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Biomedical subjects

A Smith

Publications and source records attributed to A Smith.

At least 775 records · Page 43Linked to original sources
PubMed1993

Penetrating cardiac trauma: surgical and nursing management.

Penetrating cardiac injuries occur not only in military settings, but also in the civilian arena. This article focuses on the incidence, etiology, and pathophysiology of gunshot wounds and stabbing injuries. Diagnosis, treatment, and surgical approaches of penetrating cardiac injuries are presented. A clinical case study of a left ventricular stabbing injury is described and relevant nursing interventions and follow-up care addressed.

Adult↗
PubMed1993

Ventricular expression of atrial natriuretic peptide after orthotopic cardiac transplantation.

In order to determine if atrial natriuretic peptide is produced by the human ventricle after transplantation, specimens were obtained from 54 separate right ventricular endomyocardial biopsies from 14 transplant recipients (age range 10-19 years) and were analyzed with simultaneous plasma samples. Radioimmunoassay techniques were used to determine plasma and tissue levels of atrial natriuretic peptide in each biopsy specimen, and blot hybridizations with the atrial natriuretic peptide c deoxyribonucleic acid probe were performed once for each patient. Mean plasma levels of atrial natriuretic peptide were obtained from the right ventricle (106 +/- 12 pg/ml); there was a positive correlation with end diastolic pressure (r = 0.7, P < 0.0001). Plasma levels, however, were not significantly increased during rejection episodes. Atrial natriuretic peptide was detectable in all ventricular biopsy specimens--mean 989 +/- 164 pg/mg soluble protein. Mean tissue level during rejection episodes was 1163 +/- 17 and following treatment of rejection was 411 +/- 147--however, this difference was not significant (P = 0.55). In 6 patients biopsied within 1 month of transplantation initial myocardial levels were significantly higher than those obtained at the following biopsy (P < 0.05). Despite these initially high tissue levels no correlation was found with time posttransplantation. Ventricular tissue levels positively correlated with systolic ventricular pressure, r = 0.3, P < 0.05, but there was no significant correlation with other hemodynamic parameters. The normalized atrial natriuretic peptide messenger ribonucleic acid signal from the slot blot hybridization was 59 +/- 6 mm (peak height of signal intensity) range 20-110 mm. The expression of atrial natriuretic peptide gene was also confirmed by Northern blot analysis. The ventricular messenger ribonucleic acid signal contained a single hybridizing band of approximately 920 nucleotides. Thus, we have demonstrated that atrial natriuretic peptide production by the human ventricle is independent of innervation. The consistent atrial natriuretic peptide gene expression and detection by radioimmunoassay in apparently healthy ventricles was unexpected but may reflect the use of immunosuppressive drugs, or perhaps subclinical graft dysfunction.

Adolescent↗
PubMed1993

Analysis of bacterial phospholipid markers and plant monosaccharides during forage degradation by Ruminococcus flavefaciens and Fibrobacter succinogenes in co-culture.

Marker components of the phospholipids of Ruminococcus flavefaciens and Fibrobacter succinogenes were identified for studies on the degradation of forage by these bacteria growing in mixed culture. The principal fatty acid methyl esters and dimethyl acetals detected varied between strains and were influenced by the addition of a mixture of higher volatile fatty acids and vitamins to the medium, but these effects were small compared to the differences between the species. When two strains of R. flavefaciens were grown on a mixture of clover and ryegrass, and on barley straw in the presence or absence of two strains of F. succinogenes, the solubilization of plant material tended to be lowered by the presence of F. succinogenes. R. flavefaciens was the predominant bacterium among colonies recovered from roll tubes, and the phospholipids were primarily those of R. flavefaciens. Analysis of the culture supernatant liquids showed that F. succinogenes produced greater amounts of free and bound xylose from both clover and straw than did R. flavefaciens. With both forages, cultures containing the two species produced more soluble free arabinose, and less soluble-bound arabinose, than either species grown alone.

Animal Feed↗
PubMed1993

Characterization of an acute micromegakaryocytic leukaemia: evidence for the pathogenesis of myelofibrosis.

The current hypothesis for the pathogenesis of myelofibrosis involves the intramedullary release of growth factors from defective or abnormal megakaryocytes. We describe a case of an acute micromegakaryocytic leukaemia, in a patient with chronic myelofibrosis, that provides additional evidence for this concept. The micromegakaryocytes, which reached 223 x 10(9)/l, were characterized morphologically by both light and electron microscopy, immunocytochemically and by platelet peroxidase activity. The cells were shown to have a mature cytoplasm, containing alpha granules and the associated proteins; vWF:Ag, fibrinogen, fibronectin and protein S. DNA analysis, by both a Seescan Solitaire Plus image analysis system and flow cytometry, revealed nuclear immaturity, with 92% of cells being diploid. Serum markers of connective tissue synthesis, namely carboxy terminal peptide of procollagen I (PICP), procollagen terminal peptide III (PIIIP) and laminin all increased significantly following transformation and were associated with an increase in platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta). These observations support the current hypothesis for bone marrow fibrosis formation and provide, for the first time, a link between in vivo growth factor release, bone marrow stromal turnover and megakaryocyte mass. In addition, the release of biologically active TGF-beta may explain both the increased fibronectin and angiogenesis characteristic of myelofibrotic bone marrow.

