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Biomedical subjects

V Jagannathan

Publications and source records attributed to V Jagannathan.

At least 19 recordsLinked to original sources
PubMed2005

Efficacy and optimal dose of sildenafil in primary pulmonary hypertension.

PURPOSE: We aimed to assess the effects of sildenafil and evaluate optimal dosing in primary pulmonary hypertension (PPH). Sildenafil selectively inhibits phosphodiesterase 5 (PDE5), which is abundant in pulmonary and penile tissue. This results in increasing nitric oxide (NO) at tissue level leading to pulmonary vasodilatation. SUBJECTS AND METHODS: Our study was a prospective study of sildenafil in 15 consecutive patients with severe symptomatic PPH of NYHA class III-IV. All patients were stabilized for a minimum period of 5 days with antifailure medications. Sildenafil was started at 50 mg twice daily for 4 weeks and increased to 100 mg bid for 4 more weeks in a step-up protocol. Primary end-points were change in Borg dyspnea index, NYHA class and 6-min walk distance, estimated at baseline 1, 2, 4 and 8 weeks. RESULTS: NYHA class (baseline 3.8 +/- 0.4 vs. 4 weeks 2.4 +/- 0.5, p = 0.002), Borg dyspnea index (8.1 +/- 1.7 vs. 4.4 +/- 1.9, p = 0.0007), 6-min walk distance (234 +/- 44 vs. 377 +/- 128 m, p = 0.001) and Pulmonary artery pressure (125 +/- 15 vs. 113 +/- 18 mm Hg p = 0.05) are significantly improved with sildenafil 50 mg bid at 4 weeks. Increasing the dose to 100 mg bid did not produce further benefit. Echocardiography parameters of right heart dimensions and functions did not change markedly in the study period. CONCLUSION: Sildenafil is well tolerated with no adverse effects in severe pulmonary hypertension. It reduces symptoms, improves effort tolerance and controls refractory heart failure significantly by 2 weeks in 70% of patients at 50 mg twice daily. Three patients (20%) failed to respond with sildenafil.

Adult↗
PubMed2004

Safety and efficacy of angiotensin-converting enzyme inhibitors in symptomatic severe aortic stenosis: Symptomatic Cardiac Obstruction-Pilot Study of Enalapril in Aortic Stenosis (SCOPE-AS).

BACKGROUND: Animal models have demonstrated a benefit of angiotensin-converting enzyme inhibitors (ACEI) in experimental aortic stenosis (AS), and intravenous nitroprusside has shown hemodynamic improvements in AS with left ventricular (LV) dysfunction. Although routinely used in most heart failure situations, ACEI are avoided in AS because of the risk of hypotension. We aimed to determine the clinical tolerance and efficacy of the ACEI enalapril in the setting of symptomatic severe AS. METHODS: Patients with symptomatic severe AS were enrolled in a randomized, double-blinded, controlled trial to enalapril or placebo arms after initial stabilization. Standard antifailure medications were continued. Enalapril was started at 2.5 mg bid and increased to 10 mg bid. The primary end points were development of hypotension and improvements in Borg dyspnea index and 6-minute walk distance at 1 month. Secondary end points were minor ACEI intolerance, cough, presyncope, improvement in New York Heart Association class, and echocardiographic parameters. RESULTS: Fifty-six patients were enrolled (37 in the enalapril arm and 19 in the placebo arm). Enalapril was tolerated without hypotension or syncope when LV systolic function was preserved. Three of 5 patients with LV dysfunction and congestive heart failure had hypotension and were withdrawn. Patients who tolerated enalapril (n = 34) demonstrated significant improvement in NYHA class, Borg index (5.4 +/- 1.2 vs 5.6 +/- 1.7, P =.03), and 6-minute walk distance (402 +/- 150 vs 376 +/- 174, P =.003) compared with control subjects. Within the enalapril group, patients with associated regurgitant lesions improved the most. CONCLUSIONS: ACEI are well tolerated in symptomatic patients with severe AS. Patients with congestive heart failure with LV dysfunction and low normal blood pressure are prone to have hypotension. Enalapril significantly improves effort tolerance and reduces dyspnea in symptomatic AS.

Adult↗
PubMed2004

Canadian Cardiovascular Society classification of effort angina: an angiographic correlation.

BACKGROUND: The Canadian Cardiovascular Society classification (CCSC) remains the standard for grading angina in patients with chronic stable angina. The utility value of this angina grading system in predicting the severity of coronary artery disease is not clear. AIM: We studied the relationship between the clinical angina grade and the angiographic severity of underlying coronary artery disease. MATERIALS AND METHODS: The participants in the study were 493 patients with stable angina who had undergone coronary angiography from 1998 to 2001. They were grouped according to their anginal grading and the number of vessels diseased. Significant lesions were defined as 50% narrowing for the left main and 70% for the left and right coronaries and their major branches. STATISTICAL ANALYSIS: The chi2-test was used for statistical analysis and a P-value <0.05 was taken as significant. RESULTS: There was no significant difference between the four angina class patients and the incidence of single-, double- and triple-vessel involvement. Class 1 patients had less left main trunk disease than class 4 patients. Class 3 and 4 patients had significantly fewer normal coronary angiograms. CONCLUSIONS: There is generally little correlation between coronary artery disease and the CCSC of effort angina except for left main disease. Presence or absence of angina rather than the CCSC should indicate the need for coronary angiography.

