Donor MHC Class I Peptides in Conjunction With Self-Epitopes Induce Donor-Specific Tolerance in a Dose-Dependent Manner But Unable to Abrogate Chronic Rejection

Understanding specific tolerance mechanisms is a primary goal of transplantation science. We have previously shown that hosts treated with MHC class I protein have donor sequences in the alpha1-helix of the alpha1 domain on a background of self-epitopes, resulting in the development of donor-specific tolerance. However, the nature of class I alloantigenic determinants that regulate the alloimmune response remains unclear. The alpha1-helical sequence of RT1.A,1 which shares RT1.A(u) sequences, was substituted in the RT1.A(a) molecule to produce the composite [alpha1h(l/u)]-RT1.A(a) MHC class I allochimeric molecule. Immunodominant epitopes were identified within the hypervariable region of the alpha1 domain of RT1.A(a) (ACI), RT1.Al (Lewis, LEW), and RT1.A(u) (Wistar Furth [WF]). To clarify the mechanisms of tolerance development through presentation of donor-type immunogenic epitopes and cryptic self-epitopes we used synthetic peptides corresponding to donor immunogenic determinants with peptides derived from recipient self-sequences (RT1.A(a)--aa 10 to 49 P1 and 91 to 120 P3; and P2 RT1.A(l/u) 50 to 90). ACI recipients of LEW and WF cardiac allografts were injected through the portal vein (PV) at day 0 with four doses (2, 0.5, 0.25, and 0.125 mg/rat) of three peptide mixtures in conjunction with subtherapeutic CsA (10 mg/kg for 3 days). Allograft survival was strongly dose-dependent. Only low-dose regimens were consistent in tolerance induction, but such therapy did not abrogate development of chronic rejection (CR), unlike allochimeric therapy with soluble MHC class I protein. Different effects of protein or synthetic peptide therapies on development of CR suggest that development of specific tolerance is an active immunologic process and it depends on the form of allogeneic epitopes presented.

Allochimeric therapy induces unique regulatory T cells that mitigate chronic rejection

Induction of tolerance to an allogeneic graft without the need for nonspecific immunosuppression is a major goal of transplantation therapy. We have shown that treatment with molecularly engineered, allochimeric [alpha(1h)(1/u)]-RT1.Aa class I MHC antigens bearing donor-type Wistar-Furth (WF, RT1.A(u)) or Lewis (LEW, RT1A(1)) amino acid substitutions for host-type ACI (RTI.A(a)) sequences in the alpha(1)-helical region induces donor-specific tolerance to cardiac allografts in rat recipients. The mechanisms involved in the establishment and maintenance of specific allograft tolerance are still not fully understood. It is now clear that acquisition of transplantation tolerance is an active, highly regulated, multistep process. According to the pool size model of allograft tolerance, the allograft outcome, rejection, or tolerance often depend on the balance between cytopathic and regulatory T cells (T-regs). This study examined mechanisms of chronic rejection (CR) development on a model of cardiac transplant tolerance after adoptive transfer of T-regs followed by allochimeric therapy. Generation of T-regs was demonstrated in vitro by MLR coculture and confirmed by adoptive transfer of T cells from primary recipients to secondary hosts. To confirm the true nature of regulatory cells, we performed a second transfer into tertiary recipients. Unlike T-regs from tolerant hosts, T cells from naive rats did not prolong graft survival. Histological evaluation of T-regs-transfected groups showed absence of visible CR. In contrast, T-regs generated in recipients after high-dose cyclosporine treatment failed to inhibit CR in transferred singeneic recipients. Allochimeric therapy triggers generation of unique regulatory lymphocytes that mitigate development of chronic rejection through regulation of anti-inflammatory mechanisms and down-regulation of alloantibody response.

Cost analysis of Down syndrome screening in advanced maternal age

OBJECTIVE

To analyze the potential cost and efficacy of Down syndrome screening in the population with advanced maternal age.

