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Biomedical subjects

A B Taylor

Publications and source records attributed to A B Taylor.

15 recordsLinked to original sources
PubMed1991

Prognostic features of children with idiopathic dilated cardiomyopathy.

The presenting features and long-term outcome of 39 children (median age 6.5 months, range 1 day to 16 years) with idiopathic dilated cardiomyopathy (IDC) were reviewed to help determine the appropriate management of these patients. Four outcome groups were identified: those who died, improved, had IDC resolved or received transplants. Presenting clinical features of age, sex, race, congestive heart failure, cardiomegaly, and degree of systolic ventricular dysfunction did not predict final outcome. Left ventricular hypertrophy on the electrocardiogram was seen significantly more often in children who improved than in those who died or in whom IDC resolved (p = 0.002). A rhythm disturbance was also seen more often in those who died than in those who survived (p = 0.025). Of 36 patients treated medically, 12 (33%) died, 15 (42%) improved and 9 (25%) resolved. Eighteen of 26 (69%) patients presenting at age less than or equal to 2 years survived, whereas 6 of 10 patients greater than 2 years survived. There were no differences based on age at presentation, in the time to death or time of follow-up. Three patients received orthotopic heart transplants, 1 of whom died from graft failure. Thus, no clinical feature including age at presentation consistently predicts ultimate outcome in children with IDC.

Arrhythmias, Cardiac↗
PubMed1991

Doppler echocardiographic evaluation of streptokinase lysis of thrombosed right-sided St. Jude Medical valves in patients with congenital heart defects.

Four episodes of St. Jude Medical prosthesis leaflet thrombosis were serially evaluated by two-dimensional and Doppler echocardiography during treatment with streptokinase. Three patients aged 4, 11, and 24 years with congenital heart disease had St. Jude Medical valves in pulmonary positions (two cases) for tetralogy of Fallot and in the tricuspid position (one case). The duration of thrombosis was not known in any patient. Leaflet immobility and its resolution were demonstrated by echocardiography and were confirmed fluoroscopically. Continuous wave Doppler echocardiography showed abnormal stenotic gradients in thrombosed valves that were reduced after thrombolysis. These studies demonstrate the utility of two-dimensional and Doppler echocardiography in serial evaluation of prosthetic pulmonary and tricuspid valve thrombosis during thrombolysis.

Adult↗
PubMed1991

Effects of perinatal alcohol exposure and dietary calcium supplements on skeletal and dental growth in rats.

Osteoporosis, hypocalcemia and skeletal size reduction are all common correlates of perinatal alcohol exposure. The present study assesses the effects of dietary calcium supplements on reversing perinatal alcohol-induced osteopenia. One hundred and twenty-nine offspring from Fisher 344 rats received 14% v/v alcohol in tap water from conception to weaning or 3 months of age followed by dietary calcium supplements (230 mg/kg/day) to 6 months of age. Significant group effects (p less than 0.001) were noted for all 12 dental and skeletal dimensions measured. Results suggest that calcium therapy following perinatal alcohol exposure may ameliorate alcohol-induced osteopenia in exposed offspring.

Alcohol Drinking↗
PubMed1990

Real-time, automated, interactive cardiac electrophysiology testing.

We describe a new automated interactive system that performs all of the functions required for complete evaluation of the intracardiac conduction system, for inducing, terminating and analyzing tachydysrhythmias, and for locating and characterizing accessory atrioventricular (AV) connections and ectopic foci. In the first year of operation, the system was used to conduct 210 electrophysiology studies. These ranged from simple postoperative evaluation of the conduction system to complete tachycardia studies during pharmacological manipulation of the patient. Patient age at time of catheterization ranged from 6 days to 70 years, with median age of 8 years and 7 months. Advantages accruing from automated electrophysiology testing with this system included great precision and accuracy of timing measurements, flexibility in designing and implementing pacing protocols, and rapid management of induced or spontaneous dysrhythmias. Significant savings of time and labor were achieved by computer generation of reports and graphs as opposed to manual data extraction and plotting. The single most significant advantage is the ability of the system to provide information on a real-time basis, permitting the electrophysiologist to analyze, modify, extend or curtail the procedure.

Adolescent↗
PubMed1989

Advances in the treatment of supraventricular tachycardia.

