Preillness non dietary factors and habits in inflammatory bowel disease

AIM

Environmental as well as genetic factors play a role in the pathogenesis of inflammatory bowel diseases. The effects of smoking and diet have been demonstrated. Other factors have not been extensively investigated.

PATIENTS

Preillness non dietary habits and factors were studied in 88 patients with recent onset of inflammatory bowel diseases (55 with ulcerative colitis and 33 with Crohn's disease) and in matched 76 population and 68 clinic controls.

RESULTS

No significant differences were found in relation to education, housing, birth weight, breast feeding in infancy and current weight. The current body mass index was significantly lower in patients as compared to clinic controls (p < 0.05). More patients had low levels of physical activity during the preillness period as compared to controls (p < 0.001 vs clinic controls), while more controls engaged in moderate (p < 0.05) or high levels of physical activity in the corresponding periods. Patients spent fewer hours in strenuous physical activity as compared to controls (NS). Patients slept fewer hours per day (p < 0.05 vs clinic controls). More patients than controls experienced stressful life events during the year prior to onset of symptoms (p < 0.05 for patients with Crohn's disease against both controls and all patients vs population controls).

CONCLUSIONS

Other environmental factors besides smoking and diet may affect the pathogenesis of inflammatory bowel disease.

Biometric analysis of physiologically structured pure bacterial cultures recovering from starvation

Cell volume distribution patterns were used to characterize the status of physiologically heterogeneous monospecific populations of bacteria. Such physiologically structured populations typically consist of subpopulations of cells in different metabolic and regulatory states. During recovery from starvation the differentiation of active (growing, proliferating) and quiescent (nonproliferating) subpopulations becomes detectable. Since cell volume distributions may be distorted by background noise or debris, we developed a method to extrapolate size distributions from a reduced set of reliable data. The extrapolation procedure is based upon a lognormal distribution of cell sizes. By the same approach we were able to differentiate between subpopulations even when their size ranges overlapped. The analyses of size distributions were also used, partly in combination with fluorescence microscopy, to investigate the population dynamics of Pseudomonas fluorescens and Nitrosomonas europaea during recovery from energy deprivation.Key words: physiologically heterogeneous populations, cell volume distribution, population dynamics, Pseudomonas fluorescens, Nitrosomonas europaea.

[Indirect methods in the genetic diagnosis of hemophilia A]

In haemophilia A (HA), besides the direct detection of the most common mutation of the factor VIII gene (the gene inversion), it was necessary to establish indirect methods which are suitable to reveal the pattern of inheritance of the genes examined, regardless of the mutations they carry. This task can be achieved by the analysis of DNA polymorphisms located within and in the near proximity of the factor VIII gene. For diagnostic purposes we used an RFLP and two microsatellite polymorphisms. The aim of our program is to provide carrier and also prenatal diagnostics for affected families. So far we completed the analyses of 15 HA patients and 68 of their family members, and we gave prenatal diagnoses in 3 cases. According to the information content of the polymorphisms used, we expect to be able to provide DNA diagnoses to 95% of the Hungarian HA families requesting the test.

Thyrotoxicosis and the heart

This review examines the molecular mechanisms by which thyroid hormone affects the cardiovascular system in naturally occurring thyroid disease states. The potential utility of thyroid hormone therapy in the management of patients with various forms of cardiovascular disease is also discussed.

The direct vasomotor effect of thyroid hormones on rat skeletal muscle resistance arteries

The present study examines the hypothesis that the hormones have direct vasodilatory effects and attempts to determine whether the effects are endothelium-dependent. Rat skeletal muscle resistance arteries of approximately 100 microns were dissected, and vessel diameter changes were monitored using a videodetection system. After equilibration at 37 degrees C, each vessel was preconstricted with the thromboxane analog U46619 1 microM, and the percentage of dilation was measured after exposure to increasing concentrations of triiodothyronine (T3) or levothyroxine (T4) (10(-10) to 10(-7) M). Dilation in response to T3 was also measured after endothelial denudation and pretreatment with the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine (L-NNA) 10 microM, the cyclooxygenase inhibitor indomethacin 10 microM, the adenosine triphosphate-sensitive K+ channel blocker glibenclamide 1 microM, or the beta-adrenergic antagonist propranolol 1 microM. Both T3 and T4 demonstrated concentration-dependent dilation of the U46619-preconstricted vessels (P < 0.001 each), with T3 having a greater effect than T4 (P < 0.05) (36% +/- 9% [mean +/- SD] dilation at 10(-7) M T3 vs 24% +/- 6% dilation at 10(-7) M T4). In comparison, isoproterenol 10(-7) M produced 56% +/- 6% dilation. T3-mediated vasodilation was attenuated but not abolished by endothelial denudation (18% +/- 3% dilation at 10(-7) M T3) (P < 0.01), L-NNA (15% +/- 7% dilation at 10(-7) M T3) (P < 0.01), indomethacin (20% +/- 9% dilation at 10(-7) M T3) (P < 0.05), and glibenclamide (22% +/- 7% dilation at 10(-7) M T3) (P < 0.01), but it was not affected by propranolol (37% +/- 20% dilation at 10(-7) M T3) (P = 0.99). We conclude that thyroid hormones possess direct vasodilatory effects with both endothelium-independent and endothelium-dependent components.

