Use of non-invasive cardiac monitoring to guide discontinuation of postpartum magnesium sulfate in individuals with preeclampsia with severe features

OBJECTIVES

To determine the utility of using total peripheral systemic vascular resistance assessed using non-invasive cardiac monitor for individualizing the duration of postpartum magnesium sulfate in individuals with preeclampsia with severe features.

STUDY DESIGN

Single center pilot randomized controlled trial in which singleton pregnant individuals with preeclampsia with severe features were randomized to 24 h of postpartum magnesium sulfate per standard of care (control group) or individualized duration of postpartum magnesium sulfate based on reduction in post-delivery systemic vascular resistance (intervention group). Systemic vascular resistance was assessed with non-invasive cardiac monitoring using the Cheetah® system. A 30 % reduction (maintained for 1 h) from baseline post-delivery systemic vascular resistance was used as a cutoff for discontinuation of postpartum magnesium sulfate. Our primary outcome was duration of postpartum magnesium sulfate use in hours. Secondary outcomes included a composite of maternal morbidities associated with preeclampsia.

RESULTS

Of 53 individuals enrolled, we excluded 6 from this analysis due to insufficient data to assess primary outcome. Baseline characteristics of the control (n = 26) and intervention (n = 21) groups were similar. Six (28.6 %) individuals in intervention group met the systemic vascular resistance criteria and had their postpartum magnesium sulfate discontinued before 24 h. The duration of postpartum magnesium sulfate infusion was shorter in the intervention group (21.6 ± 4.7 h; range: 7-24 h) compared with control group (24 h, p = 0.02). There was no difference in secondary outcomes between the two groups. There was no difference in adverse outcomes in individuals that had magnesium discontinued earlier than 24 h.

CONCLUSION

Non-invasive monitoring of systemic vascular resistance can be a valuable tool to individualize the duration of postpartum magnesium sulfate for preeclampsia with severe features. These findings should be conformed in a larger trial.

Increasing rates of sars-cov-2 infection in newborns during the omicron variant epoch

PROBLEM

Transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from infected pregnant individuals to the fetus or newborn occurs from 1.2% to 4.3%. Our aim was to determine the rate of positivity among newborns delivered to infected mothers during epochs of different variants predominance.

METHOD OF STUDY

This is a single academic center retrospective cohort study where we reviewed the electronic health records of pregnant individuals who tested positive for SARS-CoV-2 infection and their newborns from March 2020 through January 2022. Infants born to SARS-CoV-2-positive mothers at the time of delivery or within 10 days of admission were tested for SARS-CoV-2 infection at 24-36 h of age.

RESULTS

A total of 195 mothers were positive at delivery or within 10 days of admission and had their newborns tested for SARS-CoV-2. Seven newborns (3.6%) were positive. All positive infants were asymptomatic and born to unvaccinated mothers. Newborn positivity for SARS-CoV-2 was highest during the Omicron epoch (9.4%, p = .01).

CONCLUSION

Increasing positivity rate was seen during the Omicron variant predominance. This could be attributed to postnatal acquisition of the virus, as Omicron has been associated with higher transmissibility in older children and adults.

Blood Product Replacement for Postpartum Hemorrhage

Consideration for blood products replacement in postpartum hemorrhage should be given when blood loss exceeds 1.5 L or when an estimated 25% of blood has been lost. In cases of massive hemorrhage, standardized transfusion protocols have been shown to improve maternal morbidity and mortality. Most protocols recommend a balanced transfusion involving a 1:1:1 ratio of packed red blood cells, platelets, and fresh frozen plasma. Alternatives such as cryoprecipitate, fibrinogen concentrate, and prothrombin complex concentrates can be used in select clinical situations. Although transfusion of blood products can be lifesaving, it does have associated risks.

Outcomes Following Extracorporeal Membrane Oxygenation for Severe COVID-19 in Pregnancy or Post Partum

Importance

Existing reports of pregnant patients with COVID-19 disease who require extracorporeal membrane oxygenation (ECMO) are limited, with variable outcomes noted for the maternal-fetal dyad.