Female↗
PubMed1993

Alternate, adjacent 2 and 3:1 meiotic segregation products from a balanced t(13;18) (q12;q11) carrier.

We present a case in which alternate, adjacent 2 and 3:1 meiotic segregations have occurred in the pregnancies of a female carrier of a balanced reciprocal translocation -46,XX,t(13;18) (q12;q11). Products of five conceptions effectively showed trisomy 18q, trisomy 18p or monosomy 18p. This is one of the rare rearrangements which can give rise to a variety of segregation modes including adjacent 2.

Chromosomes, Human, Pair 13↗
PubMed1993

Fluorescence in-situ hybridisation and molecular studies used in the characterisation of a Robertsonian translocation (13q15q) in Prader-Willi syndrome.

A patient with classical Prader-Willi syndrome was found to have a Robertsonian translocation 45,XY,t(13q15q)mat. On CBG banding, the translocation chromosome had a large centromere with one primary constriction. Using fluorescence in situ hybridisation, positive signals were obtained with chromosome 13 and chromosome 15 centromere probes, proving that the translocation was dicentric. NOR banding was negative in this chromosome, suggesting that the breakpoints were at 13p11 and 15p11. DNA studies showed that, while there was no deletion involving 15(q11-13), maternal uniparental disomy for chromosome 15 was present. We compare our findings with the five other cases of familial Robertsonian translocation PWS that have been reported.

Adult↗
PubMed1993

A comparative study of HLA-DRB1 typing by standard serology and hybridization of non-radioactive sequence-specific oligonucleotide probes to PCR-amplified DNA.

A double-blind study was carried out to evaluate the relative performance and reliability of the PCR/SSOP assay compared to conventional serological typing in identifying HLA-DR alleles. A total of 268 consecutive samples were entered into the study. In 14 (5.2%) of the cases, HLA-DR serology could not be performed due to poor cell viability, while in seven (2.6%) of the cases, PCR/SSOP typing could not be performed due to poor amplification or to contamination with exogenous DNA. Among samples that were successfully typed by both methods, serologic typing correctly identified 455/465 (97.9%) DR antigens, while PCR/SSOP correctly identified 464/465 (99.8%) DR alleles (p = 0.0117, McNemar's test). The majority of discrepancies in serologic typing resulted from a lack of discriminative alloantisera to identify DR6 or DR103. For the overall sample set (N = 268), serology provided accurate results in 244 (91.0%) cases, while PCR/SSOP provided accurate results in 260 (97.0%) cases (p = 0.0037). The results of this study demonstrate that PCR/SSOP typing for HLA-DRB1 alleles provides results that are equal to or surpass serological typing for HLA-DR antigens. In addition, the PCR/SSOP approach offers the advantages of better reagent availability, lower cost, more rapid turn-around time, and greater accuracy, all of which would warrant its use as an HLA typing method of choice.

Alleles↗
PubMed1993

Spectral analyses of activity of laryngeal and orofacial muscles in stutterers.

Previous studies have reported that the disfluent speech of stutterers is often associated with tremor in orofacial muscle systems. In the present report, spectral analyses of the amplitude envelopes of laryngeal and orofacial EMGs revealed that tremor-like oscillations of EMG activity, similar to those observed in orofacial muscles, are also present in laryngeal muscles during stuttered speech. Furthermore, tremor-like oscillations in orofacial and laryngeal muscles appear to be entrained in some subjects. It is speculated that autonomic systems may provide a mechanism whereby oscillations in different muscle groups may become entrained.

Adult↗
PubMed1993

Presence of a nuclear lamina in pachytene spermatocytes of the rat.

The nuclear lamina is a karyoskeletal structure located at the periphery of cell nuclei. The major constituents are the lamins, which belong to the evolutionarily conserved multigene family of intermediate filament proteins. Lamins show a conspicuous cell type-specific expression pattern. The majority of somatic cells of vertebrates express A-type (lamins A and C) as well as B-type (lamins B1 and B2) lamins. Although a lamina structure has been demonstrated to be a ubiquitous component of somatic nuclei its existence in certain meiotic stages during spermatogenesis has been a matter of debate. In this study, we investigated the expression of lamins in rat spermatogenic cells using immunological and protein-chemical methods. We report on the presence of a nuclear lamina structure in rat pachytene spermatocytes. With the aid of a novel broad-reacting lamin antibody we have demonstrated the expression of a protein that is closely related, if not identical, to lamin B1.

