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Biomedical subjects

M Lake

Publications and source records attributed to M Lake.

53 records · Page 3Linked to original sources
PubMed1985

Riboflavin as a tracer of medication compliance.

Three experiments were conducted to evaluate the accuracy of urine ultraviolet fluorescent tests for riboflavin, which has been used as a tracer for medication compliance in several clinical drug trials. Observer accuracy in discriminating riboflavin-positive or negative urine samples was found to vary with the method of observation, dose of riboflavin, observer experience, and time postingestion. The results showed that, while the 5-mg dose used in previous clinical trials was too small to permit reliable assessment of compliance, larger doses of riboflavin could produce nearly 100% accuracy for minimally trained observers who used a matching-to-sample observation procedure. The findings are discussed in terms of the potential clinical and research applications of this type of simple but reliable compliance assessment procedure.

Adult↗
PubMed1984

Determination of the composition of mixed micelles of bile salts by kinetic dialysis.

A kinetic dialysis method for determining the critical micelle concentration and the composition of mixed micelles has been adapted to study a binary system of bile acids. Using kinetic dialysis, the critical micelle concentrations of taurocholate, deoxycholate and taurodeoxycholate were determined. Monomer analysis was performed by colorimetric and radioactive tracer techniques on aliquots of the dialysates. Similarly, the composition of mixed micelles made from various molar fractions of deoxycholate and taurocholate containing tritium and 14C tracers were determined by this method. The results suggest that, for these bile acids, mixed micelle composition is largely predicted by the molar composition of the binary system. Kinetic dialysis has proven to be a rapid procedure and to yield results that agree with critical micelle concentration values previously reported.

Bile Acids and Salts↗
PubMed1984

The relationship between polyribosomal and latent membrane-bound messenger ribonucleoprotein particles in Artemia embryos.

Polysomal messenger ribonucleoprotein (mRNP) particles from developing Artemia cysts were isolated, characterized and compared with latent membrane-bound mRNP particles isolated from dormant cysts. The polyribosomal mRNP particles sedimented between 25-35 S in a sucrose gradient and had a buoyant density of 1.33 g/cm3 in Cs2So4. Latent particles had a higher sedimentation coefficient and lower buoyant density. The poly(A) + RNA in the two kinds of particles was comparable in size, 10-20 S. The protein composition of the particles, as determined by electrophoresis, was different. Polyribosomal particles contained 9 major and 6 minor proteins; a 72 k poly(A)-associated protein was present. Latent particles were characterized by a complex protein pattern ranging in apparent mol. wt between 14,000-140,000. Some proteins with similar molecular weight and isoelectric point were probably common to both kinds of particles.

Animals↗
PubMed1984

Evaluation of nonstress fetal heart rate testing in multiple gestations.

Routine serial nonstress fetal heart rate testing was evaluated in 94 patients with multiple gestations (193 fetuses). Reactive testing was associated with an uncomplicated perinatal outcome in 89% of the cases. Nonreactive fetuses had a significantly higher incidence of perinatal morbidity, including fetal distress in labor (77.8%), asphyxia (48%), and intrauterine growth retardation (28%). Overall perinatal mortality (21/1000) was nearly comparable to that observed in singleton pregnancies. Nonreactive fetuses had a perinatal death rate that was more than six times that of the reactive ones (80/1000 versus 12/1000). Antepartum nonstress testing was found to be a highly reliable and predictive tool in the assessment of multiple gestations.

Apgar Score↗
PubMed1983

The role of a grief support team following stillbirth.

The loss of a baby through stillbirth is a tragic, devastating experience for a woman and her family. Although well intentioned, physicians and nurses are often ill-prepared to provide essential emotional support. We would like to describe our experience with a multidisciplinary perinatal grief support team. In our hospital, such a team has, in part, corrected deficits in the care of these families and has functioned as an invaluable source of education and support for health care providers.

Fathers↗
PubMed1982

A review of the nonstress test.

