Induction of labor in term pregnancies with isolated polyhydramnios: Is it beneficial or harmful?

OBJECTIVE

To compare rates of adverse pregnancy outcomes in term pregnancies complicated by polyhydramnios between women who had induction of labor (IOB) versus women who had expectant management.

METHODS

This multicenter retrospective study included term pregnancies complicated by isolated polyhydramnios. Patients who underwent IOB were compared with those who had expectant management. The primary outcome was defined as a composite adverse maternal outcome, and secondary outcomes were various maternal and neonatal adverse outcomes. Univariate analyses were followed by multivariate logistic regression.

RESULTS

A total of 865 pregnancies with term isolated polyhydramnios were included: 169 patients underwent IOB (19.5%), while 696 had expectant management and developed spontaneous onset of labor (80.5%). Women who underwent IOB had significantly higher rates of composite adverse maternal outcome (23.1% vs 9.8%, P < 0.01), prolonged hospital stay, perineal tear grade 3/4, intrapartum cesarean, postpartum hemorrhage, blood products transfusion, and neonatal asphyxia compared with expectant management. While the perinatal fetal death rate was similar between the groups (0.6% vs 0.6%, P = 0.98), the timing of the loss was different. Four women in the expectant management group had a stillbirth, while in the induction group one case of intrapartum fetal death occurred due to uterine rupture. Multivariate analyses revealed that IOB was associated with a higher rate of composite adverse maternal outcome (adjusted odds ratio, 2.22 [95% CI, 1.28-3.83]; P < 0.01).

CONCLUSION

IOB in women with term isolated polyhydramnios is associated with higher rates of adverse maternal outcomes in comparison to expectant management. Further research is needed to determine the optimal approach for the management of isolated polyhydramnios at term.

Evaluating the validity of ChatGPT responses on common obstetric issues: Potential clinical applications and implications

OBJECTIVE

To evaluate the quality of ChatGPT responses to common issues in obstetrics and assess its ability to provide reliable responses to pregnant individuals. The study aimed to examine the responses based on expert opinions using predetermined criteria, including "accuracy," "completeness," and "safety."

METHODS

We curated 15 common and potentially clinically significant questions that pregnant women are asking. Two native English-speaking women were asked to reframe the questions in their own words, and we employed the ChatGPT language model to generate responses to the questions. To evaluate the accuracy, completeness, and safety of the ChatGPT's generated responses, we developed a questionnaire with a scale of 1 to 5 that obstetrics and gynecology experts from different countries were invited to rate accordingly. The ratings were analyzed to evaluate the average level of agreement and percentage of positive ratings (≥4) for each criterion.

RESULTS

Of the 42 experts invited, 20 responded to the questionnaire. The combined score for all responses yielded a mean rating of 4, with 75% of responses receiving a positive rating (≥4). While examining specific criteria, the ChatGPT responses were better for the accuracy criterion, with a mean rating of 4.2 and 80% of the questions received a positive rating. The responses scored less for the completeness criterion, with a mean rating of 3.8 and 46.7% of questions received a positive rating. For safety, the mean rating was 3.9 and 53.3% of questions received a positive rating. There was no response with an average negative rating below three.

CONCLUSION

This study demonstrates promising results regarding potential use of ChatGPT's in providing accurate responses to obstetric clinical questions posed by pregnant women. However, it is crucial to exercise caution when addressing inquiries concerning the safety of the fetus or the mother.

The association between unintended hysterotomy extensions with cesarean delivery and subsequent preterm birth

BACKGROUND

An increased risk for preterm birth has been observed among individuals with a previous second stage cesarean delivery when compared with those with a previous vaginal delivery. One mechanism that may contribute to the increased risk for preterm birth following a second stage cesarean delivery is the increased risk for cervical injury because of extension of the uterine incision (hysterotomy) into the cervix. The contribution of hysterotomy extension to the rate of preterm birth in a subsequent pregnancy has not been investigated and may shed light on the mechanism underlying the observed relationship between the mode of delivery and subsequent preterm birth.

OBJECTIVE

We aimed to quantify the association between unintended hysterotomy extension and preterm birth in a subsequent delivery.