IMPLICATIONS

Thyroid hormones may have modest direct vasodilatory effects. This may partially account for the cardiovascular actions of the hormones in hyperthyroidism or when administered pharmacologically in cardiac surgery.

Myosin heavy chain gene expression in neonatal rat heart cells: effects of [Ca2+]i and contractile activity

To determine if mechanical signals or alterations in intracellular Ca2+ concentration ([Ca2+]i) affect myosin heavy chain (MHC) gene expression in spontaneously beating, neonatal rat ventricular myocytes, contractile activity was inhibited with verapamil, KCl, or 2,3-butanedione monoxime (BDM), and their acute and chronic effects on myocyte shortening, [Ca2+]i, and MHC gene expression were examined. Despite their differing effects on [Ca2+]i, verapamil, KCl, and BDM all inhibited contractile activity and markedly downregulated beta-MHC mRNA levels to 24 +/- 5, 21 +/- 7, and 6 +/- 2% of contracting cells, respectively. In contrast, these inhibitors of contraction upregulated alpha-MHC mRNA levels to 163 +/- 19, 156 +/- 7, and 198 +/- 20% of contracting cells, respectively. Transient transfection with a rat beta-MHC promoter-luciferase expression plasmid demonstrated that all inhibitors of contraction significantly decreased beta-MHC promoter activity. Paradoxically, contractile arrest also inhibited alpha-MHC promoter activity, suggesting that increased alpha-MHC mRNA levels resulted from posttranscriptional mechanisms. Actinomycin D mRNA stability assays indicated that alpha-MHC mRNA half-life was prolonged in noncontracting cells (33 h) compared with contracting myocytes (14 h). Contraction-dependent alterations in MHC gene expression were not dependent on release of angiotensin II or other growth factors into the culture medium. Thus intrinsic mechanical signals rather than alterations in [Ca2+]i regulate alpha-MHC and beta-MHC gene expression by both transcriptional and posttranscriptional mechanisms.

[Can primary kidney clear cell adenocarcinoma be differentiated from kidney metastasis with computed tomography?]

PURPOSE

To determine if CT scan provides morphologic criteria allowing differentiation between primary renal cell cancer of the clear type (PRCCCT) and renal metastasis (RM).

MATERIALS AND METHODS

Twenty cases of PRCCCT and 20 cases of RM from various origins (excluding lymphomatous origin) were retrospectively analyzed by two independent readers. CT scans were evaluated with respect to tumor size, shape, location and number of tumors, encapsulation, contour sharpness, presence of calcification, and extrarenal involvement by tumor.

RESULTS

A tumor size > 3 cm was more frequently seen in PRCCCT than in RM (100% vs 70% respectively, P < .05). Rounded shape was more frequent in PRCCCT than in RM (90% vs 50% respectively, P < .01). Encapsulation was more frequent in PRCCCT than in RM (70% vs 10%, P < .01, respectively). Calcification was depicted only in PRCCCT (35% vs 0%, P < .01). Enlarged perirenal lymph nodes were less frequent in PRCCCT than in RM (20% vs 55% respectively, P < 0.05).

CONCLUSION

Results of our study show that a constellation of morphologic features suggest the diagnosis of PRCCCT rather than that of RM. Our study suggests that calcification is highly specific for the diagnosis of PRCCCT. However, percutaneous biopsy remains indicated to ascertain the diagnosis.

Pre-illness dietary factors in inflammatory bowel disease

BACKGROUND

The effect of environmental factors has been demonstrated in the pathogenesis of inflammatory bowel disease (IBD). Nutrition may be one of them.

AIM

To investigate the pre-illness diet in patients with recent IBD in comparison with matched population and clinic controls.