Objective

To examine maternal and perinatal outcomes associated with ECMO used for COVID-19 with respiratory failure during pregnancy.

Design, Setting, and Participants

This retrospective multicenter cohort study examined pregnant and postpartum patients who required ECMO for COVID-19 respiratory failure at 25 hospitals across the US. Eligible patients included individuals who received care at one of the study sites, were diagnosed with SARS-CoV-2 infection during pregnancy or up to 6 weeks post partum by positive nucleic acid or antigen test, and for whom ECMO was initiated for respiratory failure from March 1, 2020, to October 1, 2022.

Exposures

ECMO in the setting of COVID-19 respiratory failure.

Main outcome and measures

The primary outcome was maternal mortality. Secondary outcomes included serious maternal morbidity, obstetrical outcomes, and neonatal outcomes. Outcomes were compared by timing of infection during pregnancy or post partum, timing of ECMO initiation during pregnancy or post partum, and periods of circulation of SARS-CoV-2 variants.

Results

From March 1, 2020, to October 1, 2022, 100 pregnant or postpartum individuals were started on ECMO (29 [29.0%] Hispanic, 25 [25.0%] non-Hispanic Black, 34 [34.0%] non-Hispanic White; mean [SD] age: 31.1 [5.5] years), including 47 (47.0%) during pregnancy, 21 (21.0%) within 24 hours post partum, and 32 (32.0%) between 24 hours and 6 weeks post partum; 79 (79.0%) had obesity, 61 (61.0%) had public or no insurance, and 67 (67.0%) did not have an immunocompromising condition. The median (IQR) ECMO run was 20 (9-49) days. There were 16 maternal deaths (16.0%; 95% CI, 8.2%-23.8%) in the study cohort, and 76 patients (76.0%; 95% CI, 58.9%-93.1%) had 1 or more serious maternal morbidity events. The largest serious maternal morbidity was venous thromboembolism and occurred in 39 patients (39.0%), which was similar across ECMO timing (40.4% pregnant [19 of 47] vs 38.1% [8 of 21] immediately postpartum vs 37.5% postpartum [12 of 32]; P > .99).

Conclusions and Relevance

In this multicenter US cohort study of pregnant and postpartum patients who required ECMO for COVID-19-associated respiratory failure, most survived but experienced a high frequency of serious maternal morbidity.

Aspirin and Pravastatin for Preeclampsia Prevention in High-Risk Pregnancy

Preeclampsia is a hypertensive disorder of pregnancy affecting up to 8% of pregnancies. It is associated with significant neonatal and maternal morbidities and mortality. Although its pathogenesis is not completely understood, abnormal placentation resulting in imbalance in angiogenic factors, increased inflammation, and endothelial dysfunction are thought to be key pathways in the development of the disease. Administration of low-dose aspirin is recommended by professional societies for the prevention of preeclampsia in high-risk individuals. In this review, we summarize the evidence behind the use of low-dose aspirin and pravastatin in pregnant individuals at high risk of preeclampsia.

Decreased severity of COVID-19 in vaccinated pregnant individuals during predominance of different SARS-CoV-2 variants

Problem

Since the start of the pandemic, Pregnant individuals have been disproportionately affected by the severe acute respiratory syndrome coronavirus 2. Vaccination has been shown to be protective against severe disease. However, data on effectiveness of vaccine in reducing disease severity are limited in pregnant individuals who later developed COVID‐19.

Method of study

This is a single academic center retrospective cohort study of pregnant individuals who tested positive for COVID‐19 from December 2020 through January 2022. The cohort was divided into two groups based on vaccination status. The primary outcome of our study was progression to severe or critical disease. A secondary analysis was performed based on the timeframes of predominance of different variants of SARS‐CoV‐2, to determine whether the effect of vaccination was different during these epochs.

Results

Our cohort included 472 patients among which 125 (26.5%) were vaccinated and 347 were unvaccinated. None of the patients in the vaccinated group who later developed COVID‐19 progressed to severe or critical disease compared to 7.2% in the unvaccinated one (p < .01). Similarly, after adjusting for medical comorbidities, obesity, receipt of monoclonal antibodies, and trimester at diagnosis, vaccinated individuals who later developed COVID‐19 were less likely to be admitted to the hospital (1.6% vs. 14.7%, aOR .14, 95% CI .22–.47) compared with unvaccinated ones.