Animals↗
PubMed1993

Development of the peptidergic innervation of human heart.

The aim of the present investigation was to study the developing peptidergic innervation of the human fetal heart of 7-24 wk gestational age. An immunohistochemical approach was adopted and the total innervation visualised with antisera to general neuronal and Schwann cell markers, while the onset and development of specific neuropeptide-containing subpopulations were investigated using antisera to neuropeptide Y (NPY), somatostatin, vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and substance P (SP). Cardiac ganglia and nerves were demonstrated from 7 wk of gestation whereas peptide-immunoreactive nerves were not observed until the 10th week of gestation. NPY-immunoreactive nerve fibres constituted the major subpopulation of peptide-containing nerves identified in the fetal heart, exhibiting a descending atrial to ventricular density gradient, and were first identified during the 10th wk of gestation. Somatostatin- and VIP-immunoreactive nerves appeared at 10-12 wk of gestation and were mainly distributed in the atria. Somatostatin immunoreactivity was localised to cell bodies in cardiac ganglia, as well as to nerve fibres, indicating an intrinsic origin for this nerve subpopulation. Conversely, the other peptide-containing nerves appear to be of extrinsic origin, including those immunoreactive for VIP. Intracardiac neurons exhibit a transient expression of tyrosine hydroxylase immunoreactivity. Putative sympathetic nerve fibres, displaying tyrosine hydroxylase and NPY immunoreactivity, were demonstrated before the adrenergic innervation has previously been shown to be present by formaldehyde-induced fluorescence staining of catecholamines. The onset of the CGRP- and SP-immunoreactive innervation, at 18-24 wk of gestation, followed the appearance of other peptide-containing nerves, suggesting that the sensory, afferent innervation occurs later than the autonomic. The differential appearance and distribution of peptide-containing nerve subpopulations indicate that there is a chronological order to the development of the autonomic and sensory components of human cardiac innervation.

Calcitonin Gene-Related Peptide↗
PubMed1993

Hypertension education: patient knowledge and satisfaction.

Education of patients with various diseases, including hypertension, usually occurs at an individual level through a patient's doctor as well as via various media campaigns which also includes general community education. To evaluate their effects, the knowledge of 84 patients with hypertension was evaluated by a simple 13 question true/false questionnaire and the results compared with 58 normotensive subjects matched for sex, age and educational status. A significant difference in knowledge about hypertension could not be elicited between the two groups even when compared for sex or educational status. However, subjects > 70 years of age (hypertensives and controls) demonstrated a lower level of knowledge (P < 0.05). Further questioning of the hypertensive group elicited a high level of satisfaction with their doctor's educational skills (68%) and 57% were satisfied with their own knowledge. Nevertheless, 70% requested more information about their disease. These results suggest a reasonable level of knowledge within the general community presumably reflecting community education programmes. While hypertensive patients were not more knowledgeable under the test conditions, they were reasonably satisfied with their knowledge which they stated came primarily from their doctor. Nevertheless, these findings question the effectiveness of some current patient education initiatives.

Female↗
PubMed1992

Detection in life of confirmed Alzheimer's disease using a simple measurement of medial temporal lobe atrophy by computed tomography.

The medial temporal lobe of the brain is important for normal cognitive function, notably for memory, and is the region with the most extensive pathological change in Alzheimer's disease (AD). We wanted to find out if atrophy of the medial temporal lobe could be detected in life in patients in whom a diagnosis of AD was subsequently established histopathologically. The minimum width of the medial temporal lobe, measured by temporal-lobe-oriented computed tomography (CT) about one year before death, in 44 patients with a histopathological diagnosis of AD (cases) was nearly half (0.56 of the median) that in 75 controls of the same age with no clinical evidence of dementia (95% confidence interval 0.51-0.61). There was little overlap between the distributions of measurements in cases and controls. A cut-off (< 0.79 MoM) selected to yield a 5% false-positive rate gave an expected detection rate of 92%. A cut-off selected to yield a false-positive rate of 1% (< 0.70 MoM) yielded a 79% detection rate. 20 of the 44 patients with histopathologically diagnosed AD had been scanned more than once before death, and the test (cut-off < 0.79 MoM) was positive in all 20 more than a year before and in 9/10 more than 2 years before death. In 10 subjects with dementia but with histopathology excluding AD, the mean minimum width of the medial temporal lobe was significantly greater than that in the cases with AD, but was not significantly different from that in controls. Medial temporal lobe CT is a non-invasive, rapid, simple and effective test for AD which could have immediate application firstly in improving the accuracy of prevalence and incidence studies and, secondly, for the identification of groups of high-risk patients in the evaluation of novel treatments for AD. In the future, it could be applied as a screening test.

Aged↗