MR imaging–derived oxygen-hemoglobin dissociation curves and fetal-placental oxygen-hemoglobin affinities

PURPOSE: To generate magnetic resonance (MR) imaging–derived, oxygen-hemoglobin dissociation curves and to map fetal-placental oxygen-hemoglobin affinity in pregnant mice noninvasively by combining blood oxygen level–dependent (BOLD) T2* and oxygen-weighted T1 contrast mechanisms under different respiration challenges. MATERIALS AND METHODS: All procedures were approved by the Weizmann Institutional Animal Care and Use Committee. Pregnant mice were analyzed with MR imaging at 9.4 T on embryonic days 14.5 (eight dams and 58 fetuses; imprinting control region ICR strain) and 17.5 (21 dams and 158 fetuses) under respiration challenges ranging from hyperoxia to hypoxia (10 levels of oxygenation, 100%–10%; total imaging time, 100 minutes). A shorter protocol with normoxia to hyperoxia was also performed (five levels of oxygenation, 20%–100%; total imaging time, 60 minutes). Fast spin-echo anatomic images were obtained, followed by sequential acquisition of three-dimensional gradient-echo T2*- and T1-weighted images. Automated registration was applied to align regions of interest of the entire placenta, fetal liver, and maternal liver. Results were compared by using a two-tailed unpaired Student t test. R1 and R2* values were derived for each tissue. MR imaging–based oxygen-hemoglobin dissociation curves were constructed by nonlinear least square fitting of 1 minus the change in R2*divided by R2*at baseline as a function of R1 to a sigmoid-shaped curve. The apparent P50 (oxygen tension at which hemoglobin is 50% saturated) value was derived from the curves, calculated as the R1 scaled value (x) at which the change in R2* divided by R2*at baseline scaled (y) equals 0.5. RESULTS: The apparent P50 values were significantly lower in fetal liver than in maternal liver for both gestation stages (day 14.5: 21% ± 5 [P = .04] and day 17.5: 41% ± 7 [P < .0001]). The placenta showed a reduction of 18% ± 4 in mean apparent P50 values from day 14.5 to day 17.5 (P = .003). Reproduction of the MR imaging–based oxygen-hemoglobin dissociation curves with a shorter protocol that excluded the hypoxic periods was demonstrated. CONCLUSION: MR imaging–based oxygen-hemoglobin dissociation curves and oxygen-hemoglobin affinity information were derived for pregnant mice by using 9.4-T MR imaging, which suggests a potential to overcome the need for direct sampling of fetal or maternal blood. Online supplemental material is available for this article

Distributed CONGEST Algorithm for Finding Hamiltonian Paths in Dirac Graphs and Generalizations

We study the problem of finding a Hamiltonian cycle under the promise that the input graph has a minimum degree of at least $n/2$, where $n$ denotes the number of vertices in the graph. The classical theorem of Dirac states that such graphs (a.k.a. Dirac graphs) are Hamiltonian, i.e., contain a Hamiltonian cycle. Moreover, finding a Hamiltonian cycle in Dirac graphs can be done in polynomial time in the classical centralized model. This paper presents a randomized distributed CONGEST algorithm that finds w.h.p. a Hamiltonian cycle (as well as maximum matching) within $O(\log n)$ rounds under the promise that the input graph is a Dirac graph. This upper bound is in contrast to general graphs in which both the decision and search variants of Hamiltonicity require $\tilde{\Omega}(n^2)$ rounds, as shown by Bachrach et al. [PODC'19]. In addition, we consider two generalizations of Dirac graphs: Ore graphs and Rahman-Kaykobad graphs [IPL'05]. In Ore graphs, the sum of the degrees of every pair of non-adjacent vertices is at least $n$, and in Rahman-Kaykobad graphs, the sum of the degrees of every pair of non-adjacent vertices plus their distance is at least $n+1$. We show how our algorithm for Dirac graphs can be adapted to work for these more general families of graphs

In search of signaling pathways critical for ovarian graft reception: Akt1 is essential for long-term survival of ovarian grafts

