Biochemical modulation of 5-bromo-2'-deoxyuridine and 5-iodo-2'-deoxyuridine incorporation into DNA in VX2 tumor-bearing rabbits.

The thymidine analogues 5-bromo-2'-deoxyuridine (Brd-Urd) and 5-iodo-2'-deoxyuridine (IdUrd) compete with thymidine for incorporation into the DNA of replicating cells. This incorporation results in radiosensitizing effects which are directly related to the degree of analogue substitution. In vitro and in vivo evidence suggests that preadministration or coadministration of the thymidylate synthetase inhibitors fluorouracil and 5-fluoro-2'-deoxyuridine (FdUrd) can modulate analogue incorporation into DNA. We have evaluated in the rabbit VX2 tumor model the effects of thymidylate synthetase inhibitor (fluorouracil or FdUrd) coadministration (as 24-hour, intravenous infusions) on the incorporation of BrdUrd or IdUrd into the DNA of relevant normal tissues (bone marrow, gut mucosa) and intrahepatic VX2 tumor. Tissues were harvested and processed for gas chromatography-mass spectrometry analysis of the thymine, 5-bromouracil, and 5-iodouracil contents in hydrolyzed DNA. Coadministration of FdUrd resulted in statistically significant (P less than .01) enhancement of IdUrd incorporation into the DNA of intrahepatic VX2 tumor and normal (bone marrow and duodenal mucosa) rabbit tissues. Coadministered fluorouracil, on the other hand, significantly enhanced IdUrd incorporation only into DNA of intrahepatic VX2 tumor. Statistically significant enhancement of BrdUrd incorporation was achieved only with FdUrd coadministration and then only into the DNA of intrahepatic VX2 tumor. The percent of thymine replaced by analogue (I) is related to the steady-state arterial plasma drug concentration (C) by the Michaelis-Menten equation: I = I(MAX.) C/(C50 + C). The primary effect of FdUrd coadministration on BrdUrd incorporation into VX2 tumor DNA was a reduction of the C50 parameter (plasma BrdUrd concentration eliciting I = I(MAX)/2) from 8.17 microM to 1.78 microM. On the other hand, the I(MAX) parameter (I as C approaches infinity) was only slightly affected (29.7% to 25.2%). Thus, the degree to which the modulator enhanced analogue incorporation varied inversely with the analogue's steady-state plasma concentration. These results, which describe potential tissue specificity of modulator efficacy and characterize the effects of thymidylate synthetase inhibitor modulation on thymidine analogue incorporation pharmacodynamics, should provide guidance as to dose scheduling of BrdUrd and IdUrd in clinical trials for improved tumor specificity of uptake.

A simple method for long-term biliary access in large animals.

A simple method to obtain long-term access to the biliary tree in dogs and pigs is presented. In ten dogs and four pigs, a cholecystectomy was performed, the cystic duct isolated, and a catheter inserted into the cut end of the cystic duct. The catheter was connected to a subcutaneous infusion port, producing a closed, internal system to allow long-term access. The catheter placement was successful in three of the pigs and all of the dogs. Thirty-five cholangiograms were obtained in the 13 subjects by accessing the port with a 20 gauge Huber needle and injecting small amounts (4-10 mL) of contrast under fluoroscopic control. Cholangiograms were obtained up to four months after catheter placement without evidence for catheter failure or surgically induced changes in the biliary tree. This model provides a simple, reliable means to obtain serial cholangiograms in a research setting.

Floxuridine-associated sclerosing cholangitis. A dog model.

The authors developed a dog model for the biliary sclerosis that occurs as a severe complication of protracted hepatic arterial floxuridine (FUDR) infusions (using implanted drug delivery systems) in patients with hepatic cancers. Infusaid pumps attached to hepatic arterial catheters were used for protracted infusions in ten mixed breed hounds. To allow repeated cholangiograms, the animals' gallbladders were removed and catheters connected to subcutaneous infusion ports were positioned in the cystic ducts. Five treated dogs received FUDR 0.3 mg/kg/day through the pump for a total of 30 days. Five control dogs received only saline through the pump. Cholangiograms were obtained before and after treatment in all animals. In the control group, serum liver function test results and the cholangiographic appearance of the biliary tree remained within normal limits. By contrast, in the FUDR-treated group, serum glutamic-pyruvic transaminase and alkaline phosphatase progressively rose above normal, starting 2-3 weeks into FUDR infusion, followed by hyperbilirubinemia (7-28 mg/dl peak levels) beginning 4 to 6 weeks after initiation of the drug infusion. Cholangiograms revealed focal strictures involving the central bile ducts (five dogs) and diffuse attenuation of the intrahepatic ducts (four dogs). Thus, the liver function abnormalities and the cholangiographic findings in this dog model mimic the hepatobiliary toxicity in sensitive patients receiving similar treatment.

