First-trimester maternal serum PP-13, PAPP-A and second-trimester uterine artery Doppler pulsatility index as markers of pre-eclampsia

OBJECTIVE

To evaluate whether measurement of maternal serum placental protein-13 (PP-13) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks of gestation alone or in combination with second-trimester uterine artery pulsitility measured by Doppler velocimetry is useful in predicting those women who will develop pre-eclampsia

METHODS

This was a nested case-control study of pre-eclampsia cases with controls matched for gestational age and storage time for the maternal serum. Samples were collected as part of a first-trimester prenatal chromosomal anomaly screening program and were routinely tested for PAPP-A. PP-13 was tested using an enzyme linked immunosorbent assay (ELISA) by an examiner who was blinded to pregnancy outcome. All patients also underwent uterine artery Doppler flow velocimetry to measure the mean pulsatility index (PI) at 22-24 weeks' gestation.

RESULTS

There were 446 controls and 44 cases with early pre-eclampsia where delivery was induced prior to 35 weeks. In addition there were a further 44 cases with pre-eclampsia in which delivery was not induced before term. Median PP-13 levels for controls, all cases and early pre-eclampsia cases were 176.9, 121.9 and 111.7 pg/mL, with multiples of the median (MoMs) of 1.00, 0.69 and 0.63, respectively (P < 0.001). PAPP-A MoMs were 1.00, 0.89 (P = 0.076) and 0.89 (P = 0.042) and mean PIs were 1.0, 1.6 (P < 0.001) and 1.7 (P < 0.001) for controls, all cases and early cases, respectively. Receiver-operating characteristics (ROC) curve analysis for either all cases or early cases vs. controls yielded areas under the curve for PP-13, PAPP-A and PI respectively of 0.68 (95% CI, 0.61-0.74; P < 0.001), 0.56 (95% CI, 0.49-0.63; P = 0.076) and 0.79 (95% CI, 0.72-0.87; P < 0.001) for all cases and 0.71 (95% CI, 0.63-0.79; P < 0.001), 0.59 (95% CI, 0.51-0.68; P = 0.076) and 0.86 (95% CI, 0.77-0.94; P < 0.001) for early cases. At a specificity set to 0.80 the sensitivities were 0.50, 0.23 and 0.76 for PP-13, PAPP-A and PI in the early cases and 0.44, 0.24 and 0.73 in all cases. Combining PP-13 and PI using logistic regression analysis yielded an area under the curve of 0.84 (95% CI, 0.78-0.90; P < 0.001) and a sensitivity of 0.74 in all cases, and 0.90 (95% CI, 0.84-0.96; P < 0.001) and a sensitivity of 0.79 for early cases. PAPP-A with PI gave an area under the curve of 0.82 (95% CI, 0.76-0.90; P < 0.001) and a sensitivity of 0.76 in all cases. Combining PAPP-A with PP-13 and PI did not add significantly to the sensitivity.

CONCLUSION

First-trimester PP-13 levels may be useful in predicting pre-eclampsia and early pre-eclampsia, and the accuracy of the method increases when coupled with second-trimester Doppler PI measurement. First-trimester PAPP-A provides some prediction for pre-eclamspia when combined with PI but does not add to the prediction of early pre-eclampsia when PP-13 and PI are used together. Further studies are required to establish the real value of PP-13 in first-trimester screening for pre-eclampsia.

A novel approach to first-trimester screening for early pre-eclampsia combining serum PP-13 and Doppler ultrasound

OBJECTIVE

To investigate the value of maternal serum placental protein 13 (PP-13) measurement and uterine artery Doppler during first-trimester screening in the prediction of early pre-eclampsia.

METHODS

This was a nested case-control prospective study of pregnancies at 11 + 0 to 13 + 6 weeks of gestation. The pulsatility index (PI) of blood flow in the uterine arteries and the maternal serum concentration of PP-13 were measured in 10 women who went on to develop pre-eclampsia that necessitated delivery before 34 weeks, and in 423 unaffected women. Results were expressed as multiples of the gestation-specific median in controls (MoM). A logistic regression model was used to predict detection and false-positive rates.

RESULTS

In the cases that developed pre-eclampsia requiring delivery before 34 weeks, compared with the unaffected pregnancies, the median uterine artery PI was higher (1.43 MoM) and the median serum PP-13 level was lower (0.07 MoM; P < 0.001, Wilcoxon rank sum test for both). Modeling predicted that for a 90% detection rate of pre-eclampsia requiring delivery before 34 weeks, the false-positive rate of screening by PP-13 was 12%, by uterine artery PI was 31% and by a combination of the two methods was 9%. A policy of contingency screening, whereby all women are screened by maternal serum PP-13 and only the 14% at highest risk are then screened by Doppler, achieved a detection rate of 90% with an overall false-positive rate of 6%.

CONCLUSION

Effective screening for pre-eclampsia requiring delivery before 34 weeks can potentially be provided by assessment of a combination of maternal serum PP-13 and uterine artery Doppler in the first trimester of pregnancy.

ICSI outcome in patients with transient azoospermia with initially motile or immotile sperm in the ejaculate

BACKGROUND

In patients with transient azoospermia, few sperm may be found in the ejaculate. We investigated the outcome of ICSI in patients with transient azoospermia.

METHODS

Records of patients with transient azoospermia referred during a 42 month period were reviewed. If only immotile sperm were found, the sample was incubated with 30% human serum albumin (HSA) before motility re-assessment. If still immotile, mechanical assessment of sperm viability was utilized. Study groups were: (A) motile sperm; (B) motility achieved by HSA; (C) no motility, but viability assessed by a mechanical technique; and (D) control group with sperm counts from 1 to 5 x 10(6)/ml. There were 57 couples (cycles) in the study group and 43 couples (cycles) in the control group.

RESULTS

Age, days of stimulation and endometrial thickness were comparable among groups. In 29.8% of the cycles, only immotile sperm were found. Fertilization and cleavage rates were higher in groups A and D than in groups B and C. Clinical pregnancy rate/cycle and live birth rate/cycle were not different among groups. No congenital malformations were found in newborns.

CONCLUSION

Fertilization and cleavage rates were lower in patients with initially immotile sperm compared with those with initially motile sperm and oligoasthenoteratozoospermia patients. Clinical pregnancy and viable pregnancy rates were not statistically different among groups, although when only immotile sperm were present both clinical pregnancy and live birth rate were lower in comparison with cycles with motile sperm.