METHODS

Three screening methods defining Down syndrome risk for women with advanced maternal age were analyzed: advanced maternal age; advanced maternal age and maternal serum triple screen; and advanced maternal age, maternal serum triple screen and genetic sonogram. Costs for all tests and procedures were estimated. Procedure-related loss for amniocentesis was assumed to be 1:200. Efficacy was defined as: number of amniocenteses performed, number of Down syndrome cases detected, procedure-related losses, Down syndrome cases detected per fetal loss, cost per Down syndrome case detected and total cost of screening.

RESULTS

In 1999 in the USA, there were 530,610 women with advanced maternal age at 16 weeks' gestation carrying an estimated 4,043 fetuses with Down syndrome. Screening by maternal age alone would result in the 100% detection of Down syndrome cases, but would require over 530,000 amniocenteses and result in 2,653 procedure-related losses. Combining age with serum screen and genetic sonogram would detect 97.6% of Down syndrome cases, but would require only 119,791 amniocenteses and result in 599 procedure-related losses. The projected cost per Down syndrome case detected using age screening is 219,109 dollars versus 155,992 dollars using serum screen and genetic sonogram.

CONCLUSIONS

The combination of advanced maternal age, maternal serum screen and genetic sonogram would result in the fewest procedure-related losses and lowest cost per Down syndrome case detected.

The limits of narratives in understanding teacher thinking

Researchers have argued that narrative provides insight into teachers' thinking and a model for the storage of knowledge about teaching. Concurrently, however, there are numerous cautions about using narratives as data sources. The present study addresses two problems: the limits of narrative as a data source and the feasibility of productively analyzing narratives. It also addresses the question of whether teachers actually store information as narratives. For the study, 23 deaf or hearing teachers of the Deaf participating in a project on integrating technology into teaching were interviewed about their experiences as teachers in general and in using technology in the classroom in particular. They rarely generated stories spontaneously. Rather, responses were related to the nature of the stimulus question. For example, when asked about their "worst class," teachers did not provide complete narratives but instead gave responses containing problems without resolutions. The study results suggest that teachers do not store information about teaching as narratives, but nonetheless can expertly construct narratives when given the right opportunity.

Evaluation and follow-up of fetal hydronephrosis

OBJECTIVE

To determine the antenatal course and neonatal follow-up of isolated fetal hydronephrosis.

METHODS

We reviewed our ultrasonography database from January 1989 to June 1999 for all cases of unilateral or bilateral fetal hydronephrosis that had at least 1 follow-up ultrasonographic examination. Cases were defined as mild, moderate, or severe depending on the renal pelvis anteroposterior diameter and gestational age. Data were analyzed using the chi2 test with the Fisher exact test where appropriate. Medical records were reviewed, and telephone interviews were performed to determine which infants received follow-up after birth.

RESULTS

Of 57,966 ultrasonographic examinations in 20,049 women during the study period, 393 patients met criteria for evaluation. Of these, 347 (88%) had fetuses with mild hydronephrosis. Most of these had complete resolution during the pregnancy. Forty patients had fetuses classified as having moderate hydronephrosis, and 6 patients had fetuses with severe hydronephrosis. Of those classified as moderate hydronephrosis, 15% resolved, 25% improved, 48% remained unchanged, and 12% worsened during the pregnancy. There were no cases of in utero resolution in the severe group; however, 4 of 6 cases improved to moderate or mild, and 2 cases remained unchanged. Of the cases identified prenatally, 25 received consultation by a pediatric urologist in the newborn period, and 7 of these required surgical intervention.

CONCLUSIONS

Our population-based data suggest that most cases of mild hydronephrosis will resolve before delivery. In contrast, cases of moderate or severe hydronephrosis are less likely to have resolution in utero and are more likely to worsen or remain unchanged. Of those fetuses with persistent hydronephrosis, only a small number required some surgical intervention after birth. This information is useful in counseling the patient whose fetus is noted to have isolated hydronephrosis.

Is an isolated fetal cardiac echogenic focus an indication for fetal echocardiography?