Conclusion

Vaccination against SARS‐CoV‐2 in pregnant individuals who later develop a breakthrough infection, is associated with decreased progression to severe or critical COVID‐19, and need for hospital and ICU admissions. Vaccination is specifically effective during the predominance of the more severe Delta variant.

The Quantose Insulin Resistance Test for Maternal Insulin Resistance: A Pilot Study

OBJECTIVE

Insulin resistance (IR) increases during pregnancy which can lead to hyperinsulinemia, gestational diabetes mellitus (GDM), and neonatal hypoglycemia (NH), especially in obese women. Glucose tolerance testing (GTT) is used clinically to evaluate IR in pregnancy. Quantose IR score index is a novel blood screen of IR validated in nonpregnant individuals. The score is generated using an algorithm that combines insulin and three biomarkers of fatty acid pathways (α-hydroxybutyrate, oleic acid, linoleoyl-glycerophospocholine). Our objective was to determine the validity of Quantose IR test (Metabolan Inc. Morrisville, NC) in assessing IR in pregnant obese women, as compared with the homeostatic model assessment of insulin resistance (HOMA-IR), and its ability to predict GDM and NH.

STUDY DESIGN

Women between 10^0/7 and 13^6/7 weeks of gestation with a pre-pregnancy or early pregnancy body mass index more than 30 kg/m², and no pregestational diabetes, were included. Fasting blood samples were collected at 10^0/7 to 13^6/7 (T1) and 24^0/7 to 28^0/7 (T2) weeks. Quantose IR and HOMA-IR were calculated. All women underwent an early (T1; indicated for women with obesity) and a T2 glucose tolerance tests. GDM was diagnosed using the two-step approach, and NH was defined as a neonatal glucose less than 40 mg/dL in the first 24 hours of life. Linear regression and receiver operating characteristic curves were used for analysis.

RESULTS

The trial enrolled 100 patients. Ten subjects (10%) were diagnosed with GDM in the second trimester and none in the first trimester. At T1, Quantose IR (R²= 0.48), but not 1-hour glucose tolerance test (R²= 0.07), correlated with HOMA-IR. Similar correlations were observed at T2. The 1-hour glucose tolerance test followed by HOMA-IR and Quantose IR (area under the curve [AUC]: 0.82, 0.68, and 0.62, respectively) were predictors of GDM. Quantose IR (AUC: 0.74) and 1-hour glucose tolerance test (AUC: 0.72) at T1 and T2 (AUC: 0.75; AUC: 0.93; respectively) were best predictors of NH. The best cut offs, sensitivities, and specificities for prediction of NH were determined.

CONCLUSION

Similar to nonpregnant individuals, Quantose IR appears to be a valid measure of IR in obese pregnant women. First trimester Quantose IR is a predictor of GDM diagnosed in the second trimester and NH. Given that it requires a single blood draw and no glucose challenge, it may be a useful test to evaluate and monitor IR in pregnancy. Our findings may be used as pilot data to explore the potential use of Quantose IR in pregnancy further.

KEY POINTS

· Traditional testing methods for insulin resistance in pregnancy are often performed late, are time consuming, and unpleasant to patients.. · The first trimester one-step Quantose IR test reflects insulin resistance in pregnancy and predicts GDM and neonatal hypoglycemia.. · This is the first known prospective clinical study validating Quantose IR score index in an obstetrical population at risk for developing GDM..

[Poor results and complications in the use of focused shockwaves and radial pressure waves in musculoskeletal pathology]

The application of focused shockwaves and radial pressure waves in musculoskeletal pathology has had a great development in the last decade. Although most of the publications have highlighted their safety and efficacy, poor results and complications can occur. This review analyzes the main causes of its poor results, adverse effects, and complications, emphasizing their prevention.

Factors influencing different types of malocclusion and arch form-A review

AIM

This review intends to highlight malocclusion as a multifactorial issue and review the different factors that influence different types of malocclusion and arch form.