Patients with supraventricular tachycardia should be able to lead a perfectly normal life without significant treatment related side effects. Many of these patients have normal hearts and no other significant medical problems. Using the techniques described above, no patient should have significant symptoms from SVT.

Anti-Arrhythmia Agents↗
PubMed1979

Nucleolar reorganization in liver cells of the aging rat.

The nucleoli of rat liver cells duplicate in great detail the life-long series of reorganizational changes encountered in kidney and intestinal epithelial cells. The ultrastructural components of the large, loosely organized polymorphous nucleoli, which are dominant in the rapidly multiplying stem cells of embryos, are readily accessible for chemical activities. Smaller, more compact amphinucleoli are dominant in more mature cells, which were characterized by Smetana ('70) as "idling" cells, showing slowly continuing ribosome formation and RNP synthesis. In older cells bipartite nucleoli become dominant and are reorganized in increasing numbers from the younger amphinucleoli. These, however, are not replaced in equal numbers from the shrinking pool of polymorphs of young cells which have greatly reduced mitotic potential. Paralleling the shifts in dominant nucleolar types, the high level of protein synthesis declines in older cells not only in the quantity of proteins synthesized but also in kinds of enzymes produced. These fail to meet the structural and functional requirements of aging cells leading ultimately to the onset of age-related degenerative changes. Again it is noted that separation of the karyosomal DNA from the plasmosomal RNA-protein complex of the nucleolus may lead to possible breakdown of the DNA-dependent RNA-protein transcription system ultimately bringing protein synthesis to a very low level in the senescent animal.

Aging↗
PubMed1979

Blood pressure, heart rate, pressure-rate product and electrocardiographic changes in healthy children during treadmill exercise.

Heart rate, systolic and diastolic blood pressure, rate-pressure product and electrocardiographic changes were measured in 288 healthy children during treadmill exercise. A constant speed (3.5 miles/hour) protocol was used to facilitate the measurements of physiologic data during exercise. Because responses to exercise vary with size, the children were separated into four groups according to body surface area. Comparisons were also made between male and female and between black and white children. The values for heart rate and systolic pressure showed excellent reproducibility in repeated tests. These data establish for clinical use reference values for children during treadmill exercise.

Adolescent↗
PubMed1979

Aortoplasty compared with resection for coarctation of the aorta in young children.

We repaired coarctation of the aorta in a group of 18 children less than 3 years old, using either resection with end-to-end anastomosis (8 patients, Group 1) or patch graft aortoplasty (10 patients, Group 2). The two groups were similar preoperatively in age, pressure difference between proximal and distal aorta (delta PA0), and severity of aortic arch hypoplasia. Three patients, all less than 2 months old, died early postoperatively. Among the survivors, the right brachial artery systolic pressure was significantly higher in Group 1 (133.1 +/- 7.0 mm Hg) (mean +/- standard error of the mean) than in Group 2 (102.5 +/- 7.2 mm Hg) (p less than 0.05). The delta PA0 was significantly higher in Group 1 (33.0 +/- 7.5 mm Hg) than in Group 2 (5.1 +/- 2.3 mm Hg) (p less than 0.01). Three patients in Group 1 required reoperation and were treated with patch graft aortoplasty; relief of delta PO0 was complete in 2. Patch graft aortoplasty is more effective than resection in reducing proximal aortic systolic pressure and in relieving delta PA0 in infants and small children with coarctation of the aorta.

Aorta, Thoracic↗
PubMed1979

Cardiac valve replacement in children: comparison of tissue with mechanical prostheses.

Replacement of cardiac valves in children has been associated with high rates of mortality and morbidity in the past. We have compared 24 children from 2 to 18 years of age who have received mechanical valves with 24 children who have received porcine valves. The groups were similar except that (1) there were more mitral operations in the mechanical valve group and more aortic operations in the porcine valve group; (2) more porcine than mechanical valves were implanted in recent years; and (3) the porcine valve group comprised more young patients under 8 years and required more complex operations. Early and late mortality rates were higher in the mechanical than in the porcine valve group. Major late complications were seen in 50 percent of the mechanical valve group and 13 percent of the porcine group. Implantation of an adult-sized aortic valve was made possible in all patients by the use of aortic augmentation annuloplasty. Higher operative mortality rates in the mechanical valve group may have been related more to technique of myocardial preservation during operation than to type of valve. Although differing rates of late morbidity and mortality may also have been related to myocardial preservation and other technical factors, the type of valve used seemed to be an important determinant of the better results in the porcine group. Despite unknown durability of the porcine valve, our data suggest that the safest prosthetic valve to use in children at this time is the glutaraldehyde-fixed porcine prosthesis.

