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Biomedical subjects

J A Evans

Publications and source records attributed to J A Evans.

At least 19 recordsLinked to original sources
PubMed1992

Patterns of acrorenal malformation associations.

Limb and urinary tract defects have frequently been reported to occur together as components of a single acrorenal field defect or in many multiple malformation syndromes. However, the concordance of such anomalies has rarely been studied on a population basis or the relationships between specific limb and renal defects defined. This paper documents the patterns of acrorenal associations seen in over 1,500,000 infants born in Hungary in 1975-1984. In all, 1 in 1,800 infants had a limb deficiency and 9% of these (75 cases) had a urinary tract anomaly. Urinary tract anomalies were most commonly seen with radial ray defects, micromelia and amelia. The commonest recognized patterns were VACTERL association and the cloacal exstrophy and caudal regression sequences. Chromosomal and single gene defects also occurred. Numerical taxonomic techniques delineated six main clusters of patients. Important groupings included micromelia with renal agenesis, split hand/foot with hydronephrosis, and radial ray anomalies with VACTERL defects. The radial ray groups differed in the nature of the VACTERL anomalies seen and with respect to laterality, symmetry, and non-VACTERL anomalies. There was a strong association of bilateral limb defects with bilateral renal anomalies and unilateral with unilateral. Ipsilateral defects tended to occur in typical VACTERL cases, while contralateral defects tended to occur with additional non VACTERL midline anomalies. Although renal and limb anomalies are associated, in almost all cases malformations in other systems are also present. The precise nature of the malformation patterns seen appear to reflect differences in the nature and magnitude of the underlying dysmorphogenetic processes as well as the timing of their effects.

Abnormalities, Multiple↗
PubMed1992

The effect of bone structure on ultrasonic attenuation and velocity.

The relationship between the structure of bovine cancellous bone, and its ultrasonic propagation parameters is investigated by means of a novel technique involving the application of large static loads, thereby changing the porosity in a controlled manner. The results show that for frequencies in the range 0.4 to 1 MHz, porosity decreases up to 35% are associated with a reduction in attenuation of up to 500%, whereas the velocity increases by roughly 35% for the same changes. The data taken overall suggest that in determining the ultrasonic attenuation coefficient at these frequencies, the amount of material in a given bone section is significantly less important than the distribution of that material.

Animals↗
PubMed1992

Bone ultrasonic attenuation in women: reproducibility, normal variation and comparison with photon absorptiometry.

The reproducibility of two methods of measuring broadband ultrasonic attenuation (BUA) in the calcaneus have been studied. An improvement in reproducibility in vivo from 9.6% to 2.8% between old and new techniques has been observed. Measurements of the calcaneus using BUA were correlated with measurements of bone mineral density measured by dual energy x-ray absorptiometry in the lumbar spine, femur and total body and bone mineral content in the distal and proximal forearm measured by single photon absorptiometry. For the older BUA technique the correlation coefficients ranged between r = 0.27 and r = 0.34. For the newer BUA technique the correlation coefficients ranged between r = 0.49 and r = 0.62 and were all significant (P less than 0.001).

Absorptiometry, Photon↗
PubMed1992

Combined effect of infection and heavy wrapping on the risk of sudden unexpected infant death.

Three methods were used to investigate the role of infection in sudden unexpected infant death (SUD): (i) microbiological comparison of SUD victims and matched, live, community controls; (ii) postmortem classification of the contribution of infection to death; and (iii) case-control analysis of the relative risk associated with both infection and heavy wrapping. Limited sampling from the upper respiratory tract and gut in SUD victims and controls showed no significant excess of viral infection in the SUD victims (odds ratio = 1.98, 95% confidence interval (CI) 0.9 to 4.5). At postmortem examination, infection explained death in 3/95 babies and may have contributed to death in 37/95. Over 70 days of age, the combined presence of viral infection and wrapping in excess of 10 togs produced an odds ratio of SUD of 51.5 (95% CI 5.64 to 471.48) compared with wrapping of less than 6 togs. Viral infection was not a major risk factor as long as babies were lightly wrapped. In heavily wrapped babies the presence of a viral infection greatly increased the risk of SUD.

