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Biomedical subjects

W D Whybrew

Publications and source records attributed to W D Whybrew.

At least 37 records · Page 2Linked to original sources
PubMed1978

Use of partial exchange transfusion preoperatively in patients with sickle cell hemoglobinopathies.

Sickle cell anemia and other severe sickle cell disorders (hemoglobin SC and hemoglobin S-thalassemia) are known to complicate surgical procedures in susceptible patients. Although transfusions have been used preoperatively to increase the packed cell volume, we have recently used the method of partial exchange transfusion in the treatment of patients with these disorders in the preoperative period. Forty-two patients with significant sickle cell hemoglobinopathies underwent operative procedures on various surgical services. The goal was to obtain a hemoglobin A percentage of 40 or above in each case, and this required 480 to 1,150 c.c. of buffy coat poor washed red cells (mean 820 c.c.). The number of complications in the intraoperative and postoperative period in this study was compared to those found in the literature. There was a significant decrease in morbidity and mortality rates noted with the use of these transfusions. There appeared to be a great advantage on a cost-benefit ratio, as well as an improvement in the physiologic state of the patient. Although the results of this study show significant improvement over previous investigations, there are many facets unknown concerning the use of this modality under these and other conditions. Therefore, further investigation of this method and restriction of the method of Level III referral centers is advocated until enough patients have been studied to assess the long- and short-term complications of the procedure.

Adolescent↗
PubMed1978

Injection of corticosteroids into mother to prevent neonatal respiratory distress syndrome.

In this study, 500 mg. of hydrocortisone were injected intravenously into 126 women every 12 hours for four doses in a double-blind, randomized fashion. These 126 subjects were at risk for delivery of a premature infant because of premature labor of fetomaternal disease necessitating intervention. There were 67 patients in the treatment group and 59 in the placebo group. All patients had immature lecithin/sphingomyelin ratios and/or were at less than 34 weeks' gestation. From these data, it appeared that there was a significant decrease in respiratory distress syndrome when the treatment group was compared to the placebo group. The neonatal survival rates also were improved significantly by steroid treatment. There was no demonstrable adverse steroid effect in mothers of fetuses in the long-term or short-term follow-up period, although a significant number of patients were lost to follow-up and the methodology of infant evaluation was imprecise. It would appear from these data that the injection of steroids is beneficial in mothers at risk of being delivered of premature infants. However, many questions remain to be answered before this method can be relied upon as therapy for women with premature labor.

Adolescent↗
PubMed1977

Separation of isoacceptor cysteine transfer ribonucleic acids of bakers' yeasts.

Isoacceptor species of certain amino acid-specific transfer ribonucleic acids (tRNAs) were fractionated by gel permeation chromatography using Sephadex G-100. The separation is attributed to the 20% ethanol-1% NaCl solvent and to the characteristics of Sephadex. Isoacceptor tRNAs specific for cysteine, arginine, phenylalanine, and histidine were recovered from commercial tRNA of yeast by this method. Highly purified cysteine-specific tRNA, obtained by a method which would not be expected to separate isoacceptor molecules when fractionated by this procedure, was shown to contain two cysteine isoacceptor tRNAs.

Amino Acyl-tRNA Synthetases↗
PubMed1977

The lecithin/sphingomyelin ratio in cases associated with fetomaternal disease.

The efficacy of correlating the L/S ratio in the amniotic fluid with fetal lung maturity has been substantiated in normal pregnancies. In gestations complicated by fetomaternal diseases, however, the assay is less reliable. This study involves 555 pregnancies in which there was a significant maternal, fetal, or placental disorder. The L/S ratio was related to fetal respiratory maturity as measured by Dubowitz criteria and the occurrence of RDS. The results show that pre-eclampsia, chronic hypertension, diabetes (Class D, E, F), significant cardiovascular disease, severe hemoglobinopathies, various congenital anomalies, chronic placental insufficiency, and prolonged ruptured membranes accelerated the L/S ration. Conversely, mild diabetes (Class B, C), intrinsic renal disease, hepatitis, collagen disease, hydrops fetalis, syphilis, and toxoplasmosis were associated with a delay in the L/S ratio. A significant increase in erroneous responses was noted in these patients when the L/S ratio was correlated to infant maturity and to the incidence of RDS. Possible mechanisms for these findings are discussed.

Amniotic Fluid↗
PubMed1977

Mechanism for the incorporation of S-(1,2,3,4-tetrahydro-2-hydroxy-1-naphthyl)-L-cysteine into protein.