METHODS

Quantified dietary histories were obtained from 87 patients with recent IBD (54 ulcerative colitis (UC) and 33 Crohn's disease (CD)) and 144 controls. Odds ratios (OR) for IBD were derived for intake levels of various foods.

RESULTS

A high sucrose consumption was associated with an increased risk for IBD (OR 2.85 (p = 0.03) against population controls and 5.3 (p = 0.00) against clinic controls). Lactose consumption showed no effect while fructose intake was negatively associated with risk for IBD (NS). Similar trends were noted in UC and CD. A high fat intake was associated with an increased risk for UC; this was particularly marked for animal fat (OR 4.09, p = 0.02) and cholesterol (OR 4.57, p = 0.02). A high intake of fluids (p = 0.04), magnesium (p = 0.04), vitamin C, and fruits (NS) was negatively associated with the risk for IBD, while a positive association was found for retinol (p = 0.01). Most of the findings were similar in UC and CD except for potassium and vegetable consumption which showed a negative association only with risk for CD.

CONCLUSIONS

An association was found between pre-illness diet and subsequent development of UC and CD. The effect of dietary components may be primary or modulatory.

Characterization of the human multidrug resistance protein containing mutations in the ATP-binding cassette signature region

A number of mutants with single amino acid replacements were generated in the highly conserved ATP-binding cassette (ABC)-signature region (amino acids 531-543) of the N-terminal half of the human multidrug resistance (MDR1) protein. The cDNA variants were inserted into recombinant baculoviruses and the MDR1 proteins were expressed in Spodoptera frugiperda (Sf9) insect cells. The level of expression and membrane insertion of the MDR1 variants was examined by immunostaining, and MDR1 function was followed by measuring drug-stimulated ATPase activity. We found that two mutations, L531R and G534V, practically eliminated MDR1 expression; thus these amino acid replacements seem to inhibit the formation of a stable MDR1 protein structure. The MDR1 variants G534D and I541R were expressed at normal levels with normal membrane insertion, but showed a complete loss of drug-stimulated ATPase activity, while mutant R538M yielded full protein expression but with greatly decreased ATPase activity. Increasing the ATP concentration did not restore MDR1 ATPase activity in these variants. Some amino acid replacements in the ABC-signature region (K536I, K536R, I541T and R543S) affected neither the expression and membrane insertion nor the ATPase function of MDR1. We found no alteration in the drug-sensitivity of ATP cleavage in any of the MDR1 variants that had measurable ATPase activity. These observations suggest that the ABC-signature region is essential for MDR1 protein stability and function, but alterations in this region do not seem to modulate MDR1-drug interactions directly.

Viewing of self and nonself images in a group of captive orangutans (Pongo pygmaeus Abellii)

Reports on self-recognition in great apes have been mostly derived from experimental studies of mirror behavior (mark test) requiring anesthetization of the animals. We investigated a relatively noninvasive technique to study this behavior. In two experiments with a group of captive orangutans (1 adult male, 3 adult females, 1 juvenile male, and 1 juvenile female), we presented combinations of blank posters, life-size portraits of each individual in the group, a mirror, and videos. Durations of viewing and patterns of viewing were recorded. The prominent features of the viewing were the differences among the individuals in frequency, duration, and pattern of viewing. Some evidence of mirror-based self-referent behavior (behavior in which the activity of the animal with its body was related to the activity of the image in the mirror) was seen in the juvenile female, but more was seen in one adult female. This adult female spent the most time viewing the mirror and was the only animal to view her own portrait more than the other portraits in one session. In addition, she moved from one portrait to another, and back to the first, and to her own portrait and the mirror in a pattern resembling comparison of the two portraits as well as of her portrait and her mirror image. It is suggested that data based on self-referent behavior of the same animal during self-viewing in a mirror and during viewing of its self-portrait and on behavior observed in the mark test are worth further investigation.

Dynamic gadolinium-enhanced subtraction MR imaging--a simple technique for the early diagnosis of Legg-Calvé-Perthes disease: preliminary results

PURPOSE

To determine whether the simple technique of dynamic gadolinium-enhanced subtraction MR imaging, which is available on standard MR units, can detect ischemia of the femoral head in children with early Legg-Calvé-Perthes disease (LCP).

MATERIALS AND METHODS

Bone perfusion of eight hips in four patients (mean age 7.5 years) was studied using dynamic gadolinium-enhanced subtraction MR imaging at the onset of proven LCP (with initial negative plain films). Enhancement of subtracted images was compared with that on standard MR images and with bone scintigraphy findings.