Bacterial Infections↗
PubMed1992

A study of the relationship between routine ultrasound quality assurance parameters and subjective operator image assessment.

Comparisons have been made between a number of routine quality assurance (QA) measurements and a number of related subjective aspects of image quality. These comparisons between lateral resolution and perceived definition, dynamic range and subjective grey-level assessment, and slice thickness and overall image quality appraisal showed very poor correlation. We deduce from this that other QA parameters are needed to quantify good image quality as defined by the operators.

Evaluation Studies as Topic↗
PubMed1992

Some clotting factors in plasma during danazol therapy: free and total protein S, but not C4b-binding protein, are elevated by danazol therapy.

Anabolic steroids are known to increase the plasma concentrations of certain plasma proteins. In four patients given treatment with danazol, an attenuated androgen, the concentrations of heparin cofactor II, Hageman factor (factor XII), protein C, and both free and total protein S increased significantly when tested 39 to 103 days after the start of therapy. The titers of these proteins in samples obtained 21 days to 5 years after therapy was discontinued were similar to those before treatment, except for total protein S, the titer of which remained elevated. No significant changes in the titers of C4b binding protein or plasma plasmin inhibitory activity were found.

Adult↗
PubMed1991

Computer assisted analysis of hand radiographs in infantile hypophosphatasia carriers.

Hand radiographs of 49 carriers of infantile hypophosphatasia and 67 non-carriers were evaluated using two Apple IIe Computer Programs and an Apple Graphics Tablet. CAMPS (1) was used to determine the bone lengths and calculate the metacarpophalangeal profiles. A newly developed program (ADAM) was used to determine bone density based on percent cortical area of the second metacarpal. Carriers of infantile hypophosphatasia had significantly less dense bones.

Adolescent↗
PubMed1991

Dependence of the velocity and attenuation of ultrasound in bone on the mineral content.

Measurements of the attenuation and velocity of ultrasound from 0.3 to 0.8 MHz have been performed on a number of bovine cancellous bone samples. The influence of bone mineral content has been isolated by measuring the acoustic properties of the samples at various stages of demineralization resulting from controlled nitric acid attack. The correlation coefficient r, between the attenuation at different frequencies and bone density was found to be in the range 0.68-0.97. Broadband ultrasonic attenuation (BUA) was also calculated and produced r values between 0.84 and 0.99. The velocity measurements indicated a correlation greater than 0.97 in all cases. Thus velocity is the parameter most sensitive to changes in bone mineral density alone. Attenuation and BUA are less well correlated presumably because of a sensitivity to minor structural change.

Animals↗
PubMed1991

A circulating factor(s) mediates cell depolarization in hemorrhagic shock.

Cell depolarization in hemorrhagic shock has been attributed to hypoperfusion, but the mechanism remains unclear. Suspensions of single cell lines loaded with the potential-sensitive fluorescent dye bis-(1,3-dibutylbarbiturioc acid) trimethine oxonal (DIBAC) and exposed for 30 minutes to rat plasma drawn either before or after hemorrhagic shock (bled 20 mL/kg: mean arterial blood pressure less than 40 mmHg) were studied. Plasma drawn after, but not before, hemorrhage led to partial depolarization regardless of cell type (rat H9C2 skeletal muscle, A-10 smooth muscle, C-9 liver, adrenal, kidney, red blood cell [RBC], white blood cell [WBC]) or species (cat, dog, pig RBC; cat WBC; mouse C2C12 skeletal muscle; and human intestinal smooth muscle [HISM]). Dialysis did not remove the factor(s), suggesting a molecular weight of more than 10,000 daltons. The factor appeared within 5 minutes of shock. The depolarization amplitude increased as a function of plasma concentration and demonstrated saturation kinetics indicating specific receptor binding. Cells were equivalently oxygenated, excluding hypoperfusion as a necessary condition for depolarization. Tumor necrosis factor or platelet activating factor alone or in combination were not effective in this system. Stable measurements can be obtained with this noninvasive system that avoids cell injury consequent to cell impalement with electrodes. This system provides a sensitive in vitro bioassay that should permit identification of the plasma factors mediating cell depolarization, as well as definition of the responsible intracellular mechanisms.

