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Biomedical subjects

D L Jones

Publications and source records attributed to D L Jones.

At least 73 records · Page 4Linked to original sources
PubMed1997

Developing a generic health status measure for use in a computer-based outcomes infrastructure.

This descriptive, correlational study was designed to determine the sensitivity of a generic health status instrument to patient population and to time. The study sample included adult patients undergoing total joint replacement (TJR), adult patients in acute congestive heart failure (CHF), and pediatric patients receiving chemotherapy (PediOnc). A 2 x 3 (population x time) ANOVA for TJR and CHF demonstrated a significant main effect of time (F = 8.0, p = .0006) and a significant interaction effect between time and population (F = 14.4, p < .0001) for functional status. In the PediOnc subsample (HSOD child version), the highest scores for all HSOD factors with the exception of functional status were at Time 3. There was also a significant main effect of time on health care involvement, on the caregiver factor, and the family factor. These results support the sensitivity of the HSOD to patient population and to time.

Adult↗
PubMed1996

Cost savings using a stepped-care prescribing protocol for nonsteroidal anti-inflammatory drugs.

OBJECTIVE: To lower nonsteroidal anti-inflammatory drug (NSAID) costs while maintaining quality patient care and clinician satisfaction. DESIGN: Before and after 21-month trial with one study site and two control sites and a questionnaire that was sent to 203 clinicians. SETTING AND SUBJECTS: Two military medical centers and two affiliated primary care clinics. All beneficiaries filling outpatient NSAID prescriptions. INTERVENTIONS: An NSAID prescribing protocol was implemented requiring a trial of either ibuprofen or indomethacin before new prescription of more expensive NSAIDs. One control center used an NSAID computer cost-prompt and the other had no intervention. MAIN OUTCOME MEASURES: The proportion of expensive NSAIDs prescribed at each institution and total NSAID costs adjusted for prescription volume. Clinician acceptance and patient impact were assessed by the questionnaire. RESULTS: Study site clinicians (n=158) reported very few protocol-related patient care problems. A minority (9%) of study site clinicians considered the protocol very bothersome, and only 2% felt it should be discontinued. Quarterly use of expensive NSAIDs at the study site fell from 34% to 21%, decreasing costs by 30% (P<.001). In contrast, the site with a computer cost-prompt had only a 5% decrease in NSAID costs, while costs at the site with no intervention increased 2%. CONCLUSIONS: For drugs with similar benefits and adverse effects, a "stepped formulary" approach requiring an initial trial of one of the less expensive agents can maintain physician prescribing choices and satisfaction while lowering costs.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Interactions of the human papillomavirus E7 protein with cell cycle regulators.

Human papillomavirus (HPVs) critically depend on the cellular machinery for the replication of their genome. Viral replication is restricted to the differentiated strata of the skin that are normally growth arrested. Hence, the HPVs have developed strategies to subvert cellular growth regulatory pathways and are able to uncouple cellular proliferation and differentiation. The HPV E7 protein can overcome the activity of some cyclin-dependent kinase inhibitors, associate with cyclin/cyclin dependent kinase complexes and bind to and destabilize the retinoblastoma tumor suppressor protein. These biological activities contribute to the carcinogenic potential of the high risk HPV E7 proteins which are consistently expressed in HPV-positive cervical carcinomas.

Amino Acid Sequence↗
PubMed1996

Effect of growth factors on growth of bovine parathyroid cells in serum-free medium.

Published work has suggested a possible role of the epidermal growth factor receptor (EGFr) in parathyroid disease. Bovine parathyroid cells (BPCs) are frequently used as a tissue model for studying parathyroid disorders. We have studied the effect of the EGFr ligands EGF and transforming growth factor alpha (TGFalpha), alone and with insulin-like growth factors IGF-I and IGF-II on BPC growth. Experiments were run in triplicate and repeated three times. Cell numbers were assessed on day 5 by colorimetric MTT assay as well as by tritiated thymidine uptake. Results show that TGFalpha alone (p < 0.05) and IGF-I and IGF-II alone (p < 0.05) significantly stimulated growth over controls (t-test). Furthermore, the combination of TGFalpha with IGF-I and IGF-II exhibited significant enhancement above that seen with IGF-I and IGF-II alone (p < 0.01). EGF did not stimulate growth over controls. EGFr may be expressed in BPCs, but TGFalpha exhibits a more potent growth stimulus than EGF. Addition of IGF-I or IGF-II to the growth medium further enhances this effect.