STUDY DESIGN

We performed a retrospective cohort study using electronic perinatal data collected from 2 university-affiliated obstetrical centers. The study included patients with a primary cesarean delivery of a term, singleton live birth and a subsequent singleton birth in the same catchment (2005-2021). The primary outcome was subsequent preterm birth <37 weeks' gestation; secondary outcomes included subsequent preterm birth at <34, <32, and <28 weeks' gestation. We assessed crude and adjusted associations between unintended hysterotomy extensions and subsequent preterm birth with log binomial regression models using rate ratios and 95% confidence intervals. Adjusted models included several characteristics of the primary cesarean delivery such as maternal age, length of active labor, indication for cesarean delivery, chorioamnionitis, and maternal comorbidity.

RESULTS

A total 4797 patients met the study inclusion criteria. The overall rate of unintended hysterotomy extension in the primary cesarean delivery was 6.0% and the total rate of preterm birth in the subsequent pregnancy was 4.8%. Patients with an unintended hysterotomy extension were more likely to have a longer duration of active labor, chorioamnionitis, failed vacuum delivery attempt, second stage cesarean delivery, and persistent occiput posterior position of the fetal head in the primary cesarean delivery and higher rates of smoking in the subsequent pregnancy. Multivariable analyses that controlled for several confounders showed that a history of hysterotomy extension was not associated with a higher risk for preterm birth <37 weeks' gestation (adjusted rate ratio, 1.55; 95% confidence interval, 0.98-2.47), but it was associated with preterm birth <34 weeks' gestation (adjusted rate ratio, 2.49; 95% confidence interval, 1.06-5.42).

CONCLUSION

Patients with a uterine incision extension have a 2.5 times higher rate of preterm birth <34 weeks' gestation when compared with patients who did not have this injury. This association was not observed for preterm birth <37 weeks' gestation. Future research should aim to replicate our analyses with incorporation of additional data to minimize the potential for residual confounding.

Labor Induction in Women with Isolated Polyhydramnios at Term: A Multicenter Retrospective Cohort Analysis

Background: With the increasing popularity of elective induction after 39 + 0 weeks, the question of whether induction of labor (IOL) is safe in women with isolated polyhydramnios has become more relevant. We aimed to evaluate the pregnancy outcomes associated with IOL among women with and without isolated polyhydramnios. Methods: This was a multicenter retrospective cohort that included women who underwent induction of labor at term. The study compared women who underwent IOL due to isolated polyhydramnios to low-risk women who underwent elective IOL due to gestational age only. The main outcome measure was a composite adverse maternal outcome, while the secondary outcomes included maternal and neonatal adverse pregnancy outcomes. Results: During the study period, 1004 women underwent IOL at term and met inclusion and exclusion criteria; 162 had isolated polyhydramnios, and 842 had a normal amount of amniotic fluid. Women who had isolated polyhydramnios had higher rates of the composite adverse maternal outcome (28.7% vs. 20.4%, p = 0.02), prolonged hospital stay, perineal tear grade 3/4, postpartum hemorrhage, and neonatal hypoglycemia. Multivariate analyses revealed that among women with IOL, polyhydramnios was significantly associated with adverse composite maternal outcome [aOR 1.98 (1.27-3.10), p < 0.01]. Conclusions: IOL in women with isolated polyhydramnios at term was associated with worse perinatal outcomes compared to low-risk women who underwent elective IOL. Our findings suggest that the management of women with polyhydramnios cannot be extrapolated from studies of low-risk populations and that clinical decision-making should take into account the individual patient's risk factors and preferences.

Impacted fetal head extraction methods at second stage cesarean and subsequent preterm delivery: A multicenter study

OBJECTIVE

Second-stage cesarean delivery (CD) is associated with subsequent preterm birth (PTB). It has been suggested that an increased risk of PTB after second-stage cesarean delivery could be linked to a higher chance of cervical injury due to the extension of the uterine incision. Previous studies have shown that reverse breech extraction is associated with lower rates of uterine incision extensions compared to the "push" method. We aimed to investigate the association between the method of fetal extraction during second-stage CD and the rate of spontaneous PTB (sPTB), as well as other maternal and neonatal outcomes during the subsequent pregnancy.

METHODS

This was a multicenter retrospective cohort study. The study population included women in their first subsequent singleton delivery following a second-stage CD between 2004 and 2021. The main exposure of interest was the method of fetal extraction in the index CD ("push" method vs. reverse breech extraction). The primary outcome of this study was sPTB <37 weeks in the subsequent pregnancy. Secondary outcomes were overall PTB, trial of labor, and other adverse maternal and neonatal outcomes. Univariate analysis was followed by multiple logistic regression modeling.

