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Biomedical subjects

C R Thompson

Publications and source records attributed to C R Thompson.

At least 19 recordsLinked to original sources
PubMed1999

Significance of serum antibodies reactive with flavoprotein subunit of succinate dehydrogenase in thyroid associated orbitopathy.

AIMS: Thyroid associated orbitopathy (TAO) is an autoimmune disorder of extraocular muscles and orbital connective tissue. Identification of the principal target antigens would help the understanding of the pathogenesis of the disease and possibly lead to the development of specific therapies in the future. The purpose of this study was to measure serum antibodies against the flavoprotein subunit of succinate dehydrogenase in patients with TAO and correlate their presence with factors of TAO. METHODS: Sera of patients with active TAO of 6 months' duration or less were tested for antibodies against the flavoprotein subunit of succinate dehydrogenase. Clinical data were obtained by retrospective review of patients' charts. Enzyme linked immunosorbent assay was used to test sera for serum antibodies against purified succinate dehydrogenase. RESULTS: 38 patients with TAO and 32 healthy age and sex matched controls were included in the study. Anti-flavoprotein antibodies were detected in 24 out of 38 patients with TAO (63.16%) and in five out of 32 healthy controls (15.63%) (p<0.01). Neither age, sex, duration of thyroid disease, thyroid status, treatment of thyroid disease, smoking history, duration of orbitopathy, activity of orbitopathy, nor the presence of lid retraction were significantly associated with the presence of serum anti-flavoprotein antibodies (p>0.05). However, the total number of rectus muscles affected in both eyes of the patients was significantly correlated with the finding of a positive antibody test (p<0.05). CONCLUSIONS: Serum antibodies reactive with the flavoprotein subunit of succinate dehydrogenase are associated with extraocular muscle involvement in active TAO of recent onset.

Adult↗
PubMed1998

Ventricular rupture during coronary angioplasty for acute reinfarction.

Ventricular rupture following acute myocardial infarction usually leads to hemopericardium and death from cardiac tamponade. We describe a patient who had cardiac rupture during direct angioplasty for reinfarction 3 days following an acute anterior myocardial infarction. In this instance, ventricular rupture presented as a severe form of reperfusion injury. The current literature on reperfusion injury and risk factors for cardiac rupture are discussed.

Aged↗
PubMed1998

Rebuilding the healthcare system in Mostar: challenge and opportunity.

A basic premise of this article is that the political and ethnic division of the city of Mostar imperils community health planning efforts beyond those normally encountered in the aftermath of war. Bosnia and Herzegovina is divided among ethnic groups, and the city of Mostar is further subdivided between the Croatian and Muslim interest groups. In that respect, Mostar presents a very special challenge to those planning the reconstruction of the health care delivery infrastructure. A new healthcare delivery plan was organized by the Federation of Bosnia and Herzegovina in 1996. This paper examines obstacles involved in implementing that plan in light of some epidemiological indicators of current health conditions.

Bosnia and Herzegovina↗
PubMed1998

Arterial embolism complicating implantable cardioverter defibrillator shocks with normal ventricular function.

A 69-year-old man developed an embolus to his right femoral artery 24 h following the insertion of an implantable cardioverter defibrillator (ICD), with multiple shocks administered in the early postoperative period. He had nonobstructive hypertrophic cardiomyopathy with normal left ventricular function and no evidence of left atrial or ventricular thrombus seen on pre- or postoperative transthoracic echocardiography. There was no evidence of atrial fibrillation documented before or after implantation of the device. He had no other known risk factors for thromboembolic disease. Thromboembolic phenomena as a complication of ICD use have been described but arterial emboli believed related to ICD shocks have not been reported in patients without impaired systolic function.

Aged↗
PubMed1997

Population-based study of risk of venous thromboembolism associated with various oral contraceptives.