Animals↗
PubMed1996

Oral cancer education in dental schools: survey of Texas dental students.

BACKGROUND: Senior dental students at the three Texas dental schools were surveyed about their attitudes and perceptions of their knowledge and skills in areas related to prevention, detection, and diagnosis of oral cancer, and the management of oral sequelae of cancer therapy methods. A 16-item survey was distributed to a total of 251 fourth-year dental students. A total of 198 completed surveys were returned, for a response rate of 79%. RESULTS: Just over half of the students had observed a biopsy of oral tissue or read a biopsy report, but only about one fourth had actually performed the procedure. Respondents who had observed or performed a biopsy or who had read a biopsy report were significantly more likely to report that they were comfortable with their competence in performing a biopsy. Although only about half (57%) reported that tobacco-use cessation programs had been discussed in their training and only 14% had received actual training, a much larger percentage intended to provide cessation materials or training in their practices. Likewise, only a fourth had been instructed in prescribing nicotine replacement therapy, but almost two-thirds planned to do so in their practices. Most respondents felt they were comfortable with their skills in counseling patients about oral cancer risk factors, and most felt they would be able to recognize a malignant lesion. Almost all had been taught full head and neck examination technique, and most (84%) were comfortable with their skills in performing such an examination. Smaller percentages reported instruction in the management of the oral sequelae of chemotherapy and radiation therapy. CONCLUSIONS: Future practitioners are more comfortable with skills that have been practiced in training. These data suggest that an increased emphasis on certain aspects of cancer education within the dental curriculum would result in a more confident, competent practitioner.

Biopsy↗
PubMed1996

Responses within nonfederal hospitals in Pennsylvania to the Americans with Disabilities Act of 1990.

BACKGROUND AND PURPOSE: This study described responses within nonfederal hospitals in Pennsylvania to the Americans With Disabilities Act of 1990 (ADA). SUBJECTS: The target population consisted of all 277 nonfederal hospitals licensed by the Pennsylvania Department of Health and Department of Public Welfare. METHODS: Questionnaires were mailed to the 270 chief administrators for the 277 hospitals. RESULTS: One hundred seventeen questionnaires (43.3%) were returned. More facilities had trained their managers regarding the ADA versus their nonmanagerial employees. Overall, 80.3% of the hospitals had an ADA committee or coordinator. Fifty-four percent of the respondents reported that job accommodations cost less than $500. Approximately 45% of the participants cited that the percentage of new construction costs spent to increase accessibility in their hospitals was less than 4.9%. More complaints and legal matters were received by facilities regarding the employment provisions of the ADA rather than the accessibility provisions. CONCLUSION AND DISCUSSION: The results suggest that hospitals need to monitor ADA-related expenses, more employee training is needed to ensure the ADA's success, and more representation is needed on hospital committees by rehabilitation personnel and individuals with disabilities.

Analysis of Variance↗
PubMed1996

Effects of autonomic manipulation on ventricular fibrillation and internal cardiac defibrillation thresholds in pigs.

Autonomic tone may contribute to cardiac arrhythmogenesis and influence the efficacy of implantable defibrillators. Fifty-two anesthetized pigs were randomized to: (1) methacholine (n = 12); (2) nitroprusside (n = 12); (3) phenylephrine (n = 12); (4) carbachol (n = 8); and (5) saline (n = 8). Ventricular fibrillation threshold (VFT) and triplicate defibrillation thresholds (DFT) were obtained before and during each intervention. Mean (+/- SE) VFT was increased with: methacholine (76 +/- 10.6 V vs 39 +/- 7.1 V, P < 0.001); phenylephrine (68 +/- 10.5 V vs 38 +/- 6.2 V, P < 0.001); and carbachol (106 +/- 11.5 V vs 30 +/- 6.5 V, P < 0.0001). Nitroprusside and saline failed to alter VFT. Mean (+/- SE) DFT was decreased with: methacholine (7.7 +/- 0.8) vs 9.7 +/- 0.8 J, P < 0.001); phenylephrine (9.8 +/- 0.9 J vs 11.3 +/- 1.0 J, P < 0.05); and carbachol (9.2 +/- 0.7 J vs 12.2 +/- 0.8 J, P < 0.0001), remaining unchanged following nitroprusside and saline infusion. Thus, modulation of autonomic tone modified arrhythmia susceptibility and the energy necessary for defibrillation, increased parasympathetic tone, increased VFT, and decreased DFT. Evaluation of autonomic balance, particularly parasympathetic tone, may be useful with the implantation of automatic defibrillators.