OBJECTIVE

To determine whether the presence of an isolated fetal cardiac echogenic focus should be an indication for fetal echocardiography.

METHODS

We reviewed our fetal echocardiography and obstetrics databases from January 1992 through July 1999. The study groups were formulated from patients referred for fetal echocardiography. Patients referred for echocardiography because of a single isolated fetal cardiac echogenic focus were compared with patients referred for other indications. The sensitivity, specificity, and positive and negative predictive values were calculated for an isolated echogenic focus as a marker for structural cardiac abnormalities as detected by fetal echocardiography.

RESULTS

Of 10,406 fetuses seen for ultrasonography, 1908 had fetal echocardiography. Cardiac abnormalities were identified in 3.4% (65 of 1908) of the fetuses that had echocardiography. The prevalence of an isolated echogenic focus was 2.2% (230 of 10,406) and was the indication in 12.1% (230 of 1908) of our echocardiograms. Only 1 of the 230 fetuses with an isolated echogenic focus had a structural cardiac defect (membranous ventricular septal defect). An isolated echogenic focus as a marker for congenital cardiac defects resulted in sensitivity and specificity of 1.5% and 87.6%, respectively. The positive and negative predictive values were 0.4% and 96.2%, respectively The relative risk for an echogenic focus in predicting congenital cardiac defects was 0.11 (95% confidence interval, 0.02-0.82).

CONCLUSIONS

An isolated fetal cardiac echogenic focus is not an efficacious marker for congenital cardiac defects. It should not be the sole indication for fetal echocardiography.

Blood pressure monitoring during pregnancy

Hypertensive disease in pregnancy represents a significant health problem in the world, and ranks second only to thromboembolism as a cause of maternal mortality in the USA. In addition, hypertension is associated with both perinatal morbidity and mortality secondary to direct effects on the fetus as well as the iatrogenic preterm deliveries performed for maternal indications. Conventional (office, mercury column or aneroid manometry) blood pressure measurement is the most common screening test performed during prenatal visits. During the past several years, investigators have focused on the use of 24-h ambulatory and automated self (or home) blood pressure monitoring during pregnancy. This review article summarizes the current literature on both ambulatory and home blood pressure monitoring in pregnancy and how they relate to various clinical aspects of hypertension in pregnancy.

Irreversible maternal brain injury during pregnancy: a case report and review of the literature

Maternal brain death or massive injury leading to persistent vegetative state during pregnancy is a rare event. Since 1979, 11 cases, including the current one, of irreversible maternal brain damage in pregnancy have been reported. In all but one, the pregnancies were prolonged with a goal of achieving delivery of a viable infant. Current advances in medicine and critical care enable today's physician to offer prolonged life-support to maximize the chances for survival in the neonate whose mother is technically brain dead. We present a case at our institution and review all previously published cases in the English literature for comparison as well as make management recommendations.

Outcome of pregnancies complicated by ruptured membranes after genetic amniocentesis

OBJECTIVE

We sought to compare perinatal outcomes of pregnancies complicated by preterm premature rupture of membranes after genetic amniocentesis with pregnancies complicated by spontaneous preterm premature rupture of membranes at a similar gestational age.

STUDY DESIGN

A retrospective study was performed in which a computerized database was reviewed to identify all patients presenting to our institution with preterm premature rupture of membranes within 48 hours of a genetic amniocentesis from July 1988 to August 1999. Control subjects were matched for gestational age at preterm premature rupture of membranes. Patients were all managed expectantly. Outcomes were compiled from review of medical records. Descriptive statistics, the Student t test, and the chi(2) test were used, with P <.05 considered significant.

