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Biomedical subjects

J Thomas

Publications and source records attributed to J Thomas.

At least 1,117 records · Page 62Linked to original sources
PubMedDate not supplied

Complications common to ventricular assist device support are rare with 90 days of DeBakey VAD support in calves.

The DeBakey VAD is a miniaturized, electromagnetically driven axial flow pump intended for long-term ventricular assist. Safety and performance data from six calves implanted with the complete DeBakey VAD system are reported elsewhere; here we describe complications and necropsy findings for these same six animals, all of which survived 90 days. The study was conducted according to a uniform protocol, which included anticoagulation and antibiotic prophylaxis. Clinical complications tracked included bleeding, cardiovascular abnormalities (e.g., arrhythmias, tachycardia unrelated to pain, bradycardia), hemolysis, hepatic dysfunction, renal dysfunction, thromboembolism (neurologic or peripheral), or infection. Each adverse event was retrospectively categorized with regard to severity (mild, moderate, severe) and relationship to device. Clinical findings were confirmed by necropsy. There was no evidence of systemic infection, thromboembolism, hemolysis, or renal or hepatic dysfunction in these six animals during the study period. A single adverse event was noted in each of two of the calves. Both events were considered mild according to the predefined criteria. Bleeding related to the surgical implantation procedure and requiring reoperation occurred in one animal. The other animal had evidence of a superficial infection at the exit site of the cables on the left lateral thoracic wall; the infection did not extend into the thoracic cavity. Chronic, healed small renal infarct scars were present in several animals. Mild valvular endocardiosis was observed in two calves and mild fibroelastosis was present in the endocardium at the site of the inflow cannula in three calves; however, these lesions were not considered clinically significant. No other gross or histologic abnormalities were noted at necropsy. In conclusion, calves implanted with the complete DeBakey VAD for 90 days demonstrated few complications and had no significant necropsy findings. Complications common to ventricular assist device (VAD) support (i.e., hemolysis, infection, bleeding, thromboembolism) were rare during long-term support (90 days) with the DeBakey VAD.

Animals↗
PubMedDate not supplied

Evaluation of plasma catecholamines in humans. Correlation of resting levels with cardiac responses to beta-blocking and sympatholytic drugs.

The changes in systolic time intervals (STI) following reduction of adrenergic activity was used to validate supine resting plasma catecholamines (CATs) as an index of sympathetic activity. Blockade of sympathetic activity was achieved by two means in two groups: propranolol (10 mg i.v.) and clonidine (0.3 mg p.o.). The diminished sympathetic effect was evidenced by slowing (p less than 0.01) of heart rate with both drugs and the reduction (p less than 0.01) of blood pressure with clonidine. There was no correlation in our study between resting plasma CATs (norepinephrine alone or total), and changes in heart rate and preejection period (PEP). Moreover, to avoid changes in PEP that could be related to differences in blood pressure levels (clonidine-reduced blood pressure while propranolol did not), the changes in PEP were corrected for the change of mean arterial pressure (MAP) in the same patients (delta PEP/(delta MAP and % delta PEP/% delta MAP). No correlation could be found, still, between resting supine plasma CATs and these ratios. The difficulty in demonstrating a correlation between resting plasma CATs and the immediate cardiac response to adrenolytic agents can be explained by the number of factors influencing plasma levels. Circulating plasma CATs represent the spillover from adrenergic nerve endings, and, therefore, their level would depend on several factors including sympathetic nervous system activity, rate of reuptake, and rate of degradation.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Papillary thyroid carcinoma and related thyroid neoplastic lesions: a light microscopic study with emphasis on nuclear changes.

A total of 187 thyroid lesions consisting of 2 cases of Grave's disease, 21 cases of multinodular goiter, 40 follicular adenomas and 124 low-grade papillary thyroid carcinomas were studied to identify intermediate neoplastic lesions in the spectrum of nuclear changes between benign reactive thyroid follicles and low-grade thyroid papillary carcinoma. The lesions were examined and classified on the basis of the following nuclear features: fine chromatin seen in the thyroid papillary carcinomas and coarse chromatin seen in follicular carcinomas. Cases with Hürthle cell changes were excluded from the study. Cases with nuclei containing coarse chromatin were classified in the group of follicular adenomas with a coarse chromatin pattern. The neoplastic thyroid lesions containing fine chromatin showed a spectrum of nuclear changes ranging between reactive follicular lesions and papillary thyroid carcinoma with lymph node metastasis. Such lesions were classified as follicular adenomas with a fine chromatin pattern. The nuclei of these lesions were graded into mild to marked "nuclear atypia with a fine chromatin pattern". The degree of atypia depended on the degree and extent of nuclear changes. Encapsulated follicular adenomas with a fine chromatin pattern and with mild atypia (11 cases), moderate atypia (13 cases), marked atypia (27 cases), and encapsulated or nonencapsulated papillary thyroid carcinoma were characterized by uniform nuclei; with mild, moderate and marked nuclear atypia in less than 2/3 of the cell population and marked nuclear atypia in more than 2/3 of the cell population; and measuring 5.4-6.3, 6.0-7.2, 6.3-9 and 7.2-10 microns in diameter, respectively. Follow-up of cases of papillary thyroid carcinoma fulfilling the above criteria showed lymph node metastasis in 33% of cases, whereas follicular adenomas with a fine chromatin pattern, including cases originally diagnosed as papillary carcinoma, showed no evidence of lymph node or distant metastasis in a follow-up period of 30 months to 15 years. In the thyroid tissue surrounding papillary thyroid carcinoma or encapsulated follicular adenoma with a fine chromatin pattern and marked atypia, adenomatous nodules with a fine chromatin pattern and with low-grade nuclear atypia were identified. The adenomatous nodules with a fine chromatin pattern and with mild, moderate and marked atypia showed architectural, cytoplasmic and nuclear features similar to those of follicular adenoma with a fine chromatin pattern of the same grade. Of interest, a large number of cases of follicular adenoma with a fine chromatin pattern had areas with features of follicular adenoma with a coarse chromatin pattern.

