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Biomedical subjects

A Smith

Publications and source records attributed to A Smith.

At least 1,081 records · Page 60Linked to original sources
PubMed1986

Interactions between speech and finger movements: an exploration on the dynamic pattern perspective.

Under the dynamic perspective for motor control, movement is viewed as an "emergent" property, arising from cooperative relationships among limit-cycle oscillators. This is in contrast to more traditional approaches to motor control in which a central representation of movement is usually assumed to exist. The assertion that coordination of movement arises from interactions between oscillatory processes leads to some unexpected predictions. In particular, interactions between frequency and amplitude of simultaneously performed speech and manual tasks are predicted, because the organism "parameterizes" all ongoing oscillatory processes as a "total unit." Using quantitative analyses, we have demonstrated that interactions between speaking and finger tapping do occur in both the amplitude and frequency domains. Such interactions, however, do not appear to be as simple as those predicted by proponents of the dynamic pattern perspective.

Female↗
PubMed1986

Seasonal changes in testicular structure and function in the blue fox (Alopex lagopus), as quantified by morphometric analysis and measurement of adenylate cyclase activity.

The volume of the blue fox testis showed 5-fold changes during the year, associated with considerable changes in cellular composition. The seminiferous epithelium was maximally regressed in August, when 94% of tubules contained only spermatogonia. By late October, approximately 6 months before the mating season, 40% of tubules contained primary spermatocytes. From the middle of January until the end of April all tubules contained spermatids or more advanced haploid cells. Tubular diameter increased by 73% during testicular re-development, and epithelial height increased 3-fold. Regression to the basal state occurred during May to July. The volume densities of the seminiferous epithelium and of interstitial tissue remained approximately constant throughout the year. Soluble Mn2+-dependent adenylate cyclase activity showed seasonal variations that paralleled those of the haploid germ cell population and testicular volume, whereas somatic cell adenylate cyclase activity was relatively constant.

Adenylyl Cyclases↗
PubMed1986

Pulmonary absorption of carboxyfluorescein in the rat.

The pulmonary absorption of the fluorescent marker 6-carboxyfluorescein (CF) has been characterized. CF was administered intratracheally (i.t.) as a fluid instillate to pentobarbitone-anaesthetized rats at doses of 0.5 and 2 mg kg-1. The absorption was characterized by both model-independent and model-dependent pharmacokinetic analyses of blood concentration data with reference to previous intravenous (i.v.) studies. The mean fraction available (F) of CF was 90 and 112% with a mean absorption time of 107 and 109 min for the lower and higher doses, respectively. The terminal half-life for the i.t. administered CF (73 and 83 min for the 0.5 and 2 mg kg-1 doses, respectively) was significantly longer (P less than 0.001) than after i.v. dosing (18 min). This indicates a slow pulmonary absorption of CF. Blood concentration-time profiles could not be adequately described by models involving a simple first-order absorption process; a model incorporating two simultaneous first-order inputs gave a much better description, its absorption rate constants differing by almost two orders of magnitude.

Absorption↗
PubMed1986

Acute effects of meals, noise and nightwork.

An experimental study of the acute effects of meals, noise and nightwork showed that there was a post-meal impairment in detection of targets in a cognitive vigilance task. This was found both during the day and at night, although certain features of the results suggested that the day and night effects were not equivalent. Noise increased the number of false alarms but reduced the post-meal impairment in hit rate. Subjects with low levels of trait or state anxiety showed the greatest post-lunch impairments in performance, but this effect was reduced when the meal was eaten at night.

Achievement↗
PubMed1986

Immunocytochemical localization of carbonic anhydrase isozymes I, II, and III in rat skeletal muscle.

Specific antisera were raised against the three carbonic anhydrase (CA) isozymes, CAI, CAII, and CAIII, and were used to determine the fiber distribution of these isozymes in skeletal muscle. Fiber types were determined by ATPase staining, and the CA isozymes were detected using a peroxidase-anti-peroxidase (PAP) technique. All three isozymes were present in type I fibers; CAII and CAIII were exclusive to these fibers, and CAI were also present in some small type 2A fibers.

