A rhesus macaque model of Streptococcus pneumoniae carriage.

BACKGROUND: Nasopharyngeal colonization by Streptococcus pneumoniae precedes pneumococcal disease. Elucidation of procedures to prevent or eradicate nasopharyngeal carriage in a model akin to the human would help to diminish the incidence of both pneumonia and invasive pneumococcal disease. METHODS: We conducted a survey of the nasopharynx of infant rhesus macaques from our breeding colony, in search of natural carriers of S. pneumoniae. We also attempted experimental induction of colonization, by nasopharyngeal instillation of a human S. pneumoniae strain (19F). RESULTS: None of 158 colony animals surveyed carried S. pneumoniae in the nasopharynx. Colonization was induced in eight of eight infant rhesus by nasopharyngeal instillation and lasted 2weeks in 100% of the animals and 7weeks in more than 60%. CONCLUSION: Rhesus macaques are probably not natural carriers of S. pneumoniae. The high rate and duration of colonization obtained in our experiments indicates that the rhesus macaque will serve as a human-like carriage model.

Leptin, body composition, adrenal and gonadal hormones among captive male baboons.

Morphometric and hormonal measures were collected from 21 captive savanna baboons (Papio cynocephalus) maintained at the Tulane National Primate Research Center in order to determine age-related patterns in leptin levels over the life course as well as their relationships to body composition and adrenal and gonadal steroids. Comparison of leptin levels between peri-pubertal, adolescent, young adult, and fully mature males show lower levels among adolescent as compared with young adult males (P = 0.05 by Kruskal-Wallis ANOVA). In addition, abdominal fat varied among age groups (P = 0.003 by Kruskal-Wallis ANOVA) with the peri-pubertal animals lower than the adolescents, young adults, and prime adults. However leptin was not related to any measure of body composition, including abdominal fat, or to adrenal hormones (dehydroepiandrosterone, dehydroepiandrosterone-sulfate, and cortisol) or gonadal hormones (testosterone and estradiol). Age-related changes in leptin appear similar to those reported for captive rhesus macaques, while the failure to find an association between leptin and abdominal fat is interestingly different. These results confirm elevated levels of leptin in captive baboons compared with their wild counterparts and suggest that they result from changes in fetal development.

Pediatric recipients of three or more hepatic allografts: results and technical challenges.

BACKGROUND/PURPOSE: Children who require a liver transplant at an early age risk chronic allograft rejection (CAR) and other causes of allograft loss. Multiple retransplants may be required for long-term patient survival. The authors evaluate this approach based on our results and technical difficulties. METHODS: Charts of 7 children who received 3 or more liver transplants from 1989 to the present were reviewed retrospectively. RESULTS: A total of 151 children required liver transplantation at our institution since 1989. Of these, 4 boys and 3 girls (mean age, 6.2 years; range, 3 to 14 years) have received 3 or more allografts. The etiology of liver failure for the penultimate allograft was CAR (n = 6) and hepatic artery thrombosis (HAT; n = 1). Five cases required modification of portal vein or hepatic artery anastomoses. Two patients with vena caval strictures required supradiaphragmatic vena caval reconstruction. The original Roux-en-Y limb was adequate for biliary reconstruction in all cases. Five children currently are alive (survival rate, 71%) with good graft function having had a mean follow-up of 23 months (range, 2 to 48 mos.). CONCLUSIONS: The operative procedure for the multiple hepatic transplant child is challenging. The transplant team must be prepared for intraoperative issues such as extended organ ischemia time during hepatectomy, extensive blood loss, and potential need for creative organ revascularization techniques. Overall, multiple retransplant results are good and justify the use of multiple allografts.

Placental changes associated with fetal outcome in the Plasmodium coatneyi/rhesus monkey model of malaria in pregnancy.

Term placentas collected surgically from seven Plasmodium coatneyi-infected rhesus monkeys, one abortion, and five controls were evaluated histopathologically. The placentas from Plasmodium-infected dams had more significant pathologic changes than those from controls for six parameters (P < 0.05) and higher numbers of activated (LN5 + Zymed) macrophages in the intervillous space (IVS) (P = 0.0173). Total parasite load (TPL) was defined as the sum of all weekly peripheral infected red blood cell counts for each trimester and for the entire pregnancy. High first trimester PLs were more likely to result in fetal demise (P = 0.0476) or increased placental damage in surviving infants. As trimester 2-3 TPL increased, so did the number of activated macrophages (P < 0.05) and the total malaria pigment scores (P < 0.05). Low birth weight (LBW) and intrauterine growth retardation (IUGR) were associated with high pigment scores and high numbers of activated macrophages in the IVS. High placental damage scores were not associated with IUGR, LBW, or early infant mortality.