METHODS

An online article search was performed on the factors influencing malocclusion and arch form from January 1990 through April 2020. The search was performed within the Google, Rutgers library, PubMed, MEDLINE databases via OVID using the keywords mentioned in the PubMed and MeSH headings for the English language published articles January 1990 through April 2020, which evaluated different factors that influence malocclusion and arch form.

RESULTS

Of the 300 articles found in initial search results, 31 articles met the inclusion criteria set for this review. These 31 studies were directly related to the factors that impact malocclusion and different arch forms.

CONCLUSION

Genetic inheritance, genetic mutations, age, gender, ethnicity, dental anomalies like macrodontia, congenital diseases, muscular diseases, hormone imbalance, and human behaviour are all factors that influence malocclusion and arch forms. The elements within the individual's control like behaviours can aid in preventing malocclusion. However, it seems as if the underlying reason for most of these factors indicates that malocclusion is a by-product of genetics and pathology.

A randomized controlled trial of Dilapan-S vs Foley balloon for preinduction cervical ripening (DILAFOL trial)

OBJECTIVE

The objective of the study was to test the hypothesis that Dilapan-S is not inferior to the Foley balloon for preinduction cervical ripening at term.

STUDY DESIGN

Pregnant women ≥37 weeks scheduled for induction with unfavorable cervix (≤3 cm dilated and ≤60% effaced) were randomly assigned to 12 hours of either Foley balloon inflated with 60 mL saline or Dilapan-S for cervical ripening. If the cervix remained unfavorable, then 1 more round of the assigned dilator was used. Management following ripening was left up to the clinical providers. The primary outcome was vaginal delivery. A satisfaction survey was also obtained after the preinduction period. Sample size was based on a noninferiority margin of 10%, 90% power, and an estimated frequency of vaginal delivery of 71% in Foley balloon and 76% in Dilapan-S.

RESULTS

From November 2016 through February 2018, 419 women were randomized (209 to Foley balloon; 210 to Dilapan-S). In the intent-to-treat analysis, vaginal delivery was more common in Dilapan-S vs Foley balloon (81.3% vs 76.1%), with an absolute difference with respect to the Foley balloon of 5.2% (95% confidence interval, -2.7% to 13.0%) indicating noninferiority for the prespecified margin. The difference was not large enough to show superiority. Noninferiority was confirmed in the per-protocol population (n = 204 in the Foley balloon, n = 188 in Dilapan-S), supporting the robustness of the results. Secondary outcomes were not different between groups, except for a longer time the device remained in place in Dilapan-S compared with the Foley balloon. Maternal and neonatal adverse events were not significantly different between groups. A priori interaction analyses showed no difference in the effect on vaginal delivery by cervical dilation at randomization, parity, or body mass index >30 kg/m². Patients with Dilapan-S were more satisfied than patients with the Foley balloon as far as sleep (P = .01), relaxing time (P = .001), and performance of desired daily activities (P = .001).

CONCLUSION

Dilapan-S is not inferior to the Foley balloon for preinduction cervical ripening at term. Advantages of Dilapan-S over Foley include Food and Drug Administration approval, safe profile, no protrusion from the introitus, no need to keep under tension, and better patient satisfaction.

Laparoscopic Modified Vecchietti Technique for Mayer-Rokitansky-Küster-Hauser (MRKH) Syndrome: Report of Two Cases

Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a congenital disorder characterized by uterine aplasia and aplasia of the upper part of the vagina. It presents with primary amenorrhea in a 46, XX individual. In this paper, we report the cases of two patients with MRKH syndrome treated with the laparoscopic modified Vecchietti technique using the optimized new instruments. A neovagina was successfully created in these two patients. This minimally invasive technique offers improvements in terms of operative time, complications, and functionality.

Recurrent twin pregnancy, with the second a heterotopic pregnancy, following clomiphene citrate stimulation: an unusual case and a review of the literature

Multiple gestations are on the rise with the advent of artificial reproductive technologies. Even with ovulation induction using clomiphene citrate alone, the twinning rate can reach up to 9 percent. We report a case of recurrent twin gestation after treatment with clomiphene citrate, with the second pregnancy being heterotopic. We also review, using Medline and PubMed, previously reported cases of recurrent twin gestation after treatment with clomiphene citrate published before June 2014. Patients undergoing ovulation induction for oligoovulation, anovulation, or unexplained infertility should always be counseled about the possibility of multiple gestation prior to the treatment including the probability, although low, of a heterotopic pregnancy.