Adolescent↗
PubMed1977

Lumbar epidural analgesia in labour: a 24-hour service provided by obstetricians.

Of 309 consecutive cases of epidural analgesia provided by obstetricians, 250 set up by junior obstetric staff. Midwives managed the epidural analgesia and gave the top-up doses as part of their traditional role in providing pain relief in labour. This practice was thought to be influential in producing a high sponn epidural analgesic service can safely be provided by obstetricians in a small maternity hospital.

Anesthesia, Epidural↗
PubMed1977

Electron microscopy of the connective tissues between longitudinal and circular muscle of small intestine of cat.

Electrotonic spread of applied potentials was observed between longitudinal and circular muscle layers of the small intestine with no rectification. Nexal junctions were demonstrated between muscle fibers of each layer. Connective tissue cells bridged between the two muscle layers. These showed structural characteristics of fibrocytes and of interstitial cells. Some nexuses were seen between connective tissue cells and between these cells and muscle fibers of each layer but in most junctions the membranes were 10-18 nm apart. Since connective tissue can serve for electrical conduction between cultured heart cells and since electrical properties of intestinal muscle permit transmission with low degrees of coupling, it is suggested that interstitial cells and fibrocytes may electrically couple longitudinal and circular muscle layers of cat intestine.

Action Potentials↗
PubMed1977

Nucleolar reorganization in cells of the kidney of the rat and its relation to aging.

A process of nucleolar reorganization apparently identical to that encountered in intestinal epithelial cells (Adamstone and Taylor, '72) develops in kidney cells of aging rats. The polymorphic nucleoli of young tubule cells soon change to amphinucloeli and, while terminal nucleolar reorganization is delayed in cells of collecting tubules, in the nephrons nucleoli soon begin to undergo terminal reorganization becoming bipartite structures with separate plasmosomes and karyosomes. This suggests disruption of the DNA-dependent RNA protein transcription system and failure to maintain the flow of messenger RNA into the cytoplasm. Old cells are not discarded immediately from the kidney tubules and they retain much rough endoplasmic reticulum, numerous ribosomes and polysomes and large plasmosomes. Thus a high RNA concentration is known to develop in old kidney tissue while protein synthesis is also known to be low (Kanungo et al., '70; Buetow and Ghandi, '73). Nucleolar counts show gradual increase in bipartite nucleoli at the expense of amphinucleoli and in the senescent kidney bipartite nucleoli predominate. It is suggested that nucleolar reorganization, with final separation of plasmosomes and karyosomes, includes the process of nucleolar segregation and is triggered by some innate nucleolar mechanism in response to encoded genetic information stored in the nucleolus during nucleogenesis. At this time both DNA and RNA are incorporated into the developing nucleolus. It is also to be noted that two shifts in nucleolar dominance occur with advancing age. These may be fundamental to the process of aging and to the onset of senescence. Furthermore, the changes in dominant nucleolar types are the direct result of the process of nucleolar reorganization.

Aging↗
PubMed1977

Fetal heart rate monitoring during caesarean section.

The fetal heart rate was monitored during 30 deliveries by Caesarean section. General anaesthesia, but not epidural analgesia, caused a loss of beat-to-beat variation, but appeared to have no other adverse effects on fetal heart rate. The loss of beat-to-beat variation occurred after intravenous thiopentone and was most marked when atropine was used as premedication.

Anesthesia, Epidural↗
PubMedDate not supplied

Cesarean section with regional anesthesia using an extendable epidural block.

Epidural analgesia was used for 86 deliveries by cesarean section. The placement of a catheter in the epidural space allowed adjustment of the extent of the block so that supplementary analgesia was required in only six patients. Continuous fetal heart rate monitoring was of practical clinical value, especially in treating maternal hypotension. Symptomatic hypotension was avoided or corrected by the intravenous infusion of Hartmann's solution and by the use of a lateral tilt of the operating table. Eleven patients had a blood pressure of less than 100 mm Hg, and in three of these, there was an adverse effect on the fetal heart trace.

Anesthesia, Conduction↗