Animals↗
PubMed1996

Effects of aging on sarcoplasmic reticulum function and contraction duration in skeletal muscles of the rat.

The impact of aging on the Ca2+ pump function of skeletal muscle sarcoplasmic reticulum (SR) was investigated using SR-enriched membrane vesicles isolated from the slow-twitch soleus muscle (SM) and the relatively fast-twitch gastrocnemius muscle (GM) isolated from adult (6-8 mo old) and aged (26-28 mo old) Fischer 344 rats. In addition, isometric twitch characteristics of SM and GM were determined in situ in adult and aged rats under anesthesia. The rates of ATP-supported Ca2+ uptake by SM SR was markedly lower ( approximately 50%) in the aged compared with adult at varying Ca2+ (0.11-8.24 microM) concentrations. Kinetic analysis of the data revealed age-associated decrease in maximum activity reached (Vmax) and increase in the concentration of Ca2+ giving half of Vmax. In contrast, no significant age-related difference was observed in ATP-supported Ca2+ uptake activity of GM SR. The Ca(2+)-stimulated adenosinetriphosphatase (ATPase) activities and the amount of Ca(2+)-ATPase protein did not vary significantly with aging in SM or GM SR. Also, no significant age-related difference was observed in the content of the ryanodine receptor (Ca(2+)-release channel) or the Ca2+ binding protein, calsequestrin in SM and GM SR. In isometrically contracting SM, the time to peak force, half-relaxation time, and contraction duration were significantly prolonged in the aged compared with adult, whereas there was no age-related difference in maximum developed force. None of these isometric twitch parameters differed significantly with age in the GM. These results demonstrate that the effects of aging on skeletal muscle contractile properties and SR function are muscle specific. Furthermore, the data strongly suggest that impairment in SR Ca2+ pump function, apparently due to uncoupling of ATP hydrolysis from Ca2+ transport, contributes to the age-associated slowing of relaxation in the soleus muscle.

Aging↗
PubMed1996

Seroprevalence of hepatitis B virus among school-age children in the Stann Creek District of Belize, Central America.

Adults in the Stann Creek District of Belize have a high prevalence of hepatitis B virus (HBV) infection, but the age of onset of these infections is unclear. We conducted a seroprevalence study of hepatitis B markers among Stann Creek school-age children to provide information for planning a hepatitis B vaccine program. The overall prevalence in 587 students was high for antibody to hepatitis B core antigen (anti-HBc) (43.3%) and hepatitis B surface antigen (HBsAg) (7.7%). There was marked variation of anti-HBc by school and by the predominant ethnic groups attending those schools. Maya had the highest prevalence (76%), followed by Mestizo (50%), Garifuna (37%), and Creole (25%). Children less than nine years of age attending the rural primary schools (mostly Mayan and Mestizo) had significantly higher prevalence of anti-HBc than did children attending the urban primary school (mostly Garifuna and Creole) (P < 0.05). Anti-HBc was found in 42% and 36% of students at the two high schools. Of the five schools tested, only at the urban primary school did anti-HBc positivity increase with age. Based on an analysis of the cost of serologic screening before immunization compared with mass vaccination, preimmunization serologic screening resulted in vaccine program cost savings in four of the five schools. Because most children in the rural areas contract hepatitis B before entering school, immunization against HBV should be integrated into the routine infant immunization program.

Adolescent↗
PubMed1996

Protein kinase C alpha, beta immunoreactivity in baker's yeast, lobster and wheat germ.

The immunoreactivity of PKC alpha (protein kinase C alpha) and PKC beta in wheat germ, lobster tail muscle and three strains of yeast was analysed by Western blotting with mouse anti-PKC active fragments. The potency of the immunoreactivity of PKC alpha activity was much greater than that of PKC beta. The occurrence of multiple bands may be due to PKC self-interactions and/or the interactions between PKC and other molecules. The evolutionary conservation of PKC alpha and PKC beta implies that these PKC isoenzymes may play important roles in Ca2+/lipid-dependent signal transduction and cell growth in these eukaryotes.

Animals↗
PubMed1995

Subparsec-scale structure and evolution of Centaurus A (NGC5128).

