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Biomedical subjects

J Augustine

Publications and source records attributed to J Augustine.

At least 37 records · Page 2Linked to original sources
PubMed1994

Dose-related effects of magnesium on myocardial function in the neonate.

The antagonistic effects of magnesium ion as a calcium ion blocker may decrease calcium influx associated with ischemia. However, the effect of magnesium on the preischemic neonatal myocardium has not been investigated previously. The purpose of this study was to investigate the effects of the administration of increasing doses of magnesium on left ventricular performance in the neonate. We assessed left ventricular function (pressure-volume data obtained by the conductance catheter/micromanometer technique) in three groups (n = 6 in each) of newborn pigs (3 to 5 days old) differing with respect to magnesium concentrations. End-systolic elastance did not change during infusion in group A (magnesium = 1.2 mmol/L), whereas in groups B (magnesium = 8 mmol/L) and C (magnesium = 16 mmol/L) it decreased significantly (P < .05) to 67 +/- 6% and 44 +/- 8% of baseline, respectively. The decrease in end-systolic elastance was associated with a significant reduction in cardiac output (P < .05) and stroke work (P < .05) in group C. After administration of magnesium, end-systolic elastance returned to baseline in group B in contrast to group C (78 +/- 3% of baseline value, P < .05). The slope constant of the end-diastolic pressure-volume relation decreased significantly (P < .05) from the preinfusion baseline values of 0.42 +/- 0.08 mL-1 in group B and 0.46 +/- 0.05 mL-1 in group C to 0.3 +/- 0.04 and 0.26 +/- 0.03 mL-1, respectively, versus no change in group A.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Ultrastructural variations and assessment of malignant transformation risk in oral leukoplakia.

Oral cancer is the most common malignancy in India, having a well defined precancerous state, leukoplakia. Various follow-up studies have shown that only 4 to 18% of oral leukoplakia lesions subsequently progress into invasive malignancy over a period of time. This study evaluates the potential of electron microscopy in the early detection of malignant changes in leukoplakia. The study revealed that of the 25 leukoplakia lesions examined, 7 showed changes akin to malignancy. Predominant ultrastructural alterations observed were reduplication and discontinuity of the basal lamina, basal cells with pleomorphic and bizarre nuclei containing perichromatin and interchromatin granules, prominent intercellular spaces and poorly formed desmosomes. Since none of these changes were evident under light microscopy the study demonstrates the value of electron microscopy in evaluating oral carcinogenesis. A long term follow-up of such patients is needed to understand the prognostic implications of these ultrastructural variation and how they can be used as a base line for better light microscopic evaluation.

Cell Transformation, Neoplastic↗
PubMed1993

Multilocular cystadenoma of the liver with mural nodules.

Hepatobiliary cystadenoma, characterised by the interposition of a mesenchymal stroma beneath the epithelium and the connective tissue layer, is a tumor described exclusively in women. These tumors have a potential for malignant transformation. Complete surgical excision is mandatory. We report a case cystadenoma with mesenchymal stroma (CMS), with mural nodules in the cyst wall, similar to those described in ovarian mucinous cystadenoma.

Cystadenoma↗
PubMed1993

Effects of high plasma epinephrine and Ca2+ concentrations on neonatal myocardial function after ischemia.

