Antigen sampling by intestinal M cells is the principal pathway initiating mucosal IgA production to commensal enteric bacteria.

Secretory IgA (SIgA) directed against gut resident bacteria enables the mammalian mucosal immune system to establish homeostasis with the commensal gut microbiota after weaning. Germinal centers (GCs) in Peyer's patches (PPs) are the principal inductive sites where naive B cells specific for bacterial antigens encounter their cognate antigens and receive T-cell help driving their differentiation into IgA-producing plasma cells. We investigated the role of antigen sampling by intestinal M cells in initiating the SIgA response to gut bacteria by developing mice in which receptor activator of nuclear factor-κB ligand (RANKL)-dependent M-cell differentiation was abrogated by conditional deletion of Tnfrsf11a in the intestinal epithelium. Mice without intestinal M cells had profound delays in PP GC maturation and emergence of lamina propria IgA plasma cells, resulting in diminished levels of fecal SIgA that persisted into adulthood. We conclude that M-cell-mediated sampling of commensal bacteria is a required initial step for the efficient induction of intestinal SIgA.

Physeal arrest due to laser beam damage in a growing child.

A laser beam applied directly to epiphyseal cartilage may damage the cartilage selectively without affecting adjacent bone. The damaged physis is replaced by bone, which forms a bone bridge between the metaphysis and epiphysis, similar to the bone bridges that follow fracture of any long bone. This case report documents damage to two distal phalangeal epiphyseal plates as a sequela of laser beam injury. This resulted in premature partial physeal closure (physeal bars), which in turn caused progressive angular deformity and relative shortening of the digits, requiring multiple osteotomies for correction. This report suggests that special care must be exercised when using laser therapy near physes in growing children.

Reverse segmental pedicled ulna transfer as a salvage procedure in wrist fusion.

A new technique for wrist fusion using vascularized bone graft is described. A distally based, pedicled segment of the distal ulna, nourished by the ulnar artery or the distally based palmar-ulnar branch of the anterior interosseus artery was used in three patients to restore carpal height after infection (n=2) or tumour resection (n=1). The forearm is converted to a situation similar to a wide ulnar resection. All three wrist fusions healed uneventfully. This new technique is suitable in cases where a vascularized bone graft is required, but microsurgical techniques are not appropriate or are rejected by the patient.

Vascularized free fibular transfer combined with autografting for the management of fracture nonunions associated with radiation therapy.

BACKGROUND: The purpose of this study was to evaluate the functional results, rates of union, and complications associated with vascularized free fibular transfer combined with autografting for the treatment of nonunions in previously irradiated bone. METHODS: Seventeen patients who had had eighteen vascularized free fibular transfers combined with autografting for the treatment of nonunion of a fracture in previously irradiated bone were included in this study. There were eleven female patients and six male patients. Eight patients had a bone neoplasm and nine, a soft-tissue neoplasm. The diagnosis was Ewing sarcoma in four patients; lymphoma, malignant fibrous histiocytoma, and rhabdomyosarcoma in two patients each; and cavernous hemangioma, metastatic breast carcinoma, reticulum-cell sarcoma, myxosarcoma, hemangiopericytoma, and fibrosarcoma in one patient each. The remaining patient had a soft-tissue tumor for which the diagnosis was not known. All patients received radiation therapy. The average dose was 5564 centigray. There were no recurrent tumors. The average interval between the radiation therapy and the original fracture was 111 months. The fracture was in the femur in thirteen patients, in the humerus in three, and in the tibia in one. All patients had operative or nonoperative treatment, or both, of the initial fracture, and two had iliac-crest bone-grafting after the initial open reduction and internal fixation procedure. The ages of the patients ranged from thirteen to eighty-two years at the time of the vascularized free fibular transfer. All fibular transfers were applied as onlay grafts because no nonunion was associated with a large segmental defect. Cancellous autogenous bone graft from the iliac crest was used as an additional graft at the proximal and distal junctions of the graft with the bone and at the fracture site in all patients. The average duration of follow-up after the vascularized free fibular transfer was fifty-seven months (range, twenty-eight to 112 months). RESULTS: Sixteen of the eighteen fracture sites united, after an average of 9.4 months (range, three to twenty-four months). Thirteen patients had an excellent result, one had a good result, two had a fair result, and one had a failure of treatment. Four patients had an infection, including one who continued to have a nonunion. The other three patients had union after treatment with antibiotics, debridement, and removal of the hardware. Another patient who had a recalcitrant nonunion eventually required an above-the-knee amputation. CONCLUSIONS: On the basis of this review, we suggest that microvascular fibular transfer combined with autografting is an appropriate treatment option for difficult nonunions associated with previously irradiated bone.