Evidence is presented which indicates that S-(1,2,3,4-tetrahydro-2-hydroxy-1-naphthyl)-L-cysteine (THN-cysteine), formed by the reaction of 1,2-epoxy-THN with cysteine, can be incorporated into protein; The position of incorporation of THN-cysteine into protein would depend on whether the epoxide of THN reacts with cysteinyl-tRNACyS or with cysteine. In both cases, the mechanism of incorporation of THN-cysteine into protein is the same as for the natural amino acids. For example, the incorporation of THN-cysteinyl-tRNACyS is stimulated by Poly-UG, the code for tRNACyS, and would be expected to be substituted for cysteine in protein being synthesized, whereas THN-cysteine not previously esterified to tRNA is activated by the isoleucyl- and valyl-RNA synthetases, and its incorporation is stimulated by Poly-AU and Poly-UG, respectively. Consequently, in this case, THN-cysteine would substitute for isoleucine and valine during protein synthesis.

Cysteine↗
PubMed1977

Amniotic fluid tests for fetal maturity in normal and abnormal pregnancies.

The lecithin-sphingomyelin (L/S) ratio is acknowledged to be superior to most procedures for predictinf fetal lung maturity in normal pregnancy. In complicated gestations, however, errors have been reported. This study involves 686 normal gestations and 389 pregnancies complicated by fetomaternal diseases. The L/S ratio, creatinine level, and percent of fat-staining cells were measured in samples of amniotic fluid from these patients. The results showed good correlation of all three tests with fetal maturity as measured by weight, Dubowitz criteria, and incidence of respiratory distress syndrome in the normal patients. In the complicated pregnancies, however, the creatinine was unacceptable in up to 30% of the cases. The L/S ratio likewise decreased in accuracy for all parameters of fetal maturity measured. The Nile blue staining of the fetal cells appeared to be the most consistent technic in these cases. A fetal maturity battery comprised of these three assays and other methods of assessing fetal health is advocated in pregnancies complicated by certain disease states.

Amniocentesis↗
PubMed1977

Nile blue and fetal maturity. Further investigations.

The consistency of results using Nile blue staining of fetal cells in amniotic fluid to estimate fetal maturity has been demonstrated. Recently, evidence to support this method has been published from this laboratory. Several biochemical and technical factors were cited as important to the success of the method. This report deals with further testing of several Nile blue dyes (hydrochloride and sulfate) necessitated by changes in production and federal regulation of this compound. The results show Nile blue hydrochloride (HCl) to be the most superior dye regardless of color index. Buffered solutions (6.6) of Nile blue A (sulfate) improve its performance, but not to levels demonstrated by the HCl preparation. Storage at room temperature adversely affects each dye; however, the sulfate variety appears to be the most unreliable under these circumstances. For best results, it is recommended that Nile blue HCl be used and the solution (buffered or normal) be kept refrigerated.

Amniotic Fluid↗
PubMed1976

Metabolites of meperidine in the fetal and maternal serum.

Although meperidine appears to be the safest obstetric analgesic agent, it has been associated with infant respiratory depression in certain situations. It would appear that the incidence of fetal depression related to meperidine is dependent on the time of injection prior to delivery, the quantity of drug administered, and the rate of maternal metabolism of the analgesic. Previous work showed that meperidine is metabolized in the maternal system by one of three patterns. The present study demonstrates that the particular maternal serum pattern is characteristic for the individual, regardless of whether the patient is pregnant or not, and that the fetal depression, although usually mild, can be correlated with fetal pH data as well as Apgar scores. In addition, this study supports indirectly the contention that metabolites of meperidine rather than the parent compound cause fetal depression. It would appear, therefore, that in certain obstetric cases with a higher probability for infant depression, other analgesic agents might be considered, especially if the serum pattern indicates meperidine is being metabolized.

Apgar Score↗
PubMed1976

Fluctuation of fetal hemoglobin in sickle-cell anemia.

A reduction of morbidity and mortality rates in homozygous sickle-cell patients was found in those with high fetal hemoglobin (HbF) levels. This factor would lead one to believe that an adequate amount of this substance would be protective to a patient with this hemoglobinopathy. This study utilizing pregnant and nongravid females, as well as males, followed for long periods of time indicates that the HbF level fluctuates with crisis. Some patients had low HbF levels with many crises and others had high amounts of HbF with no crises. However, many patients with high levels on one occasion demonstrated a decrease in HbF levels when crisis occurred. More importantly, no patient had high levels of HbF during a crisis although the amount was elevated before and after the episodes. The possible explanation and ramifications of this finding are discussed.

Anemia, Sickle Cell↗