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Biomedical subjects

A Smith

Publications and source records attributed to A Smith.

At least 901 records · Page 50Linked to original sources
PubMed1990

Imaging and therapy of small cell carcinoma xenografts using 131I-labeled monoclonal antibody SWA11.

The IgG2a monoclonal antibody SWA11 has been evaluated as a radioimmunotherapeutic agent for use in the treatment of small cell cancer of the lung. This antibody was initially selected for in vivo localization studies in a nude mouse model system because of its high affinity for the SW2 small cell cancer cell line in vitro. Following i.v. injection of 125I labeled antibody into nude mice bearing SW2 xenografts good selective accumulation was observed with 10.5% of injected material/g of tumor. The level remained constant from day 2 to day 4 following injection. At day 4 the tumor:blood ratio was 7:1 and tumor:liver, tumor:kidney, and tumor:lung ratios were 17:1, 24:1, and 12:1, respectively. Initial radioimmunotherapeutic studies performed on established small cell cancer of the lung xenografts have shown reduction in tumor burden following a single injection of 300 microCi of 131I labeled SWA11 with no evidence of regrowth up to day 34 postinjection. Histological evaluation of treated tumors revealed large areas of necrosis and extensive fibrosis. A few residual cells of tumor origin could be observed and these displayed atypical morphology. The clonogenic potential of such cells remains to be determined by long term observation.

Animals↗
PubMed1990

Frequency of 47, +21 in cells of blood cultures from couples with habitual spontaneous abortion.

Karyotyped specimens of peripheral blood from 1,055 chromosomally normal individuals (573 females, 482 males) presenting with habitual spontaneous abortion were examined for aneuploidy. Trisomy 21 was noted in six of 14,802 cells. These data were not significantly different from those obtained on chromosomes 19 and 20, or the data obtained from three different, smaller, control groups. The low rate of trisomy 21 cells found in this study suggests that we cannot extrapolate from events in somatic cells in mitosis to nondisjunction events in meiosis.

Abortion, Habitual↗
PubMed1990

Normal variations in the relationship of the tricuspid valve to the membranous septum in the human heart.

The anatomy of the antero-septal commissure of the tricuspid valve and its relationship to the membranous part of the septum are described in 72 normal hearts from subjects ranging in age from 25 weeks gestation to 13 months. Three major patterns were found. According to whether the contiguous leaflets were fused at the commissure, joined at the circumference of the orifice, or left a gap at the commissural site, the varieties are described as undivided, annular, or gap commissure, respectively. Commissures of annular type showed further morphological varieties, as did the patterns of division of the membranous septum into its atrioventricular and interventricular components. Dominance of the atrioventricular component and/or absence of the interventricular membranous septum were encountered in 38 cases out of 72 (52%). This finding demonstrates that dominance of the atrioventricular membranous septum during fetal life and infancy is not universal. The variability noted in the morphology and position of the antero-septal commissure was not associated with other positional variations of the tricuspid valve.

Fetus↗
PubMed1990

Endothelial cell transformation in primary biliary cirrhosis: a morphological and biochemical study.

There is increasing interest in the changes of the endothelial lining of the hepatic sinusoids during the development of chronic liver disease. In this study we looked for evidence of hepatic sinusoidal endothelial cell transformation and basement membrane production in patients with primary biliary cirrhosis. Morphological transformation to vascular-type endothelial cells, as evidenced by the development VIII-related antigen, was seen at the interface between portal tracts or fibrous septae and hepatic parenchyma; the most marked changes were observed in patients with established cirrhosis. Increased immunohistochemical staining for the basement membrane components type IV collagen and laminin was also found in a similar distribution. Raised serum levels of hyaluronic acid, a glycosaminoglycan metabolized by normal hepatic endothelial cells, were found in most patients and correlated strongly with advancing histological stage. Furthermore, significant positive correlations were found between serum hyaluronic acid and serum levels of laminin and type IV collagen. The unique structure of the normal endothelial lining of the hepatic sinusoids is important in the maintenance of hepatic function. Our data show that significant changes in endothelial cell structure and function occur in primary biliary cirrhosis and appear to be a contributing factor to the progression of the disease. Further studies are needed to determine the extent and importance of these changes in other forms of chronic liver disease.