A SARC global collaborative phase II trial of R1507, a recombinant human monoclonal antibody to the insulin-like growth factor-1 receptor (IGF1R) in patients with recurrent or refractory sarcomas

10503

Background: The IGF1 system has been implicated in sarcoma development and inhibition of IGF1R function has been shown to induce clinical responses in select sarcomas. Methods: Objectives included response rate (RR) and progression-free survival (PFS) to R1507 in patients with recurrent or refractory Ewing's (ES, 2 cohorts- primary refractory vs. others) osteo (OS), synovial (SS), rhabdomyosarcoma (RMS), and other sarcomas. Eligibility included recurrent/refractory measurable disease, age ≥ 12 yrs, life expectancy ≥ 6 weeks, Karnofsky PS ≥ 70, adequate renal, hepatic and bone marrow function. R1507 was administered i.v. at 9 mg/kg over one hour weekly. Response was assessed by WHO criteria every 6 wks X 4 and every 12 wks thereafter. A two-stage design (Green and Dahlberg) was used. The endpoint for the primary refractory ES cohort was PFS at week 18 (planned n=65). RR was the primary endpoint for the remaining cohorts (planned n=240). Results: From 12/07–12/08, 203 eligible patients from 29 centers across the US, Europe and Australia were enrolled. Age ranged from 12–85 yrs (median=27 yrs) and 126 were male. Verified histologic subtypes were ES (n=71), OS (n=43), RMS (n=28), SS (n=25), and others (n=25). 15 severe adverse events were reported in 9 patients, the most common being fatigue (n=2), thrombocytopenia (n=2), dehydration (n=2), and hyperglycemia (n=2). Clinically significant activity has been observed in ES, RMS and OS with several dramatic responses seen in ES and RMS. Independent radiologic review is currently ongoing and updated data will be presented. Conclusions: The rapid accrual amongst many centers in diverse geographical locations demonstrates the feasibility of collaborative research in sarcomas. R1507 is well tolerated and a promising new agent for the treatment of various sarcomas. SARC and Roche are collaborating in additional clinical trials to better define the role of R1507 in the treatment of selected sarcomas.

[Table: see text]

Osteoporosis: combination therapy for better or worse

Osteoporosis is a condition that is associated with an increased susceptibility for fractures. In the past few years, several drugs have become available that can reduce the incidence of fractures in patients with osteoporosis. Since these drugs work through different cellular mechanisms, combining agents of different classes may have an additive or multiplicative effect on fracture risk reduction. Combination treatments that have been evaluated in clinical trials include bisphosphonates with estrogen, raloxifene or PTH/ bisphosphonates and PTH/ estrogen. In general, these trials have shown increases in bone mineral density over that observed with each agent alone. However, whether anti-fracture efficacy is improved, or worsened remains to be established. This article reviews the combination treatments that have been evaluated in clinical trials, with a discussion of the potential benefits and risks that those treatments entail. Integrating safety and cost issues will eventually determine whether those combinations will become the standard of care.

The effects of group psychological debriefing on acute stress reactions following a traffic accident: a quasi-experimental approach

The purpose of this study was to evaluate the effects of a Group Psychological Debriefing (GPD) on acute stress reactions and perceptions following a traumatic situation. A group of military personnel (N = 9) and a group of voluntary civilian firefighters (N = 9) were exposed to severe stress during rescue work in a tunnel following a fatal traffic accident. Both groups participated in an operational debriefing and received brief stress management counseling after the incident. In addition the military personnel also participated in a structured 2.5 hour GPD after the accident. Two weeks later both groups completed the Coping Style Questionnaire (CSQ-30), the Impact of Event Scale (IES), the Post Traumatic Symptom Scale (PTSS-10), the General Health Questionnaire (GHQ-30) and questions about stress and coping after the incident. Lower frequency of symptoms were found in the GPD compared to the non-debriefed group measured by the PTSS-10. Single item analyzes of the scale revealed lower levels of symptoms related to emotional arousal in the GPD participants. Furthermore, the GPD participants revealed more positive personal outcomes than the non-debriefed group after the accident. The total PTSS-10 score and mental preparedness were the two variables that were best able to classify participants as belonging to the two groups, thus indicating significant clinical differences between the debriefed and non-debriefed group and the potential usefulness of PTSS-10 scale as a brief screening inventory after traumatic events.