RESULTS

During the study period, 2969 index CD during second stage were performed, of those 583 met the inclusion criteria, of whom 234 (40.1%) had fetal extraction using the reverse breech extraction method, while 349 (59.9%) had the "push" method for extraction. In univariate analysis, women in those two groups had statistically similar rates of sPTB (3.7% vs. 3.0%; odds ratio [OR] 1.25, 95% CI: 0.49-3.19) and overall PTB (<37, <34 and <32 weeks), as well as other maternal, neonatal, and trial of labor outcomes. This was confirmed by multivariate analyses with an adjusted OR of 1.27 (95% CI: 0.43-3.71) for sPTB.

CONCLUSION

Among women with a previous second-stage CD, no significant difference was observed in PTB rates in the subsequent pregnancies following the "push" method compared to the reverse breech extraction method.

Failed vacuum and preterm delivery risk in the subsequent pregnancy: a multicenter retrospective cohort study

BACKGROUND

Second-stage cesarean delivery is associated with subsequent preterm delivery. Failed vacuum-assisted delivery is a subgroup of second-stage cesarean delivery in which the fetal head is engaged deeper in the pelvis and, thus, is associated with an increased risk of short-term maternal complications.

OBJECTIVE

This study aimed to investigate the maternal and neonatal outcomes of women at their subsequent delivery after a second-stage cesarean delivery with failed vacuum-assisted extraction vs after a second-stage cesarean delivery without a trial of vacuum-assisted extraction.

STUDY DESIGN

This was a multicenter retrospective cohort study. The study population included all women in their subsequent pregnancy after a second-stage cesarean delivery who delivered in all university-affiliated obstetrical centers (n=4) in a single geographic area between 2003 and 2021. Maternal and neonatal outcomes of women who had second-stage cesarean delivery after a failed vacuum-assisted delivery were compared with women who had second-stage cesarean delivery without a trial of vacuum-assisted delivery. The primary outcome of this study was preterm delivery at <37 weeks of gestation. The secondary outcomes were vaginal birth rate and other adverse maternal and neonatal outcomes. Univariate analysis was followed by multiple logistic regression modeling.

RESULTS

During the study period, 1313 women met the inclusion criteria, of whom 215 (16.4%) had a history of failed vacuum-assisted delivery at the previous delivery and 1098 (83.6%) did not. In univariate analysis, women with previously failed vacuum-assisted delivery had similar preterm delivery rates (<37, <34, <32, and <28 weeks of gestation), a successful trial of labor after cesarean delivery rates, uterine rupture, and hysterectomy. However, multivariable analyses controlling for confounders showed that a history of failed vacuum-assisted delivery is associated with a higher risk of preterm delivery at <37 weeks of gestation (adjusted odds ratio, 2.05; 95% confidence interval, 1.11-3.79; P=.02), but not with preterm delivery at <34 or <32 weeks of gestation.

CONCLUSION

Among women with a previous second-stage cesarean delivery, previously failed vacuum-assisted delivery was associated with an increased risk of preterm delivery at <37 weeks of gestation in the subsequent birth.

Unintended lower-segment hysterotomy extension at cesarean delivery and the risk for uterine rupture during a subsequent trial of labor

OBJECTIVE

To evaluate the association between unintended uterine extension in cesarean delivery and uterine scar disruption (rupture or dehiscence) at the subsequent trial of labor after cesarean delivery (TOLAC).

METHODS

This is a multicenter retrospective cohort study (2005-2021). Parturients with a singleton pregnancy who had unintended lower-segment uterine extension during the primary cesarean delivery (excluding T and J vertical extensions) were compared with patients who did not have an unintended uterine extension. We assessed the subsequent uterine scar disruption rate following the subsequent TOLAC and the rate of adverse maternal outcome.

RESULTS

During the study period, 7199 patients underwent a trial of labor and were eligible for the study, of whom 1245 (17.3%) had a previous unintended uterine extension and 5954 (82.7%) did not. In univariate analysis, previous unintended uterine extension during the primary cesarean delivery was not significantly associated with uterine scar rupture in the following subsequent TOLAC. Nevertheless, it was associated with uterine scar dehiscence, higher rates of TOLAC failure, and a composite adverse maternal outcome. In multivariate analyses, only the association between previous unintended uterine extension and higher rates of TOLAC failure was confirmed.

CONCLUSION

A history of unintended lower-segment uterine extension is not associated with an increased risk for uterine scar disruption following subsequent TOLAC.