Living donor liver transplantation in critically ill children.

From December 1993, St Christopher's Hospital for Children, Philadelphia, PA, USA has provided living donors the opportunity to donate a portion of their liver to children who are critically ill. This report evaluates the results of living donor liver transplants (LDLT) in critically ill children. We retrospectively reviewed the first 22 LDLT at our institution and compared the patient and graft survival of the nine critically ill children with the 13 stable children. Twenty-two LDLT have been performed at our institution between December 1993 and October 1997. Nine of 22 transplants [United Network for Organ Sharing (UNOS) Status I] were performed in children who were critically ill. Thirteen of the LDLT (UNOS Status II and III) were performed on stable children either in the hospital or admitted electively from home. The median weight and age at the time of transplant were 7 kg (range 4.6-54.5 kg) and 16 months (range 3 months-12 yr), respectively, and there was no statistical difference between the two groups. In critically ill children the 1-yr allograft and patient survival was 66% and 89%, respectively, exceeding the published results from UNOS for patients on life support (59.5% graft and 69.7% patient survival at 1 yr). One-yr allograft and patient survival in the stable children was 92.3% and 100%, respectively. All living donors are alive and well with normal liver function. In conclusion, our results show that LDLT is a viable approach for transplantation in critically ill children with liver failure and should be offered to potential donors.

Plasmodium coatneyi in the rhesus monkey (Macaca mulatta) as a model of malaria in pregnancy.

Pregnant women with Plasmodium falciparum infection are at increased risk for complications such as anemia and cerebral malaria. In addition, the infants of these women suffer intrauterine growth retardation (IUGR), low birth weight (LBW), congenital infection, and high infant mortality. Although much has been learned from studies of malaria during human pregnancy, progress has been limited by the lack of a suitable animal model. Nonhuman primates are of particular interest because, other than the armadillo, they are the only animals with a discoidal, villous, hemochorial placenta like that of humans. We have established a model of malaria during human pregnancy by inoculating pregnant rhesus monkeys (Macaca mulatta) with Plasmodium coatneyi (a sequestering parasite) during the first trimester. In our initial experiment, four monkeys were inoculated with a fresh inoculum containing 10(8) viable parasites from an infected donor monkey. All four monkeys became parasitemic seven days postinoculation (PI) and three monkeys aborted 7-10 days PI coincident with high peak parasitemias (41,088-374,325 parasites/mm3). Although abortion is one of the outcomes observed in Plasmodium-infected women, the intent of this study was to examine the effects of Plasmodium infection throughout gestation. Since the rapid onset of high parasitemia may have been responsible for the abortions, a decision was made to reduce the size of the effective inoculum. Six additional pregnant monkeys were inoculated with a frozen isolate taken from the same donor containing 10(6) parasites. These six animals became parasitemic by 14 days PI and, along with monkey E412, carried their infants to term. These seven infants weighed significantly less at term than the infants of uninfected mothers (P = 0.0355). Symmetrical IUGR was detected by ultrasound in one fetus with an LBW of 334 g. Another LBW infant (300 g) had asymmetrical growth retardation, which has been associated with uteroplacental insufficiency and was consistent with the lower placental weights found in infected dams compared with controls (P = 0.0455). The infant with symmetric IUGR died at five days of age, while the other is alive but congenitally infected. The IUGR, LBW, congenital infection, postnatal infant mortality, and early abortions observed in these animals suggest that P. coatneyi in pregnant rhesus monkeys is a valid model of malaria in human pregnancy. This model should provide the opportunity to study questions about malaria in pregnancy that have been difficult to study in humans.

Results of transplantation for acute and chronic hepatic allograft rejection.