Experimental carpal reverse-flow pedicle vascularized bone grafts. Part I: the anatomical basis of vascularized pedicle bone grafts based on the canine distal radius and ulna.

We investigated the detailed extraosseous and intraosseous vascular anatomy of the distal radius and ulna in 55 pairs of canine forelimbs. Ten specimens were used for compartment identification. One hundred specimens were investigated after intra-arterial injection with red latex or Batson's compound. The extraosseous vascular network, including the nutrient artery location, was studied by delicate dissection and soft tissue digestion. Two superficial and 4 deep arteries were found on the dorsal aspect, with constant relationships to the retinaculum. On the palmar aspect, bony nutrient vessels rose from the branches of the radial artery (descriptive anatomy). The vascular supply of the canine distal forelimb was very consistent and enabled the design of 5 vascularized pedicle bone grafts similar to those described in humans (applied anatomy). These reverse-flow pedicle grafts may be placed in the carpus, allowing the canine forelimb to serve as an experimental model for the study of vascularized carpal bone grafting. (J Hand Surg 2000; 25A:34-45.

Experimental carpal reverse-flow pedicle vascularized bone grafts. Part II: bone blood flow measurement by radioactive-labeled microspheres in a canine model.

Reverse-flow pedicle vascularized bone grafts (VBGs) from the radius, commonly used for carpal nonunion and avascular necrosis, provide superior clinical results. In this experimental study bone blood flow in canine distal radius VBGs was measured to determine the status of the bone circulation immediately after elevation (group 1) and 2 weeks later (group 2). Immediate VBG flow (group 1) was substantial, but significantly less than the contralateral undisturbed distal radius (8.42 mL/min/100 g and 16.53 mL/min/100 g, respectively). At 2 weeks after surgery (group 2) VBG flow was compared with nonvascularized control grafts. Vascularized bone graft flow was significantly higher than group 1 (mean, 33.72 mL/min/100 g). Minimal flow was seen in the conventional graft control (0.62 mL/min/100 g). This study demonstrates that reverse-flow pedicle radius VBG maintain enhanced bone circulation long-term. Given the similarity of human and canine distal radius vascular anatomy, these data support the clinical use of reverse-flow VBG for carpal pathology. (J Hand Surg 2000; 25A:46-54.

Function of the vascular endothelium after hypothermic storage at four degrees Celsius in a canine tibial perfusion model. The role of adrenomedullin in reperfusion injury.

The function of the vascular endothelium after cold storage at 4 degrees Celsius for one, three, five, and seven days was investigated in a canine tibial perfusion model. Function was assessed in terms of changes in perfusion pressure, changes in the concentration of endothelin in the venous effluent from the perfused tibiae, adrenomedullin-induced vascular smooth-muscle relaxation, and norepinephrine-induced pressor responses in the presence of acetylcholine, N(G)-monomethyl-L-arginine acetate (an inhibitor of nitric oxide synthesis), or indomethacin (an inhibitor of prostaglandin synthesis) in phase 1 of the study. In phase 2 of the study, the effect of the infusion of tetraethylammonium (a potassium-channel blocker that inhibits the activity of endothelium-derived hyperpolarized factor) was analyzed. The baseline perfusion pressures increased in a time-dependent manner (p < 0.05). In tibiae that had been stored for one or three days, the production of endothelin-1 was less than one picogram per milliliter, but it markedly increased to a mean (and standard error of the mean) of 8.7 +/- 3.2 and 10.8 +/- 4.3 picograms per milliliter in tibiae that had been stored for five and seven days, respectively (p < 0.05). Acetylcholine attenuated the norepinephrine-induced pressor response in all groups (storage at 4 degrees Celsius for one, three, five, or seven days) compared with the response in the control tibiae (p < 0.05). Perfusion of acetylcholine in the tibiae that had been stored for three days significantly attenuated the pressor response to norepinephrine compared with that in the tibiae that had been stored for five days (p < 0.05). In the presence of N(G)-monomethyl-L-arginine acetate, the norepinephrine-induced pressor response significantly increased only in the tibiae that had been stored for one day (p < 0.05). In the presence of indomethacin, the norepinephrine-induced pressor response significantly decreased in the tibiae that had been stored at 4 degrees Celsius for one, three, or five days (p < 0.05). Infusion of adrenomedullin relaxed vascular smooth muscle in the tibiae that had been stored for one, three, five, or seven days (p < 0.05). In phase 2 of the study, perfusion of tetraethylammonium in the presence of acetylcholine increased the norepinephrine-induced pressor response in the tibiae that had been stored at 4 degrees Celsius for seven days to a mean of 168 +/- 20 per cent, whereas perfusion with acetylcholine alone attenuated the norepinephrine-induced pressor response to a mean of 54.6 +/- 3.7 per cent.