Actomyosin↗
PubMed1986

Tomographic imaging of the human thyroid using 124I.

After receiving between 100 and 300 mu Ci of the positron-emitting radioisotope 124I (half-life, 4.2 days), 64 patients with a variety of thyroid disorders were imaged with a high resolution positron camera. A 3-dimensional image of the distribution of radioiodine uptake within the thyroid was obtained from a single 10- to 15-min scan. This image may be viewed as a sequence of 2-mm thick transverse, sagittal, or frontal sections or as a 3-dimensional shaded surface. The functional volume of the thyroid may be estimated by counting the volume elements (voxels) inside the thyroid surface. The precision of the estimate varied from 6-15%, depending on the size and clinical status of the thyroid. The volume estimation procedure was validated with phantoms and with the thyroids of patients who subsequently underwent partial thyroidectomy. This 3-dimensional imaging technique may be useful for diagnosis and management of thyroid diseases.

Adenoma↗
PubMed1986

Monoclonal antibodies binding to the human neutrophil C3bi receptor have disparate functional effects.

Three monoclonal antibodies (MAb)--OKMI, 7C3, and 60.3--immunoprecipitated a common 170-kd neutrophil membrane antigen closely associated with, or identical to, the C3bi receptor (CR3). Despite binding to a common receptor, these antibodies displayed marked differences in their effects on C3bi-mediated neutrophil function as assessed by the binding and ingestion of opsonized zymosan and the subsequent triggering of the respiratory burst. Antibody 7C3 caused a time-dependent, irreversible inhibition of the neutrophil oxidative response to opsonized zymosan that correlated with capping of the bound antibody. In contrast, antibody 60.3 caused an immediate inhibition of the neutrophil oxidative response to opsonized zymosan that required the continuous presence of exogenous antibody to achieve the maximal inhibitory effect. Antibody OKMI demonstrated minimal inhibition of O2- release. Despite their functional differences, binding of either 7C3 or 60.3 led to up-regulation of new antigen, presumably from intracellular sites as previously described using OKMI. Crossed immunoprecipitations of radiolabeled neutrophil lysates indicated that each MAb bound to different antigens near or within the CR3 complex. Thus three MAb binding to the neutrophil CR3 receptor each caused receptor up-regulation but had markedly different functional effects on the cell.

Antibodies, Monoclonal↗
PubMed1986

Architecture of the ventricular mass and atrioventricular valves in complete transposition with intact septum compared with the normal: I. The left ventricle, mitral valve, and interventricular septum.

Venous correction for complete transposition with intact ventricular septum remains the preferred surgical option in most centers (Mustard or Senning procedures). The long-term function of the morphologically right ventricle and tricuspid valve, which continue to sustain the systemic circulation thereafter, remains a matter of concern. Some centers have been performing arterial redirection ("arterial switch") as the surgical treatment of transposition. Consequently, the status of the left ventricle and mitral valve is of equal interest. Yet, detailed morphological studies of the ventricles, atrioventricular valves, and their tension apparatus in "simple" complete transposition are lacking. We have examined the morphology of the left ventricle and the spatial relationships of the component parts of the interventricular septum (part I) as well as the morphology of the right ventricle and the tricuspid valve (part II). A total of 77 specimens with complete transposition and intact ventricular septum were examined and compared with 50 normal hearts. Consistent deformities were noted in relation to the orientation of the ventricular septum. The ratios of ventricular outlet to the inlet lengths were increased in both ventricles and the posterior arterial valve was abnormally related to the atrioventricular valves. These anomalies are similar in some respects to those found in atrioventricular septal defects. Their significance in relation to long-term function remains unclear.

Child, Preschool↗
PubMed1986

Xp21/autosome translocations. Case report and risk for Duchenne muscular dystrophy.