BACKGROUND: Four studies published since December, 1995, reported that the incidence of venous thromboembolism (VTE) was higher in women who used oral contraceptives (OCs) containing the third-generation progestagens gestodene or desogestrel than in users of OCs containing second-generation progestagens. However, confounding and bias in the design of these studies may have affected the findings. The aim of our study was to re-examine the association between risk of VTE and OC use with a different study design and analysis to avoid some of the bias and confounding of the earlier studies. METHODS: We used computer records of patients from 143 general practices in the UK. The study was based on the medical records of about 540,000 women born between 1941 and 1981. All women who had a recorded diagnosis of deep-vein thrombosis, venous thrombosis not otherwise specified, or pulmonary embolus during the study period, and who had been treated with an anticoagulant were identified as potential cases of VTE. We did a cohort analysis to estimate and compare incidence of VTE in users of the main OC preparations, and a nested case-control study to calculate the odds ratios of VTE associated with use of different types of OC, after adjustment for potential confounding factors. In the case-control study, we matched cases to controls by exact year of birth, practice, and current use of OCs. We used a multiple logistic regression model that included body-mass index, number of cycles, change in type of OC prescribed within 3 months of the event, previous pregnancy, and concurrent disease. FINDINGS: 85 women met the inclusion criteria for VTE, two of whom were users of progestagen-only OCs. Of the 83 cases of VTE associated with use of combined OCs, 43 were recorded as deep-vein thrombosis, 35 as pulmonary thrombosis, and five as venous thrombosis not otherwise specified. The crude rate of VTE per 10,000 woman-years was 4.10 in current users of any OC, 3.10 in users of second-generation OCs, and 4.96 in users of third-generation preparations. After adjustment for age, the rate ratio of VTE in users of third-generation relative to second-generation OCs was 1.68 (95% CI 1.04-2.75). Logistic regression showed no significant difference in the risk of VTE between users of third-generation and second-generation OCs. Among users of third-generation progestagens, the risk of VTE was higher in users of desogestrel with 20 g ethinyloestradiol than in users of gestodene or desogestrel with 30 g ethinyloestradiol. With all second-generation OCs as the reference, the odds ratios for VTE were 3.49 (1.21-10.12) for desogestrel plus 20 g ethinyloestradiol and 1.18 (0.66-2.17) for the other third-generation progestagens. INTERPRETATION: The previously reported increase in odds ratio associated with third-generation OCs when compared with second-generation products is likely to have been the result of residual confounding by age. The increased odds ratio associated with products containing 20 micrograms ethinyloestradiol and desogestrel compared with the 30 micrograms product is biologically implausible, and is likely to be the result of preferential prescribing and, thus, confounding.

Adolescent↗
PubMed1997

Small hemodynamic effect of typical rapid volume infusions in critically ill patients.

OBJECTIVES: To determine what volumes are commonly used for rapid volume infusions in critically ill patients admitted to the intensive care unit (ICU) for > 12 hrs; and to determine the effectiveness of a typical rapid volume infusion in producing hemodynamic change and increasing left ventricular end-diastolic volume. DESIGN: A prospective survey of clinical practice (part 1) and a prospective clinical investigation (part 2). SETTING: Two hospital ICUs (11 and six beds) of which one is university affiliated. PATIENTS: Critically ill patients admitted to the ICU for > 12 hrs. INTERVENTIONS: Infusion of 500 mL of normal saline over 5 to 10 mins. MEASUREMENTS AND MAIN RESULTS: For 1 month, we recorded the volume and composition of all volume infusions given as a rapid bolus in patients admitted to the ICU for > 12 hrs. We then measured the effected the median rapid volume infusion in a subset of 13 patients by measuring hemodynamics (using arterial and pulmonary artery flotation catheters) and left ventricular end-diastolic area (using transgastric short-axis views from transesophageal echocardiograms). During 470 patient days, 159 rapid volume infusions were administered. The average rapid volume infusion administered was 390 +/- 160 mL (median 500; interquartile range 250 to 500). Crystalloid solutions were used for two thirds of the rapid volume infusions and colloid solutions were used for one third of the rapid volume infusions. The rapid volume infusion of 500 mL of saline did not significantly increase mean arterial pressure (78.0 +/- 11.9 to 79.3 +/- 14.6 mm Hg), cardiac index (4.3 +/- 1.7 to 4.6 +/- 1.8 L/min/m2), right atrial pressure (11.1 +/- 3.8 to 12.4 +/- 3.3 mm Hg), left ventricular end-diastolic area (8.6 +/- 1.7 to 9.1 +/- 1.8 cm2/m2), or left ventricular end-systolic area (3.5 +/- 1.5 to 3.6 +/- 1.5 cm2/m2). Pulmonary artery occlusion pressure increased slightly but significantly from 12.9 +/- 3.4 to 14.7 +/- 3.3 mm Hg (p < .05). CONCLUSIONS: After patients are admitted to the ICU for > 12 hrs, rapid volume infusions are common therapeutic interventions but the rapid volume infusions are typically small. The effect of a typical rapid volume infusion on hemodynamics and left ventricular areas in these patients is surprisingly small.