End-to-end versus end-to-side arterial anastomosis patency in microvascular surgery.

The patency rates of microsurgical end-to-end and end-to-side anastomosis in the rat carotid artery were studied. Seventy end-to-end and seventy end-to-side arterial anastomoses, using 10-0 nylon interrupted sutures, were performed on 140 Sprague-Dawley rats. Findings indicated 100% patency in end-to-end as well as end-to-side immediately and 1 week post-anastomosis. This investigation suggests that there is no significant advantage between the methods studied based on vessel patency alone. The decision to perform an end-to-end vs. an end-to-side arterial anastomosis should be based upon the clinical circumstances encountered, since no significant difference in patency rates exists.

Interaction of endothelial eccrine mechanisms and human adrenomedullin on vascular resistance in canine bone.

Adrenomedullin is a novel peptide known to be one of the most potent vascular smooth muscle relaxing agents in vivo. The aim of this study is to investigate the effect of adrenomedullin in relation to nitric oxide, prostaglandins and endothelium-derived hyperpolarized factor (EDHF). A 0.1-ml bolus of 1 nmol human adrenomedullin is a potent inhibitor of the pressor response to exogenous norepinephrine infusion in an ex vivo canine tibia perfusion model for a duration of at least 70 min (P < 0.005). This attenuation of vascular smooth muscle contraction occurs even when nitric oxide production is blocked by NG-monomethyl-L-arginine acetate (L-NMMA) infusion and EDHF is blocked by tetraethylammonium infusion, although the effect is of shorter duration (at least 10 min). Indomethacin as well does not affect the suppression of norepinephrine-induced vascular smooth muscle contraction. Based on these data, human adrenomedullin has both nitric oxide- and EDHF-dependent mechanism as well as a nitric oxide- and EDHF-independent mechanism.

The results of treatment of synovitis of the wrist induced by particles of silicone debris.

Synovitis of the wrist induced by particles of silicone debris is a destructive inflammatory process. Many silicone-rubber carpal implants remain in place, and there are few reports regarding the treatment of this condition. The purpose of the present study was to examine the results of treatment of synovitis induced by particles of silicone debris. Twenty-eight patients were identified, with use of computerized indexing, as having been evaluated for silicone-induced synovitis between 1972 and 1992. Seventeen of the twenty-eight patients were included in the study. At the time of the latest follow-up, twelve of the seventeen patients had pain, thirteen of the fourteen patients for whom radiographs were available had evidence of osteolysis typical of that associated with debris-induced synovitis, and eight of the seventeen patients reported difficulty with activities of daily living because of problems with the wrist. Seven patients had been treated non-operatively, and ten had been treated operatively. With the small number of patients available for study, we could not detect a significant difference between the two groups with respect to pain, perceived limitation of motion, difficulty with activities of daily living, grip strength, or the total range of motion of the wrist. There was no significant difference between the two groups with regard to the age at the time of the initial procedure, the time to the diagnosis of the synovitis, and the duration of follow-up after treatment. There was no clear advantage to removal of the implant and débridement with or without arthrodesis of the wrist or other reconstructive procedures. We recommend caution when a reconstructive or salvage procedure in the wrist is selected for a patient who has synovitis induced by particles of silicone debris.

Apoptosis is a pathway responsible for the resolution of endotoxin-induced alveolar type II cell hyperplasia in the rat.