Endometrium-to-myometrium relative echogenicity coefficient. A new sonographic approach for the quantitative assessment of endometrial echogenicity

A computer program was developed to assess the endometrial echogenicity relative to the myometrial one, based on the gray-level processing of the midsagittal uterine image. The endometrial region of interest was specified within the upper part of the uterine cavity. The adjacent area of the myometrium was used to determine the reference brightness. The endometrial region of interest was analyzed along the anteroposterior uterine axis, as a set of thin strips directed parallelly to the midcavitary line. The endometrial/myometrial relative echogenicity coefficient (E/M REC) was computed for each strip and displayed graphically as a function of the distance from the midcavitary line. The area under the E/M REC curve within the limits of the total endometrial width was defined as total area (TA) and was used as a measure of the endometrial echogenicity. This parameter was assessed in 9 patients during their normal ovulatory cycles and in 29 IVF-treated patients with mechanical infertility. TA has a significant linear increase during the days of the ovulatory cycles. TA was found in high correlation with log(estradiol). TA can be used reliably for sonographic endometrial dating in ovulatory cycles.

Adeno-associated virus-based vectors in gene therapy

Adeno-associated virus (AAV) vectors were shown capable of high efficiency transduction of both dividing and nondividing cells and tissues. AAV-mediated transduction leads to stable, long-term transgene expression in the absence of apparent immune response. These properties and the broad host range of AAV vectors indicate that they constitute a powerful tool for gene therapy purposes. An additional potential benefit of AAV vectors is their ability to integrate site-specifically in the presence of Rep proteins which can be expressed transiently, thus limiting their suspected adverse effects. The major restrictions of AAV as vectors are their limited genetic capacity and strict packaging size constraint of less than 5 kb. Another difficulty is the labor-intensive and expensive procedure for the production and packaging of recombinant AAV vectors. The major benefits and drawbacks of AAV vectors and advances made in the past 3 years are discussed.

Acute primary Chlamydia trachomatis infection in male adolescents after their first sexual contact

BACKGROUND

Chlamydia trachomatis infection occurs primarily among youth sexually active persons. Few studies have evaluated the kinetics of markers of infection in male adolescents after their first sexual contact.

DESIGN

Primary C trachomitis infection in 4 young male adolescents after their first sexual contact was diagnosed by polymerase chain reaction and antigen detection in sequential first voiding urine and urethral specimens, respectively. Serial serum samples were assessed for the presence of specific IgA and IgG antibodies.

RESULTS

Both polymerase chain reaction and antigen detection correctly identified all cases of primary C trachomatis infection. The polymerase chain reaction method was, however, an earlier marker of infection. Three patients were seronegative at presentation. Two of these subsequently seroconverted to either IgA or IgG, while the third remains seronegative. The time interval from onset of symptoms to seroconversion ranged from 10 to 25 days.

CONCLUSIONS

Although polymerase chain reaction and antigen and serologic detection have previously been described in primary C trachomatis infection, this report documents the variability of these markers during the first phase of infection in non-sexually active young male adolescents. C trachomatis can be acquired by male adolescents after their first sexual contact; however, there is a prolonged period when the patient is seronegative, yet infections can occur.

Expression of the insect parvovirus GmDNV in vivo: the structural and nonstructural proteins are encoded by opposite DNA strands

The nucleotide sequence of GmDNV, an insect parvovirus, reveals large open reading frames (ORFs) on both strands of the viral replicative form DNA. Previously, we identified two viral transcripts within the polyadenylated RNA fraction of infected host larvae (Gross et al., 1990, J. Invertebr. Pathol. 56, 175-180). In this work we used hybridization of single-stranded, unidirectional probes to RNA blots to show that the two transcripts, synthesized in vivo in GmDNV-infected Galleria mellonella larvae, are of antiparallel orientation. To determine their coding specificities, polyadenylated RNAs were isolated from hybrids with DNA from the left and right halves of the viral genome and translated in a rabbit reticulocyte system. The "right," 2.4-kb hybrid-selected RNA was shown to direct the synthesis of four polypeptides that comigrated with the four viral capsid proteins and were immunoprecipitated with anti-GmDNV serum. Translation of the "left," 1.8-kb RNA yielded three polypeptides, none of which was detected among the viral capsid proteins. This type of expression strategy is unique among vertebrate and most invertebrate parvoviruses, which use only one DNA strand to encode all their proteins. On the other hand, the basic organization of parvoviruses, in which the regulatory and structural proteins are encoded, respectively, by two clusters of ORFs located at the left and right halves of the genome, is conserved.

Activated protein C resistance and factor V Leiden mutation can be associated with first-as well as second-trimester recurrent pregnancy loss

PROBLEM

To examine whether the occurrence of activated protein C resistance (APCR) and factor V Leiden mutation differs in women with first- compared to women with second-trimester unexplained recurrent pregnancy loss.

METHOD OF STUDY

Seventy eight consecutive women with two or more unexplained post-embryonic recurrent pregnancy losses and 139 fertile women with at least one successful pregnancy and no abortions were prospectively investigated for APCR and the factor V Leiden mutation. No women were pregnant at the time of investigation. APCR was defined as APC sensitivity ratio (APC SR) of < or = 2.0. All patients with an APC SR < or = 2.4 were investigated for the factor V Leiden mutation. Women in this study were divided into three groups. Group A included only women with a history of recurrent first-trimester embryonic loss (37 women) and Group B included women with second-trimester abortions with or without additional first-trimester abortions (41 women). Group C included the controls (139 women).

RESULTS

APCR and factor V Leiden mutations were significantly more prevalent in all recurrent pregnancy loss patients in this study as compared to controls. 38%(30/78) and 19%(15/78) in contrast to 8% (11/139) and 6% (8/139), respectively. All three groups in the study were comparable regarding age, parity, and number of living children, whereas Groups A and B were also comparable regarding gravidity. Mean APC SRs were significantly higher in Group C as compared to Groups A and B. The incidence of APCR was significantly higher in Groups A and B, as compared to controls, 27 and 49% in contrast to 8%, respectively. Moreover, the incidence of the factor V Leiden mutation was significantly higher in Groups A and B as compared to Group C, 16 and 22% as distinct from 6%, respectively. The incidence of APCR was higher in Group B as compared to Group A, 49% in contrast to 27%, with borderline significance: however, the factor V Leiden mutation did not significantly differ between the two groups.