Perinatal outcomes in nulliparous women with a history of multiple pregnancy losses according to number of previous pregnancy losses

BACKGROUND

While it is widely acknowledged that pregnancy losses can lead to negative outcomes for both mothers and fetuses, there is limited information available on the specific levels of risk associated with each additional pregnancy loss.

OBJECTIVE

This study aimed to investigate the effect of number of previous pregnancy losses among nulliparous women on maternal and neonatal adverse outcomes.

STUDY DESIGN

This was a multicenter retrospective cohort study. The study population included all nulliparous women with singleton pregnancies who delivered in all university-affiliated obstetrical centers in a single geographic area between 2003 and 2021. Maternal and neonatal outcomes of women who delivered at our medical centers and had varying numbers of previous pregnancy losses were compared with women who had no previous pregnancy loss. The primary outcome of this study was preterm delivery rate at <37 weeks of gestation. The secondary outcomes were adverse maternal and neonatal outcomes. Univariate analysis was performed using multiple logistic regression modeling.

RESULTS

During the study period, 97,904 nulliparous women met the inclusion and exclusion criteria. Of those women, 84,245 (86%) had no previous pregnancy losses (reference group), 10,724 (11%) had 1 previous pregnancy loss, 2150 (2.2%) had 2 previous pregnancy losses, 516 (0.5%) had 3 previous pregnancy losses, 160 (0.2%) had 4 previous pregnancy losses, and 99 (0.1%) had ≥5 previous pregnancy losses. Women who had previous pregnancy losses had significantly higher rates of preterm delivery, hypertensive disorders of pregnancy, diabetes mellitus (pregestational and gestational), unplanned cesarean delivery, perinatal death, neonatal intensive care unit admissions, and neonatal hypoglycemia. The risks of preterm delivery and most other adverse obstetrical outcomes correlated with the number of previous pregnancy losses. Multivariate analyses showed that each previous pregnancy loss was associated with an additional, significant, increased risk of preterm delivery of 14% at <37 weeks of gestation, 37% at <34 weeks of gestation, 45% at <32 weeks of gestation, and 77% at <28 weeks of gestation.

CONCLUSION

A history of previous pregnancy losses increased the risk of preterm delivery and other perinatal outcomes in a dose-dependent manner. To minimize perinatal complications, obstetricians should be aware of the risks and complications in this unique population, consider close monitoring of the cervical length, and maintain high vigilance in case of complications with special attention to other potentially modifiable risks.

Association between One Abnormal Value on 3-Hour Oral Glucose Tolerance Test and Adverse Perinatal Outcomes in Twin Gestation

AIM

To investigate whether women with twin gestation and one abnormal value on the diagnostic 3-hour oral glucose tolerance test (OGTT) are at an increased risk of adverse perinatal outcomes.

METHODS

This was a retrospective multicenter study of women with twin gestation, comparing four groups: (1) normal 50-g screening, (2) normal 100-g 3-hour OGTT, (3) one abnormal value on the 3-hour OGTT, and (4) GDM. Multivariable logistic regressions adjusted for maternal age, gravidity, parity, previous CDs, fertility treatments, smoking, obesity and chorionicity were used.

RESULTS

The study included 2,597 women with twin gestations, of which 79.7% had a normal screen, and 6.2% had one abnormal value on the OGTT. In adjusted analyses, women with one abnormal value were found to have higher rates of preterm delivery <32 weeks, large for gestational age neonates, and composite neonatal morbidity of at least one fetus, however, similar maternal outcomes as those with a normal screen.

CONCLUSION

Our study provides evidence that women with twin gestation and one abnormal value on the 3-hour OGTT are at an increased risk of unfavorable neonatal outcomes. This was confirmed by multivariable logistic regressions. Further research is needed to determine whether interventions such as nutritional counseling, blood glucose monitoring, and treatment with diet and medication would improve perinatal outcomes in this population.