Mid-tarsal and tarsometatarsal arthrodesis for primary degenerative osteoarthrosis or osteoarthrosis after trauma.

We report the long-term results of arthrodesis of the mid-tarsal and tarsometatarsal joints, performed for osteoarthrosis after dislocation with or without a fracture (seventeen patients [seventeen feet]), for primary degenerative osteoarthrosis (twenty-one patients [twenty-two feet]), or for inflammatory arthritis (two patients [two feet]). All forty patients (forty-one feet) had a severe loss of function because of pain. The average age of the patients who had primary degenerative osteoarthrosis was sixty years (range, twenty-seven to seventy-five years) and that of the patients who had post-traumatic osteoarthrosis was forty years (range, twenty-three to sixty-seven years); the two patients who had inflammatory arthritis were forty-four and seventy years old. Thirty-seven patients (thirty-eight feet; 93 per cent) were satisfied with the results of the procedure after an average duration of follow-up of six years (range, two to seventeen years). Union was achieved after 176 (98 per cent) of the 179 attempted arthrodeses, and only one of the three non-unions necessitated an operative repair. A skin slough developed in two patients, one of whom needed operative débridement. Five patients noted at least one prominent metatarsal head postoperatively, but none of these patients needed débridement because of abnormal callus formation. A stress fracture of the second metatarsal developed in three patients, but all three fractures responded to immobilization of the foot. An incisional neuroma developed in three patients, but none of these patients needed additional treatment. We believe that patients who have a severe loss of function due to osteoarthrosis of the mid-tarsal or tarsometatarsal joints can be managed successfully with tarsometatarsal or mid-tarsal arthrodesis, or both.

Technical report: chronic and acute intracochlear infusion in rodents.

As a follow-up to the Brown et al., 1993 technique, we have made several improvements to the micro-cannula, osmotic pump procedure, enabling chronic intracochlear infusions while maintaining hearing. In addition, acute bolus injection techniques are briefly described in guinea pig, rat and mouse.

In vivo binding and hearing loss after intracochlear infusion of KHRI-3 antibody.

The IgG1 mouse monoclonal antibody (MAb) KHRI-3, binds to an antigen of 65-68 kDa expressed on inner ear supporting cells in guinea pigs. We previously showed [Nair et al. (1995) Monoclonal antibody induced hearing loss. Hear. Res. 83, 101-113] that mice carrying the KHRI-3 hybridoma develop high frequency hearing loss and loss of hair cells in the basal turn suggesting that this MAb causes immune-mediated sensorineural hearing loss. To evaluate the specificity of this effect, sterile KHRI-3 and control IgG1 preparations were infused directly into the guinea pig cochlea using Alzet mini-osmotic pumps. Assessments included: (1) hearing, measured by click auditory brain stem responses (ABRs); (2) in vivo antibody binding; and (3) the structural integrity of the organ of Corti. Nine animals were infused with KHRI-3 preparations and 5 controls were infused with control IgG1. Four guinea pigs given KHRI-3 developed 25-55 dB hearing loss. Control animals showed no difference from baseline. In vivo binding of KHRI-3 was detected in the organ of Corti in 6 of the 9 animals, including all 4 that had hearing loss. No staining was observed with control antibody. Confocal microscopy revealed that the in vivo KHRI-3 antibody binding pattern was identical to that obtained by incubating fixed tissue in vitro with KHRI-3. Histologic examination revealed an increased frequency of hair cell loss in KHRI-3 treated ears when compared to either the contralateral ears of the same guinea pigs or the IgG1 treated ears of control animals. The lesions in the infused ears of guinea pigs were scattered throughout the cochlea from base to apex. These experiments demonstrate the following points: (1) Antibodies can be chronically infused directly into the cochlea of living animals. (2) The KHRI-3 antibody binds to live supporting cells within the organ of Corti. (3) Infusion of an inner ear specific antibody affects auditory function. (4) The infusion of irrelevant antibody had no effect on the structure or function of the ear. This system provides an animal model for further studies of antibody-induced sensorineural hearing loss.

KHRI-3 monoclonal antibody-induced damage to the inner ear: antibody staining of nascent scars.