CONCLUSIONS

APCR and factor V Leiden are associated with unexplained recurrent pregnancy loss. The occurrence of APCR and factor V Leiden seems to be linked to post-embryonic first-trimester as well as second-trimester recurrent pregnancy loss. The significance of acquired, non-heritable APCR in recurrent fetal loss patients, especially in the second-trimester aborters, is still to be determined.

Assessment of endometrial receptivity for gestation in patients undergoing in vitro fertilization, using endometrial thickness and the endometrium-myometrium relative echogenicity coefficient

OBJECTIVE

To evaluate the outcome of in vitro fertilization (IVF) treatment in relation to the sonographic parameters of the endometrium.

DESIGN AND METHODS

Seventy-five patients with no uterine pathology (age 31.1 +/- 5.4 years) treated in our IVF clinic for various indications were assessed during 75 cycles in which good-quality (grades 1 and 2) embryos were transferred. Controlled ovarian stimulation was achieved by the long protocol (gonadotropin releasing hormone agonist and gonadotropins). The bilayered endometrial thickness (BET), estradiol, luteinizing hormone and progesterone serum levels were measured in 272 tests. A special computer program was used to measure endometrial echogenicity relative to myometrial echogenicity. The gray-level data were analyzed on the basis of the midsagittal sonographic uterine image. Endometrium-myometrium relative echogenicity coefficient (E/M REC) values were computed and displayed graphically along the anteroposterior axis of the endometrial layers in the upper part of the uterine cavity. The area under the E/M REC curve within the BET limits was defined as the relative echogenicity area (REA) and was used as a measure of endometrial echogenicity. Each cycle was sampled in six time segments representing desensitization, follicular and luteal phases. Assigning the day of ovum pick-up as day 0, the time segments of each cycle were: first, day -20 to day -11; second, day -10 to day -6; third, day -5 to day -2; fourth, day 0; fifth, day +7 to day +14; sixth, day +15 to day +21.

RESULTS

A total of 276 embryos were transferred (3.68 +/- 1.01 per cycle), of which 223 were of good quality (2.97 +/- 1.51 per cycle). An intrauterine pregnancy was diagnosed in 29 patients. All patients in this study had a BET of > 5 mm in the third and the fourth time segments. There was no significant difference in BET and REA between pregnant and non-pregnant patients tested in the first to the fifth time segments of the IVF cycles. Both BET and REA measured in the sixth time segment were significantly higher in pregnant compared to non-pregnant patients.

CONCLUSIONS

Our results suggest that the proposed sonographic assessment of the endometrium shows no benefit in characterization of uterine receptivity in IVF patients with a reactive endometrium. High BET and REA values can indicate pregnancy during the sixth time segment, when the decidualization of the endometrium is well established.

A possible role for activated protein C resistance in patients with first and second trimester pregnancy failure

Thrombophilia was recently suggested as a possible factor in recurrent pregnancy losses. We studied prospectively 125 patients (mean age 31.4 +/- 5.6 years) with one or more first or second trimester pregnancy losses for the prevalence of activated protein C resistance (APCR). Proteins C and S antigens, antithrombin III, anticardiolipin, and lupus anti-coagulant were also evaluated. Patients with uterine malformations, hormonal abnormalities, chromosomal translocations and infectious causes were excluded. A control group of 125 women with no past fetal loss were matched with the study group. Whenever the APC-sensitivity ratio (APC-SR) was </=2.2, polymerase chain reaction for factor V mutation (Leiden) was performed. Heterozygosity for the mutation was found in 18 patients (14.4%) compared with seven heterozygous among 125 control group (5. 6%; P < 0.05). Acquired APCR (APC-SR 1.8 and Leiden negative) was revealed in seven patients (5.6%) in the study group and in three of the controls (2.4%; not significant). The rate of preclinical pregnancy losses (17/48) and second trimester miscarriages (10/48) in mutation carriers was significantly higher than in patients with no APCR (25/214) and (14/214) respectively (P < 0.001 and P < 0.01 respectively). Live birth rate was not different between the two groups. Occurrence of APCR with any kind of pregnancy loss calculated per patient, in our study group, was approximately 1/7, 1/4 and 1/5 with one, two and three or more pregnancy losses respectively. These findings suggest that assessment of APCR should be considered in a more extended evaluation of such patients.

Directed integration of minute virus of mice DNA into episomes

Recent studies with adeno-associated virus (AAV) have shown that site-specific integration is directed by DNA sequence motifs that are present in both the viral replication origin and the chromosomal preintegration DNA and that specify binding and nicking sites for the viral regulatory Rep protein. This finding raised the question as to whether other parvovirus regulatory proteins might direct site-specific recombination with DNA targets that contain origin sequences functionally equivalent to those described for AAV. To investigate this question, active and inactive forms of the minute virus of mice (MVM) 3' replication origin, derived from a replicative-form dimer-bridge intermediate, were propagated in an Epstein-Barr virus-based shuttle vector which replicates as an episome in a cell-cycle-dependent manner in mammalian cells. Upon MVM infection of these cells, the infecting genome integrated into episomes containing the active-origin sequence reported to be efficiently nicked by the MVM regulatory protein NS1. In contrast, MVM did not integrate into episomes containing either the inactive form of the origin sequence reported to be inefficiently nicked by NS1 or the active form from which the NS1 consensus nick site had been deleted. The structure of the cloned MVM episomal recombinants displayed several features previously described for AAV episomal and chromosomal recombinants. The findings indicate that the rules which govern AAV site-specific recombination also apply to MVM and suggest that site-specific chromosomal insertions may be achievable with different autonomous parvovirus replicator proteins which recognize binding and nicking sites on the target DNA.

Accurate diagnosis of postabortal placental remnant by sonohysterography and color Doppler sonographic studies

The decision whether to perform uterine curettage for postabortal bleeding depends on the ability to demonstrate placental remnants in the uterine cavity. However, diagnosis of postabortal trophoblastic residua by conventional ultrasonography may be inconclusive. We report our experience with the use of combined sonohysterography and color Doppler to demonstrate a placental polyp after early pregnancy termination.

