Biomedical subjects
Publications and source records attributed to F Manning.
We report the successful management of a case of hemolytic disease and hydrops fetalis secondary to anti Rh 17 antibodies in a woman with the rare D-- phenotype. We discuss the efficacy of intravenous immunoglobulins in treating hemolytic disease of the newborn infant.
BACKGROUND/PURPOSE: The accurate and early diagnosis of intestinal ischemia remains difficult chiefly because of a lack of a suitable marker that is noninvasive and easy to use. The glutathione S-transferases (GST) are a family of cytosolic enzymes involved in detoxification and released from a variety of cells when the cell membrane is damaged. The enzymes are distributed widely in the intestine and show isoform specificity in their distribution throughout the intestinal tract. Several previous reports have shown the utility of these enzymes in the diagnosis of liver and renal graft damage during and after organ transplantation. The object of this study was to determine if GST levels correlated with histologic changes of intestinal ischemia in a controlled animal model of mesenteric intestinal ischemia. METHODS: Control and experimental male Sprague-Dawley rats underwent laparotomy and ligation of the Superior Mesenteric Artery (SMA) and both control and experimental animals were studied at 30, 60, 90, 120, and 240 minutes. Blood taken from the Inferior Vena Cava (IVC) and Portal Vein (PV) and jejunal and ileal perfusates were assayed for alpha and mu isoforms of GST using a commercially available enzyme immunoassay. In addition, jejunal and ileal segments were sampled and reviewed by a histopathologist blinded to the group being studied. RESULTS: A reproducible pattern of intestinal ischemia was noted with worsening grades of injury observed with greater ligation times. Luminal alpha and mu GST release (as measured by the appearance in luminal perfusate) increased with increasing ischemia times. Increased ischemia times resulted in increased levels of alpha and mu GST in both portal and systemic venous samples but lagged behind the appearance of raised luminal GST values. CONCLUSIONS: The results suggest that GST may be an interesting and useful marker in the early detection of intestinal ischemia. Its detection in peripheral blood has implications for a more detailed study design to determine the sensitivity and specificity of this marker in more diverse clinical conditions such as necrotizing enterocolitis and superior mesenteric artery occlusion.
BACKGROUND: The mortality rate associated with acute mesenteric ischaemia (AMI) remains high. Diagnosis is frequently confounded by the non-specific history and physical signs, in conjunction with the absence of a reliable biological assay. Glutathione S-transferase (GST) is an enzyme with a crucial role in cellular homoeostasis, the alpha isoenzyme of which is highly specific to small bowel and liver. This study assessed alphaGST as a marker for AMI. METHODS: Twenty-six patients with acute abdominal pain were enrolled. Each patient manifested a diagnostic dilemma, with a potential diagnosis of AMI. Plasma was reserved for alphaGST assay during routine blood testing and stored at -20 degrees C for analysis. A final diagnosis was made by autopsy, laparotomy, a definitive other investigation or a return to full health. RESULTS: Twelve patients had AMI. Plasma alphaGST was significantly increased in patients with AMI (P < 0.0001). Although pH differed and other biochemical changes occurred, only alphaGST accurately predicted AMI. CONCLUSION: A threshold of 4 ng/ml for alphaGST was 100 per cent sensitive and 86 per cent specific for AMI. If these observations can be confirmed, evaluation of alphaGST may reliably predict the presence or absence of AMI.
BACKGROUND AND PURPOSE: Body positioning exerts a strong effect on pulmonary function, but its effect on other components of the oxygen transport pathway are less well understood, especially the effects of side-lying positions. This study investigated the interrelationships between side-lying positions and indexes of lung function such as spirometry, alveolar diffusing capacity, and inhomogeneity of ventilation in older individuals. SUBJECTS AND METHODS: Nineteen nonsmoking subjects (mean age=62.8 years, SD=6.8, range=50-74) with no history of cardiac or pulmonary disease were tested over 2 sessions. The test positions were sitting and left side lying in one session and sitting and right side lying in the other session. In each of the positions, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), single-breath pulmonary diffusing capacity (DLCO/VA), and the slope of phase III (DN2%/L) of the single-breath nitrogen washout test to determine inhomogeneity of ventilation were measured. RESULTS: Compared with measurements obtained in the sitting position, FVC and FEV1 were decreased equally in the side-lying positions, but no change was observed in DLCO/VA or DN2%/L. CONCLUSION AND DISCUSSION: Side-lying positions resulted in decreases in FVC and FEV1, which is consistent with the well-documented effects of the supine position. These findings further support the need for prescriptive rather than routine body positioning of patients with risks of cardiopulmonary compromise and the need to use upright positions in which lung volumes and capacities are maximized.