We present a series of 8.4-GHz very-long-baseline radio interferometry images of the nucleus of Centaurus A (NGC5128) made with a Southern Hemisphere array, representing a 3.3-year monitoring effort. The nuclear radio jet is approximately 50 milliarcseconds in extent, or at the 3.5-megaparsec distance of NGC5128, approximately 1 parsec in length. Subluminal motion is seen and structural changes are observed on time scales shorter than 4 months. High-resolution observations at 4.8 and 8.4 GHz made in November 1992 reveal a complex morphology and allow us to unambiguously identify the self-absorbed core located at the southwestern end of the jet.

Journal Article↗
PubMed1995

Chronic rapid atrial pacing. Structural, functional, and electrophysiological characteristics of a new model of sustained atrial fibrillation.

BACKGROUND: Despite the clinical importance of atrial fibrillation (AF), the development of chronic nonvalvular AF models has been difficult. Animal models of sustained AF have been developed primarily in the short-term setting. Recently, models of chronic ventricular myopathy and fibrillation have been developed after several weeks of continuous rapid ventricular pacing. We hypothesized that chronic rapid atrial pacing would lead to atrial myopathy, yielding a reproducible model of sustained AF. METHODS AND RESULTS: Twenty-two halothane-anesthetized mongrel dogs underwent insertion of a transvenous lead at the right atrial appendage that was continuously paced at 400 beats per minute for 6 weeks. Two-dimensional echocardiography was performed in 11 dogs to assess the effects of rapid atrial pacing on atrial size. Atrial vulnerability was defined as the ability to induce sustained repetitive atrial responses during programmed electrical stimulation and was assessed by extrastimulus and burst-pacing techniques. Effective refractory period (ERP) was measured at two endocardial sites in the right atrium. Sustained AF was defined as AF > or = 15 minutes. In animals with sustained AF, 10 quadripolar epicardial electrodes were surgically attached to the right and left atria. The local atrial fibrillatory cycle length (AFCL) was measured in a 20-second window, and the mean AFCL was measured at each site. Marked biatrial enlargement was documented; after 6 weeks of continuous rapid atrial pacing, the left atrium was 7.8 +/- 1 cm2 at baseline versus 11.3 +/- 1 cm2 after pacing, and the right atrium was 4.3 +/- 0.7 cm2 at baseline versus 7.2 +/- 1.3 cm2 after pacing. An increase in atrial area of at least 40% was necessary to induce sustained AF and was strongly correlated with the inducibility of AF (r = .87). Electron microscopy of atrial tissue demonstrated structural changes that were characterized by an increase in mitochondrial size and number and by disruption of the sarcoplasmic reticulum. After 6 weeks of continuous rapid atrial pacing, sustained AF was induced in 18 dogs (82%) and nonsustained AF was induced in 2 dogs (9%). AF occurred spontaneously in 4 dogs (18%). Right atrial ERP, measured at cycle lengths of 400 and 300 milliseconds at baseline, was significantly shortened after pacing, from 150 +/- 8 to 127 +/- 10 milliseconds and from 147 +/- 11 to 123 +/- 12 milliseconds, respectively (P < .001). This finding was highly predictive of inducibility of AF (90%). Increased atrial area (40%) and ERP shortening were highly predictive for the induction of sustained AF (88%). Local epicardial ERP correlated well with local AFCL (R2 = .93). Mean AFCL was significantly shorter in the left atrium (81 +/- 8 milliseconds) compared with the right atrium 94 +/- 9 milliseconds (P < .05). An area in the posterior left atrium was consistently found to have a shorter AFCL (74 +/- 5 milliseconds). Cryoablation of this area was attempted in 11 dogs. In 9 dogs (82%; mean, 9.0 +/- 4.0; range, 5 to 14), AF was terminated and no longer induced after serial cryoablation. CONCLUSIONS: Sustained AF was readily inducible in most dogs (82%) after rapid atrial pacing. This model was consistently associated with biatrial myopathy and marked changes in atrial vulnerability. An area in the posterior left atrium was uniformly shown to have the shortest AFCL. The results of restoration of sinus rhythm and prevention of inducibility of AF after cryoablation of this area of the left atrium suggest that this area may be critical in the maintenance of AF in this model.

Animals↗
PubMed1995

Improved time-frequency filtering of signal-averaged ECGs.