Adult↗
PubMed1997

Anterior visual pathway gliomas.

The benign anterior visual pathway glioma undoubtedly is the most controversial subject in neuro-ophthalmology. Although we are persuaded by the evidence that they are true neoplasms rather than hamartomas, the controversy over their biological nature seems moot, as they have a low growth potential. That is not to say that serious visual loss is not common or that, in some cases (especially among those lesions arising in the chiasmalhypothalamic region), tumor-related death and disability cannot occur. These posteriorly located lesions may cause hydrocephalus, and shunting is required if that occurs. The need for shunting in such cases may be the only point on which experts agree. What has yet to be established is whether any of the forms of therapy now available for anterior visual pathway gliomas without hydrocephalus is better than no treatment. Surgery, radiation, and chemotherapy all carry risks. A randomized, controlled study, if feasible, would be apt to settle the issue. The low incidence of these tumors might frustrate attempts to complete such an investigation in a reasonable period. A team of physicians should manage patients with benign anterior visual pathway gliomas. Radiologists, neurologists, neurosurgeons, radiation oncologists, pediatricians, endocrinologists, and oncologists all have a role, but the neuro-ophthalmologist should be the leader. Neuro-ophthalmologists are in the unique position of being able to recognize and document changes in the patient's visual function. Furthermore, neuro-ophthalmologists, being disinterested, are free to choose without bias from among the various management options. The malignant anterior visual pathway glioma is not a subject of controversy. The clinical features at presentation are apt to be misinterpreted as evidence of an inflammatory or ischemic neuropathy rather than the announcement of a fatal brain tumor. Though these patients receive radiotherapy and chemotherapy, these measures have not improved survival significantly, and the outcome is uniformly fatal. The only positive thing that can be said about the malignant gliomas of the anterior visual pathway is that they are so rare.

Adolescent↗
PubMed1996

Laser induced bubble formation in the retina.

BACKGROUND AND OBJECTIVE: The immediate thermodynamic effects of absorption of a laser pulse in the retina are theoretically studied to understand underlying physical damage mechanisms at threshold fluences. Damage is most likely to occur at threshold levels in the retinal pigment epithelium due to the strong absorption by the melanosomes. METHODS: The retinal pigment epithelium is modeled as an aqueous environment with absorption occurring at small spherical sites with absorption coefficients representative of melanosomes. For laser pulse durations of less than 10(-6) seconds, heat conduction is negligible during energy deposition and the resulting large energy density in the melanosomes will cause vaporization of the medium immediately surrounding a melanosome. RESULTS: We developed expressions for calculating the size of bubbles produced as a function of pulse characteristics and melanosome properties. We show that for pulse durations between 10(-6) and 10(-9) seconds, bubble formation will occur for laser fluences that are smaller than those required to cause Arrhenius-type thermal damage. CONCLUSION: Bubble formation is likely to be the mechanism of threshold damage to the retina for laser pulses durations in the time regime between 10(-6) and 10(-9) seconds.

Absorption↗
PubMed1996

Serum from patients with chronic renal insufficiency alters growth characteristics and ANP mRNA expression of adult rat cardiac myocytes.