Factors Associated with Failed Trial of Labor after Cesarean, among Women with Twin Gestation-A Multicenter Retrospective Cohort Study

Objective: Twin trial of labor after a cesarean section (TOLAC) is associated with a lower success rate of vaginal delivery than singleton TOLAC, and a higher rate of adverse outcomes in comparison to an elective repeat cesarean delivery. This study aims to investigate the factors associated with failed TOLAC, among women with twin gestation. Study design: A multicenter retrospective cohort study was undertaken. All women with twin pregnancies attempting a trial of labor after a previous cesarean in two university-affiliated obstetrical centers, between 2005 and 2021 were included. The study population included women with a twin gestation where twin A presented in the vertex position, a single previous low segment transverse section, and those who were eligible for a vaginal delivery. Labor, maternal, and neonatal characteristics were compared. A univariate analysis was undertaken, followed by multivariate analysis (aORs; [95% CI]). Results: A total of 160 women attempting a twin TOLAC were included. Vaginal birth after cesarean was achieved in 86.3% of these cases. Assisted reproductive technology (ART), the lack of oxytocin use for augmentation during labor, the lack of epidural analgesia, and preterm birth before 34, 32, and 28 gestational weeks were all found to be associated with failed TOLAC. In the multivariate analysis, cervical dilation on admission (aOR 0.6 [0.40−0.82], p < 0.01), no use of oxytocin (aOR 5.2 [1.36−19.73], p = 0.02), gestational age at delivery (aOR 0.8 [0.65−1.00], p = 0.047) and lack of epidural analgesia (aOR 4.5 [1.01−20.16], p = 0.049), were all found to be significantly associated with failed TOLAC. Conclusion: In the investigated population of women with twins undergoing TOLAC, the use of epidural analgesia, the use of oxytocin and increased cervical dilation to the delivery room are associated with a higher rate of vaginal delivery, and may reduce the risk of repeat cesarean delivery.

Mode of preterm delivery and risk of recurrent preterm delivery, a multicenter retrospective study

OBJECTIVE

To examine whether mode of preterm delivery is associated with the risk of recurrent preterm delivery in subsequent pregnancy.

STUDY DESIGN

A multicenter retrospective study. Women with the first two consecutive singleton deliveries at two university-affiliated medical centers between August 2005-March 2021, with first delivery occurring spontaneously < 37 weeks of gestation were included. Excluded were women with multifetal pregnancies in either pregnancy and those with an indicated first preterm delivery. A univariate analysis was followed by a multivariate analysis.

RESULTS

A total of 1,019 women with spontaneous preterm first delivery were included. Of those, 141 (13.8 %) underwent cesarean delivery in their first preterm delivery, while 878 (86.2 %) had a vaginal delivery. Univariate analysis revealed that women who underwent cesarean delivery in their first delivery had, during the subsequent delivery: longer mean gestational age at delivery (37.8 ± 3.3 vs 36.8 ± 3.7 weeks; p < 0.01), but statistically similar rates of recurrent preterm delivery both < 37 weeks and < 34 weeks (23.4 % vs 27.2 % and 7.1 % vs 10.6 %; p = 0.34 and p = 0.20, respectively). Multivariate analysis revealed that mode of delivery- cesarean - in the preterm delivery was not associated with recurrent pre-term delivery (0.66 (0.41-1.04), p = 0.07).

CONCLUSION

Mode of delivery in first preterm delivery is not associated with higher or lower rates of recurrent preterm delivery.

Transplantation of ex vivo expanded cord blood cells using the copper chelator tetraethylenepentamine: a phase I/II clinical trial

The copper chelator tetraethylenepentamine (TEPA; StemEx) was shown to attenuate the differentiation of ex vivo cultured hematopoietic cells resulting in preferential expansion of early progenitors. A phase I/II trial was performed to test the feasibility and safety of transplantation of CD133+ cord blood (CB) hematopoietic progenitors cultured in media containing stem cell factor, FLT-3 ligand, interleukin-6, thrombopoietin and TEPA. Ten patients with advanced hematological malignancies were transplanted with a CB unit originally frozen in two fractions. The smaller fraction was cultured ex vivo for 21 days and transplanted 24 h after infusion of the larger unmanipulated fraction. All but two units contained <2 x 10(7) total nucleated cells (TNCs) per kilogram pre-expansion. All donor-recipient pairs were mismatched for one or two HLA loci. Nine patients were beyond first remission; median age and weight were 21 years and 68.5 kg. The average TNCs fold expansion was 219 (range, 2-620). Mean increase of CD34+ cell count was 6 (over the CD34+ cell content in the entire unit). Despite the low TNCs per kilogram infused (median=1.8 x 10(7)/kg), nine patients engrafted. Median time to neutrophil and platelet engraftment was 30 (range, 16-46) and 48 (range, 35-105) days. There were no cases of grades 3-4 acute graft-versus-host disease (GVHD) and 100-day survival was 90%. This strategy is feasible.