A recently proposed time-frequency filtering technique has shown promising results for the enhancement of signal-averaged electrocardiograms. This method weights the short-time Fourier transform of the ensemble-averaged signal, analogous to the spectral domain Wiener filtering of stationary signals. In effect, it is a self-designing, time-varying Wiener filter applied to the high-resolution electrocardiogram (HRECG). In this study, the authors empirically show that the performance of the proposed technique is about 2-3 dB lower over the critical late-potential portion of the HRECG than the optimal fixed-window, time-frequency filter based on ideal a priori knowledge of statistics. Although this ideal knowledge and performance is unattainable in practice, these results suggest that there remains potential for modest improvement. To narrow this gap in performance, improvements based on alternative structures for the time-frequency filter, including time-varying short-time Fourier transform windows, are proposed. Simulation results show that an improved fixed-window technique can potentially yield an improvement of about 1-1.5 dB. By using properly chosen time-varying windows, the performance could potentially be improved of about 1-1.5 dB. By using properly chosen time-varying windows, the performance could potentially be improved even further. Thus, the improved techniques could produce an HRECG using fewer averages than the existing method, or that could tolerate a lower initial signal-to-noise ratio.

Algorithms↗
PubMed1995

Cephalometric comparison of characteristics in chronically snoring patients with and without sleep apnea syndrome.

OBJECTIVE: The purpose of this investigation is to cephalometrically study 50 snoring patients with and without sleep apnea and to determine whether cephalograms can be used as a diagnostic tool to differentiate persons who are chronic snorers from persons with sleep apnea. STUDY DESIGN: A sample of 30 sleep apnea patients was compared with a sample of 20 chronic snorers without sleep apnea as documented by polysomnography. Forty cephalometric measurements were determined to study various skeletal, soft tissue, and airway abnormalities. RESULTS: This study showed that both groups presented multiple cephalometric abnormalities. Only four measurements differed significantly between the two samples. In the sleep apnea group the maxilla was retropositioned and the hypoid bone displaced inferiorly and distally as compared to nonapneic snorers. CONCLUSIONS: Because of the overall presence of abnormal cephalometric findings in both samples and given similar age and weight ranges, a differential diagnosis between chronic snorers with and without sleep apnea cannot be reliably based on standard cephalometric evaluation alone.

Adult↗
PubMed1995

High voltage shock induced cellular electrophysiological effects: transient refractoriness and bimodal changes in action potential duration.

The cellular electrophysiological effects of defibrillation shocks on the myocardium during ventricular fibrillation are not clear. The present study investigated the effects of high voltage shocks on membrane potentials of isolated guinea pig and pig papillary muscles during rapid activations simulating ventricular fibrillation. High voltage shocks induced an action potential with a prolonged duration, followed by a transient refractory state. Subsequent action potentials following this refractory state had shortened durations. The duration of the transient refractory state varied in proportion to shock intensity and stimulation rate, whether the shock was biphasic or monophasic. Shock induced prolonged depolarization was not a consistent finding and mainly observed with slow stimulation rates. In conclusion, high voltage shocks induce bimodal changes of the action potential duration associated with a transient refractory state during rapid activation. The rate dependency of this refractory state suggests that the duration of the shock induced refractory state may be longer in the fibrillating than the normal beating heart, and may contribute to successful defibrillation.

Action Potentials↗
PubMed1995

Information requirements underlying medical decision making in the diagnosis and early management of spontaneous subarachnoid hemorrhage.

The research reported here investigated an area in which improved information would significantly enhance decision making focusing upon the diagnosis and management of spontaneous subarachnoid hemorrhage (SAH). The incidence of SAH is low, but morbidity and mortality are high. Furthermore, nonspecialists acting as gatekeepers to specialist care may not possess the required knowledge base and diagnostic skills to make reasonable decisions. The information used by experts was evaluated and an expert consensus established. An analysis of nonspecialist decision making was then completed, and finally the expert consensus was utilized to identify both the information deficits and the training requirements of nonspecialists.

Decision Theory↗
PubMed1995

Immunoreactivity of PKC gammalambda and RACK1 in baker's yeast, lobster and wheat germ.

Varied patterns of immunoreactive bands of protein kinase C gamma (PKC gamma) and receptor for activated C-kinase-1 (RACK1) were detected by analysis of Western blots in crude extracts of wheat germ, lobster tail meat, and three strains of baker's yeast. Anti-PKC lambda also reacted with wheat germ and yeast extracts, but failed to react with the lobster extract. The findings may implicate a regulatory role and an evolutionary conservation of these PKC isoenzymes and their receptor proteins in eukaryotes.

Animals↗