Left ventricular hypertrophy is very prevalent among patients with renal insufficiency. Known hypertrophic factors, such as systemic hypertension, do not adequately account for the prevalence of left ventricular hypertrophy in these patients. Circulating growth factors may stimulate cardiomyocyte growth and contribute to the development of left ventricular hypertrophy. The effects of sera from patients with (n = 30) and without (n = 5) chronic renal insufficiency on the growth of cultured adult cardiomyocytes were compared. An adult rat cardiomyocyte primary culture system was established with a high purity of cardiomyocyte population as confirmed by immunocytochemical staining of cardiac contractile proteins. Myocytes responded with increased [3H]thymidine incorporation when treated with angiotensin II, epidermal growth factor, hydrocortisone and insulin, and with increased [3H]phenylalanine incorporation when treated with parathormone, isoproterenol, phenylephrine and insulin. Renal insufficiency serum stimulated [3H]thymidine incorporation was 1.5 times that of the control (P < 0.02) and also tended to increase incorporation of [3H]phenylalanine compared to the control (P = N.S.). Increased [3H]thymidine incorporation by renal insufficiency serum did not correlate with serum insulin, parathormone or glucose in the renal insufficiency patients. A quantitative reverse transcriptase polymerase chain reaction (RT-PCR) method was used to measure renal insufficiency serum-induced atrial natriuretic peptide mRNA expression in cultured cardiomyocytes. Atrial natriuretic peptide (ANP) mRNA was increased 1-3-fold in cardiomyocytes treated with renal insufficiency sera in comparison to control sera. These data suggest that circulating growth factor(s) may contribute to the development of cardiac hypertrophy in patients with renal insufficiency.

Animals↗
PubMed1996

Melanin granule model for laser-induced thermal damage in the retina.

An analytical model for thermal damage of retinal tissue due to absorption of laser energy by finite-sized melanin granules is developed. Since melanin is the primary absorber of visible and near-IR light in the skin and in the retina, bulk heating of tissue can be determined by superposition of individual melanin granule effects. Granules are modeled as absorbing spheres surrounded by an infinite medium of water. Analytical solutions to the heat equation result in computations that are quick and accurate. Moreover, the model does not rely on symmetric beam profiles, and so arbitrary images can be studied. The important contribution of this model is to provide a more accurate biological description of sub-millisecond pulse exposures than previous retinal models, while achieving agreement for longer pulses. This model can also be naturally extended into the sub-microsecond domain by including vaporization as a damage mechanism. It therefore represents the beginning of a model which can be applied across the entire pulse duration domain.

Animals↗
PubMed1996

A potential clinical method for calculating transmural left ventricular filling pressure during positive end-expiratory pressure ventilation: an intraoperative study in humans.

OBJECTIVES: This study sought to investigate whether right atrial pressure could be used to estimate pericardial pressure during positive end-expiratory pressure (PEEP). BACKGROUND: Because of elevated intrathoracic pressure during PEEP, pulmonary capillary wedge pressure may not accurately reflect left ventricular preload. An estimate of pericardial pressure during PEEP would allow assessment of transmural filling pressure. METHODS: In eight patients, at the start of cardiac surgery, pericardial and pleural pressures were recorded by balloon transducers placed over the anterolateral left ventricular wall. We also recorded intravascular pressures and left ventricular short-axis area by transesophageal echocardiography. RESULTS: A stepwise increase in PEEP from 0 to 15 cm H2O caused a linear increase in pleural pressure from 0.3 +/- 0.6 (mean +/- SEM) to 6.1 +/- 0.8 mm Hg (p < 0.01). Pericardial pressure increased from 2.3 +/- 0.5 to 5.9 +/- 0.6 mm Hg (p < 0.01). The correlation between right atrial (Pra) and pericardial pressure (Pperic) was good: Pra = 0.85 x Pperic + 1.8, r = 0.77. The correlation between changes in right atrial pressure and in pericardial pressure was better: delta Pra = 0.96 x delta Pperic -0.2, r = 0.97. Pulmonary capillary wedge pressure increased with PEEP (p < 0.05), whereas left ventricular area decreased (p < 0.05). However, there was a progressive reduction in transmural pressure, calculated as wedge pressure minus pericardial pressure (p < 0.05), and in transmural pressure, estimated as wedge pressure minus right atrial pressure (p < 0.05). The estimated transmural filling pressure correlated (r = 0.86) with end-diastolic area. CONCLUSIONS: The present observations suggest that right atrial pressure may be used to estimate changes in pericardial pressure with PEEP and that pulmonary capillary wedge pressure minus right atrial pressure is a potentially clinically useful approximation of transmural filling pressure.

