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D Hayes

Publications and source records attributed to D Hayes.

At least 19 recordsLinked to original sources

Feasibility of using intracardiac impedance measurements for capture detection.

Energy consumption and longevity of modern pacemakers are determined by the controlling electronic circuitry and by the stimulation energy. While with technological progress the electronics' energy consumption has been reduced significantly, clinical practice shows that many cardiac pacemakers are programmed to suboptimal settings with regard to minimization of pacing energy consumption. Several methods for optimizing pacemaker output settings have been proposed in the past. The most promising concept is an output parameter optimizing pacemaker with automatic capture detection. We examined whether it is possible to distinguish between effective and ineffective pacemaker stimulus capture by analyzing high pass filtered intracardiac impedance signals that are derived from standard bipolar pacing leads. In one series of 11 patients undergoing replacement or implantation of chronic bipolar pacemakers, four patients during electrophysiology studies, and eight volunteers undergoing invasive electrophysiology trials, we examined intracardiac impedance signals obtained with various stimulation rates and output parameter settings. Additionally we analyzed a series of five patients with implanted pacemakers that can measure and telemeter intracardiac impedance signals. Several evaluation concepts have been analyzed regarding their ability to discriminate between effective and ineffective stimuli. We developed an adequate algorithm that detects capture or loss of capture at different output parameter settings based on intracardiac impedance analysis. The sensitivity is 98.5% and specificity is 91% to loss of capture for the currently investigated algorithm and this can be used to determine the optimal setting of pulse width and amplitude with regard to energy consumption. This concept is currently under realization in the external programmer and in the future an implementation of these algorithms within the pacemaker itself is intended.

Algorithms

Salvage of hemodialysis access in infected arteriovenous fistulas.

Infection combined with additional complications of arteriovenous fistulas is a serious threat to access in patients with upper-extremity polytef (polytetrafluoroethylene) grafts. We present three cases of infected access grafts that were treated with systemic antibiotics, excision of the grafts, and primary anastomosis of the arterialized vein to artery for access salvage. The new arteriovenous fistulas were used immediately, preventing interruptions in hemodialysis regimens. This technique of immediate reconstruction allows the surgeon to utilize the arterialized outflow vein and save other sites of access for future use.

Aged

Cosmetic results after surgery, chemotherapy, and radiation therapy for early breast cancer.

Adjuvant chemotherapy (CT) is increasingly being used in conjunction with radiation therapy (RT) in the treatment of early stage breast cancer. To assess the effect of CT on the cosmetic outcome of the irradiated breast, we retrospectively reviewed the cosmetic results of patients who received either cyclophosphamide-methotrexate-fluorouracil (CMF) or doxorubicin-based chemotherapy in conjunction with breast irradiation between 1968 and 1985. The overall cosmetic results were evaluated by the physician as "excellent," "good," "fair," or "poor" using a standardized scale. The CT group consisted of 170 patients treated with CT and RT administered either concurrently or sequentially (CT before RT, after RT, or both) with a minimum of 24 months of cosmetic follow-up. These were compared to an RT alone control group of 170 patients who did not receive CT and were matched by tumor size, radiation technique, and year of treatment. At 36 months, the cosmetic scores for the CT group compared to RT alone were 47% versus 71% excellent (p less than 0.01), 36% versus 19% good, and 17% versus 9% fair or poor. For the 50 patients treated with concurrent CMF and RT, the scores were 31% excellent, 45% good, and 24% fair/poor, whereas for the 118 patients treated with sequential RT and CT they were 54%, 31%, and 14%, respectively. There was no difference between those patients who received sequential CMF and those treated with doxorubicin. We conclude that adjuvant chemotherapy adversely affects the cosmetic outcome of breast irradiation, but that this effect is not clinically significant unless CMF is administered concurrently with RT. Patients treated with either sequential CMF or doxorubicin-based CT had only a slight decrement in their cosmetic result compared to patients treated without CT.

Antineoplastic Combined Chemotherapy Protocols

Pseudosarcomatous lesions of the urinary bladder.

The clinical, microscopical, immunocytochemical and ultrastructural features of five cases of benign mesenchymal proliferative lesions of the urinary bladder, mimicking sarcoma, are presented. Four of the five patients are alive and disease-free following diagnosis, an interval ranging from 9 months to 9 years, mean 4 years. A fifth patient, who had a pseudosarcomatous stromal response adjacent to a urinary transitional cell carcinoma, now has invasive transitional cell carcinoma. The lesions revealed a striking microscopical, immunocytochemical and ultrastructural similarity to nodular fasciitis, suggesting the lesions represented a bizarre mesenchymal proliferative response to inflammation.

Adult

Separation of rat pituitary secretory granules by continuous flow electrophoresis.

The separation of growth hormone-containing cytoplasmic secretory granules from the rat pituitary gland by continuous flow electrophoresis is described. The results are consistent with the hypothesis that granule subpopulations can be separated due to differences in surface charge; these, in turn, may be related to the oligomeric state of the hormone.

Animals

Combined epidural and general anesthesia for abdominal aortic surgery.