Intracochlear infusion of the KHRI-3 monoclonal antibody results in in vivo binding to guinea pig inner ear supporting cells, loss of hair cells and hearing loss. To further characterize the basis for KHRI-3-induced hearing loss, antibody was produced in a bioreactor in serum-free medium, affinity purified, and compared to conventionally prepared antibody by infusion into the scala tympani using mini-osmotic pumps. In vivo antibody binding was observed in 10 of 11 guinea pigs. A previously unreported pattern of KHRI-3 antibody binding to cells involved in scar formation was noted in five guinea pigs. All but one of the KHRI-3-infused animals demonstrated a hearing loss of > 10 dB in the treated ear. In five of 11 animals the threshold shift was 30 dB or more, and all had hair cell losses. In one guinea pig infused with 2 mg/ml of antibody, the organ of Corti was absent in the basal turn of the infused ear. This ear had a 45-50 dB threshold shift but, curiously, no detectable antibody binding in the residual organ of Corti. Organ of Corti tissue was fragile in antibody-infused ears. Breaks within the outer hair cell region occurred in 5/11 infused ears. The contralateral ears were normal except for one noise-exposed animal that demonstrated hair cell loss in the uninfused ear. Three animals were exposed to 6 kHz noise (108 dB) for 30 min on day 7. Antibody access to the organ of Corti may be increased in animals exposed to noise, since the strongest in vivo binding was observed in noise-exposed animals. Loss of integrity of the organ of Corti seems to be the primary mechanism of inner ear damage by KHRI-3 antibody. The binding of KHRI-3 antibody in new scars suggests a role of the antigen in scar formation. Antibodies with binding properties similar to KHRI-3 have been detected in 51% of patients diagnosed with autoimmune sensorineural hearing loss; thus, it seems likely that such autoantibodies also may have pathologic effects resulting in hearing loss in humans.

Tibial tubercle-medial malleolar distance in determining tibial nail length.

OBJECTIVE: To assess the accuracy of a previously undescribed method of determining tibial nail length based on anatomic landmarks. DESIGN: Cadaveric study. METHODS: Four methods of tibial nail length determination were compared. Nail lengths for each of fourteen cadaveric lower extremities were determined using full-length scanograms, spotograms, acrylic template overlays, and the distance between the tibial tubercle and the medial malleolus (TMD). Each tibia was then nailed. The accuracy of each method was then evaluated. RESULTS: The full-length scanogram method resulted in incorrect nail lengths in eleven of fourteen (79 percent) cases. Six of fourteen (43 percent) incorrect nail lengths resulted from the use of spotograms. All measurements made with the Template technique yielded nails that were too short (100 percent). The TMD method rendered four of fourteen (29 percent) nails of incorrect size. CONCLUSION: The tibial tubercle-medial distance (TMD) proved an easy, inexpensive, and accurate method of preoperative nail assessment.

First metatarsocuneiform motion: a radiographic and statistical analysis.

Fifty volunteers with 100 asymptomatic feet were evaluated by physical examination, radiographic analysis, and questionnaire. This investigation was used to evaluate first metatarsocuneiform motion and establish normal values at this joint. Normal first ray sagittal range of motion was 4.37 degrees (SD, +/- 3.4 degrees). The shape of the distal cuneiform was then categorized by three classification methods. Multiple independent variables were cross-referenced to determine their relationship with motion and shape at the distal cuneiform. Hyperflexibility of the thumb correlated with first ray hypermobility. No correlation was found between first ray motion and sex, age, intermetatarsal angle, side, skin stretch, hyperextension of the knee, hyperextension of the elbow, or shape of the distal cuneiform.

Radiographic assessment of the second metatarsal: measure of first ray hypermobility.

Hypermobility of the first metatarsal cuneiform joint has been implicated as a cause of the hallux valgus deformity. The objective definition of hypermobility at this joint, however, has not been clearly defined. We used a modified Coleman block test to accentuate motion at the first metatarsal cuneiform joint in order to measure physiologic limits of motion in vivo. This motion was compared with radiographic analysis of the feet, which included the hallux valgus angle, intermetatarsal angle, and medial cortical thickening at the midshaft of the second metatarsal. This assessment was performed on 100 feet (50 right feet and 50 left feet in 50 patients). The average intermetatarsal angle was 8.7 degrees (range, 4-14 degrees), the average hallux valgus angle was 11 degrees (range, 4 degrees of varus to 30 degrees of valgus), and the average midshaft medial cortical thickness was 3.2 mm (range, 2.0-5.5 mm). Pearson's correlation coefficient was calculated to compare these factors. The relationship between variables was found to be small (r < or = 0.2). Motion was noted to occur in the normal foot at this joint and a range of normal values for medial cortical thickness was identified.