Bone mineral density of the Lebanese reference population

We determined the bone mineral density (BMD) of normal Lebanese subjects and compared results with US/European reference data. The investigation was conducted at one center, and included 858 women and 165 men aged 20-79 years. Spine, femoral and radial BMD measurements were made using dual-energy X-ray absorptiometry. Age-related changes in BMD were similar in form to those of US/European reference data. However, BMD values of Lebanese were generally lower than US/European values. Spine BMD of Lebanese women was about 8% lower than US/European values between ages 20 and 59 years, and 5-6% lower for ages 60-79 years. Femoral neck BMD values for Lebanese women were 8% lower in the young adult years (age 20-39 years), but only 2-3% lower in the postmenopausal years, compared with US/European women. There were smaller postmenopausal decreases in femoral and radial BMD in Lebanese women compared with US/European women, which led to a convergence of BMD after age 70 years. The BMD of Lebanese men was 5-8% lower than US/European values throughout the age range (20-79 years). The effect of weight on BMD ranged from 0.2% to 0.4% per kilogram. Height was not significantly associated with BMD when both height and weight were entered in multiple regression analyses. The prevalence of osteoporosis appeared to be overestimated if the US/European reference data, rather than Lebanese reference data, were used to calculate T-scores.

Measuring post-traumatic stress: a psychometric evaluation of symptom--and coping questionnaires based on a Norwegian sample

The purpose of this study was to evaluate the psychometric characteristics of the Norweigian versions of the Impact of Event Scale, the Post Traumatic Stress Scale-10 item version and General Coping Questionnaire-30 item version. A group of 40 male and 56 female medical students was tested one week and four months after having started dissection of cadavers for the first time. The results showed that all scales had good internal consistency and test-retest reliability. The student sample scored lower on the IES and PTSS-10 than comparable groups of traumatized subjects. A gender difference emerged, with female subjects scoring higher than male subjects. The factor analysis of the instruments indicated good construct validity for the symptom scales. The analysis of content validity related to DSM IV criteria indicated that the IES and PTSS-10 may have some limitations in their predictive validity of PTSD. Taken together, the three scales have shown good psychometric properties and could be used in future research and clinical work.

Coping strategies and mental health problems in a military unit

The aim of the present study was to investigate the effect of different coping styles on the development of self-reported mental health problems in a radically changing context. This was investigated, using a longitudinal design, by following soldiers from before entering service to 8 months of service. Based on their scores on the 30-item General Coping Questionnaire, soldiers were allocated to one of three groups: those whose coping styles were emotional, avoidance, or task focused. These three groups were assessed four times. The General Health Questionnaire (30-item version), Ursin's Health Inventory, and the Alcohol Use Disorders Identification Test (AUDIT) were used as dependent measures. Avoidance-focused soldiers reported an increase in General Health Questionnaire scores over time. Furthermore, the avoidance-focused copers revealed higher scores on the AUDIT questionnaire as well as an increase in AUDIT scores over time. The present study showed that there was an interaction of personality variables and contextual factors involved. More specifically, young subjects with a preference for an avoidance-focused coping strategy are at greater risk of experiencing symptoms of mental health problems compared with task-focused and emotion-focused subjects when exposed to a radically changing environment.

Posttraumatic stress symptoms in nonexposed, victims, and spontaneous rescuers after an avalanche

A company from the Norwegian Army was investigated 2 weeks and 4 months after they were hit by an avalanche during a winter exercise. The subjects were divided into victims, spontaneous rescuers, and nonexposed subjects. The results showed that exposed subjects (victims and rescuers) reported higher levels of symptoms compared to nonexposed subjects. No differences were found among exposed subjects. The level of symptoms was also higher than comparable previous research both on victims and professional rescuers or nonprofessionals assigned a role as rescuers. All groups showed decrement in symptoms on the 4-month follow-up.