The cytosolic glutathione S-transferase (GST) enzymes serve as ideal biomarkers of organ damage as they exhibit many of the required characteristics, i.e. specific localisation, high cytosolic concentration and relatively short half-life. The role of GSTs as early indicators of organ damage is applicable to both human and animal models. Because of the regio-specific localisation of the different isoforms of GST in liver and kidney, simultaneous monitoring of classes of GSTs in biological matrices permits the identification of specific areas of damage within a particular organ. Immunoassays have been developed which quantify canine alpha GST and roden microGST (Yb1). The immunoassays are solid phase EIAs, where GST in the sample or standard is captured by a specific anti-GST antibody coated onto the solid phase. After washing, a specific enzyme-labelled IgG conjugate is added which binds to the captured GST. After a further washing step, substrate is added and a colour developed. The absorbance is measured on an ELISA plate reader and is directly proportional to the amount of GST present in the sample. The assays are performed at room temperature and can be completed within 3 h. The immunoassays are specific for each GST and have a range of 0-100 micrograms/l. A range of assay parameters were investigated to validate the EIAs for GST detection. The assays are sensitive and reproducible. CV for inter- and intra-assay variation were below 9% for Yb1 assay and below 20% for the canine alpha GST EIA. Recovery of spiked GST over the standard curve range was 102 and 99%, respectively. No prozone effect was observed and samples exhibited linearity of dilution in both assays. Validation has shown that using these enzyme immunoassay, Yb1 and canine alpha GST can be measured accurately and precisely in biological matrices, tissue homogenates and cell lines and that changes in GST levels can be detected. The use of these assays have important applications in both in vitro and in vivo toxicity studies, where GST's serve as sensitive marker of hepatocellular and renal cell integrity.
Factor VIII performs a critical role in the blood coagulation cascade but is extremely labile. We have carried out chemical studies on a fully functional recombinant Factor VIII (rFVIII) using a variety of protein modifying agents, some of which were bifunctional. Thiol-specific maleimides cause no activity loss despite a substantial decrease in rFVIII's free thiol content. Mild oxidation procedures had either neutral or adverse effects on activity. Amino-specific reagents led to significant losses of rFVIII procoagulant activity. It appears that free amino groups are essential for Factor VIII's function while some at least of its many free thiol groups are not. None of these derivatives was any less labile than unmodified rFVIII. Systematic chemical modification of important proteins in this way can give useful insights into appropriate protein engineering strategies.
OBJECTIVE: The second stage of labor has been thought of as a time of particular asphyxial risk for the fetus. This perceived risk has been invoked to justify arbitrary time limits and high rates of operative vaginal delivery. The purpose of this study was to determine whether perinatal outcome worsened as the second stage lengthened. STUDY DESIGN: Over a 5-year period at one university teaching hospital, 6041 nulliparous women reached the second stage of labor with a live singleton cephalic fetus with birth weight > or = 2500 gm. A retrospective review of perinatal morbidity and mortality was performed and the results related to the duration of the second stage. RESULTS: The second stage lasted > 3 hours in 11% of nulliparous women and > 5 hours in 2.7%. There were no perinatals death unrelated to anomaly. There was no significant relationship between second-stage duration and low 5-minute Apgar score, neonatal seizures, or admission to the neonatal intensive care unit. CONCLUSION: Operative intervention in the second stage is not warranted merely because some set number of hours has elapsed.
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Factor VIII is an important blood coagulation protein whose genetic deficiency leads to the serious bleeding disorder, classic haemophilia (haemophilia A). Here we review the structure, function and analysis of this protein for diagnostic and therapeutic applications. Because factor VIII is tightly associated with von Willebrand factor some recent work on the latter is also considered so as to clarify the relationship between them.