Animals↗
PubMed1991

Consistently normal CD4+, CD8+ levels in haemophilic boys only treated with a virally safe factor VIII concentrate (BPL 8Y)

Prospective biochemical, virological and selected immunological follow up has been done for up to 32 months on 15 previously untreated haemophilic boys following treatment with an intermediate purity dry heated factor VIII concentrate (BPL 8Y). Tests for liver function and antibodies to blood-borne viruses have been assessed monthly for the first year after starting treatment and thereafter every 2 months. All patients were immunized against hepatitis B and have not developed hepatitis B core antibodies and no boy has shown any rise in alanine transaminase level nor has anyone developed antibodies to hepatitis C (HCV). All patients have remained anti-HIV seronegative. T lymphocyte subsets have been measured approximately every 4 months and in no patient has there been a significant rise in CD8+ cells; one patient showed a significant decrease in CD4+ cells but these and all CD4+ values for the other boys remained within normal age related limits. Changes in CD4+ levels in this one boy were not related to the total amount of treatment received. This group of patients who appear not to have contracted HIV, hepatitis B or non A non B hepatitis following treatment with this intermediate purity factor VIII concentrate have also not shown any consistent changes in CD4+ or CD8+ cells, which have been recorded previously in frequently treated haemophiliacs.

Aging↗
PubMed1990

Aberrant bronchi and cardiovascular anomalies.

In an investigation of malformation associations in consecutive perinatal autopsies, 4 infants were identified as having a displaced or supernumerary bronchus. Each had a different type of bronchial abnormality and 3 had congenital heart defects and other malformations. Review of the literature found 38 other cases of aberrant bronchi with additional defects, especially cardiovascular or costovertebral anomalies. Structural cardiac defects were more common in patients with super-numerary tracheal bronchi (67%) than in those with displaced tracheal bronchi (27%) or bronchoesophageal connections (23%). There was also a strong negative association (P = 0.01) of cardiovascular and costovertebral defects unless multiple anomalies were present. The combinations of anomalies seen appear to reflect relatively specific developmental field defects affected both by the spatial relationships of organs near the developing foregut and by temporal sequence. Recognition of these patterns has clinical and embryological importance. Aberrant bronchi should be considered when children with cardiac defects or multiple anomalies such as the VACTERL association have unexplained respiratory symptoms and surgeons planning to treat such bronchial abnormalities should be aware of the high frequency of abnormal vessels in these cases.

Autopsy↗
PubMed1990

Maternal serum alpha-fetoprotein in twin pregnancy.

Maternal serum alpha-fetoprotein concentration was measured at 14 to 20 weeks' gestation in 138 twin pregnancies. All patients had at least one ultrasonographic examination (86% before 20 weeks' gestation). Two pregnancies were discordant for open fetal defects (one anencephaly, one gastroschisis). The median serum alpha-fetoprotein value in the remaining 136 twin pregnancies paralleled a curve 2.5 times the median curve for singleton pregnancies over the gestational range studied. Higher serum alpha-fetoprotein values correlated significantly with increasing incidence of fetal and neonatal death, premature delivery (less than 35 weeks' gestation), and twin-to-twin birth discordance (greater than 20%), most pronounced at greater than 4 multiples of the singleton median level. A significant negative correlation between alpha-fetoprotein and birth weight was observed (p less than 0.001), but was related more to prematurity than to poor fetal growth. Theoretically, serum alpha-fetoprotein screening detected 56.5% of the twins in this study when a cutoff level of 2.5 multiples of the median was used, enhancing twin detection in the study population by 40%. These data indicate that maternal serum alpha-fetoprotein screening has a valuable role in the management of twin pregnancy, both in the detection of twins and in the prediction of perinatal outcome in twin pregnancy.

Female↗
PubMed1990

Ultrasonic attenuation and velocity in bone.

The measurement of attenuation and velocity of ultrasound in cancellous bovine femora has been studied. The dependence of both attenuation between 0.2 and 0.8 MHZ and velocity on the bone density has been measured. The results show a correlation coefficient of around 0.5 for attenuation and density, and a value of roughly 0.85 for velocity and density. The clinical consequences for the use of low frequency ultrasound as a diagnostic tool in bone disease are discussed.

Animals↗
PubMed1990

Possible association of rare autosomal folate sensitive fragile sites and idiopathic mental retardation: a blind controlled population study.

