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Biomedical subjects

M Menashe

Publications and source records attributed to M Menashe.

At least 19 recordsLinked to original sources
PubMed2002

Poor prenatal detection rate of cardiac anomalies in Noonan syndrome.

BACKGROUND: The wide variation and nonspecific nature of many of the associated ultrasonographic findings complicate prenatal diagnosis of Noonan syndrome. The aim of the present study was to define the rate of prenatal diagnosis of heart malformations in cases diagnosed postnatally with Noonan syndrome. METHODS: English-language literature review of 29 cases of Noonan syndrome examined prenatally with confirmed postnatal diagnosis and four case reports from our center. RESULTS: Cases were evaluated for cervical spine pathologies, cardiac anomalies and other pathological findings, including hydrops fetalis and polyhydramnios. Cardiac anomalies were suspected in only nine of 33 cases; three of these were associated with cystic hygroma. Cardiac anomalies were eventually diagnosed in 31/33 cases postnatally. Polyhydramnios was diagnosed in 19/33 cases in the third trimester, and hydrops fetalis was detected in eight of 33. Cystic hygroma was present in a total of nine cases at mid-trimester. CONCLUSIONS: Noonan syndrome is characterized by late-onset and progressive pathologies, particularly the associated cardiac anomalies, which develop through the course of gestation and postnatal life. This complicates or precludes prenatal diagnosis at mid-trimester or at any time in the prenatal period, and partly explains the low rate of detection of fetal cardiac lesions in this syndrome.

Female↗
PubMed1989

Measures to enhance performance of an atraumatic cesarean section in prematurity.

Cesarean sections performed for the delivery of the premature infant are known to be prone to dangers to the fetus, primarily due to contraction of the incised but as yet undelivered uterus upon the fetus, which thus entraps it. Reported is our technique for performing a cesarean section in prematurity, describing two simple yet helpful measures-halothane administered to the mother and controlled entrance to the amniotic sac, after having completed the whole uterine incision without rupturing the membrances. These measures are designed to avoid or at least, it is hoped, to reduce the occurrence of the previously mentioned severe complication.

Anesthesia, Obstetrical↗
PubMed1989

Radiologic evidence of a nuchal arm in the breech-presenting fetus at the onset of labor: an indication for abdominal delivery.

The occurrence of a nuchal arm during vaginal breech delivery is a potentially traumatic event associated with high perinatal morbidity and mortality. This problem usually cannot be anticipated and must be overcome immediately on diagnosis during the second stage of labor. The results of a retrospective analysis of radiologic studies of 115 cases of term singleton breech deliveries are presented here. A nuchal arm in the first stage of labor was diagnosed in five cases, an incidence of 4.35%. Of four vaginal breech deliveries, one case resulted in severe handicapping neonatal trauma. We suggest that radiologic diagnosis of a nuchal arm in the first stage of labor should indicate abdominal delivery.

Arm↗
PubMed1987

Interaction of trans-parinaric acid with phosphatidylcholine bilayers: comparison with the effect of other fluorophores.

The effect of the fluorophore trans-parinaric acid on the structure of lipid bilayer was studied and compared with the effect of other 'perturbants'. These include commonly used fluorophores (diphenylhexatriene, heptadecylhydroxycoumarin, cis-parinaric acid and two fatty acids, palmitic and oleic acids). Differential scanning calorimetry (DSC) and proton nuclear magnetic resonance techniques were used to evaluate structural changes in the lipid bilayers. The thermodynamic parameters of dipalmitoylphosphatidylcholine multilamellar vesicles obtained from the DSC thermograms suggest that trans-parinaric acid differs from the other 'perturbants'. trans-Parinaric acid has the most pronounced impact on the Tm, the width (delta T1/2) and the index of asymmetry of the main gel to liquid crystalline phase transition without any effect on its transition, delta H. The presence of trans-parinaric acid in the lipid bilayer of dimyristoylphosphatidylcholine small unilamellar vesicles influences the chemical shift difference between the choline protons of phosphatidylcholine molecules present in the two leaflets of the vesicle bilayer (delta delta H). This suggests that trans-parinaric acid affects the head group packing in the bilayer. Its main effect is abolishing the major alterations in head group packing that occur through the phase transition. The above data indicate that trans-parinaric acid is concentrated in the gel phase domains, whereby it stabilizes the phase separation between the gel and liquid crystalline phases, probably by affecting lipid molecules present in the boundary regions between these two domain types.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1987

Exacerbation of idiopathic pulmonary hemosiderosis in pregnancy.

Idiopathic pulmonary hemosiderosis (IPH) is a very rare disease in adults. Its occurrence in pregnancy has been described only once. A case of a 16-yr-old patient with an exacerbation of IPH during pregnancy resulting in intrauterine fetal death in the 28th week of gestation is described. The deterioration of the IPH is most probably related to the hemodynamic alterations which are at their maximum during the seventh month of pregnancy. Although rare, the case suggests that women with IPH should be followed carefully during pregnancy and, in the case of a deterioration in the patient's condition despite immunosuppressive therapy, termination of pregnancy should be considered.