Adult↗
PubMed1996

Prevalent left ventricular hypertrophy in the predialysis population: identifying opportunities for intervention.

Left ventricular hypertrophy (LVH) is present in over 70% of patients commencing dialysis. It is an independent risk factor for cardiac death, which is the cause of death in approximately 45% of patients in dialysis. The prevalence of LVH in patients earlier in the course of renal insufficiency is unknown. As part of a prospective longitudinal study evaluating the progression of comorbid diseases in patients with progressive renal disease, we evaluated LVH. In 175 consecutive patients attending a renal insufficiency clinic we obtained technically adequate echocardiograms and estimated left ventricular mass index (LVMI) using two-dimensional targeted M-mode echocardiography. We calculated LVMI using the American Society of Echocardiography cube formula method regressed to anatomic validation. The population consisted of 115 men and 60 women ranging in age from 20 to 82 years (mean age, 51.5 years). The mean creatinine was 403 +/- 207 micro mol/L (+/-SD), representing a creatinine clearance (Ccr) of 25.5 +/- 17 mL/min. Left ventricular hypertrophy was defined as LVMI greater than 131 g/m(2) in men and greater than 100 g/m(2) in women, and was present in 38.9% of the population studied. We demonstrate that the prevalence of LVH increased with progressive renal decline: 26.7% of patients with Ccr greater than 50 mL/min had LVH, 30.8% of those with Ccr between 25 and 49 mL/min had LVH, and 45.2% of patients with severe renal impairment (Ccr <25 L/min) had LVH (P = 0.05). The mean LVMI was significantly different among the three groups (97.5 g/m(2) v 114.4 g/m(2), respectively; P < 0.001). Univariate analyses revealed that age, hemoglobin, systolic blood pressure and Ccr were significantly different between the groups with and without LVH. The logistic regression model confirmed the findings of the univariate analysis: an increase in age of 5 years was associated with an increase of 3% in risk of LVH (P = 0.0094), as was an increase in systolic blood pressure of 5 mm Hg (P = 0.0018). For each 10 g/L decrease in hemoglobin, the risk of LVH increased by 6% (P = 0.0062), and for each 5 mL/min decline in Ccr the risk increased by 3% (P = 0.0168). We demonstrate the high prevalence of LVH in patients with renal insufficiency prior to the need for dialysis, which is associated with severity of renal impairment, and identify two modifiable factors (systolic blood pressure and anemia) as important predictors of LVH. We suggest that future studies should focus on interventions aimed at attenuating the impact of these factors.

Adult↗
PubMed1996

Comparison of transesophageal echocardiographic, fick, and thermodilution cardiac output in critically ill patients.

PURPOSE: Recent observations have highlighted errors in the thermodilution technique of measuring cardiac output. Thus, cardiac output measurements using transesophageal echocardiography and the Fick method were compared with simultaneous thermodilution measurements. METHODS: In 13 mechanically ventilated critically ill patients, cardiac output was determined simultaneously using (1) transesophageal echocardiography (COTEE, (2) the Fick method (COFICK, and (3) thermodilution (COTD immediately before and after a rapid infusion of 500 mL of saline. Left ventricular end-diastolic and end-systolic areas were measured using the transesophageal echocardiographic transgastric short axis view, and COTEE was calculated from the corresponding volumes. Absolute cardiac output values and the changes from before to after saline infusion (delta CO) were compared using analysis of variance, linear regression, and the Bland and Altman method. RESULTS: There were no significant differences between COTEE (8.0 +/- 3.4), COFICK (8.4 +/- 3.3), and COTD (8.3 +/- 3.0) or between delta COTEE, delta COFICK, and delta COTD using analysis of variance. However, correlations between COTEE and COTD (r2 = 0.46; P < .00001), COFICK and COTD (r2 = 0.46; P < .0001), and COTEE and COFICK (r2 = 0.42; P < .0001) were only moderately good. Using the method of Bland and Altman, the mean difference (+/-2 standard deviations) between COTEE and COTD was 0.3 +/- 4.3 L/min, between COFICK and COTD was -1.0 +/- 3.8 L/min, and between COTEE and COFICK was 0.6 +/- 5.6 L/min, whereas the difference between delta COTEE and delta COTD was 0% +/- 26%, between delta COFICK and delta COTD was 9% +/- 46%, and between delta COTEE and delta COFICK was 8% +/- 39%. CONCLUSIONS: There are substantial differences in cardiac output as measured by these three methods, best demonstrated using the method of Bland and Altman. The variability of cardiac output and its derivatives (eg, oxygen delivery) should be borne in mind when making clinical decisions on individual patients.