The expression of folate sensitive fragile sites (FS) was assessed in cord blood lymphocyte cultures obtained from 790 newborns (NB) and in peripheral blood lymphocyte cultures from 326 institutionalized mentally retarded residents (MR). The mean rate of expression of common FS and the occurrence of rare FS was significantly higher in the MR population. Age, sex and history of chronic medication use did not appear to influence common FS expression in the MR population, 3/790 (0.38%) NB and 5/326 (1.53%) MR exhibited rare autosomal folate sensitive FS, a 4-fold difference in incidence (P = 0.009, Poisson test). Four of the five MR who expressed rare FS were considered to have idiopathic MR (4/179 or 2.2%). The occurrence of rare FS in 1/147 (0.68%) MR with known etiology is not significantly different from the frequency of occurrence in the NB population (P = 0.428, Poisson test). In this population, rare FS appear to be overrepresented in the idiopathic etiology MR group.

Abnormalities, Multiple↗
PubMed1990

Influence of carbon dioxide on growth and antibiotic susceptibility of coagulase-negative staphylococci cultured in human peritoneal dialysate.

Used peritoneal dialysis fluid was collected from patients undergoing continuous ambulatory peritoneal dialysis, and its pH and composition were assessed after incubation in either air or air with 5% CO2. Precipitation of calcium, magnesium, phosphate, and proteins occurred in the dialysis fluid incubated in air at 37 degrees C and was associated with a mean pH increase of 1.23 U. Incubation of dialysis fluid in air with 5% CO2 prevented precipitation and maintained pCO2 and pH levels at those found physiologically. Coagulase-negative staphylococcal strains isolated from patients with peritonitis tended to grow less well in dialysis fluid incubated in air than in dialysis fluid incubated in the carbon dioxide-enriched atmosphere. MICs of cefuroxime, ciprofloxacin, and vancomycin for seven strains of coagulase-negative staphylococci in dialysis fluid were markedly affected by atmosphere type (16 of 21 MICs). Of these 16 atmosphere-dependent MICs, 14 were at least fourfold higher in air than in air with 5% CO2.

Air↗
PubMed1990

Influence of carbon dioxide on the surface characteristics and adherence potential of coagulase-negative staphylococci.

Coagulase-negative staphylococci obtained from patients with continuous ambulatory peritoneal dialysis-related peritonitis were cultured in nutrient broth in an atmosphere of air containing 5% carbon dioxide (reflecting the CO2 tension found in freshly used dialysate). Significant differences were observed between the surface chemistries of cells grown in the two atmospheres, as determined by X-ray photoelectron spectroscopy and changes in the cell wall protein profile. The growth atmosphere also influenced the adherence potential toward polystyrene and silicone in a proportion of strains examined. Thus, gaseous conditions can profoundly influence the nature of the staphylococcal surface, and this should be considered in any in vitro study of in vivo behavior.

Bacterial Adhesion↗
PubMed1990

Infantile hypophosphatasia: localization within chromosome region 1p36.1-34 and prenatal diagnosis using linked DNA markers.

Linkage analysis was performed on data from Manitoba Mennonite families identified by a proband with infantile hypophosphatasia (HOPS), an autosomal recessive disorder characterized by defective skeletal mineralization. Southern blot analysis of Msp-I-digested DNA from HOPS nuclear families probed with a 2.55-kb liver/bone/kidney alkaline phosphatase (ALPL) cDNA revealed two previously undescribed RFLPs at 2.4/2.3 kb and 2.0/1.9 kb. Maximum combined lod score equals 13.25 at theta = 0. This establishes very close linkage between ALPL and HOPS and allows for the regional assignment of the HOPS gene to chromosome 1p36.1-34. Prenatal RFLP studies in an informative Mennonite family correctly predicted an unaffected fetus following chorionic villus sampling at 12 wk gestation. In addition in our Mennonite population, a nonrandom association exists between the polymorphic ALPL alleles and HOPS. These results suggest that strong linkage disequilibrium exists between HOPS and the ALPL markers. This will allow for improved carrier assignment in this high-risk population. Preliminary analysis suggests approximately 1/25 Manitoba Mennonites are HOPS carriers.

Adult↗