Intravenous drug abuse causes many health problems. From March 1989 to January 1990 of 27 Rh-negative women (28 pregnancies) referred to our centre, 4 women (5 pregnancies) were Rh immunized due to the sharing of needles and blood with their Rh-positive partners. Severe hydrops was present in 4 of their 5 fetuses when they were first seen at 17-35 weeks of gestation. Only the fetus first seen at 35 weeks survived. That infant was moribund at birth and now has evidence of leukomalacia and porencephaly. The fifth fetus, not hydropic, required two intravascular fetal transfusions in order to survive. A fifth woman, immunized in a similar manner, had a spontaneous abortion. These fetuses represent some of the earliest and severest examples of hydrops fetalis ever seen at our centre. The severity of their fetal hemolytic disease is probably due to the fact that their mothers' exposure to Rh(D) antigen by blood sharing was continuous and ongoing. Because of their aberrant behaviour, these women have suffered irreversible reproductive damage.
In a prospective, blinded clinical study, the relationship between amniotic fluid free-floating particles measured by a dynamic ultrasound imaging method and phospholipid profile was studied in 82 women undergoing amniocentesis between 26-42 weeks' gestation. None of 11 patients with sonographically clear amniotic fluid had a mature phospholipid profile (lecithin-sphingomyelin ratio greater than 2 and detectable phosphatidylglycerol). Thirty-eight of 71 women (53%) with turbid or markedly turbid amniotic fluid had a mature phospholipid profile. The sensitivity of this method was 100%, specificity 25%, positive predictive value 53%, and negative predictive value 100%. Although the finding of sonographically clear amniotic fluid may eliminate unnecessary amniocentesis, markedly turbid amniotic fluid is not a reliable indicator of a mature amniotic fluid phospholipid profile.
Chorionic villi sampling (CVS) has become a first trimester alternative to amniocentesis for prenatal diagnosis. The cytogenetic findings in 150 experimental samples are presented. The ages of the mothers ranged from 12 to 35 years, but the majority of them were 18 and 19 years of age. Various parameters of culturing and processing the samples in order to improve the method, were investigated. Short term incubation for 48 h was the method routinely employed in processing the biopsies for cytogenetic analysis. In the first series of 100 cases one mosaic case (46,XX/45,X), one Robertsonian translocation (13;14), one marker chromosome and one fragment were found. The foetal tissues were not analysed for chromosomes. In the second series of 50 samples, one case of mosaicism was found in the chorionic villi (46,XX/47,XX, 18q-), but this abnormality was absent in the foetal tissue. One variant inv(9) was observed in the foetal tissue as well as in the chorionic villi. In all other cases the karyotypes from the chorionic villi samples matched those of the corresponding foetal samples. There was no maternal contamination in this series of 50 samples. The discrepancies in the cytogenetic results from other investigators are discussed.
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Severe oligohydramnios, defined as a condition in which the largest pocket of amniotic fluid measures less than 1 cm in its vertical axis as determined by an ultrasound method, was observed in 113 patients in a population of 15,431 referred high-risk patients (0.7%). In all cases, intervention took place unless there was a recognized structural anomaly or extreme prematurity. Overall gross perinatal mortality was 132.7/1000, and the incidence of major anomaly was 13.3%. With intervention the corrected perinatal mortality rate was 17.7/1000, a rate not significantly different from that observed in the entire population. All end points of perinatal mortality were significantly increased in patients with severe oligohydramnios, in comparison with randomly selected control subjects with normal amniotic fluid. These findings are interpreted to indicate that severe oligohydramnios in a structurally normal fetus is an indication for delivery.
Nicotine (0.14--0.25 mg/kg), injected intravenously or intraarterially into conscious pregnant ewes, caused a decrease in fetal PaO2 within 5 minutes, persisting for up to 30 minutes. There was a significant fall in the incidence of fetal breathing movements. These changes did not occur if the ewe was treated with an alpha-blocking agent (phentolamine) or if the nicotine was infused for 30 minutes at 0.27 to 0.85 mg/minute. Nicotine crossed the placenta; fetal concentrations equaled those in the ewe 5 minutes after the injection and remained at or above maternal levels for 1 hour. Nicotine given directly to the fetus (0.005--0.03 mg/kg estimated fetal weight) stimulated fetal breathing movements in a dose-related manner. We suggest that the maternal injection of nicotine results in a fall of uterine blood flow by a sympathomimetic action, leading to transient fetal hypoxemia and a reduction of fetal breathing movements and that a similar phenomenon may occur when a pregnant woman smokes cigarettes.
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In 18 women with uncomplicated pregnancies smoking two cigarettes significantly reduced the proportion of the time that fetal breathing movements were present.