The hypothesis that combined epidural and light general anesthesia for infrarenal abdominal aortic surgery is associated with a more stable intraoperative course and less postoperative morbidity than general anesthesia alone was tested. The authors compared intraoperative hemodynamic variables and postoperative morbidity between a group with combined epidural and general anesthesia (n = 30) and a group with general anesthesia (n = 19). Patients who had combined epidural and general anesthesia were given epidural bupivacaine intraoperatively and epidural morphine postoperatively. After cross-clamping of the aorta, cardiac index and pulmonary capillary wedge pressure did not change in the group with combined epidural and general anesthesia, whereas cardiac index decreased (mean change, 0.30 L/min/m2; P = 0.0006) and pulmonary capillary wedge pressure increased (mean change, 1 mm Hg; P = 0.007) in the group with general anesthesia. After unclamping, cardiac index increased in both groups (mean change, 0.26 L/min/m2, P = 0.002, and 0.30 L/min/m2, P = 0.001, respectively). Postoperatively, the necessity for ventilatory support and the incidence of respiratory failure were lower in the combined epidural and general anesthesia group than in the general anesthesia group (P = 0.0002 and P = 0.018, respectively). In addition, vasodilator therapy was required less frequently in the group with combined epidural and general anesthesia (P = 0.002). Duration of intensive care unit stay was shorter in the combined epidural and general anesthesia group (2.7 days v 3.8 days, P = 0.003). These data indicate that for infrarenal abdominal aortic surgery, combined epidural and general anesthesia is associated with more stable intraoperative hemodynamics and significantly less postoperative morbidity than general anesthesia alone.

Adult

An investigation of vanishing bone disease.

Vanishing bone disease is a rare condition producing local deformity and instability. Fibrovascular tissue replaces bone completely but the mechanism of bone destruction and resorption is unknown and there is controversy regarding the presence or absence of osteoclasts in the disease. Radiography, clinical chemistry, light microscopy, transmission electron microscopy (TEM) and cytochemistry were used to investigate the condition of a young woman presenting early in the disease process. We detected atypical ultrastructure in osteoblasts and endothelial cells. The rare osteoclasts, numerous mononuclear phagocytes and vascular endothelium found in the condition reacted positively for the enzyme acid phosphatase. Aggressive local excision of diseased tissue and insertion of a free vascularized bone graft at an advanced stage of the disease, accompanied by subsequent radiotherapy for residual disease only were successful in rehabilitating the affected forearm and hand.

Adult

Tartrate resistant acid phosphatase positive splenic lymphoma: a relatively benign condition occurring in a time-space cluster?

Conventional light and electron microscopic studies, together with cytochemical and immunocytochemical staining procedures, were carried out to ascertain whether the lymphomata of four elderly female patients living within 10 kilometers of each other, who presented within a short space of time with massive splenomegaly and varying cytopenia, belonged to any particular subgroup of lymphoma. In each case the lymphoma had a diffuse pattern and mature B cell phenotype. The malignant cells were of uniform cell type, slightly larger than admixed polymorphonuclear leucocytes, and showed minimal nuclear irregularity and positivity for tartrate resistant acid phosphatase (TRAP) staining. Their clinical and morphological features were compared with those of other lymphoproliferative disorders, but while sharing some features in common with each condition, this small group of patients seemed to have a unique combination of findings. The cytopenias of all four responded well after removal of the spleen and their disease has not been aggressive. It is concluded that these patients have a distinct subgroup of lymphoma, which it is important to recognise so that inappropriate use of aggressive cytotoxic drugs can be avoided.

Acid Phosphatase

Acute effects of carbon monoxide exposure on individuals with coronary artery disease.

The purpose of this study was to determine, using more objective evidence than that reported in previous studies, whether or not exposures to carbon monoxide that produce approximately 2% or 4% blood carboxyhemoglobin levels cause an exacerbation of myocardial ischemia during a progressive exercise test. The objective measurements were based on the development of electrocardiographic evidence of ischemia. In addition, time to onset of angina pectoris was studied. Male subjects, ages 35 to 75, with stable exertional angina pectoris and positive exercise treadmill tests with reproducible ischemic ST-segment changes in their electrocardiograms, were studied. In addition, each subject fulfilled at least one of the following criteria of coronary artery disease: angiographic evidence of at least a 70% occlusion of one or more major coronary artery; prior documented myocardial infarction; or a positive exercise thallium test. Each subject was evaluated on four separate occasions, a qualifying visit and three blinded test visits, which involved exposure (in random order) to air without added carbon monoxide and to air that contained carbon monoxide concentrations calculated to produce approximately 2.2% or 4.4% carboxyhemoglobin, measured by gas chromatography, at the end of the exposure period. These immediate postexposure target levels were set 10% higher than the desired postexercise carboxyhemoglobin levels of 2.0% and 4.0% because exercise while breathing room air results in loss of carbon monoxide. The actual one-minute postexercise levels reached were 2.0% +/- 0.1% (mean +/- standard error of the mean) and 3.9% +/- 0.1%. On each test day, the subject performed a symptom-limited exercise test on a treadmill, was exposed for approximately one hour to air or to one of two levels of carbon monoxide in air, and then performed a second exercise test. Time to the onset of ischemic ST-segment changes and time to the onset of angina were determined for each exercise test. The percent difference for these endpoints on the pre- and postexposure exercise tests was determined, and then the results on the 2%-COHb-target day and the results on the 4%-COHb-target day were compared to those on the control day. Data from the 63 subjects who completed the three test visits and met all protocol criteria were analyzed. There were 5.1% (p = 0.01) and 12.1% (p less than or equal to 0.0001) (trimmed mean) decreases in the time to development of ischemic ST-segment changes after the 2%- and 4%-COHb-target exposures, respectively, compared to the control day.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult

Characterization of preribosomal ribonucleoprotein particles from Tetrahymena pyriformis.