Previous studies showed that intratracheal instillation of endotoxin induces transient type II cell hyperplasia in the rat lung and described some of the mechanisms involved in the proliferative response of type II cells. The purpose of the present study was to investigate how long the type II cell hyperplasia persists and how it is resolved. The portion of epithelial cells in hyperplastic lesions of the rat lung expressing cyclin D1, an indicator for cells in the G1 phase of the cell cycle, was greatest at 3 d post instillation and decreased after 4 and 6 d. The fate of the proliferating epithelial cells was traced by injecting the rats with 5-bromo-2' deoxy uridine (BrdU) 2 d post instillation, the peak time point for maximum incorporation of BrdU. Exfoliated BrdU-positive epithelial cells were detected in the alveolar spaces in tissue sections from rats 4, 5, and 6 d post instillation. BrdU-positive epithelial cells showed flattened nuclei at 6 and 10 d post instillation. Expression of the 116 kD poly(ADP-ribose) polymerase (PARP) was low in type II cells from control rats, and was increased at 3, 4, and 6 d post instillation. In cells obtained by lavage, only a 35 kD cleavage product of PARP was detected, which is an indicator of necrotic cell death. In isolated type II cells from rats 3, 4, and 6 d post endotoxin instillation, progressive cleavage of the PARP to its 89 kD residual fragment was detected, which is a direct evidence for the activation of caspases. Furthermore, apoptotic epithelial cells with condensed nuclei were identified by electron microscopy in rats 4 d post instillation. These results indicate that apoptosis is an additional mechanism for the resolution of endotoxin-induced lung epithelial hyperplasias.

Tibia-hindfoot osteomusculocutaneous rotationplasty with calcaneopelvic arthrodesis for extensive loss of bone from the proximal part of the femur. A report of two cases.

We report a new technique to create an effective lower extremity weight-bearing stump for two patients who had extensive segmental loss of femoral bone proximal to the distal femoral condyles. One patient had previously had complete resection of the proximal part of the femur because of an infection following the insertion of a custom femoral replacement and hip arthroplasty prosthesis. The other patient had had débridement of the femur from the subcapital line to the femoral condyles because of post-traumatic osteomyelitis after failure of a reconstruction with a massive allograft. Both patients were managed with a tibia-hindfoot osteomusculocutaneous rotationplasty after transtarsal (Chopart) amputation, with calcaneopelvic arthrodesis to create stable fixation of the extremity to the pelvis; this fixation allowed flexion, extension, abduction, and adduction of the hip by means of the retained tibiotalar and subtalar joints. At the time of the latest follow-up (at thirty-three and forty-four months), both patients were bearing full weight, without pain, with the use of a standard above-the-knee-amputation prosthesis. We report this procedure as a useful alternative to disarticulation at the level of the hip in patients who have massive loss of femoral bone and destruction of the hip joint in association with scarred and previously infected soft tissues and are not considered to be candidates for other forms of limb-preservation reconstruction. The patient must be willing to accept the equivalent of a low above-the-knee amputation and recognize the potential value of a weight-bearing stump.

Ulnar styloid impaction syndrome.

A series of 8 patients each with an excessively long ulnar styloid that was impacting the triquetrum, causing chondromalacia, synovitis, and pain, is presented. Four patients developed symptoms as a result of an injury and 4 had no definable acute precipitating injury. The average age at the time of surgery was 34 years. There were 3 male and 5 female patients. The average follow-up period was 34 months. All patients were treated by open partial ulnar styloidectomy. Outcome was evaluated clinically and by means of patient questionnaire and radiographs. Pain decreased from a preoperative average score of 3.5 to a postoperative average score of 1.3, which equates to mild pain requiring no medication. All but 1 patient returned to their previous employment unrestricted. The average preoperative ulnar styloid length was 7.4 mm and the average ulnar styloid process index was 0.41, which is almost twice normal. There were no complications. It is likely that an excessively long ulnar styloid has important implications for the kinematics of the lunatotriquetral interval. Details of the diagnosis of this condition, including a new provocative test, and operative management are discussed.

Effect of the duration of room-temperature ischemia on function of the vascular endothelium: the role of adrenomedullin in reperfusion injury.