Analysis of Variance↗
PubMed1994

Mobile Minos elements from Drosophila hydei encode a two-exon transposase with similarity to the paired DNA-binding domain.

Elements related to the Tc1-like Minos mobile element have been cloned from Drosophila hydei and sequenced. Southern blot and sequence analyses show that (i) the elements are actively transposing in the Drosophila hydei germ line, (ii) they are characterized by a striking degree of sequence and size homogeneity, and (iii) like Tc1, they insert at a TA dinucleotide that is probably duplicated during the process. The nucleotide sequences of two elements, Minos-2 and Minos-3, differ at only one position from each other and contain two nonoverlapping open reading frames that are separated by a putative 60-nucleotide intron. The amino-terminal part of the Minos putative transposase shows sequence similarity to the paired DNA-binding domain. Forced transcription of a modified Minos element that was introduced into the Drosophila melanogaster germ line by P element-mediated transformation resulted in the production of accurately spliced polyadenylylated RNA molecules. It is proposed that Minos-2 and/or Minos-3 may encode an active transposase containing an amino-terminal DNA-binding domain that is distantly related to the paired DNA-binding domain.

Amino Acid Sequence↗
PubMed1994

Juxtacardiac pleural pressure during positive end-expiratory pressure ventilation: an intraoperative study in patients with open pericardium.

OBJECTIVES: This study was conducted to measure the cardiac constraining effect of the lungs during positive end-expiratory pressure and relate extracardiac pleural pressure (radial stress) to airway pressure, right atrial pressure and left ventricular filling. BACKGROUND: During positive end-expiratory pressure ventilation, the extracardiac pressure is elevated, and therefore intracavitary filling pressure does not reflect ventricular preload. Estimates of this pressure might be useful clinically to assess left ventricular preload. METHODS: In eight patients who had undergone coronary or valvular surgery and whose pericardium was left widely open, a flat pleural balloon transducer was placed over the anterolateral left ventricular wall. We recorded pulmonary capillary wedge pressure, right atrial pressure and left ventricular short-axis end-diastolic area by transesophageal echocardiography. Incremental positive end-expiratory pressure was applied. RESULTS: Extracardiac pleural pressure increased (p < 0.01) from 0.6 +/- 1.8 (+/- SD) to 2.4 +/- 1.8, 5.3 +/- 1.5 and 8.2 +/- 1.5 mm Hg at a positive end-expiratory pressure of 5, 10 and 15 cm H2O, respectively. The slope relating extracardiac pleural pressure to positive end-expiratory pressure (in mm Hg) was 0.70 +/- 0.10, and the intercept was zero. Increasing extracardiac pleural pressure was associated with a progressive increase in pulmonary capillary wedge pressure and a decrease in left ventricular end-diastolic area. Consequently, although pulmonary capillary wedge pressure and left ventricular area changed in opposite directions, the value of pulmonary capillary wedge pressure minus extracardiac pleural pressure correlated positively with left ventricular area (r = 0.95, p < 0.001). Changes in right atrial pressure (Pra) correlated with changes in extracardiac pleural pressure (Ppleural): delta Pra = -0.3 + 0.56. delta Ppleural (r = 0.89, p < 0.001). CONCLUSIONS: In postoperative patients with open pericardium, pulmonary capillary wedge pressure minus extracardiac pleural pressure predicts left ventricular end-diastolic area during positive end-expiratory pressure. Further studies should be done to determine whether the observed relations between airway pressure and extracardiac pleural pressure and between right atrial pressure and extracardiac pleural pressure may give clinically useful estimates of left ventricular preload during positive end-expiratory pressure.

Aged↗