Endothelium↗
PubMed1990

Noise, performance efficiency and safety.

This paper summarises our current knowledge of the non-auditory effects of noise on performance efficiency and safety. This topic has been studied both in the laboratory and in the field, and detailed accounts of the results for laboratory studies have been presented elsewhere, so only the main conclusions are given here. There have been few field studies of the effects of noise on accidents and productivity and these are discussed in detail here. Overall, the results from the laboratory and field both suggest that noise may influence efficiency and safety, although further prospective studies with appropriate interventions are required to give us more precise information about these effects.

Accident Prevention↗
PubMed1990

Male infertility and its treatment: a review of over 4700 patients treated for male related infertility.

Changes in semen parameters are presented for 4708 patients treated for infertility. The largest group comprised patients with oligoasthenozoospermia of various grades (57.7%). Improvement in the seminal state was noted in 70.3%. The percentage of achieved normospermia increased proportionally to the initial semen state. Pregnancy rate also increased proportionally to the initial seminal state. Among the patients' wives 20.4% conceived: 28.2% of these pregnancies had occurred after having achieved normospermia, while in 71.8% the seminal states were still below the accepted normal values.

Humans↗
PubMed1990

Morphology of pulmonary atresia with intact ventricular septum in patients dying after operation.

In 1976, we adopted staged surgical management of pulmonary atresia with intact ventricular septum: stage 1 = establishment of a systemic to pulmonary artery shunt; stage 2 = open reconstruction of the right ventricular outflow tract and pulmonary valve; and stage 3 = closure of the shunt and interatrial communication. The morphological features of nine specimens obtained from 10 patients who died were reviewed. Special attention was given to features that might have influenced the poor surgical outcome in these patients. Survival after stage 1 depends on adequate systemic to pulmonary artery blood flow, initially as a combination of ductus arteriosus and shunt flow, with subsequent modification if the ductus closes. After stage 2, survival is influenced by left ventricular function and mitral valve function. The success of final correction (stage 3) depends largely on the morphology of both ventricles and their atrioventricular valves. It appears that the behavior of the ductus arteriosus and the size of the shunt are of vital importance for the survival of the infant. In 3 of the specimens, no right ventricular outflow tract was present, and in 2 others, short chordal attachments of the mitral valve were observed. Staged surgical correction appears to be a satisfactory approach if these considerations are taken into account.

Aorta, Thoracic↗
PubMed1990

The isolation of large molecular mass procyanidins from grain sorghum and their interaction with [14C]methyl bovine serum albumins.

1. Three protein-free procyanidin fractions with molecular masses of 4000, 8000 and 10,000-50,000 were isolated from a bird resistant sorghum grain. 2. The interaction between the largest procyanidin and 88 or 1% methylated bovine serum albumin (14C labelled) is stronger with the more methylated protein over a range of 0-2.75 ionic strength at pH 5. This indicates the involvement of apolar forces throughout the range though apolar forces were more pronounced from 0.7-2.75 ionic strength. 3. In the interaction between procyanidins of different molecular masses and 88% 14C-methylated bovine serum albumin the smaller procyanidins exhibited a more pronounced sigmoidal precipitation pattern than the larger with an increase in their concentrations.

Animals↗
PubMed1990

The role of extracellular calcium in ischemia/reperfusion injury in skeletal muscle.