Administration of catecholamines to newborn infants may potentiate reperfusion injury because of increased transsarcolemmal Ca2+ influx and the presence of less developed sarcoplasmic reticulum in the immature hearts. We investigated the effect of administration of epinephrine (1.5 micrograms/kg per minute for 120 minutes) before ischemia and modified serum ionized Ca2+ concentrations in the cardioplegic solution and perfusate on postischemic left ventricular systolic and diastolic function in 25 piglets (5 to 7 days old) undergoing 90 minutes of cold blood cardioplegic arrest. The piglets were divided into four groups; Ca2+ 1.2 mmol/L, group A (n = 6), Ca2+ 0.25 mmol/L, group B (n = 6), Ca2+ 1.2 mmol/L and epinephrine, group C (n = 6), Ca2+ 0.25 mmol/L and epinephrine, group D (n = 7). Left ventricular function was assessed by a conductance catheter in the left ventricle measuring end-systolic and end-diastolic pressure-volume relationships during transient vena caval occlusion. By analysis of covariance, only Ca2+ concentration was important in predicting ventricular function recovery after ischemia (p < 0.01). End-systolic elastance decreased in all groups after ischemia; the magnitude was significantly greater in the normal groups (51% versus 35%, p < 0.01). There was a significant increase in the chamber stiffness index after administration of epinephrine before ischemia (p < 0.05). Groups with low Ca2+ perfusate (B and D) had no change in chamber stiffness index after ischemia. In contrast, there was a significant increase in chamber stiffness in the normal Ca2+ groups with (C) or without (A) epinephrine after ischemia (p < 0.05). Adenosine triphosphate stores declined significantly in the normal Ca2+ groups--48% versus 18% in the low Ca2+ groups (p < 0.01). We conclude that low Ca2+ concentrations in the perfusate and cardioplegic solutions better preserve left ventricular function in the normal and in epinephrine-stressed neonatal heart after ischemia.

Adenosine Triphosphate↗
PubMed1993

The protective effect of magnesium on acute catecholamine cardiotoxicity in the neonate.

Neonates undergoing heart surgery are exposed to high levels of circulating catecholamines. Our objective was to determine to what extent administration of magnesium counters epinephrine-induced cardiotoxicity. We assessed left ventricular function (pressure-volume data obtained by the conductance catheter/micromanometer technique) and ultrastructure in newborn pigs 3 to 5 days of age before and after administration of epinephrine alone (2 micrograms/kg/min, group A, n = 6) and simultaneously with magnesium sulfate (8 mmol/L, 5 ml/hr, group B, n = 6). Plasma levels of magnesium were maintained at 200% to 250% of control, and ionized calcium was maintained at normal levels. During administration of epinephrine, there was a significant increase in end-systolic elastance from 8.9 +/- 2 to 15 +/- 3 mm Hg/ml in group A and from 7.8 +/- 2 to 16 +/- 3 mm Hg/ml in group B (p < 0.05). This increase was accompanied by an increase in chamber stiffness index (p < 0.05) and shortening of the time constant of isovolumic relaxation (p < 0.05; group A, 19 +/- 3 to 13 +/- 3 msec; Group B, 20 +/- 2 to 15 +/- 2 msec). After epinephrine was discontinued, however, systolic and diastolic indexes returned to baseline levels in group B, whereas group A exhibited a significant reduction in end-systolic elastance (5 +/- 1 mm Hg/ml; p < 0.05) and an increase in chamber stiffness index (0.7 +/- 0.08 versus 0.4 +/- 0.1 ml-1; p < 0.05) and time constant (25 +/- 1 versus 19 +/- 3 msec). Left ventricular dysfunction in group A was associated with focal sarcolemmal rupture and mitochondrial swelling, whereas only minor reversible changes (microvesicular lipid accumulation) were seen in group B. We conclude that magnesium has a protective effect against epinephrine-induced cardiotoxicity because of its blocking action on calcium influx of ionized calcium and could be of therapeutic benefit in the perioperative period.

Adenosine Triphosphate↗
PubMed1992

Malignant systemic mastocytosis.

Malignant Systemic Mastocytosis is a very rare condition. Only about less than 40 well documented cases have been reported as per the available literature. The paper presents the case report of a 54 year old male patient who presented with huge hepatosplenomegaly and abdominal lymphadenopathy. Splenectomy specimen was 17 x 16 x 10 cm size with cut surface studded with numerous tiny 1-2 mm nodules. Histologic sections of spleen showed extensive mast cell (typical and atypical) infiltrates. Liver biopsy and abdominal lymphnode biopsy specimens and bone marrow smears also showed similar infiltration by mast cells. Special stains done for non-specific esterase and chloracetate esterase showed strong positivity for mast cells. The results of immunohistochemical and electron microscopic studies are also presented.

Humans↗
PubMed1992

Tissue binding pattern of plant lectins in benign and malignant lesions of thyroid.