[Comparison of polymerase chain reaction and ELISA in the diagnosis of Chlamydia trachomatis infection]

Chlamydia trachomatis (CT) is the most frequent cause of sexually transmitted disease in the western world. However, only a few cases have been reported from Israel. Because of the frequent absence of symptoms, its high prevalence, rapid spread, and the seriousness of complications, the quality of the diagnostic test for this microorganism is very important. Cell culture has always been regarded as the "gold standard" in diagnosis. However, factors such as collection, transport time and storage can negatively influence the sensitivity of culturing. We evaluated a polymerase chain reaction (PCR) assay (Amplicor CT, Roche Molecular Systems) for the detection of CT. CT-PCR was compared with a non-culture method (ELISA) in cervical, urethral and first-void urine specimens in 30 patients attending our sexually transmitted disease clinic. There were 16 males and 14 females; in 16 of them (53%) CT-PCR was positive. However, in only 6 of the latter (38%) was CT-ELISA also positive. 7 urine specimens from males with non-specific urethritis had a positive CT-PCR and a negative CT-ELISA. There were discrepancies between ELISA and the PCR test in 10 (3 females) of the 30. We confirm other studies indicating the PCR to be a highly sensitive assay for detecting CT infection from urogenital specimens. CT-PCR from first-void urine provides a noninvasive technique for routine screening of CT infection in both symptomatic and asymptomatic males and females.

Heterotopic pregnancy after ovulation induction and assisted reproductive technologies: a literature review from 1971 to 1993

OBJECTIVE

To review and analyze records on heterotopic pregnancy occurring after ovulation induction and assisted reproductive technologies.

DATA IDENTIFICATION

Case reports in the English literature related to the topic were identified through a computerized bibliography search up to December 1993.

CONCLUSIONS

The incidence of heterotopic pregnancies increased in recent years because of the escalating use of new reproductive technologies in infertile patients and has stabilized at approximately 1:100 pregnancies with these procedures. The main reasons for development of such a condition in these patients are past tubal or pelvic disease and multiple ovulations or multiple ET. Progress has been made in diagnosis of heterotopic pregnancy during the last two decades, mainly because of development of ultrasonographic techniques, especially transvaginal ultrasonography. Treatment of heterotopic pregnancy should be prompt to avoid maternal morbidity and mortality from extensive intraperitoneal bleeding. No increased intrauterine fetal mortality due to hemoperitoneum has been proven in the present review, except in advanced cornual pregnancies. More experience is needed for application of new treatment modalities such as salpingocentesis, which are used successfully for ectopic pregnancy, in treatment of heterotopic pregnancy. With early diagnosis and skillful treatment, the outcome of the intrauterine pregnancy is favorable and its survival rate should increase in the future.

An early gene of the Chlorella virus PBCV-1 encodes a functional aspartate transcarbamylase

PBCV-1 belongs to a family of large viruses that replicate in the exsymbiont green algae Chlorella strain NC64A. The viral, 330-kb DNA genome encodes a relatively large number of functionally active proteins including restriction and modification enzymes, DNA polymerase, glycosylation, and cell wall degrading enzymes. Sequencing of the viral DNA, now in progress, revealed many major open reading frames (ORF), which resemble known genes in sequence data bases and which have not previously been found in viral genomes. Here we report on the identification and characterization of one such gene, aspartate transcarbamylase (ATCase), an enzyme that catalyzes the committing step in the de novo biosynthetic pathway of pyrimidines. The cloned gene is highly homologous to a variety of plant ATCases and includes the typical ATCase catalytic motif. When cloned into the pGEX-2T expression vector, a fusion protein with ATCase activity could be demonstrated and distinguished from the host ATCase activity. The viral enzyme is expressed early and transiently in the infection. To our knowledge, this is the first virus known to encode and express its own de novo nucleotide precursors' synthetic enzymes.

[Diagnostic and therapeutic approach to sexually transmitted diseases]

In an ongoing study we evaluated 71 males and 32 females attending our sexually transmitted diseases (STD) clinic. Intraurethral or endocervical swab specimens were cultured for Neisseria gonorrhea (NG), Ureaplasma urealyticum (UU), Mycoplasma homines (MH), Herpes simplex virus (HSV) and Chlamydia trachomatis (CT), using an ELISA technique and the polymerase chain reaction (PCR). HIV antigen, hepatitis B (HBV) and Treponema pallidum (TP) seropositivity were tested by ELISA. Mean age was 33.4 and range 15-72 years. 83 patients (81%) used condoms only rarely, 35 (35%) had multiple sexual partners and 83 (81%) were treated empirically prior to evaluation. Dysuria and urethral discharge were found in 47 (45.6%), of whom 34 (33%) were males; the majority of females were asymptomatic. A specific etiology for STD was found in 53 patients (51.4%) and 1/3 had more than 1 pathogen. CT, UU, MH, HSV, NG and TV were found in 27, 24, 5, 3, 2 and 1, respectively. 8 patients were seropositive for HBV and 1 for TP; all were seronegative for HIV. CT was the most prevalent pathogen found. All patients with STD symptoms should be screened for all sexually transmitted pathogens, since many of them have more than 1 pathogen. STD clinics in Israel should be developed in conjunction with microbiology laboratories for better management of STD in the community.

S-Adenosylmethionine and methylation

S-Adenosylmethionine (AdoMet or SAM) plays a pivotal role as a methyl donor in a myriad of biological and biochemical events. Although it has been claimed that AdoMet itself has therapeutic benefits, it remains to be established whether it can be taken up intact by cells. S-Adenosylhomocysteine (AdoHcy), formed after donation of the methyl group of AdoMet to a methyl acceptor, is then hydrolyzed to adenosine and homocysteine by AdoHcy hydrolase. This enzyme has long been a target for inhibition as its blockade can affect methylation of phospholipids, proteins, DNA, RNA, and other small molecules. Protein carboxymethylation may be involved in repair functions of aging proteins, and heat shock proteins are methylated in response to stress. Bacterial chemotaxis involves carboxymethylation and demethylation in receptor-transducer proteins, although a similar role in mammalian cells is unclear. The precise role of phospholipid methylation remains open. DNA methylation is related to mammalian gene activities, somatic inheritance, and cellular differentiation. Activation of some genes has been ascribed to the demethylation of critical mCpG loci, and silencing of some genes may be related to the methylation of specific CpG loci. Viral DNA genomes exist in cells as extrachromosomal units and are generally not methylated, although once integrated into host chromosomes, different patterns of methylation are correlated with altered paradigms of transcriptional activity. Some viral latency may be related to DNA methylation. Cellular factors have been found to interact with methylated DNA sequences. Methylation of mammalian ribosomal RNAs occurs soon after the synthesis of its 47S precursor RNA in the nucleolus before cleavage to smaller fragments. Inhibition of the methylation of rRNA affects its processing to mature 18S and 28S rRNAs. The methylation of 5'-terminal cap plays an important role in mRNA export from the nucleus, efficient translation, and protection of the integrity of mRNAs. Another important function of AdoMet is that it serves as the sole donor of an aminopropyl group that is conjugated with putrescine to form, first, the polyamine spermidine, and then spermine.

