The Effect of MHC Antigen Matching Between Donors and Recipients on Skin Tolerance of Vascularized Composite Allografts.

The emergence of skin-containing vascularized composite allografts (VCAs) has provided impetus to understand factors affecting rejection and tolerance of skin. VCA tolerance can be established in miniature swine across haploidentical MHC barriers using mixed chimerism. Because the deceased donor pool for VCAs does not permit MHC antigen matching, clinical VCAs are transplanted across varying MHC disparities. We investigated whether sharing of MHC class I or II antigens between donors and recipients influences VCA skin tolerance. Miniature swine were conditioned nonmyeloablatively and received hematopoietic stem cell transplants and VCAs across MHC class I (n = 3) or class II (n = 3) barriers. In vitro immune responsiveness was assessed, and VCA skin-resident leukocytes were characterized by flow cytometry. Stable mixed chimerism was established in all animals. MHC class II-mismatched chimeras were tolerant of VCAs. MHC class I-mismatched animals, however, rejected VCA skin, characterized by infiltration of recipient-type CD8+ lymphocytes. Systemic donor-specific nonresponsiveness was maintained, including after VCA rejection. This study shows that MHC antigen matching influences VCA skin rejection and suggests that local regulation of immune tolerance is critical in long-term acceptance of all VCA components. These results help elucidate novel mechanisms underlying skin tolerance and identify clinically relevant VCA tolerance strategies.

Kidney-induced cardiac allograft tolerance in miniature swine is dependent on MHC-matching of donor cardiac and renal parenchyma.

Kidney allografts possess the ability to enable a short course of immunosuppression to induce tolerance of themselves and of cardiac allografts across a full-MHC barrier in miniature swine. However, the renal element(s) responsible for kidney-induced cardiac allograft tolerance (KICAT) are unknown. Here we investigated whether MHC disparities between parenchyma versus hematopoietic-derived "passenger" cells of the heart and kidney allografts affected KICAT. Heart and kidney allografts were co-transplanted into MHC-mismatched recipients treated with high-dose tacrolimus for 12 days. Group 1 animals (n = 3) received kidney and heart allografts fully MHC-mismatched to each other and to the recipient. Group 2 animals (n = 3) received kidney and heart allografts MHC-matched to each other but MHC-mismatched to the recipient. Group 3 animals (n = 3) received chimeric kidney allografts whose parenchyma was MHC-mismatched to the donor heart. Group 4 animals (n = 3) received chimeric kidney allografts whose passenger leukocytes were MHC-mismatched to the donor heart. Five of six heart allografts in Groups 1 and 3 rejected <40 days. In contrast, heart allografts in Groups 2 and 4 survived >150 days without rejection (p < 0.05). These data demonstrate that KICAT requires MHC-matching between kidney allograft parenchyma and heart allografts, suggesting that cells intrinsic to the kidney enable cardiac allograft tolerance.

Vascularized composite allograft tolerance across MHC barriers in a large animal model.

Vascularized composite allograft (VCA) transplantation can restore form and function following severe craniofacial injuries, extremity amputations or massive tissue loss. The induction of transplant tolerance would eliminate the need for long-term immunosuppression, realigning the risk-benefit ratio for these life-enhancing procedures. Skin, a critical component of VCA, has consistently presented the most stringent challenge to transplant tolerance. Here, we demonstrate, in a clinically relevant miniature swine model, induction of immunologic tolerance of VCAs across MHC barriers by induction of stable hematopoietic mixed chimerism. Recipient conditioning consisted of T cell depletion with CD3-immunotoxin, and 100 cGy total body irradiation prior to hematopoietic cell transplantation (HCT) and a 45-day course of cyclosporine A. VCA transplantation was performed either simultaneously to induction of mixed chimerism or into established mixed chimeras 85-150 days later. Following withdrawal of immunosuppression both VCAs transplanted into stable chimeras (n=4), and those transplanted at the time of HCT (n=2) accepted all components, including skin, without evidence of rejection to the experimental end point 115-504 days posttransplant. These data demonstrate that tolerance across MHC mismatches can be induced in a clinically relevant VCA model, providing proof of concept for long-term immunosuppression-free survival.

Skin grafts from genetically modified α-1,3-galactosyltransferase knockout miniature swine: A functional equivalent to allografts.