N-acetyl D-galactosamine specific lectins were isolated from the seeds of Jack Fruit (Artocarpus integrifolia) and Winged bean (Psophocarpus tetragonolobus) and D-galactose specific lectin was isolated from peanut (Arachis hypogaea). These lectins were conjugated to Horse Radish Peroxidase (HRP) and were used to study the lectin binding properties of benign and malignant lesions of the thyroid. For comparison of the results 10 normal fresh autopsy specimens were included in the study. The Peanut lectin (PNL) and Jack fruit lectin (JFL) conjugates showed positive binding with the cells in different lesions, while Winged Bean Lectin (WBL), despite its having a common inhibitory sugar, showed no binding even after neuraminidase treatment. These lectins revealed difference in the composition of glycoconjugates of benign and malignant thyroid cells. The HRP conjugated JFL and PNL may be of use in distinguishing carcinomatous tissues from benign tissues which makes them potential tools in the differential diagnosis of thyroid lesions.

Diagnosis, Differential↗
PubMed1991

Age-related response to epinephrine-induced myocardial stress. A functional and ultrastructural study.

Left ventricular systolic and diastolic function before, during, and after a 2-hour intravenous infusion of epinephrine at either 0.5 micrograms/kg/min or 2 micrograms/kg/min were assessed by pressure-volume data obtained by conductance catheter micromanometer technique and correlated with cardiac ultrastructure and plasma levels of epinephrine in neonatal (3-5 days old, n = 12) versus adult (3-4 months old, n = 11) pigs. Administration of epinephrine at 0.5 micrograms/kg/min resulted in an increase in end-systolic elastance (Ees) only in adults, whereas at 2.0 micrograms/kg/min Ees increased in both groups. After 2-hour administration of epinephrine at 2.0 micrograms/kg/min, Ees decreased significantly (p less than 0.05) from the preinfusion baseline value of 8.9 +/- 2 (mean +/- SD) to 5 +/- 1.7 mm Hg/ml, and a significant (p less than 0.05) increase in left ventricular volume elasticity (VdP/dV) from 0.4 +/- 0.02 to 1.4 +/- 0.2 mm Hg occurred in neonates versus no change from baseline in either Ees or VdP/dV in the adults. These changes in the neonates were associated with sarcolemmal rupture and mitochondrial Ca2+ granule deposition versus normal cardiac ultrastructure in the adults. We conclude that the neonatal myocardium is more susceptible to cardiotoxicity from circulating epinephrine.

Aging↗
PubMed1990

Evaluation of porous polyethylene for external ear reconstruction.

Autogenous rib cartilage and silicone rubber are materials currently used for ear reconstruction. Increased morbidity and operative time with rib cartilage grafts and a high rate of extrusion with silicone implants render them less than ideal for reconstruction of the human ear. The purpose of the current investigation is to determine the efficacy of porous polyethylene as an alternative synthetic material for ear reconstruction. Porous polyethylene and silicone rubber discs of equal sizes in two thicknesses were implanted in lieu of the cartilage in the external ear of eight baboons. Histological evaluation of the sites after nine weeks revealed excellent anchorage of the thin porous polyethylene implants (1.5 mm) in the surrounding tissues. Silicone rubber implants, however, were encapsulated in a thickened granulation tissue capsule. When thicker implants (3.0 mm) were used, exposure or extrusion occurred in all cases. Porous polyethylene implants demonstrated only partial exposure; half of the silicone rubber implants were extruded; and the other two silicone rubber implants were almost completely extruded. Porous polyethylene was thus better incorporated into the soft tissues than silicone rubber as long as the overlying soft tissues were not stressed by an oversized implant or inadequate soft tissue coverage.

Animals↗
PubMed1990

Waldenstrom's macroglobulinaemia.

Waldenstrom's macroglobulinaemia is a rare form of monoclonal plasma cell dyscrasia in which there is excess production of immunoglobulin M. Clinically the patient has features of hyperviscosity syndrome and the effects of bone marrow replacement by lympho-plasmacytoid cells. We report here two such cases seen within a period of two months.

Female↗
PubMed1990

Effects of low perfusate Ca2+ concentration on newborn myocardial function after ischemia.

