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Biomedical subjects

J L Sebastian

Publications and source records attributed to J L Sebastian.

16 recordsLinked to original sources
PubMed2005

A PDA-based instructional tool to monitor students' cardiac auscultation during a medicine clerkship.

Cardiac auscultation is an important skill for medical students to master but students' exposure to cardiac auscultation is often unmonitored. The objective of this study was to gather data at the point of care about students' cardiac auscultation experience on a required medicine rotation using a Personal Digital Assistant (PDA) 'murmur form'. During an eight-month period, 120 M3 students used the authors' PDA-based learning tool to record information on 940 heart sounds and murmurs. Some 93% of all heart sounds/murmurs reported by students were verified by either a faculty member (56%) or a supervising resident (43%). A PDA can be a useful tool to monitor students' experiences of cardiac auscultation and to track direct observation of such skills by faculty or residents. Medical students are eager to use technology at the point of care to practice their clinical skills.

Clinical Clerkship↗
PubMed2001

Biexponential model for predicting weight loss after gastric surgery for obesity.

BACKGROUND: Following gastric restrictive surgery, morbidly obese patients rarely achieve their ideal body weight defined by Metropolitan Life tables. The final body weight will depend on the initial body composition because there will be greater weight loss from fat than lean body mass. The purpose of this study was to develop a mathematical model that accurately estimates the rate and extent of weight loss following gastric bypass surgery. METHODS: Patients underwent gastric bypass followed by intensive medical therapy and serial bioelectrical impedance analysis (BIA) body composition measurements. Differential equations were derived to model weight loss. RESULTS: Weight loss in the fat and lean body compartments followed monoexponential decay kinetics with differing rate constants. Total body weight loss (W(T)) at time t was W(T) = k(f)(k(f) - k(l)) (W(f(o))e(-k(f)t) + W(l(o))e(-k(l)t)), where W(fo) and W(lo) are the initial fat and lean body masses determined by BIA and k(f) and k(l) are the rate constants for the fat and lean compartments, respectively. Following surgically induced weight loss, k(f) = 7.61 +/- 1.27 x 10(-2), and k(l) = -0.93 +/- 0.13 x 10(-2), with the ratio of residual sum of the squares to the total sum of the squares of 98.8%. CONCLUSION: Accurate prediction of weight loss depends on the initial fat and lean compartment mass since each of these loses weight at a different rate and to a different extent. When these effects are accounted for, the total body weight loss can be accurately predicted for any given time following surgery.

Adult↗
PubMed2000

Use of oral anticoagulants in older patients.

Recently published American and British guidelines have comprehensively reviewed the indications for long term anticoagulation. The best evidence currently available supports the use of long term oral anticoagulants in patients with nonvalvular atrial fibrillation (NVAF), venous thromboembolic disease, ischaemic heart disease, mural thrombi, and mechanical heart valves. Selected patients with valvular heart disease, cerebral vascular disease, and peripheral arterial disease may also benefit from the use of these drugs. When no specific contraindications are present, elderly patients with either paroxysmal or persistent NVAF should be considered candidates for treatment with anticoagulants. Pooled analyses of the results from 9 randomised trials demonstrate that warfarin significantly reduces the risk of ischaemic stroke in patients with NVAF, particularly those in a 'high risk' category defined by the presence of additional clinical or echocardiographic risk factors. Long term anticoagulation does not appear to be justified in patients with NVAF considered to be at 'low risk' for stroke. Because the prevalence of NVAF and most other cardiovascular conditions increases with advancing age, many elderly patients will be candidates for thromboprophylaxis. The potential benefit of long term anticoagulation must be carefully weighed against the risk of serious haemorrhage in such patients. Bleeding complications with anticoagulant drugs appear to occur more frequently in older patients than in younger individuals. Advanced age (>75 years), intensity of anticoagulation [International Normalised Ratio (INR) >4.0], history of cerebral vascular disease (recent or remote), and concomitant use of drugs that interfere with haemostasis [aspirin (acetylsalicylic acid) or nonsteroidal anti-inflammatory drugs] are among the most important variables in determining an individual's risk for major bleeding with anticoagulants. Older patients often display increased sensitivity to the effects of warfarin, both in the early induction phase and during the long term maintenance phase of therapy. Conditions such as congestive heart failure, malignancy, malnutrition, diarrhoea and unsuspected vitamin K deficiency, enhance the prothrombin time response. The decision to interrupt anticoagulant therapy before elective surgery in elderly patients should evaluate the thrombotic risk of such a manoeuvre versus the risk of bleeding if anticoagulants are continued. In non-surgical patients, excessively elevated INRs without associated haemorrhage can usually be managed by simply witholding one or several doses of warfarin. If more rapid reversal is needed, small doses of phytomenadione (vitamin K1) can be administered safely without overcorrection or the development of vitamin K-induced warfarin resistance.