BACKGROUND/PURPOSE: Transplantation for rejection is a requirement in liver transplant recipients when allograft failure is imminent. The authors evaluated the outcome of these children and their allografts. METHODS: The medical records of 129 children who received a liver transplant were reviewed retrospectively. Twelve children required transplantation for biopsy-proven rejection--10 chronic and two acute. Overall patient and graft survival were compared with children receiving primary liver transplants. The current allograft function of the patients undergoing transplants was also reviewed. Statistical significance was determined by Fisher's Exact test. RESULTS: Twelve children received at least one retransplant for biopsy-proven rejection. Graft survival at 1 year was 58% (v 79% for primary transplants) and patient survival was 83% (vs 89%). Two allografts were lost because of primary allograft nonfunction. Three additional allografts were lost-two to recurrent rejection and one to hepatic artery thrombosis. Two patients who lost a second transplant to rejection required a total of seven transplants to treat rejection. Two children died, one of primary nonfunction and one of adenovirus pneumonia. The 10 surviving patients all have excellent graft function (total bilirubin, 0.74 +/- 0.38, aspartate aminotransferase, 40 +/- 22). CONCLUSION: These data suggest that transplantation for rejection can be accomplished safely with a patient survival rate comparable to primary liver transplantation; however, graft loss is excessive and underscores the need for more adequate immunosuppression.

Sensorineural hearing loss in children after liver transplantation.

OBJECTIVE: To investigate risk factors for sensorineural hearing loss (SNHL) in children after liver transplantation. DESIGN: Retrospective medical record review. SETTING: Pediatric tertiary care hospital. PATIENTS: One hundred twenty-five consecutive children who received liver transplants between March 1, 1987, and June 30, 1996. MAIN OUTCOME MEASURES: The presence of SNHL (bone conduction threshold of >35 dB of hearing loss in at least 1 frequency) and the cause of the liver abnormality in all 125 patients. In addition, among the subset of children who had biliary atresia and underwent transplantation before 2 years of age, the total dose (milligrams per kilogram of body weight) of aminoglycoside antibiotic medications (tobramycin sulfate, gentamicin sulfate, and amikacin sulfate) and of intravenous loop diuretic agents (furosemide) was compared between children with and without SNHL. RESULTS: Audiologic evaluations were available for 66 of 125 patients, 15 (12%) of whom have SNHL. Of 5 survivors with the short-bowel syndrome, 4 have severe to profound SNHL. Of 46 children who have biliary atresia and who underwent transplantation before 2 years of age, 8 (17%) have SNHL. Among the 26 evaluable children with biliary atresia undergoing liver transplantation before 2 years of age, logistic regression analysis revealed that the most important risk factor for SNHL was the cumulative dose of amikacin (P = .05). CONCLUSIONS: Children receiving liver transplants are at an increased risk for SNHL. Those with the short-bowel syndrome have the greatest prevalence of SNHL. Among the subset of children with biliary atresia receiving liver transplants before 2 years of age, statistical analysis demonstrates a dose-response relationship between the receipt of amikacin and the occurrence of SNHL.

Genetic galactocerebrosidase deficiency (globoid cell leukodystrophy, Krabbe disease) in rhesus monkeys (Macaca mulatta).

Globoid cell leukodystrophy, or Krabbe disease, is a severe disorder of the peripheral and central nervous system myelin caused by deficient galactocerebrosidase (GALC) activity. This autosomal recessive disease affects humans and animals including dogs, mice, and rhesus monkeys. Cloning of the human and animal GALC genes opened opportunities for therapeutic trials using animal models. We describe the clinical, pathologic, and biochemical features of the affected rhesus monkey. Affected monkeys had very low GALC activity and a two base pair deletion in both copies of the GALC gene. Clinical signs of tremors, hypertonia, and incoordination led to humane euthanasia by 5 months of age. At necropsy, peripheral nerves were enlarged. Microscopically, the cerebral, cerebellar, and spinal cord white matter was infiltrated with periodic acid-Schiff-positive multinucleated globoid cells, and there was a striking lack of myelin. Peripheral nerve fibers were decreased in number and separated by Alcian blue- and safranin O-positive material. Myelin sheaths were greatly diminished. Lipid analysis of brains of 12-day-old and 158-day-old affected monkeys revealed a great excess of psychosine in white matter. The rhesus monkey model will be especially useful for exploring treatment options, including prenatal bone marrow transplantation and various approaches to gene therapy.

Reduced cyclosporine absorption preceded acute allograft rejection in a child with a liver transplant.

This case report correlates impaired cyclosporine absorption from the traditional oral formulation in a 9-year-old liver transplant recipient with subsequent acute allograft rejection. Although impaired absorption in this patient was documented by cyclosporine pharmacokinetic profiling (steady-state area under the cyclosporine concentration-time curve or AUC), no indication was evident from the pre-dose cyclosporine trough level, which was within the typical target range of blood concentrations. However, when the subject received the microemulsion formulation of cyclosporine the AUC value reflected an adequate absorption pattern. We recommend that if malabsorption is suspected in the de novo pediatric liver transplant patient, then single-sample pre-dose trough cyclosporine levels should not be relied on as an indicator of sufficient immunosuppression and that a limited sampling strategy be used to confirm or rule out impaired absorption.