Integrity of the first metatarsophalangeal joint: a biomechanical analysis.

Five fresh-frozen cadaver feet obtained from traumatic amputations were tested during hyperdorsiflexion stress of the first metatarsophalangeal joint. Three different types of injury were observed: (1) rupture of the capsule proximal to the sesamoids, (2) rupture of the plantar plate distal to the sesamoids, and (3) rupture of the capsular structures medially, allowing a lateral swing of the sesamoids around the metatarsal head. Incomplete dislocation can be associated with significant damage to the plantar plate and other soft tissues of the foot.

Popliteal sciatic nerve block for postoperative analgesia.

Eighty-six patients were evaluated prospectively following the placement of a sciatic nerve block in the popliteal fossa after a major foot or ankle operation. Needle placement was guided by a peripheral nerve stimulator and 30 ml of 0.5% bupivacaine with epinephrine was used. Ninety-seven percent of patients had a successful block. Only one patient had severe discomfort during the block placement. The block lasted an average of 20 hours. During the first 24 hours after surgery, patients took an average of three hydrocodone tablets. Twenty-two of the 23 patients who had had previous major foot or ankle surgery found that the block was better than their previous pain control regimen. No patient had complications related to the block and 95% were satisfied and would have the block again.

Neuromuscular examination of the foot and ankle.

The physical examination of a patient with a neuromuscular disorder presents challenges that are unique to other disease entities. These injuries may affect motor control of the foot, and sensory and autonomic function of the foot. This examination depends on knowledge of normal physiology and kinematics, including muscle forces and the gait cycle. The authors' approach to this examination is conducted with emphasis on three questions that are necessary for a successful examination: (1) is the foot plantigrade? (2) where is the pain located? and (3) is the foot supple?

Bipolar hemiarthroplasty for primary osteoarthritis of the hip.

One hundred twenty-five bipolar hemiarthroplasties of the hip were performed at the authors' hospital. Although the procedure was performed for acute femoral neck fractures, rheumatoid arthritis, revision hemiarthroplasty, and primary osteoarthritis, only the latter is the subject of this review. A modified Harris hip score (HHS) was used to evaluate the patients both preoperatively and postoperatively. Radiographs were taken preoperatively as well as postoperatively at 2-, 4-, 6-, and 24-month intervals. A total of 68 patients underwent bipolar hemiarthroplasty for primary hip osteoarthritis. The mean preoperative HHS was 35.5 (SEM = 1.86); the mean postoperative score was 81.2 (SEM = 1.64) with an average improvement of 45.7 (SEM = 2.03). The results of this review were compared to a control group of conventional total hip arthroplasties performed at the same institution. The mean postoperative HHS for the group of conventional arthroplasties was 87.2 (SEM = 1.07). The results of this review indicate a good clinical result from bipolar hemiarthroplasty, but significantly less postoperative function when compared to conventional total hip arthroplasty.

Component motion in bipolar hip arthroplasty: an evaluation of reamed and non-reamed acetabula.

Sixty-four patients with 67 bipolar arthroplasties of the hip were reviewed for a mean follow up of 3.1 years. The study group consisted of 46 hemiarthroplasties secondary to primary osteoarthritis of the hip and 21 hemiarthroplasties secondary to displaced subcapital hip fractures. Reaming of the acetabulum was performed in 47 of the hips studied. The Harris hip scores were not significantly affected by acetabular reaming. Total motion decreased when hips were loaded in the standing position. Reaming of the acetabulum resulted in a decrease in percent outer component motion and an increase in percent inner component motion. The non-reamed acetabula had the largest percent inner motion decrease when taken from the supine to the standing position. The reamed acetabula had significantly higher average percentage of inner component motion in both standing and supine positions. There was no patient with postoperative acetabular protrusion.

Assessment of nutrient supplement to reduce gentamicin-induced ototoxicity.