Adolescent↗
PubMed1987

Amniotic fluid protease activity, protease inhibitory activity, and fetal lung maturity.

Amniotic fluid acid protease and acid protease inhibitory activities were examined in normal pregnancies as a function of gestational age. The acid proteolytic activity of the amniotic fluid is almost constant during gestational weeks 16-29 (26 +/- 13 micrograms globin/ml/2 hrs, mean +/- SD, n = 64). The activity sharply increases after 29 weeks in a time-dependent fashion and reaches a value of 302 +/- 89 (mean +/- SD, n = 13) at 39-40 weeks gestation. Under standard conditions, the ability of amniotic fluid to inhibit bovine pepsin declined during gestation in a linear fashion from 44 +/- 13% (mean +/- SD, n = 36) at 16-18 weeks to 9 +/- 10% (mean +/- SD, n = 41) at 36-40 weeks. A correlation coefficient of r = 0.72 was found between pepsin inhibitory activity and gestational age. No consistent change was noted in the extent of inhibition of the endogenous acid protease throughout pregnancy. In 61 amniotic fluid samples, a correlation coefficient of r = 0.70 was found between acid protease activity and the lecithin/sphingomyelin (L/S) ratio. During the course of this study, five cases of respiratory distress syndrome (RDS) were diagnosed clinically. All five infants had a low protease activity (55 +/- 22 micrograms globin/ml/2 hr, mean +/- SD) as well as a low L/S ratio (0.68 +/- 0.20, mean +/- SD). In contrast, no case of RDS of the newborn was observed among 29 pregnancies with high protease activity and a high L/S ratio. The present observations may suggest a predictive value of amniotic fluid acid protease activity in assessment of fetal lung maturity.

Amniotic Fluid↗
PubMed1986

Hydrolysis of dipalmitoylphosphatidylcholine small unilamellar vesicles by porcine pancreatic phospholipase A2.

The hydrolysis of small unilamellar vesicles made of dipalmitoylphosphatidylcoline by pancreatic phospholipase A2 has been studied under various conditions of temperature and enzyme and substrate concentration using the following three different experimental protocols. When the enzyme was added to the substrate vesicles after being separately adjusted to the temperature of the experiments hydrolysis occurred instantaneously only in the temperature range where the lipid is known to exist in its gel phase, while above the transition range no hydrolysis occurred. Within the transition range, the time course of hydrolysis was characterized by initial very slow rate of hydrolysis (latency phase) followed by an abrupt increase in the rate after a time tau, which is a complex function of temperature and enzyme to substrate ratio. When an enzyme-substrate mixture was first preincubated below Tm and then temperature jumped to a temperature above or within the transition range, the latency phase was markedly shortened. When the temperature jump was to the transition range, this effect is observed even if Ca2+ is absent in the preincubation mixture. However, instantaneous hydrolysis was observed upon temperature jumping the mixture to a temperature high above Tm only if Ca2+ was present in the preincubation medium. In temperature-scanning experiments, hydrolysis was followed while changing the temperature of the enzyme-substrate mixture continuously. Heating an enzyme-substrate mixture from room temperature resulted in an abrupt onset of hydrolysis when the transition range was approached. These results lead us to conclude that two distinctly different steps precede rapid hydrolysis of dipalmitoylphosphatidylcholine small unilamellar vesicles by pancreatic phospholipase A2: a Ca2+-independent binding of the enzyme to the substrate vesicles, which for chemically pure bilayers occurs best in the gel phase. This step is followed by a Ca2+-dependent activation of the initially formed enzyme-substrate complex. The latter step only occurs under conditions where the bilayer possesses packing irregularities and probably involves a reorganization of the enzyme-substrate complex. At least one of these two steps appears to involve enzyme-enzyme interaction.

Animals↗
PubMed1986

Hydrolysis of dipalmitoylphosphatidylcholine large unilamellar vesicles by porcine pancreatic phospholipase A2.

The interaction between dipalmitoylphosphatidylcholine large unilamellar vesicles and porcine pancreatic phospholipase A2 has been studied under a variety of conditions. It was found that the presence of large unilamellar vesicles inhibits the hydrolysis of small unilamellar vesicles at room temperature, and reaction calorimetric experiments showed that protein-lipid interactions in the absence of Ca2+ occur in the gel state with a stoichiometry of about 40 phospho-lipid molecules/protein-binding site. However, hydrolysis can be induced in the gel state under conditions of osmotic shock. On the other hand, hydrolysis is usually observed within the lipid transition temperature range, but then it occurs only after a latency phase during which the hydrolysis is very slow. The duration of this latency phase reaches a minimum near the phase transition temperature. However, if the enzyme-substrate mixture is heated from low temperatures (continuously or by a temperature jump) to a temperature within the phase transition region, hydrolysis occurs instantaneously. These results are in accordance with the conclusions of the preceding paper (Menashe, M., Romero, G., Biltonen, R. L., and Lichtenberg, D. (1986) J. Biol. Chem. 261, 5328-5333) that effective binding of the enzyme to lipid vesicles occurs relatively rapidly in the gel state and that activation of the enzyme-substrate complex requires the existence of structural irregularities in the lipid bilayer. Although hydrolysis products may have a pronounced effect on the time course of the reaction in the transition range, instantaneous hydrolysis can be induced in the phase transition region in the absence of reaction products by appropriate manipulation of the experimental conditions during which no reaction products are produced. Thus reaction products are not essential for activation of porcine pancreatic phospholipase A2. Furthermore, it is shown that the fraction of lipid hydrolyzed during the latency period is a function of the initial substrate concentration in a manner inconsistent with the proposition that the accumulation of a constant critical fraction of reaction products is the basis for activation. Comparison of the results of this study with those of the preceding paper strongly support the previously proposed reaction scheme.