Split liver transplantation benefits the recipient of the 'leftover liver'.

The division of a single hepatic allograft to create two reduced-size grafts has been reported with decreased graft survival (50%) resulting in decreased enthusiasm for this approach. The authors reviewed their experience with 12 recipients of this procedure to evaluate the outcome of the children electively undergoing transplant with the "leftover liver." A retrospective review of six pairs of children receiving part of one hepatic allograft included donor anatomy, recipient operation, and allograft and patient outcomes. Recipient pairs were selected according to blood type compatibility, medical priority, and size restrictions of the larger right lobe and the smaller left lateral segment. Patient and graft survival were compared with elective and urgent patients undergoing whole or reduced-size transplants. Six donors weighed 71.8 +/- 17.4 kg and were 22.6 +/- 11.0 years of age. Recipients of the right lobe were 11.8 +/- 4.2 years of age and weighed 41.9 +/- 14 kg. Recipients of the left lateral segment were 1.81 +/- 1.1 years of age and weighed 9.85 +/- 1.82 kg. Six patients were initially offered the donor allograft because of their hospitalization, critical illness or waiting time. Six additional patients electively underwent transplantation with the leftover liver. Donor organs were screened for normal arterial anatomy. Division of the allograft was performed on the back table in the falciform groove. Generally the left lateral segment graft received the major portion of the hepatic artery and the right lobe the major portion of the portal vein. Five of six (83%) elective patients, two receiving the right lobe and three receiving the left lateral segment had prompt recovery and left the hospital without surgical complication. One recipient of a right lobe transplant died from primary allograft nonfunction. These results are not different from the outcomes of all elective patients who underwent transplantation with whole or reduced-sized transplants in the same program. The authors conclude that split liver transplantation benefits the stable patient who electively receives the liver leftover after reducing the size of a large donor liver for a critically ill child.

Absorption characteristics of a microemulsion formulation of cyclosporine in de novo pediatric liver transplant recipients.

In pediatric liver transplant recipients, oral cyclosporine (CsA) therapy may be complicated by impaired or delayed absorption during the initial weeks posttransplant. Neoral (NL) is a microemulsion preconcentrate formulation of CsA expected to increase the rate and extent of absorption of CsA and have less pharmacokinetic variability. The absolute bioavailability (F) of CsA from NL was compared with that of the currently marketed Sandimmune (SM) formulation in a double-blind, crossover study conducted in 9 pediatric liver transplant recipients (age 6 months to 11 years) between 8 and 20 days posttransplant. After determination of CsA pharmacokinetics for a steady-state intravenous dose, patients were randomized to receive a single oral dose of NL or SM in period I and the alternative formulation in period II. Clearance (Clt) and volume of distribution (Vss) values (mean +/- s.d.) calculated from the i.v. dose were similar to that previously reported for pediatric patients (Clt = 12.0 +/- 1.3 ml/min/kg; Vss = 2.2 +/- 0.2 L/kg). Mean F (+/- SD) for NL was significantly higher than SM (NL = 37.6 +/- 14.6%; SM = 24.7 +/- 8.0%; P = 0.05). Although not reaching statistical significance, the observed maximum blood concentration (Cmax) was higher, and the time to Cmax (Tmax) was shorter for NL in 8 or 9 patients. There were no significant correlations between age and any pharmacokinetic parameter for the group as a whole--however, there were statistically significant correlations between age and F for NL (r = 0.87; P = 0.02), and for age and Vss (r = 0.91; P = 0.01) for the 6 patients aged 2 years or less. In this pediatric liver transplant population, Neoral demonstrated improved absorption (% increase in F) compared to Sandimmune. In liver transplant recipients aged 2 years or less, absorption of Neoral may be a function of age and/or bowel length.

Rejection after pediatric liver transplantation is not the limiting factor to survival.