Burn is associated with a considerable burden of morbidity worldwide. Early excision of burned tissue and skin grafting of the resultant wound has been established as a mainstay of modern burn therapy. However, in large burns, donor sites for autologous skin may be limited. Numerous alternatives, from cadaver skin to synthetic substitutes have been described, each with varying benefits and limitations. We previously proposed the use of genetically modified (alpha-1,3-galactosyl transferase knockout, GalT-KO) porcine skin as a viable skin alternative. In contrast to wild type porcine skin, which has been used as a biologic dressing following glutaraldehyde fixation, GalT-KO porcine skin is a viable graft, which is not susceptible to loss by hyperacute rejection, and undergoes graft take and healing, prior to eventual rejection, comparable to cadaver allogeneic skin. In the current study we aimed to perform a detailed functional analysis of GalT-KO skin grafts in comparison to allogeneic grafts for temporary closure of full thickness wounds using our baboon dorsum wound model. Grafts were assessed by measurement of fluid loss, wound infection rate, and take, and healed appearance, of secondary autologous grafts following xenograft rejection. Comparison was also made between fresh and cryopreserved grafts. No statistically significant difference was identified between GalT-KO and allogeneic skin grafts in any of the assessed parameters, and graft take and function was not adversely effected by the freeze-thaw process. These data demonstrate that GalT-KO porcine grafts are functionally comparable to allogeneic skin grafts for temporary closure of full thickness wounds, and support their consideration as an alternative to cadaver allogeneic skin in the emergency management of large burns.

Delayed type IV hypersensitivity reaction to porcine acellular dermal matrix masquerading as infection resulting in multiple debridements.

INTRODUCTION: Delayed type IV hypersensitivity reactions are well established in the surgical setting with respect to external exposure via topical antibiotics and internal exposure via synthetic materials. In contrast, biologic matrix is derived from decellularized human or animal tissues and is consequently believed to elicit a minimal host inflammatory response. OBJECTIVE: We report a case of delayed type IV hypersensitivity reaction secondary to a biologic comprised of porcine-derived acellular dermal matrix, [Strattice™]. CONCLUSIONS: While biologic matrix is often preferred over synthetic mesh due to its decreased risk for infection, this case emphasizes that potential for hypersensitivity to the material persists. Type IV hypersensitivity reactions should be included in the differential diagnosis for suspected post-operative infections.

Human umbilical cord blood-derived mast cells: a unique model for the study of neuro-immuno-endocrine interactions.

Findings obtained using animal models have often failed to reflect the processes involved in human disease. Moreover, human cultured cells do not necessarily function as their actual tissue counterparts. Therefore, there is great demand for sources of human progenitor cells that may be directed to acquire specific tissue characteristics and be available in sufficient quantities to carry out functional and pharmacological studies. Acase in point is the mast cell, well known for its involvement in allergic reactions, but also implicated in inflammatory diseases. Mast cells can be activated by allergens, anaphylatoxins, immunoglobulin-free light chains, superantigens, neuropeptides, and cytokines, leading to selective release of mediators. These could be involved in many inflammatory diseases, such as asthma and atopic dermatitis, which worsen by stress, through activation by local release of corticotropin-releasing hormone or related peptides. Umbilical cord blood and cord matrix-derived mast cell progenitors can be separated magnetically and grown in the presence of stem cell factor, interleukin-6, interleukin-4, and other cytokines to yield distinct mast cell populations. The recent use of live cell array, with its ability to study such interactions rapidly at the single-cell level, provides unique new opportunities for fast output screening of mast cell triggers and inhibitors.

Fetal heart rate patterns preceding death in utero.

Four cases of intrauterine fetal demise in term infants are presented. From these cases and other published reports, a sequence of fetal heart rate changes preceding intrapartum death is presented. Late or variable decelerations, if unrelieved or uncorrected, lead to baseline heart rate changes of tachycardia and loss of variability reflecting loss of fetal reserve and fetal distress. This is followed by an unstable heart rate, a sinusoidal pattern, or a rapidly changing fetal heart rate. The final event is a profound bradycardia just prior to fetal demise.

Effect of mode of delivery on morbidity and mortality of infants at early gestational age.

The effect of mode of delivery on the mortality and morbidity of 26- to 32-week neonates was studied. Five hundred six consecutive deliveries at 26 to 32 weeks' gestation were reviewed. The populations were divided into high-risk and low-risk neonates by evaluation of antepartum variables known to increase neonatal risk, ie, abruptio placenta. One hundred ninety-six infants were classified as low risk. In this group, 124 vaginal and 72 cesarean section deliveries were compared using demographic, peripartum, and neonatal variables. Cesarean delivery was associated with highly significant maternal morbidity, including a 30% incidence of vertical uterine incision. No difference in neonatal mortality was shown. Cesarean delivery was associated with lower one-minute Apgar scores and a greater incidence and severity of hyaline membrane disease. No neonatal differences were shown in the incidence of trauma, intraventricular hemorrhage, or seizures. This study does not support cesarean delivery of all tiny neonates.

Bulimia nervosa in pregnancy: a case report.