ObjectiveTo explore the role of Akt1, a principle modulator of angiogenesis, in ovarian graft reception and to investigate whether Akt1 deficiency can alter ovarian graft reception.DesignExperimental mouse model.SettingResearch institute.Animal(s)Donors: Akt1 knockout (Akt1−/−) and wild types (Akt1+/+) mice. Recipients: CD-1 nude immune deficient female mice.Intervention(s)Ovaries from Akt1−/− and Akt1+/+ mice transplanted in the biceps femoris muscle of immunocompromised CD-1 mice, and ovarian graft viability, perfusion, and revascularization explored in vivo by magnetic resonance imaging (MRI).Main Outcome Measure(s)Vascular density and permeability of newly formed graft blood vessels quantified by dynamic contrast–enhanced MRI 7, 14, 30, and 60 days after grafting as indicators for angiogenesis and reestablishment of blood perfusion.Result(s)The Akt1−/− ovarian grafts showed a gradual decrease in angiogenic response with time after transplantation, ultimately leading to complete or near-complete graft destruction coinciding with massive follicular loss. Sixty days after transplantation, the mean blood volume fraction (fBV) and vessel permeability (PS) were statistically significantly lower in Akt1−/− transplants compared with Akt1+/+.Conclusion(s)Akt1 is essential for ovarian graft reception. However, surprisingly the impact of Akt1 deficiency was most profound not in the early stages of angiogenesis but rather in long-term survival of the graft

Unique in utero identification of fetuses in multifetal mouse pregnancies by placental bidirectional arterial spin labeling MRI

Non-invasive imaging is a critical part of the study of developing embryos/fetuses, particularly in the context of alterations of gene expression in genetically modified animals. However, in litter-bearing animals such as mice, the inability to accurately identify individual embryo/fetus in utero is a major obstacle to longitudinal, non-invasive in vivo studies. Arterial Spin Labeling MRI (ASL-MRI) was adopted here to determine the fetal order along the uterine horns in vivo, based upon the specific pattern of dual arterial blood supply within the mouse uterine horns. Blood enters the mouse uterus cranially through the ovarian artery, and caudally through the uterine artery. Saturation slices were alternately placed on the maternal heart or on the bifurcation point of the common iliac artery, thereby saturating either downward inflow via the ovarian arteries, or upward inflow via the uterine arteries, respectively. Saturation maps provided a unique signature with highly significant correlation between the direction-dependent magnetization transfer and the position of the fetuses/placentas along the uterine horns. The Bi-Directional ASL-MRI (BD-ASL) method reported here opens possibilities to determine and pursue phenotypic alterations in fetuses and placentas in longitudinal studies of transgenic and knockout mice models, and for studying defects in placental vascular architecture

Bypass gástrico de anastomose única (OAGB): análise sos sintomas gastrintestinais até 5 anos pós-operatório

O bypass gástrico de anastomose única (OAGB) é a terceira técnica mais utilizada no mundo, considerada eficaz na redução de peso e na emissão de comorbilidades. Entretanto, dados sobre os sintomas gastrointestinais a médio prazo são limitados. Objetivos: Avaliar os sintomas gastrointestinais de indivíduos submetidos a OAGB em três momentos pós-operatório: T1 (um a seis meses), T2 (seis a doze meses) e T3 (um a cinco anos).info:eu-repo/semantics/publishedVersio

Does Admission Hypothermia Predispose to Intraventricular Hemorrhage in Very-Low-Birth-Weight Infants?