Administration, Oral↗
PubMed2000

The use of large-scale cDNA analysis to profile differential gene expression in KYSE 410 human esophageal cancer cells after irradiation.

Atlas Human cDNA Expression Array, which includes 588 genes divided into functional classes, was used to study gene expression profiles in KYSE 410 human esophageal cancer cells irradiated in doses of 6 and 18 Gy. Considerable changes in the expression of a number of genes was found, including down-regulation of 3 cell cycle regulators and up-regulation of an apoptosis-related gene. Comparison of the expression profiles and identification of genes were performed with Atlas Vision 3.0 software.

Esophageal Neoplasms↗
PubMed1999

Hypophosphorylated retinoblastoma protein is associated with G2 arrest in esophageal squamous cell carcinoma.

Hypophosphorylated retinoblastoma (Rb) gene product binds critical transcription factors, leading to G1 arrest in a number of conditions, including following DNA damage. We have previously shown that irradiated esophageal squamous cell carcinoma (ESSC) cells undergo predominantly G2 arrest, with increases in inhibitors of Rb phosphorylation. We thus hypothesized that this G2 arrest would be accompanied by increases in hypophosphorylated Rb protein (pRb). We sequenced the Rb genes of three human ESSC lines (KYSE) following reverse transcription polymerase chain reaction of exons A-E. Western gels were performed on protein extracts for pRb. Cells were irradiated at 6 Gy, and protein was extracted at 6 h. ELISA was used to measure hypophosphorylated pRb in radiated versus control cells. Student's t test was used to compare results. All lines had wild-type Rb genes. Western gels confirmed the presence of pRb. There were significant increases in hypophosphorylated pRb in all three lines following irradiation (no line with less than a 100% increase). We have thus shown that irradiation-induced G2 arrest occurs in association with wild-type Rb genes and that there is associated hypophosphorylation of pRb. This supports our data describing a further role for other G1 mediators, such as p21, in G2 arrest. Further investigations into therapies to expoit this cell cycle checkpoint are warranted and planned.

Blotting, Western↗
PubMed1994

Cardiac decompression after operation for congenital heart disease in infancy.

Between January 1987 and July 1992, 641 infants (less than 1 year of age) underwent cardiac surgical procedures through a median sternotomy incision at the UCLA Medical Center. In 36 (5.6%), to achieve cardiac decompression, the chest was left open after the operation, or was re-opened immediately postoperatively because of low cardiac output. The incidence of cardiac decompression was 31% (4/13) after the Norwood procedure and 24% (7/29) after truncus arteriosus repair. Opening of the chest reduced intrathoracic pressure and allowed complete expansion of the lungs. Delayed sternal closure was carried out in 27 patients at a mean of 5 days (range, 2 to 14 days) postoperatively. By the time of chest closure, left atrial pressure had decreased from a mean of 12 +/- 1.4 to 8.4 +/- 0.8 mm Hg (p < 0.004), and inotropic drug support with dopamine and dobutamine had also decreased significantly. Thirteen (36%) patients died of low cardiac output and multiorgan failure (4 of them after delayed chest closure) that was complicated by sepsis in 2. The incidence of sternal wound infection was relatively low at 5.6% (2/36); 1 patient died of generalized sepsis complicating multiorgan failure and the second case occurred in a patient who survived long term after sternectomy. With optimal ventilatory and inotropic drug support and meticulous wound care, delayed sternal closure may improve the survival of infants in low cardiac output after cardiac surgical procedures.

Female↗
PubMed1993

The effect of warfarin on urine calcium oxalate crystal growth inhibition and urinary excretion of calcium and nephrocalcin.

Urine contains inhibitors of calcium oxalate (CaOx) crystal growth. One such inhibitor is nephrocalcin (NC), a glycoprotein which is made in the kidney and contains several residues of gamma-carboxyglutamic acid (Gla) per molecule. The presence of Gla may be important to its ability to inhibit crystal growth. Several studies suggest that vitamin K-dependent proteins may also play a role in renal calcium (Ca) handling, and that vitamin D deficiency may lead to excess urinary Ca loss, but the effect of the vitamin K antagonist warfarin on urinary Ca excretion and CaOx growth inhibition in humans is not known. We studied 11 men while they were taking warfarin for a mean of 252 days, and again a mean of 64 days after its discontinuation. Urinary Ca excretion did not differ between those on or off warfarin, or between those on warfarin and normal controls. The ability of the subjects' urine to inhibit CaOx crystal growth did not differ on or off warfarin, or from that of control urine, and the excretion of immunoreactive NC also did not differ between these groups. NC was found to be responsible for approximately 16% of the CaOx growth inhibition seen. These results do not suggest that vitamin K-dependent proteins play a major role in renal Ca excretion in men, or that interference with vitamin K alters NC excretion or inhibitory activity of the urine.