Brain Stem Auditory Evoked Potentials: Effects of Ovarian Steroids Correlated with Increased Incidence of Bell's Palsy in Pregnancy

To investigate the effect of ovarian steroids on the brain stem during changes of estrogen and progesterone blood levels, we recorded brain stem auditory evoked potentials with increased stimulus rates from 26 women treated for sterility by menotropins (Pergonal and Metrodin). These women were divided into three groups according to their estrogen and progesterone blood levels. The brain stem auditory evoked potential results revealed a significant delay of peak III only, with an increased stimulus rate in the group with the highest estrogen level. Estrogen may cause a brain stem synaptic impairment, presumably because of ischemic changes, and thus also may be responsible for a higher incidence of Bell's palsy during pregnancy.

Brain stem auditory evoked potentials: effects of ovarian steroids correlated with increased incidence of Bell's palsy in pregnancy

To investigate the effect of ovarian steroids on the brain stem during changes of estrogen and progesterone blood levels, we recorded brain stem auditory evoked potentials with increased stimulus rates from 26 women treated for sterility by menotropins (Pergonal and Metrodin). These women were divided into three groups according to their estrogen and progesterone blood levels. The brain stem auditory evoked potential results revealed a significant delay of peak III only, with an increased stimulus rate in the group with the highest estrogen level. Estrogen may cause a brain stem synaptic impairment, presumably because of ischemic changes, and thus also may be responsible for a higher incidence of Bell's palsy during pregnancy.

Congenital toxoplasmosis: a significant cause of neurological morbidity in Israel?

The incidence of congenital toxoplasmosis in Israel is largely unknown, as is the impact of this condition on the neurological diseases of childhood. We examined the association between toxoplasmosis and three neurological disorders: epilepsy, cerebral palsy, and nerve deafness. Ninety-five children 1-15 years of age who had one of these three diagnoses but who had not had perinatal meningitis or anoxia and had no genetic predisposition for the documented neurological disorder were eligible for the study; 109 children hospitalized for elective surgery served as age-matched controls. Demographic and serological data were analyzed by logistic regression. The prevalences of serum antibodies to Toxoplasma gondii in the study and control groups were 22% and 9%, respectively. Children with one of the three neurological disorders were significantly more likely to have IgG antibodies to T. gondii (relative risk, 2.5; P = .03). The relative risk of seropositivity was remarkably high (7.1) among children with nerve deafness (P = .01). Large-scale prospective cohort studies of pregnant women are needed to substantiate the impact of congenital toxoplasmosis on the neurological diseases of childhood in Israel.

Maternal responsiveness to infants in three societies: the United States, France, and Japan

This study examines and compares prominent characteristics of maternal responsiveness to infant activity during home-based naturalistic interactions of mother-infant dyads in New York City, Paris, and Tokyo. Both culture-general and culture-specific patterns of responsiveness emerged. For example, in all 3 locales infants behaved similarly, mothers also behaved similarly with respect to a hierarchy of response types, and mothers and infants manifest both specificity and mutual appropriateness in their interactions: Mothers responded to infants' exploration of the environment with encouragement to the environment, to infants' vocalizing nondistress with imitation, and to infants' vocalizing distress with nurturance. Differences in maternal responsiveness among cultures occurred to infant looking rather than to infant vocalizing and in mothers' emphasizing dyadic versus extradyadic loci of interaction. Universals of maternal responsiveness, potential sources of cultural variation, and implications of similarities and differences in responsiveness for child development in different cultural contexts are discussed.

Hair chromium content of women with gestational diabetes compared with nondiabetic pregnant women

Hair chromium concentration (HCC) of normal and diabetic pregnant women was determined by atomic-absorption spectroscopy. For nondiabetic pregnant women the value from 68 hair samples was 472 +/- 61 ng/g (mean +/- 95% CI); for gestational diabetics it was 734 +/- 155 ng/g from 42 hair samples. The difference was highly significant (P less than 0.005). Intermediate hair chromium concentrations were observed in 20 pregnant women with pregestational, overt diabetes mellitus (mean: 575 +/- 182 ng/g). Fifty-two women had a second hair sample taken later during pregnancy that showed a significant decrease in HCC (P less than 0.05). However, this decrease was confirmed only for the diabetic pregnant group. Age and parity did not influence the HCC. The data suggest that impaired utilization of chromium may be a possible etiology for gestational diabetes mellitus.

Stress-related hormones affect human chorionic gonadotrophin secretion from the early human placenta in vitro

The effect of a physiological range of concentrations of three stress-related hormones, oxytocin (OT), arginine-vasopressin (AVP) and prolactin (PRL) was tested upon human chorionic gonadotrophin (HCG) secretion by placental explants from early pregnancy in static and superfusion cultures. In static cultures, OT and AVP significantly increased HCG secretion, whereas PRL had no effect. In superfusion, 1-min pulses of OT induced a significant (two- to 10-fold) rise in HCG pulse amplitude compared to the control. This effect of this neuropeptide was blocked by coadministration of a specific receptor antagonist. AVP also increased the glycoprotein pulse amplitude by two- to five-fold, but only with every second pulse administered. PRL pulses caused a progressive inhibition of spontaneous HCG pulsatility. In conclusion, stress-related hormones affect placental HCG secretion in vitro. The involvement of these factors in impairing early pregnancy development is suggested.

Human gonadotropin therapy: hormonal and ultrasonographic characteristics of conceptual and nonconceptual cycles in the same women

A retrospective analysis was carried out to assess hormonal and sonographic characteristics of 52 conceptual (P-cycles) and 53 nonconceptual (F-cycles) gonadotropin treatment cycles in the same women. In the P-cycles, an exponential E2 pattern was observed up to the day of hCG (human chorionic gonadotropin) administration (day 0). In the F-cycle group, a similar pattern was observed till day (-1), and then levels plateaued. Forty-two (80.9%) of the pregnancies were achieved when the active phase was 6 +/- 1 days; seven pregnancies (14.8%) occurred when the active phase was more than 7 days. Only one of these pregnancies was a singleton viable pregnancy (P less than .05). It is, therefore, postulated that 6 +/- 1 days rising E2 and exponential E2 rise pattern up to the day of hCG are the two main monitoring variables leading to the highest percentage of viable singleton or twin pregnancies in hMG-stimulated cycles.