Ischemia-reperfusion injury to skeletal muscle, following an acute arterial occlusion is a significant cause of morbidity and mortality. The purpose of this study is to examine the role of extracellular calcium in the production of cellular necrosis following a prolonged period of normothermic ischemia. Bilateral canine gracilis muscles were made ischemic for 4.5 to 5 hr. The control muscle had normal blood reperfusion (ionized Ca2+ 1.2 mM). The treated muscle was perfused for 30 min with an oxygenated solution (ionized Ca2+ 0.11 mM) containing free radical scavengers followed by normal blood perfusion. Necrosis was determined by nitroblue tetrazolium staining after 48 hr of reperfusion. Total muscle Ca2+ was measured by atomic absorption spectrometry. Pre- and postischemic muscle Ca2+ levels were similar (2.8 +/- 0.4 vs 3.2 +/- 0.8 nmole/mg protein, n = 13, P greater than 0.1). After 30 min of reperfusion the treated muscle Ca2+ was 2.4 +/- 0.4 compared to control levels of 8.6 +/- 0.8 nmole/mg protein (P less than 0.001). Total tissue calcium returned to normal at 60 min in viable muscle, but continued to accumulate in necrotic tissue. However, the delay in initial muscle Ca2+ influx was not associated with increased overall salvage of muscle 78 +/- 9% vs 77 +/- 8% necrosis, (P greater than 0.1). In conclusion we could not demonstrate a protective effect of reduced extracellular Ca2+ during early reperfusion, and it negated our previously demonstrated beneficial effects of free radical scavengers. It was shown however that the early ability to extrude intracellular calcium was associated with significant salvage of muscle tissue.

Animals↗
PubMed1990

The use of 3H standards in 125I autoradiography.

To avoid repeated production of 125I tissue mash standards and to decrease inter-experiment variability, a set of commercially available, high activity plastic 3H standards was calibrated for use with 125I autoradiographs. Standards with a range of 2.0-7390 microCi 3H/g plastic were used since they produced autoradiographs of suitable optical density (darkness) at exposure times of 4 to more than 72 h. Tissue mash standards at 12 concentrations of 125I were produced by homogenizing rat brains and adding 125I. These were frozen and sectioned at thicknesses ranging from 6 to 120 microns and mounted on microscope slides. Each set of tissue standards, along with slides bearing the plastic 3H standards, was opposed to film for various times. The calibration of the 3H standards was done separately for each time point and section thickness. Autoradiographs were analyzed using a computer assisted image analysis system. The standard curve generated for each set of 125I-labelled tissue standards was correlated with the 3H standards. It was found that the relationship between the 3H plastic standards and the 125I tissue mash standards was not simple and depended on exposure time, thickness of the section, as well as the concentration of radioactivity in a given standard. However, this accurate calibration of the 3H standards yields long-lived standards for 125I autoradiography useful over a wide range of radionuclide concentrations, tissue thicknesses and exposure times.

Animals↗
PubMed1990

Plasma atrial natriuretic peptide after the Fontan procedure and total cavopulmonary connexion.

Plasma atrial natriuretic peptide was measured in 10 children undergoing the Fontan procedure and 3 children undergoing total cavopulmonary connexion. There was no significant difference in pre-operative plasma levels, but post-operative levels were significantly higher 48 hours after cardiopulmonary bypass in the Fontan group. There was no significant difference in plasma arginine vasopressin levels either pre- or post-operatively. Post-operative pleural effusions occurred in only 2 of the 10 patients undergoing the Fontan procedure, but were present in all 3 of those undergoing total cavopulmonary connexion. The release of atrial natriuretic peptide is an appropriate homeostatic response to volume loading and the impairment of this response in the early post-operative period may be of clinical importance.

Arginine Vasopressin↗
PubMed1990

Petit mal epilepsy and parkinsonian tremor: hypothesis of a common pacemaker.