Liver transplantation became a very successful therapy when cyclosporin A was introduced as an immunosuppressive agent. In an effort to evaluate the contribution of difficult or uncontrolled allograft rejection to mortality, the authors determined the most important factors that limited survival after liver transplantation. Eighty-two children received a total of 94 liver transplants from January 1987 to the present. Patients' records were reviewed for complications that contributed to morbidity and mortality and to assess which complications were preventable. Twelve patients died (15%), nine within 6 weeks of liver transplantation. The chief contributing cause of death was hepatic artery thrombosis (one patient), brain death after liver transplantation for fulminant hepatic failure (two patients), primary allograft nonfunction or dysfunction (two patients), allograft rejection (three patients), or other problems (four patients). Overall, hepatic artery thrombosis occurred in 3.1%, allograft rejection in 57%, fulminant hepatic failure in 7%, and donor organ dysfunction in 7%. Allograft rejection contributed directly to the cause of death in three children (4%). The authors conclude that few deaths after pediatric liver transplantation are caused by failure of immunosuppression. A high survival rate can be achieved after transplantation by eliminating the correctable complications that most frequently occur in the early postoperative period.

Isolated liver transplantation for liver failure in patients with short bowel syndrome.

The ultimate prognosis for patients with short bowel syndrome (SBS) has become progressively more favorable over the past decade. Advances in long-term total parenteral nutrition (TPN) have allowed this group of patients to meet nutritional needs while the process of intestinal adaptation occurs. Unfortunately, a subgroup of patients with SBS have hepatic failure (HF), most often secondary to TPN-induced cholestasis. Combined small bowel and liver transplantation (LT) offers a sound anatomic solution for cases of HF with SGS, but it remains experimental at this time. We propose that an isolated LT is a viable alternative mode of therapy for the patient with HF and SBS. The following characteristics were reviewed for five patients with SBS and HF who underwent LT: age at transplantation, weight, liver function, survival, intestinal length, volume of feeding before surgery, and current feeding tolerance and liver function. Four boys and one girl, aged 5.5 to 15 months (average, 11.9), had LT. The total bilirubin level at the time of transplantation was 14.4 to 37 mg/dL (average, 24.7). The patients weighed between 3.8 and 12 kg (average, 8.0), and feeding tolerance ranged from no enteric to complete enteric feeding (average, < 33% of calories by enteric feeding). Bowel loss was attributed to necrotizing enterocolitis in two cases, volvulus in two, and birth hypoxia in one. Bowel length ranged from 60 to 120 cm (average, 88.6). Four children (80%) survived LT, and the average follow-up period was 9.3 months. Three (75%) are home; one is on combined hyperalimentation and enteral feeding, and two are on full enteric feeding. One remains in a chronic care facility, on combined enteral and intravenous feeding. The average daily enteral feeding now comprises more than 70% of caloric requirements. The total bilirubin level is .6 to .8 mg/dL (average, .71). Isolated LT for HF in the patient with SBS effectively restores liver function, allowing time for further intestinal adaptation.

Monotherapy with cyclosporine for chronic immunosuppression in pediatric liver transplant recipients.

Children who survive liver transplantation (LT) suffer the adverse effects of life-long immunosuppression. In an attempt to minimize these effects, we have instituted a program of tapering immunosuppression, resulting in chronic monotherapy for children after LT. Seventy-three children ages 4 months to 19 years received LT between January 1987 and December 1992. Patient survival was 85% (62/73), with graft survival of 73%, at one year. Triple therapy with prednisone, cyclosporine, and azathioprine begun at transplant was tapered as follows: 1-2 mg/kg prednisone at discharge was reduced by .2 mg/kg every 2 months until a .2 mg/kg total was reached. Alternate-day steroids (.2 mg/kg) were begun at 1 year and discontinued at 1.5 years. AZA (1 mg/kg) was begun posttransplant and discontinued after any serious viral illness or by 1 year. Currently 37 survivors are > 18 months post-LT and were considered candidates for monotherapy. Monotherapy was attempted in 28 (76%), and 25 of these remain on monotherapy an average of 2 years later. All have normal liver function. After monotherapy and alternate-day steroids were achieved, 66% of children < 5th percentile for height at the time of transplant improved to greater than the 5th percentile. There were 3 (11%) patients who rejected while on monotherapy an average of 1.15 years after it was started. These patients had the following predisposing factors that decreased cyclosporine levels and led to rejection: common bile duct stricture, chronic and intermittent antibiotic administration for urinary tract infection, and noncompliance. In the 9 potential candidates not tapered to monotherapy, 6 have had recurrent acute or chronic rejection; 2 of these now receive FK506. We conclude that the majority of stable pediatric LT recipients may be safely tapered to chronic cyclosporine monotherapy. Increased growth is a major benefit of decreased steroid dosing in these children. Cyclosporine absorption and adequate levels are crucial for success of this approach.