&lt;i&gt;Background:&lt;/i&gt; The etiology of intraventricular hemorrhage (IVH) in very-low-birth-weight (VLBW) infants is multifactorial and is associated with low gestational age (GA) and severity of neonatal respiratory disease. The role of admission hypothermia (AHT) in the pathogenesis of IVH in VLBW infants has not yet been elucidated. We searched risk factors for IVH in VLBW infants while focusing on AHT. &lt;i&gt;Patients and Methods:&lt;/i&gt; VLBW infants ≤33 weeks’ gestation from three participating medical centers were included. From patients’ medical charts we collected variables known to be associated with IVH, focusing on AHT. AHT was defined as rectal temperature ≤35.5°C at admission to the NICU. Head ultrasound was performed at 2–5 and 6–10 days of age and before discharge. &lt;i&gt;Results:&lt;/i&gt; 271 VLBW infants were studied. Univariate analysis showed that AHT at ≤35.5°C was not significantly associated with IVH (all grades; p = 0.16), but associated with IVH grade 3–4 (p = 0.034), while AHT at ≤35°C was significantly associated with IVH (p = 0.036) and with IVH grade 3–4 (p = 0.003). Multivariate logistic regression analysis showed that AHT (at ≤35.5 and at ≤35°C) were not associated with IVH. Only four variables were independently significantly associated with IVH: GA, use of nitric oxide, hypocarbia and base deficit &gt;10. Four variables were strongly associated with severe IVH (grades 3–4): GA, hypotension, base deficit &gt;10 and hyponatremia. &lt;i&gt;Conclusions:&lt;/i&gt; In VLBW infants, AHT at ≤35.5 and at ≤35.0°C were not significantly associated with IVH. GA, use of nitric oxide, hypocarbia and base deficit &gt;10 were strongly associated with IVH.</jats:p

Gastrointestinal reported outcomes following one anastomosis gastric bypass based on a multicenter study

Objectives: To describe gastrointestinal-related side-effects reported following One Anastomosis Gastric Bypass (OAGB). Methods: A multicenter study among OAGB patients across Israel (n=277) and Portugal (n=111) who were recruited to the study based on time elapsed since surgery was performed. An online survey with information on demographics, anthropometrics, medical conditions, and gastrointestinal outcomes was administered in both countries simultaneously. Results: Respondents from Israel (pre-surgery age of 41.6±11.0 years, 75.8% females) and Portugal (pre-surgery age of 45.6±12.3 years, 79.3% females) presented mean excess weight loss of 51.0±19.9 and 62.4±26.5%, 89.0±22.0 and 86.2±21.4%, and 89.9±23.6 and 98.2±20.9% (P<0.001 for both countries), at 1-6 months, 6-12 months, and 1-5 years post-surgery, respectively. The Median Gastrointestinal Symptom Rating Scale score was similar between time elapsed since surgery groups among respondents from Israel and Portugal (≤1.97 and ≤2.12). A notable proportion of respondents from Israel and Portugal at all time points reported 1-3 bowel movements per day (≤62.8 and ≤87.6%), Bristol stool scale categories which represent diarrhea-like stools (≤51.9 and ≤56.3%), having discomfort due to flatulence (≤79.4 and ≤90.2%), and mild to severe dyspepsia symptoms (≤50.5 and ≤73.0%). Conclusions: A notable proportion of OAGB patients might experience certain gastrointestinal symptoms postoperatively, including flatulence, dyspepsia, and diarrhea-like stools.info:eu-repo/semantics/publishedVersio

Nutritional and Lifestyle Behaviors Reported Following One Anastomosis Gastric Bypass Based on a Multicenter Study

This study aimed to describe nutritional and lifestyle parameters following one-anastomosis gastric bypass (OAGB). A multicenter study among OAGB patients across Israel (n = 277) and Portugal (n = 111) was performed. Patients were approached according to the time elapsed since surgery. An online survey with information regarding demographics, anthropometrics, and nutritional and lifestyle aspects was administered in both countries simultaneously. Respondents from Israel (pre-surgery age of 41.6 ± 11.0 years, 75.8% females) and Portugal (pre-surgery age of 45.6 ± 12.3 years, 79.3% females) reported changes in their appetite (≤94.0% and ≤94.6%), changes in their taste (≤51.0 and ≤51.4%), and intolerance to specific foods (i.e., red meat, pasta, bread, and rice). Bariatric surgery-related eating recommendations were generally followed well, but a trend toward lower adherence was evident in groups with longer time elapsed since surgery in both countries. Most respondents from Israel and Portugal reported participation in follow-up meetings with a surgeon (≤94.0% and 100%) and a dietitian (≤92.6% and ≤100%), while far fewer reported participation in any follow-up meeting with a psychologist/social worker (≤37.9% and ≤56.1%). Patients following OAGB might experience changes in appetite, taste, and intolerance to specific foods. Adherence to bariatric surgery-related eating recommendations is not always satisfying, especially in the longer term post-surgery.</jats:p