A greater dependence on transsarcolemmal Ca2+ flux and immaturity of Ca2+ sequestration capacity may potentiate Ca2(+)-mediated reperfusion injury in the newborn myocardium. The effect of serum ionized Ca2+ concentration on left ventricular systolic and diastolic function after ischemia was studied in 5-7-day-old piglets undergoing a 90-minute period of cold-blood cardioplegic arrest. In the control group, Ca2+ was maintained at 1.2 mM (Group A [n = 6]). The cardioplegic solution and bypass perfusate were modified to achieve a low Ca2+ concentration, 0.25 mM, in Group B (n = 6). Left ventricular pressure-volume loops were acquired by using high-fidelity pressure-sensor-tipped and volume-conductance catheters. Ventricular function was assessed from the slope of end-systolic (Ees) and end-diastolic (k) pressure-volume relations during transient caval occlusion. Both groups showed a significant reduction in Ees after ischemia (p less than 0.05). Intergroup comparison of Ees after ischemia demonstrated a better recovery of the systolic function in the low Ca2+ group, 64 +/- 7% versus 49 +/- 6% in the normal Ca2+ group (p = 0.05). There was a significant increase in chamber stiffness index in group A (k, 0.48 +/- 0.06 to 0.65 +/- 0.05 ml-1, p less than 0.01) versus no significant change in group B. This study shows 1) the feasibility of acquiring continuous pressure-volume data in neonatal hearts by using a conductance catheter system, and 2) better preservation of systolic function and diastolic compliance in normal newborn myocardium by low Ca2+ concentration in the peri-ischemic period.

Animals↗
PubMed1989

Ackerman's tumour (Verrucous carcinoma) of the oral cavity: a histopathologic study of 426 cases.

Salient histopathological features of four hundred and twenty six (426) cases of verrucous carcinoma of the oral cavity reported jointly by the Department of Oral Pathology, Dental College and Department of Pathology, Medical College, Trivandrum, during the period from January 1975 to December 1984 were evaluated. They constituted 5.27% of 7,988 primary malignant neoplasms of the oral cavity detected during the period. Locally aggressive behaviour with bone, muscle and salivary gland invasion occurred in 53% of cases. Examination of the neighbouring areas of the lesion, which showed some light on the natural evolution of the disease, is described. The gradual transformation of a hyperplastic verrucous lesion into carcinoma is appraised. Evidence suggestive of a distant metastatic spread of the tumour could not be detected.

Carcinoma, Papillary↗
PubMed1987

Tissue binding patterns of lectins in premalignant and malignant lesions of the oral cavity.

Lectins from the seeds of Jackfruit (Artocarpus integrifolia) and winged bean (Psophocarpus tetragonolobus) were isolated using an immobilized N-acetyl D-galactosamine column and conjugated to type VI horse radish peroxidase. The purified conjugate was used for the study of tissue specificities using diaminobenzidine as the substrate on dewaxed tissue sections of normal, oral leukoplakia, oral submucous fibrosis, verucous carcinoma and squamous cell carcinoma of the oral cavity. In spite of having a common inhibitory sugar, winged bean lectin did not bind to any lectins whereas Jackfruit lectin showed varying degrees of binding towards the above tissues. The difference in the nature and intensity of binding of the Jackfruit lectin suggest the utilizing this lectin in the differential diagnosis of the premalignant and malignant lesions of the oral cavity.

Carcinoma, Papillary↗
PubMedDate not supplied

Objectives to direct the training of emergency medicine residents on off-service rotations: administration.

Administrative knowledge and skills are essential for the emergency physician. This is the 12th article in a continuing series of "off-service" goals and objectives. It outlines a mechanism for conveying important points of Emergency Medicine Administration to the EM III resident. The article includes materials describing the Administrative Content, Goals and Objectives, Key Contact System, and Contents of the EM Administrative briefcase. This information should assist faculty charged with the development or revision of the Administrative literature review and experiential block rotation in an emergency medicine residency.

Curriculum↗
PubMedDate not supplied

A hemodynamic approach to resistant hypertension.

Resistant hypertension affects a minority of treated hypertensive patients, yet the resulting target organ damage causes disproportionate morbidity and increased risk of cardiovascular events. The clinical features and efforts to adjust drug treatment in a resistant hypertensive patient are described. As demonstrated, serial hemodynamic measurements using thoracic bioimpedance may provide a rationale for selection of effective combination antihypertensive therapy. (c)2000 by CHF, Inc.

Journal Article↗