Pre-clinical development of cord blood-derived progenitor cell graft expanded ex vivo with cytokines and the polyamine copper chelator tetraethylenepentamine

BACKGROUND

We have previously demonstrated that the copper chelator tetraethylenepentamine (TEPA) enables preferential expansion of early hematopoietic progenitor cells (CD34+CD38-, CD34+CD38-Lin-) in human umbilical cord blood (CB)-derived CD34+ cell cultures. This study extends our previous findings that copper chelation can modulate the balance between self-renewal and differentiation of hematopoietic progenitor cells.

METHODS

In the present study we established a clinically applicative protocol for large-scale ex vivo expansion of CB-derived progenitors. Briefly, CD133+ cells, purified from CB using Miltenyi Biotec's (Bergisch Gladbach, Germany) CliniMACS separation device and the anti-CD133 reagent, were cultured for 3 weeks in a clinical-grade closed culture bag system, using the chelator-based technology in combination with early-acting cytokines (SCF, thrombopoietin, IL-6 and FLT-3 ligand). This protocol was evaluated using frozen units derived from accredited cord blood banks.

RESULTS

Following 3 weeks of expansion under large-scale culture conditions that were suitable for clinical manufacturing, the median output value of CD34+ cells increase by 89-fold, CD34+CD38- increase by 30-fold and CFU cells (CFUc) by 172-fold over the input value. Transplantation into sublethally irradiated non-obese diabetic (NOD/SCID) mice indicated that the engraftment potential of the ex vivo expanded CD133+ cells was significantly superior to that of unexpanded cells: 60+/-5.5% vs. 21+/-3.5% CD45+ cells, P=0.001, and 11+/-1.8% vs. 4+/-0.68% CD45+CD34+ cells, P=0.012, n=32, respectively.

DISCUSSION

Based on these large-scale experiments, the chelator-based ex vivo expansion technology is currently being tested in a phase 1 clinical trial in patients undergoing CB transplantation for hematological malignancies.

Immune response to a diphtheria and tetanus toxoid administration in a three-dose diphtheria tetanus whole-cell pertussis/enhanced inactivated poliovirus vaccination schedule: a 7-year follow up

The immune response to diphtheria and tetanus toxoid components of a combined diphtheria tetanus whole-cell pertussis/enhanced inactivated poliovirus (DTwP/eIPV) vaccine, administered in a three-dose schedule to infants at 2, 3 1/2 and 10 months of age and followed by a booster at the age of 8 years, was compared with the immune profile of a group of children at the same ages given the customary DTwP vaccine schedule at 2, 4, 6, and 12 months of age and a booster at the age of 8. Diphtheria- and tetanus-antitoxin titers were measured in parallel enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA). After the reinforcing dose given at 10 months of age, diphtheria antitoxin concentrations of > or = 0.01 IU/ml were found in 100% of infants in the study group, 91.7% of whom reached a titer of > or = 0.1 IU/ml and a geometric mean titer (GMT) of 0.40 and 0.93 IU/ml in ELISA and RIA, respectively. At 3 and 6 years of age, diphtheria antitoxin values of > or = 0.01 IU/ml were detected in 100 and 94% of children with GMT of 0.043 and 0.024 IU/ml, respectively. Seropositivity and GMT values indicative of protection were measured by both ELISA and RIA after the booster at the age of 8 years. Similar results were found in the control group, although the GMT tended to be higher. A good correlation between results obtained by ELISA vs. RIA was evident throughout. Priming at 2 and 3 1/2 months with diphtheria and tetanus antitoxin, as a component of a DTwP program, and reinforcing 6 months later induced an immune response indicative of protection against the diseases, which persisted up to the age of the booster recommended at school entry.

Hepatitis A virus seropositivity among hospital and community healthcare workers in Israel-the role of occupation, demography and socioeconomic background

Hospital and community-clinic workers were tested for hepatitis A virus antibodies (HAV)-IgG to identify variables associated with presence of (HAV-IgG) and to determine whether sociodemographic background may explain all differences in HAV seropositivty among healthcare workers. Logistic regression analysis was used to identify variable associated with HAV-immunity. Multivariate logistic regression analysis revealed that HAV-seroprevalence correlated significantly (P<0.01) with age, siblings, residence in rural areas and origin. Nurse aides had an increased risk for HAV seropositivity (OR=5.04; 95% CI: 1.49-17.08) whereas physicians had a lower risk (OR=0.54: 95% CI: 0.30-0.98). Age and socioeconomic background were independently correlated with HAV immunity but did not explain all difference in HAV-seroprevalence. The higher susceptibility and elevated incidence of hepatitis A amongst physicians, prioritize primary prevention in this group.