Ribonucleoprotein particles present in extracts of nuclei prepared from Tetrahymena pyriformis labelled for 1, 2.5, 5 and 10 min with [3H]uridine during exponential growth were analysed by sedimentation through linear 10--30% sucrose gradients. After 1 min of labelling, the early ribosomal RNA precursor (36-S) is found to be associated with slowly sedimenting particles which form a broad peak centred at approximately 50 S. Other kinds of particles sedimenting at 80 S, 66 S, 60 S and 44 S are observed when labelling is carried out for longer periods (2.5, 5 and 10 min). The 80-S particle contains 29-S and 18-S RNA species together with traces of 36-S RNA; the 60-S and 44-S particles contain 26-S and 17-S RNAs respectively. Similar results were obtained when [Me-3H]methionine was used for labelling in place of [3H]uridine. Methylation of the RNA present in slowly sedimenting nuclear components (30-70-S) is rapid, reaching a plateau at 5 min while that of the faster sedimenting (70--90-S) components is still increasing after 10 min. Only three types of ribonucleoprotein particles (80-S, 66-S, and 44-S) were observed when the cells were labelled after prolonged starvation. A scheme of ribosome biogenesis based on these results is presented.

Animals

Low-frequency hearing loss in presbycusis. A central interpretation.

Elderly subjects with a central phonemically balanced (PB) and synthetic sentence identification (SSI) pattern show greater low-frequency (LF) sensitivity loss than elderly subjects with a peripheral PB-SSI pattern. This LF hearing loss is not the simple consequence of age, nor does the LF hearing loss account for depressed SSI performance. We conclude that LF sensitivity loss and a central PB-SSI pattern are both components of central aging. We discuss the implications for auditory rehabilitation of elderly subjects.

Aged

Methylated amino acids in ribosomal proteins from Escherichia coli treated with ethionine and from a mutant lacking methylation of protein L11.

In the present study, the nature, proportions and distribution of methylated amino acids in ribosomal proteins from Escherichia coli grown in the presence of ethionine and from mutant prm 1 were studied. The undermethylated ribosomes had been labeled by addition in vitro or in vivo of radioactive methyl groups from S-adenosylmethionine or from methionine. The following compounds were identified : N alpha-mono-, di- and trimethylalanines, N epsilon-mono-, di- and trimethyllysines, methylamine and N alpha-trimethylalanyllysine. Except for the latter compound and N-alpha-dimethylalanine, all other derivatives had been previously identified in the literature. It is shown that the dipeptide had been in the past mistaken for N epsilon-monomethyllysine, and arises through incomplete hydrolysis in 24 hrs of the N-terminal peptide bond of protein L11. The results of the present study are discussed in the light of previous work on ribosomal protein methylation by the authors and other workers in the field.

Alanine

RNA synthesis in starved deciliated Tetrahymena pyriformis.

Tetrahymena pyriformis which has been starved for 20 h by incubation in buffer, and then deciliated, can regenerate its cilia in about 90 min while still in suspension in non-nutrient medium. The process of reciliation is accompanied by protein synthesis which begins a few minutes after deciliation and by synthesis of ribosomal and messenger RNAs during a period extending from about 1 h to about 3 h after deciliation. Although net synthesis of RNA remains at a very low level until 1 h after deciliation, a qualitative change in the translatable poly(A)-containing messenger RNA content of deciliated cells, and in particular, formation of beta-tubulin mRNA can be detected almost immediately after deciliation.

Animals

Malignant lymphoma with a high content of epithelioid histiocytes.

A series of 12 patients with a rare malignant lymphoma containing numerous epithelioid histiocytes (MLEH), originally believed to be an atypical variant of Hodgkin's disease, is described. Clinicopathological studies suggest MLEH is a distinct entity among the non-Hodgkin's lymphomas which is generally resistant to therapy and has an unfavourable prognosis. Differentiation of the disease from angioimmunoblastic lymphadenopathy and Hodgkin's disease is discussed. In the necropsy case MLEH had transformed into a malignant lymphoma of histiocytic type.

Aged

Aging and the use of hearing aids.

Elderly subjects with both peripheral and central auditory deficits perform less well with amplification than elderly subjects with peripheral deficits only. This decrease in aided performance remains after control for degree of sensitivity loss, absolute speech understanding score, and chronological age. Furthermore, females show greater central deficits and, consequently poorer aided performance, than males. We discuss the implications of these findings for the auditory rehabilitation of the elderly.

Aged