Bulimia nervosa is an eating disorder characterized by secretive binge eating and purging with induced vomiting, laxatives, and diuretics. The disorder primarily afflicts young white women between 18-35 years of age. We report the case of a 30-year-old pregnant woman with a 17-year history of bulimia that involved up to six episodes of binging and purging daily. A multidisciplinary approach enabled outpatient management throughout gestation. The pregnancy resulted in the delivery of a normal 3000-g female infant at term. The ramifications for maternal and fetal well-being and the goals of therapeutic management are discussed.

Effect of bacterial growth on the bursting pressure of fetal membranes in vitro.

By mounting a layer of chorioamniotic membrane on a specially designed reaction vessel, we studied the effect of Escherichia coli and/or group B streptococcus growing on the decidual surface of the membranes in tissue culture or bacteriologic medium. The organisms grew equally well in either medium. When growing in tissue culture medium, either organism significantly weakened the membranes as compared with controls (membranes incubated in the absence of either organism). Membranes derived from pregnancies delivered vaginally or abdominally responded similarly. When organisms were grown in bacteriologic medium, bursting pressures did not decrease. Addition of bacteriologic medium (20-60%) to tissue culture medium did not affect bacterial growth, but inhibited significantly the lowering of bursting pressures. Bacteriologic medium also inhibited the peroxidase-H2O2-halide system in vitro. Heat-killed bacteria and/or supernatants of culture medium previously inoculated with bacteria were not effective in weakening membranes. The results suggest that live bacteria in conjunction with active membrane metabolism lead to a weakening and eventual rupture of the membranes.

Survival of infants born at 24 to 28 weeks' gestation.

Factors affecting the survival of 136 consecutive live-born infants delivered at 24 to 28 weeks' gestation during a 4-year period were analyzed. After careful assessment of gestational age, perinatal care for the fetus of at least 26 weeks' gestation was aggressive. Survival at 26 weeks was 45% and at 28 weeks, 92%. Multivariate analysis showed that the set of variables that best predicts neonatal outcome is gestational age, antepartum glucocorticoid administration, and resuscitation at birth.

Quantitative transcervical uterine cultures with a new device.

This study was initiated to examine the ability of a new device to take transcervical cultures of the endometrial cavity in the normal and postpartum uterus. Quantitative bacteriologic assessments were made. The results show there is a millionfold increase in the mean concentration of bacteria cultured from the infected puerperal uterus when contrasted with cultures from nonpregnant women and those who have just undergone repeat cesarean section. The authors conclude that the new device obtains cultures transcervically with marked reduction in contamination; however, some method for quantification of bacterial populations must complement the culture so that results differentiate between colonization and infection.

Prognostic components of the nonreactive nonstress test.

From January 1976 to November 1978, 2592 nonstress tests were performed at the authors' institution on 862 fetuses, of which 2239 (86.3%) had reactive and 353 (13.6%) had nonreactive results. Of these 862 fetuses, 842 were delivered at the authors' hospital. Of these 842 fetuses, 109 were delivered within 1 week of a nonreactive tracing and 733 were delivered within 1 week of a reactive tracing. A retrospective analysis was performed on 102 of the nonreative tracings done within 1 week of delivery to assess the significance of various components of the nonstress test on the subsequent stress test and perinatal outcome. No significant difference could be observed in the number of fetal movements and total number of accelerations as compared with the subsequent stress test. However, the nonreactive tracings of the contraction stress test (CST)-positive group differed from those of the CST-negative groups in number of accelerations over 15 beats per minute (38% versus 48%) (P < .05) and in the number of accelerations lasting longer than 20 seconds (20% versus 50%) (P < .01). The number of nonreactive fetal movements per test (2.6 versus 0.96) (P < .05) and the percentage of nonreactive fetal movements (33% versus 15%) (P < .01) were different in both groups. The growth-retarded fetus in the nonreactive group did not differ in the number of fetal movements or total accelertions when compared to fetuses born appropriate for gestational age, but the number of accelerations was more than 15 beats per minute (26% versus 50%) (P < .01) and the number of accelerations lasting 20 seconds (11% versus 28%) (P < .01) did differ significantly.

24-hour urine creatinine excretion in pregnancy.

A total of 489 consecutive 24-hour urine collection from 162 patients were analyzed for creatinine excretion. The 24-hour creatinine excretion increased with the urine volume. Creatinine excretions in 24-hour urine collections were not statistically different between in- and out-patients. The results indicate that the mean urine creatinine per 24 hours is 1.08 g for 24-hour urine volumes between 500 and 1500 ml. For urine volumes greater than 1500 ml it is 1.22 g. For 24-hour urine volumes less than 500 ml, the mean creatinine is 0.63 g.

Correlation between amniotic fluid optical density and L/S ratio.