Expression of densonucleosis virus GmDNV in Galleria mellonella larvae: size analysis and in vitro translation of viral transcription products

The RNA of densonucleosis virus type 1 (GmDNV), isolated from GmDNV-infected Galleria mellonella larvae, was shown by Northern blotting to contain five polyadenylated, viral-specific RNA species with sizes of 1.8, 2.4, 3.5, 4.0, and 5.0 kb. Poly(A)-containing RNA from whole larvae and hybrid-selected viral RNA were translated in a rabbit reticulocyte lysate system and the translation products were coelectrophoresed with proteins extracted from CsCl-purified virus. All four virion-associated proteins, namely p49, p55, p65, and p94, were present in the in vitro-translated products. However, in the majority of the experiments the most abundant translation product was a 30K polypeptide which is absent from virion extracts. The most abundant viral protein is p49, and the 49K polypeptide was also the most abundant translation product in about 30% of the preparations. The 1.8 kb transcript, which constitutes about half of the total viral RNA, is only slightly larger than the template required for a 30K polypeptide, suggesting that the latter may be a primary translation product of the smallest RNA transcript. The similarities in gene expression between densoviruses and mam malian parvoviruses are discussed.

Selective killing of transformed rat cells by minute virus of mice does not require infectious virus production

Fischer rat fibroblasts, naturally resistant to killing by the fibrotropic strain of minute virus of mice [(parvovirus MVM(p)], became sensitive to MVM when transformed by polyomavirus. This sensitization did not involve an increase in the percentage of cells which synthesized viral capsid antigens or in the percentage of cells which produced infectious virus. The addition of anti-MVM antiserum to the growth medium of MVM-infected cells had only a small effect on their survival rates, indicating that the majority of the killing effect of MVM occurs in a single cycle of infection. The data indicate that cell killing by MVM is independent of infectious virus production and thus support the notion that the preferential cytolytic effect is affected by viral cytotoxic gene products which accumulate to intolerable levels in transformed cells but not in normal ones. Finally, using cells transformed with polyomavirus and genomic and subgenomic clones of polyomavirus, we showed that the extent of sensitization to killing by MVM depended on the transforming agent used.

Kallmann syndrome: a case of twin pregnancy and review of the literature

In order to evaluate the possibilities for induction of ovulation, the functional competence of the pituitary gland of a woman with Kallmann syndrome was examined by two consecutive dynamic GnRH tests. The second test was conducted after 1 week's treatment by a GnRH pump. The results, which showed some rise of LH but no response of FSH, favored induction by hMG/hCG therapy. Three treatment cycles resulted in a twin pregnancy which was normal and was carried to term. Review of the literature shows only six previously reported pregnancies in women with Kallmann syndrome. Five of them were treated by hMG/hCG, and one by pulsatile GnRH. The two methods of induction are discussed in relation to the heterogeneity of the pituitary and ovarian function in Kallmann syndrome. We show that this heterogeneity dictates that the treatment for induction of ovulation should be individually adjusted according to the pituitary and ovarian competence.

Sensitization of transformed rat fibroblasts to killing by parvovirus minute virus of mice correlates with an increase in viral gene expression

Cultures of established rat fibroblasts transformed by the avian erythroblastosis virus were more susceptible to the cytopathic effect of the autonomous parvovirus minute virus of mice, prototype strain (MVMp), than were their untransformed homologs. This effect could be ascribed to the presence of a greater fraction of cells that were sensitive to the killing action of MVMp in transformed cultures than in their normal parents. Yet, transformed and normal lines were similarly efficient in virus uptake, DNA amplification, and capsid protein synthesis. In contrast, transformants accumulated 2.5- to 3-fold greater amounts of all three major MVM mRNA species and nonstructural protein than did their normal progenitors. Thus, in this system transformation-associated sensitization of cells to MVMp appears to correlate primarily with an increase in their capacity for the expression of the viral transcription unit which encodes nonstructural proteins and is controlled by the P4 promoter. Consistently, a reporter gene was expressed at a higher level by transformed versus normal cultures, when placed under the control of the MVM P4 promoter. As infectious MVMp was produced in larger amounts by transformed cultures, a late step of the parvoviral cycle, such as synthesis, encapsidation of progeny DNA, or both, was also stimulated in the transformed cells.

Paracentric inversion of Xq and ovarian dysfunction

We report on a paracentric inversion X(q13 q24) in a 20-year-old woman with ovarian dysfunction. The findings add evidence on the role of breakpoints in Xq13 and Xq24 in causing ovarian dysfunction. A review of the published data on paracentric inversion of chromosome X is included.

Development-dependent replication of minute virus of mice in differentiated mouse testicular cell lines

The replication of the autonomous parvovirus, minute virus of mice (MVM), requires mitotically active cells and depends on certain factors expressed by cells of particular differentiated phenotype. As an approach to the understanding of these helper functions, we studied the interaction of the fibrotropic [MVM(p)] and the lymphotropic [MVM(i)] strains of MVM with two differentiated cell lines from mouse testicular epithelial origins. The relative support given to viral expression by these cell lines varied extensively. Cells from Sertoli origin (TM4) were permissive to MVM(p) but were mostly restrictive to MVM(i). The other cell line, of Leydig cell origin (TM3), was highly restrictive to both viral strains, but the blocks to their growth in these cells were localized at different stages of their growth cycle, suggesting that the replication of MVM in these cells requires tissue-specific helper functions during at least two stages of viral replication.