A review of the developmental research and the clinical utilization of the nonstress test (NST) is presented. In contrast to the oxytocin challenge test (OCT), it is more acceptable to patients, takes less time, is easily reproducible and is less expensive. More important, there are no contraindicatioins to the nonstress test as a primary screening device. The salient points in performance of the nonstress test, developed by other investigators as well as the authors in a level III maternity center, are reviewed. Enhanced sensitivity and specificity of this method for fetal evaluation must be pursued. No one criterion for a reactive nonstress test has been universally accepted. Furthermore, which test (NST or OCT) is the first to determine fetal distress remains unresolved. The "standard of care" for bioelectrical evaluation remains pluralistic, and it should be utilized within a system that uses additional modalities of fetal assessment and sound clinical judgment.

Female↗
PubMed1980

Characterization of a poly(A)+RNA-containing structural component directly associated with cytoplasmic membranes in dormant Artemia cysts.

Poly(A)+RNA-containing material was extracted from the purified cytoplasmic membranes of dormant Artemia cysts by treatment with mild detergents. Sedimentation analysis of the extracts showed a predominant poly(A)-containing fraction at 40 S, associated with about 6% of the extracted proteins. Only limited amounts of poly(A)-containing material were found in the heavier fractions. Poly(A)+RNA extracted from the 40-S fraction sedimented around 14 S. The poly(A)-containing 40-S structures could be purified by treatment with non-ionic or zwitterionic detergents followed by resedimentation in sucrose gradients in the presence or absence of detergent. When the 40-S fraction was analyzed by isopycnic centrifugation in Cs2SO4 gradients, the main part of the poly(A)-containing material banded at a density of 1.27 g/ml. Electron-microscopic examination of this fraction revealed circular or slightly bullet-shaped profiles measuring 17-26 nm. When the 40-S fraction had been submitted to mild RNAase treatment prior to density gradient centrifugation, the material was displaced towards lower density and became less distinct. Purified 40-S particles showed a complex protein pattern not very similar to that of polyribosomal poly(A)+RNA-containing particles from developing embryos, but with components in common with unfractionated membranes. The particles also contained some lipids. The experiments indicate that a major part of the membrane-bound, latent poly(A)+RNA in dormant Artemia cysts occurs in the form of relatively uniform, detergent- and Cs2SO4-resistant structures, independent of ribosomes, but intimately associated with membrane components.

Animals↗
PubMed1980

Prognostic components of the nonreactive nonstress test.

From January 1976 to November 1978, 2592 nonstress tests were performed at the authors' institution on 862 fetuses, of which 2239 (86.3%) had reactive and 353 (13.6%) had nonreactive results. Of these 862 fetuses, 842 were delivered at the authors' hospital. Of these 842 fetuses, 109 were delivered within 1 week of a nonreactive tracing and 733 were delivered within 1 week of a reactive tracing. A retrospective analysis was performed on 102 of the nonreative tracings done within 1 week of delivery to assess the significance of various components of the nonstress test on the subsequent stress test and perinatal outcome. No significant difference could be observed in the number of fetal movements and total number of accelerations as compared with the subsequent stress test. However, the nonreactive tracings of the contraction stress test (CST)-positive group differed from those of the CST-negative groups in number of accelerations over 15 beats per minute (38% versus 48%) (P < .05) and in the number of accelerations lasting longer than 20 seconds (20% versus 50%) (P < .01). The number of nonreactive fetal movements per test (2.6 versus 0.96) (P < .05) and the percentage of nonreactive fetal movements (33% versus 15%) (P < .01) were different in both groups. The growth-retarded fetus in the nonreactive group did not differ in the number of fetal movements or total accelertions when compared to fetuses born appropriate for gestational age, but the number of accelerations was more than 15 beats per minute (26% versus 50%) (P < .01) and the number of accelerations lasting 20 seconds (11% versus 28%) (P < .01) did differ significantly.