[Organisation of psychosocial support--experiences from two accidents in the Norwegian Armed Forces]

Military units are designed and trained to operate under stress, crisis and combat. In peacetime conditions the military organization can be subject to unforeseen crisis situations, including fatal accidents during training and exercises. Such critical incidents will affect personnel, leadership, morale and organizational performance. It may also affect the relationship between the military unit and the civilian community. Recent experience has shown that good leadership, personnel support and organizational restructuring are essential elements in the recovery after critical incidents and peacetime disasters. The present study outlines a systematic approach to crisis management in formal organizations. This includes a descriptive analysis of individual and organizational interventions in two military organizations; an army unit of 150 men and a naval unit of 114 men.

Stable integrative transformation of Trypanosoma brucei that occurs exclusively by homologous recombination

A calmodulin-neomycin-resistance fusion gene was introduced into Trypanosoma brucei by electroporation, and stably transformed cell lines were obtained. In all of the transformants, the fusion gene had integrated into the host genome at the cognate locus, evidently by homologous recombination within flanking calmodulin DNA. This unusual observation distinguishes trypanosomes as the only eukaryote other than yeast known to undergo gene targeting in essentially 100% of the stable transformants. It should now be possible to systematically manipulate the trypanosome genome, directing predetermined mutations to virtually any chromosomal locus.

Efficient introduction of plasmid DNA into Trypanosoma brucei and transcription of a transfected chimeric gene

Electroporation induces efficient transient transfection of Trypanosoma brucei, and the introduced DNA can be transcribed into RNA. When we delivered a high-voltage electric pulse to cells mixed with radiolabeled pBR322, approximately equal to 15% of the plasmid DNA was taken up by the parasites. When transfecting DNA contained a segment of T. brucei ribosomal DNA that included the 5' end of the rRNA gene, the introduced plasmid directed expression of RNA; this RNA expression was shown both by dot blots and by S1 nuclease protection assays carried out under conditions specific for probe hybridization to RNA. In the absence of the ribosomal region, analogous transcription did not occur. We optimized this trypanosomal expression system with regard to electric shock strength, concentration of input DNA, and incubation time after electric shock. This technique enabling specific trypanosome DNA expression in vivo should facilitate the molecular analysis of T. brucei gene expression.

Intracellular growth factors in polycythemia vera and other myeloproliferative disorders

In polycythemia vera, idiopathic myelofibrosis, and essential thrombocytosis, hematopoietic cell proliferation is increased in the absence of a recognizable stimulus, suggesting the autonomous production of growth factors in these disorders. Sonicates of peripheral blood mononuclear cells (PBMNC) from patients with polycythemia vera, idiopathic myelofibrosis, and essential thrombocytosis contained soluble factors that stimulated the proliferation of quiescent-confluent 3T3 cells. PBMNC sonicates from normal individuals; from patients with secondary erythrocytosis, chronic myelogenous leukemia, B-cell chronic lymphocytic leukemia, and acute myelogenous leukemia; and from K-562 and HL-60 cells did not stimulate proliferation. Polycythemia vera PBMNC sonicates also induced anchorage-independent colony formation in soft agar by normal rat kidney fibroblasts. Both the mitogenic and transforming activities of the polycythemia vera PBMNC sonicates resided in the T-lymphocyte-depleted mononuclear fraction of the PBMNC and were not secreted. By gel filtration, reversed-phase HPLC and NaDodSO4/PAGE, the mitogenic and transforming activities in the polycythemia vera PBMNC were localized to three proteins with molecular masses of 13-, 17-, and 65-kDa. The 13-kDa protein was only mitogenic, and the 17-kDa protein was only transforming, whereas the 65-kDa protein had both mitogenic and transforming activity. These proteins may be involved in the autonomous hematopoiesis that characterizes polycythemia vera, idiopathic myelofibrosis, and essential thrombocytosis.