Negative and positive regulation in trans of gene expression from adeno-associated virus vectors in mammalian cells by a viral rep gene product

We previously described use of the human parvovirus, adeno-associated virus (AAV), as a vector for transient expression in mammalian cells of the gene for chloramphenicol acetyltransferase (CAT). In the AAV vector, pTS1, the CAT gene is expressed under the control of the major AAV promoter p40. This promoter is embedded within the carboxyl-terminal region of an open reading frame (orf-1) which codes for a protein (rep) required for AAV DNA replication. We show here that the rep product has additional trans-acting properties to regulate gene expression. First, deletion or frame-shift mutations in orf-1, which occurred far upstream of p40, increased expression of CAT in human 293 (adenovirus-transformed) cells. This increased CAT expression was abolished when such mutant AAV vectors were transfected into 293 cells together with a second AAV vector which could supply the wild-type AAV rep product in trans. Thus, an AAV rep gene product was a negative regulator, in trans, of expression of CAT in uninfected 293 cells. In adenovirus-infected 293 cells, the function of the AAV rep product was more complex, but in some cases, it appeared to be a trans activator of the expression from p40. In HeLa cells, only trans activation by rep was seen in the absence or presence of adenovirus. Neither activation nor repression by the rep product required replication per se of the AAV vector DNA. Thus, trans-acting negative or positive regulation of gene expression by the AAV rep gene is modulated by factors in the host cell and by the helper adenovirus.

Suppression of Ehrlich ascites tumors in mice by minute virus of mice

As a model system to study parvoviral oncosuppression, Ehrlich ascites (EA) cells were injected into the peritoneal cavities of ICR mice, and the effect of im injection of minute virus of mice (MVM) on EA tumor growth was examined. Coinjection with MVM resulted in a dramatic inhibition of EA tumor formation. Tumor suppression required viable, infectious virus. Mice that had survived one EA-MVM coinjection acquired long-term resistance to additional injections of EA cells.

Spontaneous curing of a minute virus of mice carrier state by selection of cells with an intracellular block of viral replication

We previously described a persistent infection established by the lymphotropic minute virus of mice in mouse L cells at the level of the cell population (D. Ron, P. Tattersall, and J. Tal, J. Virol. 52:63-69, 1984). This carrier state is maintained by a series of consecutive phenotypic changes which take place in both the cells and the virus and is cured spontaneously after 150 to 200 cell generations (D. Ron and J. Tal, J. Virol. 55:424-430, 1985). We show here that the cure was caused by the selection of virus-resistant cells in the culture. The resistance of these survivor cells to virus replication was due to an intracellular block. Infection of a spontaneously cured culture with the fibrotropic parental minute virus of mice resulted in a restrictive infection in which the viral replicative-form DNA was formed and amplified, but the synthesis of single-stranded progeny DNA was markedly reduced. The lymphotropic strain was blocked in these cells at an earlier stage, with little or no amplification of viral replicative-form DNA observed. These data indicate that the replication of minute virus of mice requires host-coded helper functions in at least two stages of its growth cycle.

Ultrasonographic and clinical correlates of menotropin versus sequential clomiphene citrate: menotropin therapy for induction of ovulation

Forty-six women remaining infertile with clomiphene citrate (CC) with or without human chorionic gonadotropin (hCG) were treated by either human menopausal gonadotropin (hMG, 44 cycles) or CC + hMG (33 cycles) and monitored by serum estradiol (E2) and ultrasonography. Ovarian hyperstimulation syndrome (OHS) and pregnancy outcome were compared in both regimens. In the presence of dominant follicles (greater than or equal to 18 mm) alone or with a single secondary follicle (14 to 16 mm) at hCG administration, OHS did not develop. A significant increase in OHS was noted when three or more secondary follicles were observed. Overall pregnancy rates were similar in both regimens but significantly higher when hCG was injected before rather than after the E2 peak. The results suggest secondary follicles rather than dominant follicles are a valuable sign of possible OHS development; and CC + hMG should be considered in CC-failure patients.

Formation of a host range mutant of the lymphotropic strain of minute virus of mice during persistent infection in mouse L cells

Minute virus of mice (i), the lymphotropic strain of minute virus of mice, established a persistent infection in normally restrictive L cells. The carrier state, which lasted 150 days, exhibited three clearly distinguishable stages. During the early stage (days 1 to 10 postinfection), small amounts of virus were formed. A "crisis" then developed that lasted 50 to 60 days and was characterized by massive cell lysis and high titers of virus. This was followed by a 70- to 80-day period in which small but stable quantities of virus were produced. Virus shed by the carrier culture during the latter phase had acquired an altered host range, namely, it had lost its ability to replicate in T-lymphocyte cell lines and had adapted to growth in L cells. Virus isolated at this time from a single plaque in L cells, designated hr301, was shown to possess similar host range properties. No differences, however, could be found between the DNAs of minute virus of mice (i) and of hr301 by restriction enzyme analysis, suggesting that the mutation that affected the viral host range did not involve an extensive region of the viral genome.

Differential inhibition of cellular RNAs by photosensitized trioxalen

Treatment of mouse cell cultures with 5 X 10(-6)M trioxalen (4,5',8-trimethylpsoralen, or TMP) followed by long wavelength ("near") UV-irradiation (NUV) resulted in immediate cessation of most of the cellular transcriptional activity. The effective inhibitory TMP concentrations for ribosomal RNA were lower than those affecting poly RNA containing RNA. Low molecular RNA species were only partially inhibited. Side effects, commonly caused by other drugs, were not detected. These properties, and the simplicity of their use, make psoralens attractive inhibitors of RNA biosynthesis.

Neuroactive amino acids influence gonadotrophin output by a suprapituitary mechanism in either rodents or primates

Systemic administration of excitatory amino acids (Glu or NMA) rapidly enhances LH release (rodents or primates) and GABA blocks this action (rodents). In the present study rodent and primate pituitaries were incubated with NMA, Glu and/or GABA, with or without added LH-RH. Only LH-RH affected LH release. Therefore the probable site of NMA, Glu or GABA action on LH release in both rodents and primates is suprapituitary.

Adenocarcinoma of the endometrium in Israel, 1960-1968

Data gathered during an epidemiologic study of endometrial cancer in Israel are presented. In the nine-year period of this survey, 877 new cases of primary cancer of the endometrium were diagnosed, representing an incidence of 17.8/100,00 females over the age of 25. Two thirds of the patients were in the sixth and seventh decades of life at diagnosis of the tumor. Endometrial carcinoma was two to three times more prevalent in women of European-American origin than in those of Asian-African Background. In 85% of the patients, diagnosis was made while the disease was in Stage I. A strong correlation was found between endometrial cancer, diabetes (14%), hypertension (18%), and infertility (25%). The five-year survival rate in the present survey was 69.2%. Factors affecting prognosis are clinical stage of the disease at diagnosis, degree of myometrial invasion, tumor differentiation, age of the patient, and type of treatment.