An isolated case of Duchenne muscular dystrophy in a 15-year-old retarded girl with a de novo t(X;2) (p21.2;q37) translocation is described. Her clinical history is presented, with particular emphasis on CK level determinations made at several different times during her development. The similarities between this patient and previously reported females with Duchenne muscular dystrophy are discussed with reference to de novo translocations with a breakpoint at Xp21 and the risk of DMD in such females.

Adolescent↗
PubMed1986

Architecture of the ventricular mass and atrioventricular valves in complete transposition with intact septum compared with the normal: II. The right ventricle and tricuspid valve.

After the Mustard or Senning procedure for surgical correction of complete transposition of the great arteries, the right ventricle and tricuspid valve have to support the systemic circulation for life. Consequently their function is of prime importance. In this (second) part, the detailed anatomy of the right ventricles and tricuspid valves is described in the same series of 50 normal hearts and a series of 77 with complete transposition and intact septum. 21% of the transposition specimens showed significant abnormalities of the tricuspid valve. Consistent deformities were observed in the structure of the trabecula septomarginalis and the membranous septum. The ratios of ventricular outlet to inlet lengths were increased.

Aorta↗
PubMed1985

Proteolysis of histidine-rich glycoprotein in plasma and in patients undergoing thrombolytic therapy.

Plasmin and kallikrein but not thrombin cleave purified histidine-rich glycoprotein (HRG), and heparin binding inhibits the proteolysis of HRG. To assess the proteolysis of HRG in plasma, immunoaffinity chromatography was used to isolate HRG from human plasma samples and the extent of protein cleavage was determined after electrophoresis under reduced, denaturing conditions. In blood drawn into streptokinase or into urokinase, HRG (78 kDa) was degraded producing peptides ranging in apparent molecular weight from 67 to 9 kDa. In patients undergoing thrombolytic therapy almost no intact HRG remains after 30 minutes, but the levels of circulating HRG are unchanged, indicating that cleaved HRG is not quickly or extensively removed from the circulation.

Blood Proteins↗
PubMed1985

Acute encephalopathy coincident with seroconversion for anti-HTLV-III.

Acute encephalopathy was associated with the appearance of antibodies to human T-lymphotropic virus (HTLV-III) in two patients. A third patient showed seroconversion for anti-HTLV-III, but the temporal association was not established so precisely. The illness was characterised by a prodromal period of up to 2 weeks, characterised by pyrexia, general malaise, and changes of mood. The encephalopathy culminated in epileptiform seizures in two of the patients. Electroencephalographic changes were compatible with viral encephalitis, and cerebrospinal-fluid pleocytosis was minimal. Neurological signs and symptoms resolved quickly in all patients, and no residual central-nervous-system sequelae were apparent.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Intracellular distribution of haem after uptake by different receptors. Haem-haemopexin and haem-asialo-haemopexin.

How the interaction of haemopexin with two different receptors affects its subsequent metabolism and 'intracellular' haem transport was examined by using mesohaem-haemopexin and mesohaem-asialo-haemopexin. The physical properties of the two haem proteins, including their absorption and c.d. spectra, are similar. Binding studies in vitro showed that haem-asialo-haemopexin interacts with both the haemopexin-specific and galactose-specific receptors on liver plasma membranes, but that haem-haemopexin interacts only with the haemopexin receptor. In vivo haem-asialo-haemopexin rapidly interacts with the liver via the galactose-specific receptor, since the protein is extensively catabolized and uptake is blocked by asialofetuin. Haem iron from haem-asialo-haemopexin is not accumulated in the liver to the same extent as from intact haem-haemopexin, and the native sialylated protein is not proteolysed. Moreover, after fractionation of homogenized liver by using colloidal-silica gradients, liver-associated haem-haemopexin and haem-asialo-haemopexin produced distinctly different patterns for both protein and ligand, consistent with their uptake by two distinct receptors. These results demonstrate that the interaction of haemopexin with different receptors influences its subsequent metabolic fate and that haem iron from haem-haemopexin is efficiently conserved only if it enters the liver cell via the specific haemopexin receptor.

Animals↗