Influenza surveillance during winter 1997-1998 in Israel

BACKGROUND

Each winter influenza activity is a major cause of morbidity and mortality both in Israel and worldwide.

OBJECTIVES

To identify the influenza viruses active in Israel during the winter season and to assess the extent of influenza morbidity.

METHODS

Information was collected on a population of 18,684 individuals enrolled in two community clinics in central Israel. It included the total number of visits for acute respiratory infection--including influenza and influenza-like illness (ARI/flu-like)--during a 20 week surveillance period (23 November 1997 to 27 March 1998) and the percent of influenza virus isolates in nasopharyngeal specimens from a sample of patients with ARI/flu-like collected on a weekly basis during the same period.

RESULTS

A total of 5,947 visits for ARI/flu-like were recorded among 18,684 enrolled patients in two community clinics (18.1%). The progressive increase in the number of visits for ARI/flu-like reached a peak on week 2/98 with 597 visits and a rate of 31.95 visits per 1,000 population. After this, a decrease to the initial values was evident by week 12/98. Most affected patients were in the age groups 5-14 and 65 years and over, with a rate of 733.5 and 605.3 visits per 1,000 population, respectively. Influenza virus was isolated from 92 of the 426 nasopharyngeal specimens (21.6%). The most commonly detected strain was A/Sydney/5/97 (H3N2) like (77.2%). The peak rate of isolates was recorded at the beginning of January (01/98).

CONCLUSIONS

A/Sydney/5/97 (H3N2) like-strain was the dominant influenza virus. Its presence did not prevent the simultaneous activity of influenza A/H1N1 virus. The dynamic of the clinical disease as expressed by the weekly visit rate for ARI/flu-like was similar to the temporal pattern of the virological findings. The extent of morbidity suggests moderate epidemic activity.

Cost-benefit analysis of active vaccination campaigns against hepatitis A among daycare centre personnel in Israel

OBJECTIVE

To evaluate, in economic terms, active vaccination campaigns against hepatitis A in comparison with the use of nonspecific immune globulin for the prevention of the disease among daycare centre employees in Israel.

SETTING

Hypothetical analysis of the costs and benefits related to vaccination campaigns of workers currently employed in daycare centres in Israel.

METHODS

A cost-benefit analysis was performed, comparing mass and selective active vaccination strategies for the daycare centre working force. Direct and indirect costs of diagnosis, treatment and immunisation as well as productivity loss were considered. A Markov-based model was developed using data from previous epidemiological studies and literature.

RESULTS

The benefit-to-cost ratios of selective and mass active vaccination strategies were 1.50 [net present value (NPV) $US606 396] and 0.04 (NPV-$US2.36 million), respectively (2000 values).

CONCLUSION

Under these study assumptions, the practice of administering hepatitis A active vaccine to serologically proven non-immune daycare centre workers has a cost-benefit justification, and should be widely considered in countries with a similar hepatitis A epidemiology to that in this study.

The effect of human myelomonocytic leukemic cell line (M20) derived IL-1 inhibitor on human erythroid cell development

The effect of an inhibitor of IL-1, purified from a human myelomonocytic cell line (M20) on the development of human erythroid cell development was studied. The inhibitor, is a protein of 52 kD molecular weight that is distinct immunologically and functionally from other reported IL-1 inhibitors. The experiments were performed in a two-phase culture system that allows separation of the erythroid cell development into an erythropoietin (EPO)-independent phase, where early erythroid-committed BFUe proliferate and differentiate into the more mature progenitors, CFUe, and EPO-dependent phase, where CFUe further proliferate and mature into hemoglobin-containing orthochromatic normoblasts. The results indicated that in both developmental stages the M20-derived inhibitor reversibly blocked cell proliferation without interfering with cell differentiation.

Effect of M20 interleukin-1 inhibitor on normal and leukemic human myeloid progenitors

This study aimed to assess the effect of the M20 interleukin-1 (IL-1) inhibitor on normal and leukemic hematopoietic cells. The M20-derived IL-1 inhibitor was found to inhibit the growth of various hematopoietic cells. The in vitro proliferation of myeloid cell lines in serum-containing medium or proliferation of these cells induced by IL-1 in serum-free medium (measured by 3H-TdR) were inhibited by the M20 IL-1 inhibitor. In addition, growth of normal progenitors and fresh leukemic cells stimulated by granulocyte-macrophage colony-stimulating factor (GM-CSF) (as measured by colony and liquid systems) was also inhibited by this factor. After the removal of the IL-1 inhibitor at the peak of growth inhibition, leukemic and normal progenitor cells retain their ability to grow and develop into GM-CSF colonies. These results show that the growth inhibition phenomena were reversible and did not result from a cytotoxic effect. Our data suggest that the M20-derived IL-1 inhibitor might function as a true negative growth regulator of normal and leukemic hematopoietic cells.