Angina Pectoris↗
PubMed1997

A strategy for the development of secure telemedicine applications.

Healthcare applications based on computer-supported collaboration technologies have the potential to improve the quality of care delivered to patients. Such applications can help overcome barriers to quality healthcare in the small, scattered populations of rural areas enabling telemedicine to be a part of the practice of medicine. However the growing concern about the potential for abuse through disclosure of personal health information to unauthorized parties has restricted the deployment and adoption of these potentially valuable tools. The authors, who built ARTEMIS--an Intranet healthcare collaboration facility, now describe their approach to develop secure telemedicine applications for rural healthcare practitioners.

Computer Security↗
PubMed1997

Experiences with ARTEMIS--an Internet-based telemedicine system.

ARTEMIS is one of the first systems to exploit the Internet/Intranet technologies for exchanging patient information among health care providers. The primary project goal was to develop and demonstrate a regional telehealth environment specifically to support real-time consultations among health care providers via a computer network, provide secure access to multi-media patient records and discharge summaries, facilitate authentication/digital sign-off, multi-media mail-based referrals, and network-based dictation/transcription. A prototype is deployed in southern West Virginia in a Community Care Network (CCN). The CCN consists of providers, hospitals, clinics, laboratories, that make up one "Virtual" clinic on the "Intranet". ARTEMIS employs new technologies such as Java and JavaScript for the browser, and CORBA-based "middleware" for interoperability at the server-end. Several experiments were designed for evaluating the impact of ARTEMIS on patient care. In this paper we discuss the challenges we faced and the means by which we plan to meet these challenges. We conclude by outlining new thrust areas in which we are concentrating in our next phase of development of ARTEMIS.

Computer Communication Networks↗
PubMed1997

Pharmacokinetics and CNS pharmacodynamics of the 5-HT1A agonist buspirone in humans following acute L-tryptophan depletion challenge.

This study was designed to evaluate the relationship between the pharmacokinetic(s) (PK) and CNS pharmacodynamic(s) (PD) of buspirone, an antidepressant/anxiolytic, in 6 healthy male volunteers placed on an acute L-tryptophan deficient (ATD) diet. The study was a randomized, double-blind, placebo-controlled, four-period, three-way crossover study. The first study period was a single-blind familiarization period in which all subjects received placebo. During the remaining three study periods, subjects received either placebo, 10 mg or 30 mg oral buspirone. Subjects were administered the ATD diets 5 h prior to buspirone/placebo administration during each study period. All subjects underwent serial measurements of resting electroencephalography (REEG) and vigilance electroence-phalography (VEEG), cognitive tests, subjective rating scales, and blood was sampled for determination of unbound plasma L-tryptophan, serum prolactin, serum cortisol and plasma buspirone and its active metabolite, 1-pyrimdylpiperazine (1-PP). The ATD diet reduced the unbound plasma L-tryptophan concentrations to 20% of their baseline values. The intraindividual and interindividual variability in the unbound L-tryptophan concentration drop was less than 10% and 15%, respectively. Peak L-tryptophan depletion occurred 5 h after ATD diet was administered; L-tryptophan depletion lasted for approximately 11 h, and L-tryptophan concentrations recovered to baseline values approximately 13 h after administration of the ATD diet. PK-PD analysis for buspirone showed that: 1) peak plasma concentration (Cmax) and total area under the plasma concentration-time curve (AUC infinity) for buspirone following the 10 mg dose in this study were higher than those reported previously in the literature; 2) there was a transient response in the neuroendocrine measures, subjective rating scales and the EEG, but no changes in the cognitive tests with increasing doses of buspirone; 3) the PD measures were correlated with the doses of buspirone, but not with plasma concentrations of buspirone and 1-PP; and 4) the subjective rating scales were the most sensitive indicators of buspirone's CNS effects. This study provides evidence that ATD diet is a simple, specific and non-toxic experimental method to lower plasma L-tryptophan concentrations and thereby (indirectly) deplete brain tryptophan and serotonin (5-HT) concentrations. The ATD challenge may serve as a model of depression in healthy volunteers because of its ability to induce transient symptoms of the disease. Comparison of the results from this study to those reported in the literature suggests that the use of the ATD diet decreases the buspirone-induced neuroendocrine response, increases the buspirone-induced changes in subjective rating scales and, at the same time, increases the systemic exposure to buspirone and 1-PP.

Administration, Oral↗
PubMed1995

An overview of the CERC ARTEMIS project.