Gentamicin is an aminoglycoside antibiotic used to treat gram-negative bacterial infections. Treatment with this antibiotic carries the potential for adverse side effects, including ototoxicity and nephrotoxicity. Ototoxic effects are at least in part a consequence of oxidative stress, and various antioxidants have been used to attenuate gentamicin-induced hair cell death and hearing loss. Here, a combination of nutrients previously shown to reduce oxidative stress in the hair cells and attenuate hearing loss after other insults was evaluated for potential protection against gentamicin-induced ototoxicity. Guinea pigs were maintained on a nutritionally complete standard laboratory animal diet or a diet supplemented with ß-carotene, vitamins C and E, and magnesium. Three diets with iterative increases in nutrient levels were screened; the final diet selected for study use was one that produced statistically reliable increases in plasma levels of vitamins C and E and magnesium. In two separate studies, significant decreases in gentamicin-induced hearing loss at frequencies including 12 kHz and below were observed, with less benefit at the higher frequencies. Consistent with the functional protection, robust protection of both the inner and outer hair cell populations was observed, with protection largely in the upper half of the cochlea. Protection was independently assessed in two different laboratories, using two different strains of guinea pigs. Additional in vitro tests did not reveal any decrease in antimicrobial activity with nutrient additives. Currently, there are no FDA-approved treatments for the prevention of gentamicin-induced ototoxicity. The current data provide a rationale for continued investigations regarding translation to human patients.

Morphometric analysis of the plantar plate apparatus of the first metatarsophalangeal joint.

Reliable and reproducible radiographic assessment of plantar plate integrity of the great toe is possible with standard radiographic techniques. Normal values in 100 pairs of feet (200 feet) are defined for comparison of one foot to the other and absolute values emerge if comparison is not possible. Bipartite sesamoids occurred in 13.5% of 200 feet with a 37% bilaterality.

Posttraumatic proximal migration of the first metatarsophalangeal joint sesamoids: a report of four cases.

Four cases are presented with plantar plate injury to the first metatarsophalangeal (MTP) joint and proximal retraction of the sesamoids by the flexor hallucis brevis. No history of dislocation occurred in any patient, although two had associated fractures of a sesamoid bone. Clinical and radiographic aids to the diagnosis are discussed. Clinical findings included diffuse pain beneath the first MTP joint and pain with extremes of joint motion in all patients. The anterior-posterior (AP) radiographic technique was the most helpful in determining the proximal migration of the sesamoids. By taking the AP view with both feet on the cassette and by centering the beam perpendicular to it, the diagnosis of plantar plate disruption can easily be made. Initial treatment of this disorder was nonoperative using a stiff soled shoe. With conservative treatment, two of the patients returned to preinjury activities. One patient required sesamoidectomy for resistant pain, and the final patient is still unable to return to his preinjury job requiring standing and heavy lifting.

Clear cell sarcoma presenting as an interdigital neuroma.

The incidence of malignant soft-tissue sarcomas in the general population is approximately 1.4 per 100,000. Approximately 2% of all cancer deaths are attributable to these tumors. Presented is a case history of a soft-tissue malignant neoplasm that was originally thought to be an interdigital neuroma and that eventually required a modified Chopart's amputation. A review of the literature is presented on other soft-tissue malignant tumors that have an affinity for the foot and ankle. The intention of presenting this case is to caution physicians that malignant lesions can simulate a benign process and should always be considered in the differential diagnosis of any foot mass.

Microscopic analysis of arterial microsphere distribution in rabbit liver and hepatic VX2 tumor.

Microspheres conjugated to radioisotopes and chemotherapeutic agents are playing an important investigative and clinical role in the management of metastatic neoplasms. The purpose of our investigation was to histologically assess the basis for regional intra-arterial microsphere therapy, by comparing the spatial distribution of microspheres in the tumor and liver of experimental models of hepatic metastases. Three New Zealand white rabbits with hepatic VX2 tumor implants were arterially injected with hepatic doses of either 15 or 30 million blue-dyed, polystyrene microspheres (27 microns-diameter). Microscopic examination of random liver and tumor samples revealed that 6-12 times as many microspheres were embolized within tumor than in normal liver (p less than 0.002). The majority of microspheres aggregated into clusters of various size within liver and tumor vasculature, though analysis of cluster sizes illustrated an exponentially skewed distribution toward isolated microspheres. Approximately eight times as many clusters were observed in tumor than in liver (p less than 0.008). Finally, a morphometric analysis was used to quantitate the minimal distances separating microsphere clusters, the intercluster distance (ICD). Analysis of over three thousand intercluster measurements revealed a median ICD approximately five times lower in tumor than in liver (p less than 1 x 10(-8)). This microquantitative analysis provides a fundamental description of how regional intra-arterial microsphere therapy allows the targeted delivery of microspheres to neoplastic tissue, to potentially improve the therapeutic index in the treatment of hepatic metastases.