Animals↗
PubMed1984

Toxicity to crustacea due to polypeptide-phospholipase interaction in the venom of a chactoid scorpion.

The toxic factors to isopods (crustacea) were isolated from the venom of the chactoid scorpion Scorpio maurus palmatus (Scorpionidae) by the aid of column chromatography, and their purity was assessed by disc electrophoresis, analytical ultracentrifugation, isoelectrofocusing, and amino acid analysis. The toxicity to isopods is attributed to two groups of components: (a) Low-molecular-weight basic polypeptides possessing about 3 and 8% of the crude venom lethality and paralytic potency to isopods, respectively. These components are characterized by very similar and unique amino acid compositions of 31 to 34 amino acids with molecular mass of about 3.5 kDa and a deficiency in methionine, leucine, phenylalanine, histidine, and tryptophan. (b) Toxic phospholipases are also toxic to insect but not to mammals. A lethal phospholipase which contained 37% of the total venom phospholipase activity and 11% of its toxicity to isopods was purified. This phospholipase consists of 125 amino acids (Mr 14,581) and is a hydrophobic, acidic protein composed of two isoenzymes (pI 4.7 and 4.9). This enzyme demonstrates an A2-type positional specificity (EC 3.1.1.4) with pH and temperature optima of 7.5-8.0 and 40-50 degrees C, respectively, and high calcium requirements. The lethal potency of the basic polypeptides is evidently increased by the addition of low, sublethal doses of the pure phospholipase. Such synergism was not observed with regards to their paralytic activity. The pharmacological significance of these data is discussed.

Amino Acids↗
PubMed1984

Thermodynamic characterization of the pretransition of unilamellar dipalmitoyl-phosphatidylcholine vesicles.

High-sensitivity differential scanning calorimetry of small unilamellar vesicles (SUV) made by sonication of dipalmitoylphosphatidylcholine (DPPC) reveals that the gel-liquid crystalline transition at 37 C is preceded by a pretransition at 28 C that is relatively slow (t1/2 approximately equal to 2-4 min) and has an enthalpy change of ca. 0.2 kcal/mol. On incubation at 4 C, these SUV fuse spontaneously into large unilamellar vesicles (LUV). LUV also exhibit both a pretransition and a main-phase transition. The temperature of the main transition (Tm) and the enthalpy change of both the pretransition and main transition of these fused vesicles are similar to those of large multilamellar vesicles (MLV). The enthalpy change associated with the transition at 28 C decreases in SUV in a manner directly correlated to the decrease in the apparent enthalpy change of the 37 C main transition, indicating that the smaller (low temperature) transition is indeed a pretransition that is an inherent property of SUV. Therefore, unilamellar vesicles of DPPC appear to exhibit a pretransition at a temperature that varies from 28 C for the small vesicles to 35 C for the much larger vesicles.

Calorimetry, Differential Scanning↗
PubMed1984

Maternal blood pressure response to the intravenous administration of pethidine-promethazine during labor.

A double blind study on the effect of an intravenous injection of a combination of 75 mg pethidine and 25 mg promethazine was conducted on 200 women during normal deliveries. Four groups of 50 women each received injections of pethidine and promethazine, promethazine alone, pethidine alone and normal saline. In the pethidine-promethazine group there was a significant elevation in blood pressure in the first 10 min following the injection as compared with the other groups. The mean (+/- S.D.) systolic blood pressure after the injection was 143.2 +/- 14.3 mmHg as compared with 118.9 +/- 8.4 mmHg before the injection, and the mean diastolic blood pressure as 96.9 +/- 8.4 mmHg after the injection as compared with 77.7 +/- 9.3 mmHg before the injection. 25 mg promethazine alone caused slight elevation in blood pressure which was further increased by combination with pethidine. The clinical significance of these observations is discussed.

Blood Pressure↗
PubMed1984

Corpus luteum function in ectopic pregnancy.

Serum beta HCG, progesterone, and 17 alpha hydroxy progesterone values were determined in cases of ectopic pregnancy. They were found to be significantly lower than in normal intrauterine pregnancies of the same gestational age. No correlation was found between serum beta HCG and 17 hydroxy progesterone values or between serum progesterone and 17 hydroxy progesterone values. Our results tend to support the theory that a normal feto placental unit is needed for the preservation of the function of the corpus luteum.

17-alpha-Hydroxyprogesterone↗