RESULTS

During the study period, genetic amniocentesis was performed 1101 times. Eleven (1%) women presented within 48 hours with preterm premature rupture of membranes. The mean gestational age at the time of rupture was not different between the cases in which preterm premature rupture of membranes occurred after genetic amniocentesis compared with the control subjects in whom preterm premature rupture of membranes occurred spontaneously (16.5 weeks vs 17.6 weeks, respectively). Women with preterm premature rupture of membranes after amniocentesis experienced significantly longer latency periods (124 vs 28 days; P =.0001) and delivered at more advanced gestational ages (34.2 vs 21.6 weeks; P =.0002) than those with spontaneous preterm premature rupture of membranes. The perinatal survival rate was 91% in pregnancies complicated by preterm premature rupture of membranes after genetic amniocentesis compared with a rate of 9% in control subjects (P =.005).

CONCLUSIONS

Pregnancies complicated by preterm premature rupture of membranes after genetic amniocentesis result in significantly better perinatal outcomes compared with pregnancies complicated by spontaneous preterm premature rupture of membranes at a similar gestational age. Expectant management should be considered in such cases.

Rotational versus nonrotational forceps: maternal and neonatal outcomes

OBJECTIVE

Our purpose was to evaluate maternal and neonatal morbidity associated with rotations performed with Leff forceps in comparison with nonrotational forceps deliveries.

STUDY DESIGN

A review of 267 rotational and nonrotational forceps deliveries from August 1996 through February 1998 was performed. Multiple maternal and neonatal outcome measures were compared and results were analyzed by chi(2) with the Fisher exact test and the Student t test.

RESULTS

One hundred sixty-three traditional low-forceps or outlet forceps deliveries were compared with 104 rotational forceps deliveries performed with Leff forceps. There were no significant differences between the 2 groups in maternal age, gestational age, gravidity, parity, total labor duration, birth weight, and Apgar scores. There were significantly lower rates of episiotomy, third- and fourth-degree lacerations, and sulcus lacerations in the rotation group, and the second stage of labor was also shorter. The neonatal intensive care unit admission rate was higher in the rotation group; however, none of the admissions were directly related to the mode of delivery.

CONCLUSION

Rotational deliveries performed with Leff forceps are associated with less maternal morbidity and shorter second stage of labor than are deliveries performed with traditional forceps. Leff forceps are a safe option for rotation of the persistent occipitoposterior fetal position.

Iatrogenic monoamniotic twins as a complication of therapeutic amniocentesis

BACKGROUND

Therapeutic amniocentesis has been accepted widely as a safe and efficacious way to treat the polyhydramnios-oligohydramnios sequence associated with twin-twin transfusion syndrome.

CASE

A 28-year-old woman, gravida 2, para 1, diagnosed with twin-twin transfusion syndrome at 28 weeks' gestation was treated with serial amniocenteses. The dividing membrane was ruptured inadvertently during therapeutic amniocentesis, with subsequent complete disruption of the amniotic membrane. Iatrogenic monoamniotic twins with cord entanglement and knotting resulted.

CONCLUSION

Creation of monoamniotic twins by disruption of the dividing membrane can be a complication of therapeutic amniocentesis for twin-twin transfusion syndrome. Such disruption may result in the same morbidity and mortality that are seen in naturally occurring monoamniotic twins.

The effect of EMHP on post-cardiac arrest survival of rats

1-Ethyl-2-methyl-3-hydroxy-pyrid-4-one (EMHP), a low molecular weight iron chelator that is soluble in hydrocarbon solvents and presumably in lipids, was studied for in vitro inhibition of radical-mediated peroxidation of DNA. We also investigated the acute toxicity of EMHP by administering 40, 100, and 300 mg/kg intravenously to Wistar rats, and we then examined the in vivo effect of the 40 mg/kg dose following a 10-min cardiac arrest and resuscitation in rats. EMHP prevented iron-dependent radical-mediated DNA breaks of the supercoiled plasmid Bluescribe by the Fenton reagent (400 microM iron, 30 microM H2O2) when present at EMHP/Fe ratios of 16:1 and 32:1. The 300-mg/kg dose was lethal in 3 of 5 normal rats, and the 100-mg/kg dose was associated with excessive mortality post-resuscitation. The 40-mg/kg dose was well tolerated post-resuscitation, but it did not improve either 3-day survival or neurologic outcome.