Adenoma↗
PubMedDate not supplied

Ret oncogene protein expression in papillary thyroid carcinoma and related lesions.

BACKGROUND: Activation of Ret oncogenes, particularly Ret/PTC, has been identified in papillary thyroid carcinoma (PTC). The purpose of this study was to investigate the immunostaining pattern of Ret oncogene protein in PTC and nodular non-PTC lesions with a fine chromatin pattern. MATERIALS AND METHODS: Ninety-three PTC and 139 nodular non-PTC lesions were microscopically reviewed to identify the nuclear changes of "limited nuclear features of PTC" (focal nuclear grooves, nuclear inclusions or optically clear nuclei) and areas of infiltrating carcinoma (IC) and were submitted for immunostaining with Ret oncogene protein antiserum. RESULTS: Immunoreactivity for Ret protein ranged from negative in follicular adenoma (FA) with a coarse chromatin pattern, to negative or weak reactivity in FA with a fine chromatin pattern, to strong reactivity in PTC with areas of infiltrating carcinoma (IC). In FA with fine chromatin, FA and follicular carcinoma (FC) containing an admixture of areas of coarse and fine chromatin, areas with nuclear changes with "limited nuclear features of PTC" displayed varying degrees of immunoreactivity. The intensity of immunostaining varied with the degree of nuclear change. The noninvasive component of PTC with IC usually showed more extensive and stronger reactivity than PTC without IC. PTCs with and without IC were associated with a rate of lymph node metastasis of 48% and 3%, respectively. CONCLUSIONS: The expression of Ret oncogenes (Ret/PTC, other unknown variants or wild type) is focally or extensively present in all PTC with IC. The degree of immunoreactivity is likely to be proportional to the potential for lymph node metastasis of PTC. In the context of this study and due to the specificity of Ret oncogenes, it is likely that nodular non-PTC lesions with a fine chromatin pattern and focal positive reactivity for Ret oncogene represent PTC-related lesions.

Carcinoma, Papillary↗
PubMedDate not supplied

The effect of harvesting the central one-third of the patellar tendon on patellofemoral contact pressure.

This study assessed whether removing the central one-third of the patellar tendon, with or without side-to-side repair of the patellar tendon defect, would alter patellofemoral pressure. Patellofemoral pressure was assessed by testing five stable knees from five different cadaveric donors on a specially designed hydraulic knee machine. Patellofemoral joint pressures were measured by placing pressure-sensitive film into the patellofemoral articulation. The joint was loaded in a static fashion, with quadriceps forces consistent with walking (647 N) and stair climbing (1923 N), at 30 degrees, 60 degrees, and 90 degrees of knee flexion. Using the same knees, the central one-third of the patellar tendon was then sectioned, and patellofemoral joint pressure measurements were repeated at identical knee flexion angles and quadriceps-forces. Side-to-side repair of the patellar tendon defect was performed and patellofemoral joint pressure measurements were repeated. There were no statistically significant differences between the control and sectioned values or between the control and repaired defect values. These results suggest that harvesting the central one-third of the patellar tendon--with or without side-to-side repair of the patellar tendon defect--does not alter patellofemoral pressures.

Adult↗
PubMedDate not supplied

Seroepidemiology of Helicobacter pylori infection in an urban, upper class population in Chennai.

BACKGROUND: In India, no true population-based seroepidemiological data on Helicobacter pylori infection are available. Serological studies have been done on hospital-based subjects chosen predominantly from lower socioeconomic strata. METHODS: A population-based serological study was done in a randomly selected urban, upper class population (children under 12 excluded). Of 163 households, 126 participated (response rate 77%); the number of respondents was 406. Blood was collected from 354 persons (response rate 87%). A latex agglutination test was used for serology. Demographic data, socioeconomic indicators and history of treatment for acid-peptic disease (APD) were also collected. RESULTS: The overall seroprevalence was 49.4% (95% confidence interval 44.1-54.8). Seroprevalence increased with age, ranging from 21.1% in the 12-20 years age group to 76.2% in the > 70 years group (p = 0.0003), and with larger family size (p < 0.05); it was lower among those living in nuclear families (p < 0.03). No association was found with gender, treatment for APD, and number of generations living together. CONCLUSIONS: Though the overall seroprevalence of H. pylori in this urban, educated, upper class population is high, the age-specific prevalence is different from what has been reported earlier in India; the pattern resembles that of a developed country.

Adolescent↗
PubMedDate not supplied

[Error introduced in the radiocardiographic measurement of right volume by the non linearity of the detector in high count rates (author's transl)].

The short life tracers permit the use of high activities and so allow to follow with a good statistic accuracy fast phenomenons such as the different phases of cardiac revolution. However, this advantage may be quickly limited by the dead-time of the detection unit used. It results from this, in high activities, a non linear response which introduces non negligible errors which we have calculated and verifies thanks to experience in the measurement of right ventricular volumes.

Cardiac Catheterization↗