A test that circumvents the complex methodology needed for the determination of L/S ratios has been developed. It has been observed that the optical density, measured at 400 nm, of supernatants collected from fresh amniotic fluids centrifuged at 2000 g for 10 minutes correlates with L/S ratios.

Amniotic fluid optical density and neonatal respiratory outcome.

A simple, rapid, economical, and accurate test to assess fetal pulmonary maturity on a 24-hour basis, 7 days a week, is urgently needed. A 15-minute test has been developed that correlates well with fetal pulmonary maturity. Optical density (OD) readings at 650 nm of greater than or equal to 0.15 in pigment-free, centrifuged (2000 Xg, 10 minutes) amniotic fluids obtained from gestations of 33 to 42 weeks correlate with fetal pulmonary maturity (131 of 131, 100%). When OD readings are less than 0.15 in fluids from gestations of 24 to 40 weeks, and antepartum steroids are utilized, the incidence of respiratory distress syndrome (RDS) is 8.3% (14 of 169). The true false-negative rate in this group is therefore unknown.

Relation between optical density at 650 nm and L/S ratios.

A simple and rapid test that correlates with L/S ratios has been developed. By centrifuging fresh, unfrozen amniotic fluids at 200g for 10 minutes and measuring the optical density at at 650 nm, correlation with L/S ratios is obtained. Optical density readings of 0.15 or greater correlate 100% with L/S ratios of 2.0 or greater. Optical readings below 0.15 correlate 94% with L/S ratios below 2.0.

The legal liability of the medical consultant in pregnancy.

The potential for professional liability that accompanies complications associated with obstetric care can be minimized by an understanding of the roles and responsibilities of both the consultant and the obstetrician. Critical to this is a fundamental knowledge of the medical malpractice action from a legal perspective. This article discusses several issues involved in professional liability as it relates to the obstetrician/gynecologist.

Suction-assisted lipectomy for lipodystrophy syndromes attributed to HIV-protease inhibitor use.

The addition of HIV-protease inhibitors to the arsenal of therapies for the treatment of HIV infection has resulted in significant suppression of viral load such that HIV-positive individuals experience reduced morbidity and extended life expectancy. Recently, a number of syndromes have been described involving abnormal fat distribution that may be associated with prolonged HIV-protease inhibitor therapy. These syndromes include hypertrophy of the cervicodorsal fat pad ("buffalo hump"); a tendency toward increased central adiposity ("protease paunch"); adiposity in the submental, mandibular, and lateral cheek regions of the face; and hypertrophy of adipose tissue in the breast in women. A peripheral lipodystrophy, or fat-wasting, in the extremities and face (particularly the malar and nasolabial fold regions) has also been observed. As these patients live longer and healthier lives, many are beginning to seek surgical correction of the disfigurements. In this regard, we present a review of the literature regarding these recently described syndromes to familiarize plastic and reconstructive surgeons with the unique deformities encountered in this ever-increasing patient population. We also present our results with suction-assisted lipectomy for treatment of these deformities. Physical findings, pathogenesis, and surgical management are discussed.

Laser blepharoplasty with transconjunctival orbicularis muscle/septum tightening and periocular skin resurfacing: a safe and advantageous technique.

Carbon dioxide (CO2) laser blepharoplasty with orbicularis oculi muscle tightening and periorbital skin resurfacing is a safe procedure that produces excellent aesthetic results and diminishes the occurrence of complications associated with skin and muscle resection in the lower lid, particularly permanent scleral show and ectropion. The authors present a review of 196 cases of carbon dioxide laser blepharoplasty and periocular laser skin resurfacing performed at their center from April of 1994 to September of 1998. Of these cases, 113 patients underwent four-lid blepharoplasty, 59 underwent upper lid blepharoplasty only, and 24 underwent lower lid blepharoplasty only. Prophylactic lateral canthopexy was performed in 24 patients. Concomitant procedures (brow lift/rhytidectomy/rhinoplasty) were performed in 92 patients. The carbon dioxide laser blepharoplasty procedure resulted in no injuries to the globe, cornea, or eyelashes. Combined with laser tightening of the orbicularis oculi muscle and septum and periocular skin resurfacing, the transconjunctival approach to lower blepharoplasty preserves lower lid skin and muscle. Elimination of the traditional scalpel skin/muscle flap procedure results in a dramatically lower complication rate, particularly with regard to permanent ectropion and scleral show. Laser shrinkage of the orbicularis muscle and septum through the transconjunctival incision enables the correction of muscle aging changes such as orbicularis hypertrophy and malar festoons. The addition of periocular resurfacing enables the correction of skin aging changes of the eyelid that are not addressed by traditional scalpel blepharoplasty. In addition, lateral canthopexy constitutes an important adjunct to the laser blepharoplasty procedure for the correction of lower lid canthal laxity.