Isolation and characterization of HL-60 cell variants with different potentials for spontaneous differentiation

Although HL-60 cells, an in vitro established cell line derived from a patient with acute promyelocytic leukemia, are blocked at the promyelocytic stage of myeloid differentiation, certain chemicals can induce the cells to undergo terminal differentiation into either granulocytes or macrophages. Moreover, a small fraction of the cell population undergoes differentiation spontaneously without the addition of any inducing agent. In this paper it is demonstrated that this cell line is heterogeneous with respect to the ability of the cells to differentiate spontaneously: some clones (SD+) have a higher tendency to do so than others (SD-). In semi-solid medium, SD+ cells developed diffused colonies containing mature monocytes and macrophages, whereas SD- cells developed compact colonies of promyelocytes. Based on these morphological differences the various clones were isolated and analysed. Although only a small fraction of the population actually became differentiated at any particular time, practically all the cells in the SD+ clones had the potential to differentiate spontaneously. The clones also differ in their response to differentiation inducers; whereas some agents induced complete differentiation in both types of clones, others (e.g. actinomycin C and cytosine arabinoside) induced only SD+ clones, suggesting that differentiation induced by the latter agents is related to the ability of the cells to differentiate spontaneously. Thus the potential of leukemic cells to undergo spontaneous differentiation may be an important factor when considering differentiation-inducing therapy for leukemic patients.

Self-renewal and commitment to differentiation of human leukemic promyelocytic cells (HL-60)

More than 80% of cells from a human promyelocytic leukemic cell line (HL-60) possess the capacity for self-renewal as evidenced by their ability to form large primary colonies in semisolid medium and the presence within these colonies of cells capable of subsequent colony formation. Colony development is independent of the normal regulator--the myeloid colony stimulating factor. The observed autostimulation suggests the production of specific growth promoters by the cells. Differentiation either to mature granulocytes or macrophages, induced by various agents, was associated with reduced cloning potential. Nevertheless, colonies containing differentiated cells could be developed either by cloning cells in the presence of suboptimal concentrations of inducer or by adding inducers over colonies developed in its absence. Upon differentiation, there was a morphological change from compact to diffused colony morphology due to cell mobility in the semisolid medium. Even at suboptimal concentrations of inducer more than 95% of the colonies became diffused, indicating clonal homogeneity of the population with respect to differentiation capacity. The loss of self-renewal was found to be one of the early properties which changed following the initiation of differentiation. The loss preceded not only the overt expression of maturation-specific functions but also cellular commitment to terminal differentiation; shorter contact with the inducer was required to cause loss of self-renewal than to induce an irreversible transition to differentiation. This resulted in cells that lost their self-renewal potential without being able to complete their program of differentiation.

Modulation of the maturation of human leukemic promyelocytes (HL-60) to granulocytes or macrophages

The relationship between the effects of two types of inducers on the maturation of a line of human promyelocytic cells (HL-60) was studied. The dual potentiality of these promyelocytes was demonstrated by the ability of isolated colonies to differentiate into granulocytes, following induction by dimethylsulphoxide (DMSO) or express properties specific to macrophages following exposure to 12-O-tetradecanoylphorbol-13-acetate (TPA). The differentiation process involved an irreversible step which occurred 48 h after exposure to DMSO, and a few h after exposure to TPA. This implies that the presence of the inducer in the culture medium is no more required for completion of the differentiation programme. Removal of the inducer prior to this step resulted in reversal of all the inducer-mediated effects. During the period of non-commitment the specific pathway of maturation was still undetermined; cells in which differentiation was initiated by exposure to DMSO were able to develop into macrophages after substitution of DMSO by TPA. Moreover, pre-exposure to DMSO and other inducers of granulocyte differentiation resulted in higher sensitivity to TPA, as indicated by the cell response to low TPA concentrations and more rapid expression of macrophage specific properties. These results suggest that the early stages in HL-60 differentiation are probably common to the granulocyte and the macrophage pathways.