Mechanism for circularization of linear DNAs: circular parvovirus MVM DNA is formed by a "noose" sliding in a "lasso"-like DNA structure

During an electron-microscopic survey with the aim of identifying the parvovirus MVM transcription template, we observed previously unidentified structures of MVM DNA in lysates of virus-infected cells. These included double-stranded "lasso"-like structures and relaxed circles. Both structures were of unit length MVM DNA, indicating that they were not intermediates formed during replication; they each represented about 5% of the total nuclear MVM DNA. The proportion of these structures was unchanged after digestion with sodium dodecyl sulfate/Pronase and RNase and after mild denaturation treatment. Cleavage of the "lasso" structures with EcoRI restriction endonuclease indicated that the "noose" part of the "lasso" structure is located on the 5' side of the genomic single-stranded MVM DNA. A model is presented for the molecular nature of the circularization process of MVM DNA in which the "lasso" structures are identified as intermediates during circle formation. This model proposes a mechanism for circularization of linear DNAs.

env Gene of chicken RNA tumor viruses: extent of conservation in cellular and viral genomes

The env gene of avian sarcoma-leukosis viruses codes for envelope glycoproteins that determine viral host range, antigenic specificity, and interference patterns. We used molecular hybridization to analyze the natural distribution and possible origins of the nucleotide sequences that encode env; our work exploited the availability of radioactive DNA (cDNA(gp)) complementary to most or all of env. env sequences were detectable in the DNAs of chickens which synthesized an env gene product (chick helper factor positive) encoded by an endogenous viral gene and also in the DNAs of chickens which synthesized little or no env gene product (chick helper factor negative). env sequences were not detectable in DNAs from Japanese quail, ring-necked pheasant, golden pheasant, duck, squab, salmon sperm, or calf thymus. The detection of sequences closely related to viral env only in chicken DNA contrasts sharply with the demonstration that the transforming gene (src) of avian sarcoma viruses has readily detectable homologues in the DNAs of all avian species tested [D. Stehelin, H. E. Varmus, J. M. Bishop, and P. K. Vogt, Nature (London) 260: 170-173, 1976] and in the DNAs of other vertebrates (D. Spector, personal communication). Thermal denaturation studies on duplexes formed between cDNA(gp) and chicken DNA and also between cDNA(gp) and RNAs of subgroup A to E viruses derived from chickens indicated that these duplexes were well matched. In contrast, cDNA(gp) did not form stable hybrids with RNAs of viruses which were isolated from ring-necked and golden pheasants. We conclude that substantial portions of nucleotide sequences within the env genes of viruses of subgroups A to E are closely related and that these genes probably have a common, perhaps cellular, evolutionary origin.

Assessment of fetal lung maturity by a microviscosimeter

A new method of rapid antenatal assessment of fetal lung maturity was evaluated in relation to the newborn outcome and two other accepted test. This method is based on fluorescence depolarization (FD) technique. The special instrumentation required for this method (the Microviscosimeter) was found to be simple and easy to handle even to nonprofessional personnel. Analysis of 47 samples of amniotic fluid received within 48 hours of delivery demonstrated that lung maturity threshold may be related to a numeric value (P value) measured by this technique. With a P value of less than 0.320 respiratory distress syndrome (RDS) is unlikely to develop. With a P value greater than 0.340, chances for RDS, usually severe, are high. With a P value of less than 0.340 but greater than 0.320, RDS may or may not develop. This method did not prove to be more reliable then the determination of L/S ratio by thin layer chromatography, but its advantage is that it supplies the results in less then an hour. The FD technique proved to be more reliable then the commonly used foam stability test.

In vivo suppression of EL 4 lymphomas by rabbit antitumor sera

Three of more than 50 batches of rabbit antisera raised against the mouse EL 4 lymphoma could inhibit the growth of the tumor in the syngeneic C57BL/6J mice either after exposure of the tumor cells to the antitumor globulin (ATG) in vitro or after the administration of ATG in mice preinoculated with various numbers of EL 4 cells, even though the ATG was not cytotoxic to the tumor cells in the presence of complement. The outcome of immunotherapy with ATG in tumor-bearing C57BL/6J mice depended on the tumor load, the interval between tumor inoculation and the institution of therapy, the total dose, and the schedule of administration of ATG. Complete tumor suppression could be obtained in a proportion of mice preinoculated with 10(5) EL 4 cells, i.e., 10(4) times more than the minimum number of EL 4 cells necessary for 100% tumor takes. Whole-body irradiation (400 rads) or complement depletion of tumor host by cobra venom factor had no effect on tumor suppression by ATG. No evidence of immunity against the EL 4 lymphoma could be detected in EL 4-bearing mice that survived after serotherapy. Anti-EL 4 sera raised in goats and goat and rabbit antisera raised against a lymphoma in the AKR mice have, so far, failed to show any tumor inhibition.

Purification of DNA complementary to the env gene of avian sarcoma virus and analysis of relationships among the env genes of avian leukosis-sarcoma viruses

The env gene of avian leukosis-sarcoma viruses encodes a glycoprotein that determines the host range and surface antigenicitiy of virions. We have purified radioactive DNA (cDNAgp) complementary to at least a portion of the env gene for viral subgroups A and C; complementary DNA was synthesized with purified virions of wild-type avian sarcoma virus, and RNA from a mutant with a deletion in env was used to select DNA specific to env by molecular hybridization. The genetic complexity of cDNAgp for subgroup A (ca. 2,000 nucleotides) was sufficient to represent the entire deletion and most or all of the env cistron. The deletions in env in two independently isolated strains of virus (Bryan and rdNY8SR) overlap, and cDNAgp represents nucleotide sequences common to both deletions. By contrast, we could detect no overlap between deletions in env and deletions in the adjacent viral gene src. Laboratory stocks of viral subgroups A, B, C, D and E do not contain detectable amounts of env deletions when tested by molecular hybridization; hence, segregation of deletions in env is a less frequent event that the segregation of deletions in the viral transforming gene src (Vogt, 1971). We found extensive homology among the nucleotide sequences encoding the env genes of virus strains indigenous to chickens (subgroups A, B, C, D, and E) although subgorups B, D and E appear to differ slightly from subgroups A and C at the env locus. By contrast, viruses obtained from pheasant cells (subgroups F and G) have env genes with little or no relationship to env genes of chikcen viruses. According to available data, viruses of subgroup F arose by recombination between an avarian sarcoma virus and viral genes in the genome of ring-necked pheasants, whereas subgroup G viruses may be entirely endogenous to golden pheasants.