The basic premise of this effort is that health care can be made more effective and affordable by applying modern computer technology to improve collaboration among diverse and distributed health care providers. Information sharing, communication, and coordination are basic elements of any collaborative endeavor. In the health care domain, collaboration is characterized by cooperative activities by health care providers to deliver total and real-time care for their patients. Communication between providers and managed access to distributed patient records should enable health care providers to make informed decisions about their patients in a timely manner. With an effective medical information infrastructure in place, a patient will be able to visit any health care provider with access to the network, and the provider will be able to use relevant information from even the last episode of care in the patient record. Such a patient-centered perspective is in keeping with the real mission of health care providers. Today, an easy-to-use, integrated health care network is not in place in any community, even though current technology makes such a network possible. Large health care systems have deployed partial and disparate systems that address different elements of collaboration. But these islands of automation have not been integrated to facilitate cooperation among health care providers in large communities or nationally. CERC and its team members at Valley Health Systems, Inc., St. Marys Hospital and Cabell Huntington Hospital form a consortium committed to improving collaboration among the diverse and distributed providers in the health care arena. As the first contract recipient of the multi-agency High Performance Computing and Communications (HPCC) Initiative, this team of computer system developers, practicing rural physicians, community care groups, health care researchers, and tertiary care providers are using research prototypes and commercial off-the-shelf technologies to develop an open collaboration environment for the health care domain. This environment is called ARTEMIS--Advanced Research TEstbed for Medical InformaticS.

Computer Communication Networks↗
PubMed1993

ARTEMIS: a collaborative framework for health care.

Patient centered healthcare delivery is an inherently collaborative process. This involves a wide range of individuals and organizations with diverse perspectives: primary care physicians, hospital administrators, labs, clinics, and insurance. The key to cost reduction and quality improvement in health care is effective management of this collaborative process. The use of multi-media collaboration technology can facilitate timely delivery of patient care and reduce cost at the same time. During the last five years, the Concurrent Engineering Research Center (CERC), under the sponsorship of DARPA (Defense Advanced Research Projects Agency, recently renamed ARPA) developed a number of generic key subsystems of a comprehensive collaboration environment. These subsystems are intended to overcome the barriers that inhibit the collaborative process. Three subsystems developed under this program include: MONET (Meeting On the Net)--to provide consultation over a computer network, ISS (Information Sharing Server)--to provide access to multi-media information, and PCB (Project Coordination Board)--to better coordinate focussed activities. These systems have been integrated into an open environment to enable collaborative processes. This environment is being used to create a wide-area (geographically distributed) research testbed under DARPA sponsorship, ARTEMIS (Advance Research Testbed for Medical Informatics) to explore the collaborative health care processes. We believe this technology will play a key role in the current national thrust to reengineer the present health-care delivery system.

Computer Communication Networks↗
PubMed1989

A QSAR study on renin inhibitors.

Quantitative structure-activity relationships (QSAR) were studied in a series of chain-modified peptide analogues of the active site of angiotensinogen. The activity of these renin inhibitors was found to be significantly correlated with Kier's first-order valence molecular connectivity index (1 chi v) and with the molecular weight (MW) of the molecules. The activity was less well correlated with the van der Waals volume (Vw), and not at all with the hydrophobic character (log P) of the molecules. These findings suggest that there is a strong dispersion interaction between the inhibitor molecules and the enzyme, and that hydrophobicity plays little part in the interaction.

Amino Acid Sequence↗
PubMed1982

Purification and properties of phytate-specific phosphatase from Bacillus subtilis.

An enzyme which liberates Pi from myo-inositol hexaphosphate (phytic acid) was shown to be present in culture filtrates of Bacillus subtilis. It was purified until it was homogeneous by ultracentrifugation, but it still showed two isozymes on polyacrylamide gel electrophoresis. The enzyme differed from other previously known phytases in its metal requirement and in its specificity for phytate. It had a specific requirement for Ca2+ for its activity. The enzyme hydrolyzed only phytate and had no action on other phosphate esters tested. This B. subtilis phytase is the only known phytate-specific phosphatase. The products of hydrolysis of phytate by this enzyme were Pi and myo-inositol monophosphate. The enzyme showed optimum activity at pH 7.5. It was inhibited by Ba2+, Sr2+, Hg2+, Cd2+, and borate. Its activity was unaffected by urea, diisopropylfluorophosphate, arsenate, fluoride, mercaptoethanol, trypsin, papain, and elastase.

6-Phytase↗
PubMed1981

Evaluation of a syntactic pattern recognition approach to quantitative electroencephalographic analysis.

This paper reports an experiment designed to evaluate the usefulness of a syntactic pattern recognition approach to quantitative EEG analysis. This approach provides a systematic way of organizing and interpreting spatially and temporally distributed activity in an EEG record. Many automated scoring systems evaluate only background activity, ignoring the significant transient events that may occur in an EEG. In contrast, syntactic methods allow evaluation of background activity in combination with transient events. In this paper, 454 EEGs recorded from a population of renal patients are evaluated using (1) the syntactic approach, and (2) a method based on discriminant analysis. The main finding is that the syntactic approach outperforms the discriminant analysis method when each technique is compared to visual scoring.

Electroencephalography↗