed procedure. We report a randomised prospective study of 186 fractures treated by either the Gamma nail or a dynamic hip screw. Gamma nails were implanted with significantly shorter screening times, smaller incisions, and less intraoperative bleeding. The Gamma nail group had a shorter convalescence and earlier full weight-bearing, but there was no significant difference in mortality within six months, postoperative mobility, or hip function at review. More intra-operative complications were recorded in the Gamma nail group, mainly due to the mismatching of the femoral component of the nail to the small femurs of Chinese people. Use of a smaller modified nail reduced these complications. We conclude that with careful surgical technique and the modified femoral component, the Gamma nail is an advance in the treatment of peritrochanteric fractures.

Operative treatment of unstable pelvic fractures

Unstable pelvic fractures are serious injuries. Non-operative treatment gives poor early and late results. We report the results of operative treatment of 28 unstable pelvic fractures; eight were rotatory unstable and 20 were both rotatory and vertically unstable. The average age of the patients was 33 years. All the patients underwent operation according to a definite protocol for internal fixation. Mobilization was started within 2 weeks after the operation; the average hospital stay was 9.8 weeks. With an average follow-up of 19 months, there was no mortality. In 20 patients there was no discomfort, five patients had moderate back pain and four patients walked with a limp due to leg length inequality and back pain. Twenty patients returned to gainful employment. Complications included one deep wound infection, two superficial wound infections, one dislodgement of the external fixator, and residual interval rotatory deformity of the hemipelvis. We conclude that operative treatment of unstable pelvic fractures is safe and that the early and late results are much better than those treated by non-operative means.

Ligamentotaxis for comminuted distal radial fractures modified by primary cancellous grafting and functional bracing: long-term results

Ligamentotaxis with the use of external fixator offers a sound method for treating comminuted distal radial fractures. In an effort to shorten the period of external fixation, primary cancellous bone grafting and functional bracing were used as an adjunct to ligamentotaxis. The external fixator was left in place for 3 weeks, followed by functional bracing for another 3 weeks. This paper presents the results of 54 patients with an average follow-up of 31.5 months. Results showed that 80% of the patients regained full range of motion in their hands, wrists, and forearms. More than 80% of the patients regained strong and pain-free wrist functions. Radiologically, there was no loss of reduction or shortening. Nine percent of patients suffered mild arthritic changes in the radiocarpal joints. Final assessment showed that 90% of patients had excellent or good results. Late complications were minimal, apart from the problems of the distal radio-ulnar joints.

Interlocking intramedullary nailing for supracondylar and intercondylar fractures of the distal part of the femur

Thirty-seven fractures of the distal part of the femur in thirty-five patients were treated with interlocking intramedullary nailing. All fractures were nailed by a closed technique after any intercondylar extension of the fracture had been managed by reduction and stabilization with percutaneous lag-screws. Patients who had an isolated condylar fracture or a severely comminuted intercondylar fracture were treated with other types of implants. There were thirty extra-articular (type-A) fractures and seven intra-articular (type-C1 and type-C2) fractures. Postoperatively, early mobilization exercises and weight-bearing were begun. At an average duration of follow-up of 20.5 months (range, fifteen to twenty-six months), all thirty-seven fractures had healed. There were no malunions of either the supracondylar or the intercondylar fractures. Complications were infrequent and included chronic irritation from the distal screws in three patients and delayed union in one; the latter healed with two centimeters of shortening after bone-grafting. There were no infections. The functional results were assessed with the modified knee-rating system of The Hospital for Special Surgery. Thirteen knees (35 per cent) had an excellent result; twenty-two (59 per cent), a good result; and two (5 per cent), a fair result. The results correlated with the age of the patient and the presence of an intra-articular fracture. We concluded that closed interlocking intramedullary nailing is an excellent technique for both supracondylar and simple intercondylar fractures in which closed reduction and percutaneous fixation of the articular fracture is possible.