Adult↗
PubMed1992

Successful long-term preservation of the neonatal heart with a modified intracellular solution.

UNLABELLED: Current methods of myocardial preservation for transplantation are suboptimal. A newly developed intracellular cardioplegic and storage solution (modified University of Wisconsin solution, group 1) was compared in a randomized, blinded fashion with our present clinical protocol, Stanford cardioplegic solution and saline storage (group 2) in an isolated neonatal pig model. After arrest and storage for 12 hours at 4 degrees C, biopsy specimens were taken from six group 1 hearts and five group 2 hearts for examination under an electron microscope and assessment of high-energy phosphate levels and water content. The remainder (group 1, n = 7; group 2, n = 6) were reperfused with blood for 50 minutes, after which function curves were obtained at left ventricular end-diastolic pressures of 3 to 12 mm Hg and biopsy tissue was taken. Eight control hearts (group 3) were cannulated in situ and perfused on the circuit without arrest or intervening ischemia. Stroke and minute work index curves were approximately threefold and fivefold higher for group 1 (modified University of Wisconsin solution) than for group 2 (Stanford), respectively (p less than 0.01). The hearts preserved with University of Wisconsin solution did not differ in function from unpreserved control hearts (group 3). High-energy phosphate levels were better maintained in group 1 than group 2 (p less than 0.05), and water content was lower (p less than 0.01). Semiquantitative grading of electron micrographs paralleled the functional and biochemical results. CONCLUSION: Modified University of Wisconsin intracellular solution provides markedly better heart preservation than conventionally used cardioplegic and storage solutions.

Adenosine↗
PubMed1991

Angiotensin-converting enzyme inhibitors and cough. Prevalence in an outpatient medical clinic population.

To determine the frequency of ACE inhibitor cough in an outpatient medical clinic population, a cross-sectional epidemiologic survey using mailed questionnaires was done. Patients were randomly selected from a computerized hospital pharmacy data base. The overall prevalence of cough was 19 percent in the ACE inhibitor groups compared with 9 percent in the hydrochlorothiazide-treated group. The observed odds ratio for cough among ACE inhibitor users was 2.3 (95 percent CI, 1.02 to 5.00). This study is the first systematic investigation of frequency and characteristics of ACE inhibitor cough that includes a control group. Our results suggest that cough may more frequently accompany treatment with ACE inhibitors than has been previously reported. We recommend that physicians specifically inquire about cough in patients taking an ACE inhibitor. Recognition of this side effect may prevent unnecessary testing and treatment of patients receiving ACE inhibitors.

Ambulatory Care↗
PubMed1991

Isolated muscular sarcoidosis causing fever of unknown origin: the value of gallium-67 imaging.

An unusual case of a patient with a long-standing fever of unknown origin (FUO) is presented whose gallium-67 (67Ga) images revealed increased activity only in the calf muscles bilaterally. Other imaging modalities also failed to show chest or other abnormal findings. Subsequent biopsy of the right gastrocnemius muscle revealed noncaseating granulomas consistent with the diagnosis of sarcoidosis. When using 67Ga to evaluate a patient with a FUO, imaging of the extremities should always be included. Also, when abnormal Ga-67 uptake is present in the extremities, sarcoidosis should be included in the differential diagnosis.

Adult↗
PubMed1989

Long-term use of oral anticoagulants. Current recommendations.

In many patients receiving long-term oral anticoagulation therapy, hemorrhagic complications occur less often when prothrombin time is maintained within a lower range than that required by a traditional regimen. A target prothrombin time ratio of 1.3 to 1.5 has been recommended for all circumstances except (1) prevention of thromboembolism in patients with mechanical heart valves and (2) prevention of recurrent systemic embolism. Because primary care physicians often monitor the overall treatment program of patients receiving oral anticoagulants, they need to be familiar with the indications, contraindications, and practical considerations that are associated with the use of these drugs.

Administration, Oral↗
PubMed1989

Epidemiology and interaction of risk factors in cardiovascular disease.

Many patients seen in a primary care practice have multiple risk factors for cardiovascular disease. In evaluating these patients, it is important for primary care clinicians to understand the principles of multiple risk factor assessment. Although none of the large-scale randomized primary prevention trials have convincingly proven the benefits of multiple risk factor intervention, some practical guidelines reflecting the current state of information are presented.

Cardiovascular Diseases↗
PubMed1980

Crossed ureteral ectopia with solitary kidney.

A case of crossed ectopia with a solitary kidney in a 73-year-old man is presented. The fact that the kidney is normally situated and vascularized, and the presence of a second blind homolateral ureter leads us to conclude that this is a case of crossed ureteral ectopia in a solitary kidney. The embryogenesis of the malformation is discussed.

Abnormalities, Multiple↗