Rhythmic oscillation in neuronal systems may serve physiological purposes or may interfere with normal functions of the brain. In disorders of petit mal epilepsy and parkinsonian tremor, centrally and peripherally observable rhythmic patterns are due to network oscillations of thalamocortical cells. This article reviews the afferent mechanisms that might be critically involved in controlling the ionic conductances of thalamic neurons in the behaving organism. We propose that during active behavior the subcortical aminergic and cholinergic inputs to the thalamus act as anti-burst and anti-oscillation mechanisms. We suggest further that the thalamopetal GABAergic inputs (pars reticulata of substantia nigra, entopeduncular nucleus, pallidum) are burst- and oscillation-promoting systems, whose output is controlled by the striatum. Experimental or disease-related decrease of the striatal dopamine levels is hypothesized to increase the efficacy of the GABAergic burst-promoting systems resulting in rhythmic network oscillation of thalamocortical neurons during rest. The recognition of the overlapping neuronal mechanisms in petit mal epilepsy and parkinsonian tremor, and the multistage control of thalamic oscillation suggests that drugs effectively used in petit mal attacks may be effective in levodopa-refractory parkinsonian tremor, and conversely, epileptic patients may benefit from drugs acting on the extrapyramidal system.

Epilepsy, Absence↗
PubMed1990

The vasopressin response to severe birth asphyxia.

Serial measurements of urinary arginine vasopressin (AVP) were made in six severely birth asphyxiated newborn infants. In five infants serial plasma concentrations were also evaluated. There was a strong negative correlation between plasma AVP and plasma osmolality in these infants (r = -0.52, P = 0.0012). In neither the individual babies nor the group as a whole was there a significant correlation between plasma AVP and the urinary excretion of AVP even if the latter was standardised for creatinine content. Normal development at follow up was only observed in two asphyxiated infants who had consistently low urinary arginine vasopressin levels in the first days of life. Infants with consistently high urinary vasopressin concentrations either died or were severely abnormal in their subsequent development.

Apgar Score↗
PubMed1990

Technetium-99m bone scintigraphy and mandibular condylar hyperplasia.

Radionuclide skeletal scintigraphy has been successfully used in the assessment of mandibular condylar hyperplasia (condylar hyperplasia) causing mandibular asymmetry to identify the presence of continued active growth in the condylar region. This study reviews 14 cases of mandibular asymmetry and concludes that symmetrical radionuclide uptake in the condylar regions on the bone scintigram excludes a continuing asymmetrical growth focus. Unilateral increased radionuclide uptake may often indicate an abnormally active condylar growth focus but false positive results may be encountered in patients with associated temporo-mandibular joint disease.

Adult↗
PubMed1990

Selective cytotoxic effects of a ricin A chain immunotoxin made with the monoclonal antibody SWA11 recognising a human small cell lung cancer antigen.

The potential of mouse monoclonal antibodies for recognising different antigens associated with human small cell lung cancer (SCLC) to form active immunotoxins was assessed by an indirect in vitro screening assay. The screening agent used was a conjugate made by linking ricin A chain to a sheep anti-mouse IgG Fab' fragment via a disulphide bond. The monoclonal antibodies SWA11 and SWA20 both mediated the toxic effects of ricin A chain against the HC12 classic SCLC cell line in dose-dependent fashion. The SWA11 antibody was the more effective; in combination with the screening agent at a concentration of 1 x 10(-7) M, it inhibited the incorporation of [3H] leucine into HC12 cells by 94% compared with only 44% inhibition in the case of SWA20. An immunotoxin made by the direct chemical conjugation of ricin A chain to SWA11 exhibited selective toxic effects upon HC12 cells in tissue culture inhibiting the incorporation of [3H] leucine by 50% at a concentration (IC50) of 6.2 x 10(-10) M and by 98% at 1 x 10(-7) M. SWA11-ricin A chain had an IC50 of 4.4 x 10(-10) M against the NCI-H69 classic SCLC cell line but showed no cytotoxic activity against the human lung adenocarcinoma cell line NCI-H23 at a concentration of 1 x 10(-8) M.

Antibodies, Monoclonal↗