The function of the vascular endothelium after storage at room temperature (24 degrees Celsius) for four, eight, and twenty-four hours was investigated with use of an ex vivo canine tibial perfusion model. Function was assessed in terms of changes in perfusion pressure and changes in the concentration of endothelin-1 in the venous effluent of the perfused tibiae. Endothelin-1 is a potent vasoconstrictor that is produced in low concentrations by normal endothelial cells and in increased concentrations by injured vascular endothelial cells. The mean perfusion pressures at flow rates of 1.0 and 1.5 milliliters per minute were significantly higher in the tibiae that had been stored for eight hours than in the tibiae that had been stored for four hours (p < 0.05), and they were significantly higher in the tibiae that had been stored for twenty-four hours than in the tibiae that had been stored for four or eight hours (p < 0.05). The increase in perfusion pressure with increasing duration of storage was associated with an increase in production of endothelin-1. The production of endothelin-1 in the tibiae that had been stored for eight hours (10.6 +/- 0.46 picograms per milliliter) was approximately ten times greater than that in the tibiae that had been stored for four hours (1.1 +/- 0.29 picograms per milliliter). The tibiae that had been stored for twenty-four hours had 19.1 +/- 1.5 picograms of endothelin-1 per milliliter, nearly twice that produced in the tibiae that had been stored for eight hours. Injection of acetylcholine demonstrated muscarinic receptor-mediated vasodilation in the tibiae that had been stored for four hours. In contrast, the tibiae that had been stored for eight and twenty-four hours had no evidence of acetylcholine-induced vasodilation of baseline perfusion vascular smooth-muscle tone. However, there was some preservation of endothelium-dependent vascular smooth-muscle relaxation in the tibiae that had been stored for eight and twenty-four hours, as norepinephrine-induced vascular smooth-muscle contraction was significantly greater in the presence of N(G)-monomethyl-L-arginine acetate (p < 0.05). Moreover, in the second phase of the study, a bolus injection of calcium ionophore A23187 in tibiae that had been stored for twenty-four hours relaxed vascular smooth muscle. Adrenomedullin, a novel peptide with known vasodilator properties, relaxed vascular smooth muscle in all three groups and also attenuated the pressor response to norepinephrine. In conclusion, the function of the vascular endothelium was impaired after storage at room temperature for four hours. However, the vascular endothelium in the tibiae that had been stored for twenty-four hours maintained some function with regard to the production of nitric oxide. The effect of adrenomedullin as a potent vasodilator was observed in the tibiae that had been stored for four, eight, and twenty-four hours.

Free vascularised fibular grafting for reconstruction after tumour resection.

We have reviewed 30 patients at a mean of 36 months after free vascularised fibular transfer to reconstruct massive skeletal defects after resection of primary bone tumours. There were 23 malignant and 7 benign neoplasms, half in the lower limb and half in the upper. Arthrodesis was performed in 15 and intercalary bone replacement in 15. The mean fibular graft length was 189 mm. Union was achieved in 27 (90%) at an average of 7.6 months, and the 3-year survival was 89%. There was a high complication rate (50%), but most resolved without greatly influencing the final outcome. There was local recurrence in two (6.7%), but 16 of the 24 assessed patients (67%) had satisfactory functional results. This is a reasonably effective means of reconstruction for limb salvage after resection of tumours.

Effect of human adrenomedullin on a canine tibial perfusion model in the absence of vascular endothelium.

The effect of human adrenomedullin was investigated using an ex vivo perfused canine tibial model in the absence of vascular endothelium. Adrenomedullin is a novel peptide with known vasodilator properties. In this model, a 0.1 ml bolus injection of 10(-5) M of either acetylcholine or adrenomedullin decreased vascular resistance in tibial preparations precontracted with prostaglandin F2 alpha by 88.3 +/- 3.0% and 92.8 +/- 2.8%, respectively, in the presence of vascular endothelium. Conversely, a 0.1 ml bolus injection of 10(-5) M acetylcholine produced a constrictor response after removal of vascular endothelium. A 0.1 ml bolus injection of 10(-5) M adrenomedullin decreased the baseline perfusion pressure in a dose-dependent manner for a duration of 20 minutes and also attenuated the pressor response to exogenous norepinephrine injection for at least 10 minutes compared with the control study (p < 0.05) in the absence of vascular endothelium. These data suggest that human adrenomedullin relaxes blood vessels in bone by a direct action on vascular smooth-muscle cells. In addition, the attenuation effect of human adrenomedullin on pressor responses to exogenous norepinephrine injection is independent of vascular endothelium.