Operative treatment of intraarticular fractures of the os calcis--the role of rigid internal fixation and primary bone grafting: preliminary results

The treatment of intraarticular fractures of the os calcis remains controversial. Yet it seems illogical that the subtalar joints should be treated differently from other weight-bearing joints. In this paper, we report the results of treating 64 intraarticular fractures of the os calcis by open reduction, rigid internal fixation with primary bone graft, and early mobilization. Of the 64 fractures, 23.43% were tongue-type fractures, 48.43% were joint depression, and 28.12% were comminuted. All the fractures were operated on with lateral incisions. The average period of follow-up was 10.6 months. The results showed that all the patients had minimal pain, swelling, and deformity. Subtalar joint movement was retained (67.8% of active and 80.7% of passive). Eighty percent of normal Bohler angles and 93.5% of normal crucial angles were regained. Over 80% of patients resumed working within 6 months after the injuries. We therefore concluded that the present method of treating intraarticular fractures of os calcis gives very good results.

Combined intramedullary Kirschner wire and intra-osseous wire loop for fixation of finger fractures

An intramedullary Kirschner wire was combined with an intra-osseous wire loop for fixing finger fractures. The mechanical stability of this technique to resist a bending moment in the sagittal plane was compared with four other conventional methods: single loop, loop and an oblique Kirschner wire, crossed Kirschner wires and dorsal plating. It was found that when the applied force was small, the technique was much more stable than the crossed Kirschner wires and was similar to the others. The ability to withstand mechanical failure was much better than most of the methods except the dorsal plate. This technique is recommended for replantations, transverse fractures and short oblique fractures with little comminution.

Combined Intramedullary Kirschner Wire and Intra-Osseous Wire Loop for Fixation of Finger Fractures

An intramedullary Kirschner wire was combined with an intra-osseous wire loop for fixing finger fractures. The mechanical stability of this technique to resist a bending moment in the sagittal plane was compared with four other conventional methods: single loop, loop and an oblique Kirschner wire, crossed Kirschner wires and dorsal plating. It was found that when the applied force was small, the technique was much more stable than the crossed Kirschner wires and was similar to the others. The ability to withstand mechanical failure was much better than most of the methods except the dorsal plate. This technique is recommended for replantations, transverse fractures and short oblique fractures with little comminution.

Therapy of an experimental glioma with systemic or intraneoplastic methotrexate or radiation

An intracranial mouse glioma model was used to study the effectiveness of chemotherapy with methotrexate )MTX) or radiotherapy. Maximum tolerable doses of MTX were established by toxicity studies in nontumor-bearing mice for the intraperitoneal and intracerebral routes of drug administration with and without leucovorin as an antidote. These maximum tolerable doses were then given either by the intraperitoneal route or directly into the tumor to mice bearing intracerebral tumors. The glioma model proved to be extremely useful for assessing the modalities studied, including repeated intraneoplastic injection of MTX. Dosage schedules were successfully developed for administering large amount of MTX and for preventing systemic toxicity by the administration of the antidote. Radiotherapy in single doses and 800 rads delayed the median day of death and produced several long-term survivors. Higher doses were toxic. Intraperitoneal or intraneoplastic MTX was completely ineffective as a chemotherapeutic agent for this tumor, even though very large amounts could be delivered due to the protection from systemic toxicity afforded by leucovorin. It is concluded that MTX is a poor chemotherapeutic agent for this experimental brain tumor, but that the technique of intraneoplastic administration of chemotherapeutic agents is feasible with this model system and should be studied further.

The development of an intracerebral glioma model for brain tumor chemotherapy

✓ The authors describe a brain tumor model for chemotherapy studies. The tumor is an intracerebral ependymoblastoma that kills the host in a short time (median survival, 27.5 days) and yields consistent, uniform survival curves. A suspension of tumor cells is injected into the right frontal lobe of the mouse by means of a stereotaxic frame, and produces a highly invasive, almost entirely intracranial brain tumor. The use of mice permits extensive chemotherapeutic trials for brain tumors at low cost. It is felt that this model will prove to be very useful for studies of brain tumor chemotherapy.