Delivery, Obstetric↗
PubMedDate not supplied

Antenatal prediction of fetal pH in growth restricted fetuses using computer analysis of the fetal heart rate.

We tested the accuracy of a mathematical model based on computer analysis of the fetal heart rate tracing in predicting umbilical artery pH at birth. In a previous report based on data on 38 growth-restricted fetuses, the second-order polynomial regression equation, umbilical artery pH = 7.28 + 0.002 (duration of episodes of low variation in minutes) + 0.00009 (duration of episodes of low variation in minutes), was retrospectively found to be the best model for the prediction of umbilical artery pH at birth. In the present study, this formula was prospectively tested in 29 growth restricted fetuses between 26 and 37 weeks of gestation from pregnancies with abnormal uterine and/or umbilical artery Doppler velocimetry. Computer analysis of the fetal heart rate tracing of 1 hour duration was performed within 1.5-6 hours of cesarean birth prior to the onset of labor. Umbilical artery cord blood was collected at birth with pH determined within 5 minutes of collection. Acidemia was defined as umbilical artery pH < 7.20, preacidemia pH 7.20-7.25 and nonacidemia pH > 7.25. Then, the data on all 67 growth-restricted fetuses were pooled to generate a new formula that was retrospectively assessed against the entire group. Values are reported as median (range). In the 29 prospectively evaluated cases, there was no statistical difference between the predicted and actual umbilical artery pH at birth [7.28 (7.1-7.29) vs. 7.28 (7.18-7.37), P = 0.57]. The median difference between the paired predicted and actual umbilical artery pH values was -0.001 (-0.10-0.08). The difference between the predicted and actual umbilical artery pH was zero and within +/- 0.04 in 17% (5/29) and 76% (22/29) of the cases, respectively. When the data on the 67 growth-restricted fetuses were pooled together the formula did not change. There was no difference between the predicted and actual umbilical artery pH at birth when the formula was applied to all 67 growth-restricted fetuses [7.28 (7.08-7.29) vs. 7.27 (6.97-7.37), P = 0.41]. The median difference between the paired predicted and actual pH values was -0.001 (-0.12-0.12). The difference between the predicted and actual umbilical artery pH was zero and within +/- 0.04 in 15% (10/67) and 74% (49/67) of the cases, respectively. The accuracy of the formula in correctly categorizing the umbilical artery pH at birth was: acidemia 67% (8/12), preacidemia 28% (8/29) and nonacidemia 80% (37/46), P < 0.0001. A mathematical formula using the computer analysis index of duration of episodes of low variation reliably predicted umbilical artery pH at birth. This type of noninvasive monitoring may allow for the antepartum estimation and continuous tracking of fetal pH.

Birth Weight↗
PubMedDate not supplied

Production of a biologically active variant form of recombinant human secretin.

A biologically active variant form of recombinant human secretin was produced using a gene fusion system designed to facilitate the purification of the protein. The fusion protein was recovered from the culture medium of Escherichia coli by IgG affinity chromatography, and recombinant secretin was released by cyanogen bromide treatment. A novel approach involving addition of a C-terminal Gly-Lys-Arg extension, was used to overcome the lack of amidation of recombinant proteins in Escherichia coli. The biological activity of the recombinant variant of secretin was at least 80% of the porcine secretin standard.

Amino Acid Sequence↗
PubMedDate not supplied

The bicycle seat stool in the treatment of vaginal agenesis and stenosis.

The Ingram method for creating a neovagina in women with vaginal agenesis or stenosis by using an intermittent pressure technique was performed on 45 patients between 1975 and 1982. Poor patient compliance has been the major drawback of previously reported pressure techniques. To overcome this, the Ingram method employs a unique approach using Lucite dilators and a mobile bicycle seat stool. Extensive nursing participation and a successfully treated former patient used as a motivating role model have significantly contributed to the acceptance of this method. Thirty-seven of the 45 patients were able to experience coitus subsequent to treatment.

Bicycling↗