Effect of human adrenomedullin on vascular resistance of the canine tibia.

An ex vivo model of a perfused canine tibia was used to investigate the effect of human adrenomedullin, a novel peptide with known vasodilator properties, on the vascular resistance of bone. Human adrenomedullin has a potent and long-lasting vasodilator effect in the canine tibia following precontraction of vascular smooth muscle by infusion of prostaglandin F2 alpha. A 0.1 ml bolus injection of 10(-5) M human adrenomedullin suppressed the pressor response of the canine tibia preparation to an infusion of norepinephrine by 43-52% for a duration of 100 minutes. An injection of 10(-6) adrenomedullin suppressed the pressor response to an infusion of norepinephrine by 22-23% for a duration of 40 minutes. These data suggest that human adrenomedullin may be a potent and long-acting vascular smooth-muscle relaxant in bone.

Arthrodesis of the ankle with a free vascularized autogenous bone graft. Reconstruction of segmental loss of bone secondary to osteomyelitis, tumor, or trauma.

Reconstruction after massive loss of bone about the ankle is difficult because of the limited amount of surrounding soft tissue and because of technical factors pertaining to adequate internal or external fixation. Conventional techniques are often unsuccessful because of the frequency of associated deep infection and of previous operative procedures. In this report, we describe eleven patients with a large defect of the distal aspect of the tibia who were managed at our institution with arthrodesis of the ankle with free vascularized bone graft. The defect was related to a tumor resection; an acute open fracture with bone and soft-tissue loss caused by a shotgun injury; or osteomyelitis, either alone or in combination with septic arthritis, with chronic non-union following a fracture of the ankle. A free fibular graft was used in osseous defects that were larger than four centimeters, and a free iliac-crest graft was used in smaller defects. Osteocutaneous or osteomuscular flaps were constructed to cover accompanying soft-tissue defects when necessary. A successful fusion was obtained in nine of the eleven patients. The results in the remaining two were regarded as clinical failures, and a below-the-knee amputation was performed. One amputation was done because of recurrent infection and the other, because of failure of the fracture to unite after four years.

Clinical results of the one-bone forearm.

Between 1973 and 1991, 19 patients underwent creation of a one-bone forearm at our institution as treatment for radioulnar instability secondary to trauma ("type 1" patients) or tumor resection or congenital deformity ("type 2" patients). Seventeen had failed previous reconstruction attempts. Ten one-bone forearms were constructed in neutral rotation, and nine in varying pronation (mean, 24 degrees). The distal ulna was absent or excised at the time of surgery in nine patients, partially excised in two, and shortened in one. At a mean follow-up interval of 42 months, the primary union rate was 68%, and the secondary rate was 74%. Using a rating scale devised for this study, 37% excellent, 32% good, 26% fair, and 5% poor results were noted. Poor results were statistically associated with previous trauma (type 1 patients), infection, severe nerve injury, and multiple previous surgical procedures. This is a retrospective study, and because of the limitations of such studies, no correlation of results with forearm rotational position, preoperative wrist or elbow dysfunction, fusion location, distal ulna excision or synostosis union was noted. Significant complications were noted in 10 patients, with a higher rate in type 1 patients. Although one-bone forearm construction remains a viable salvage option for forearm instability in selected patients, results may be less predictable than previously reported.

Prosthetic usage in major upper extremity amputations.

Patterns of use of contemporary prostheses by 135 patients with major upper extremity amputations were evaluated by questionnaire. Eighty-four percent of the patients were male and 16% were female. Amputation levels represented were below elbow, 44%; above elbow, 40%; and shoulder disarticulations or forequarter amputations, 16%. The follow-up interval averaged 12 years (range, 1-67 years). One hundred and thirteen patients were fitted with either a myoelectric or body-powered prosthesis. The overall rejection rate was 38%. Thirty-nine of 42 in the below-elbow amputation group used the prosthesis and appeared to benefit the most. Eight of 141 in the wrist disarticulation group used the prosthesis: as did 9 of 21 in the above-elbow amputation group. In contrast, all bilateral amputees used their prostheses. Stiff shoulders and brachial plexus injury were both predictors for poor prosthetic usage.