RESULTS

Subtraction MR imaging depicted ischemia as a widespread absence of enhancement and was in good agreement with bone scintigraphy. The subtraction technique improved the sensitivity and the specificity of MR imaging in two children. Furthermore, subtraction MR imaging allowed recognition of the pattern of early reperfusion.

CONCLUSION

Our preliminary results indicate that dynamic gadolinium-enhanced subtraction MRI is a simple and promising means of early recognition of ischemia in LCP.

Functional characteristics of myocardial bridging. A combined angiographic and intracoronary Doppler flow study

AIMS

Combined quantitative coronary angiography and intracoronary Doppler flow velocity measurements were performed to study the underlying haemodynamic mechanisms leading to myocardial ischaemia in patients with myocardial bridging in the absence of coronary artery disease.

METHODS AND RESULTS

In 42 symptomatic patients with myocardial bridging of the left anterior descending coronary artery, quantitative coronary angiography was used to measure absolute and relative vessel diameters during systole and diastole. In 14 patients, serial frame-by-frame diameter quantification during a complete cardiac cycle was performed. Intracoronary blood flow velocities were determined using a 0.014 inch Doppler flow guide wire proximal, within, and distal to myocardial bridges, and coronary flow reserve was calculated. Quantitative coronary angiography revealed a maximal systolic lumen diameter reduction of 71 +/- 16% with a persistent diameter reduction of 35 +/- 13% during mid-diastole. Flow velocities revealed increased average diastolic peak flow velocities within myocardial bridges of 38.6 +/- 19 cm.s-1 vs 22.4 +/- 7.7 cm.s-1 proximal and 18.6 +/- 4.6 cm.s-1 distal (P < 0.001), which increased during rapid pacing (64.7 +/- 25 cm.s-1, P < 0.001 vs baseline). Coronary flow reserve distal to myocardial bridges was 2.3 +/- 0.9 (vs 2.9 +/- 0.9 proximal, P < 0.05). There was a characteristic Doppler flow profile within myocardial bridges with an early diastolic overshoot, which was further augmented during rapid pacing.

CONCLUSION

Myocardial bridging is characterized by a delay in diastolic lumen gain and a concomitant increase in diastolic intracoronary Doppler flow velocities, which are enhanced by rapid pacing. In combination with a reduced coronary flow reserve and anginal symptoms these findings support the concept of a haemodynamically significant obstruction to coronary flow due to myocardial bridging in a selected subset of patients.

Improving care for minority children with asthma: professional education in public health clinics

OBJECTIVE

Recent studies have shown that lack of continuing primary care for asthma is associated with increased levels of morbidity in low-income minority children. Although effective preventive therapy is available, many African-American and Latino children receive episodic treatment for asthma that does not follow current guidelines for care. To see if access, continuity, and quality of care could be improved in pediatric clinics serving low-income children in New York City, we trained staff in New York City Bureau of Child Health clinics to provide continuing, preventive care for asthma.

METHODS

We evaluated the impact of the intervention over a 2-year period in a controlled study of 22 clinics. Training for intervention clinic staff was based on National Asthma Education and Prevention Program guidelines for the diagnosis and management of asthma, and included screening to identify new cases and health education to improve family management. The intervention included strong administrative support by the Bureau of Child Health to promote staff behavior change. We hypothesized that after the intervention, clinics that received the intervention would, compared with control clinics, have increased numbers of children with asthma receiving continuing care in the clinics and increased staff use of new pharmacologic and educational treatment methods.

RESULTS

In both the first and second follow-up years, the intervention clinics had greater positive changes than control clinics on measures of access, continuity, and quality of care. For second year follow-up data these include: for access, greater rate of new asthma patients (40/1000 vs 16/1000; P < .01); for continuity, greater percentage of asthma patients returning for treatment 2 years in a row (42% vs 12%; P < .001) and greater annual frequency of scheduled visits for asthma per patient (1.85 vs .88; P < .001); and for quality, greater percentage of patients receiving inhaled beta agonists (52% vs 15%; P < .001) and inhaled antiinflammatory drugs (25% vs 2%; P < .001), and greater percentages of parents who reported receiving patient education on 12 topics from Bureau of Child Health physicians (71% vs 58%; P < .01) and nurses (61% vs 44%; P < .05).

CONCLUSION

We conclude that the intervention substantially increased the Bureau of Child Health staff's ability to identify children with asthma, involve them in continuing care, and provide them with state-of-the-art care for asthma.

Renal cell carcinoma of clear type: correlation of CT features with tumor size, architectural patterns, and pathologic staging

The purpose of this study was to report the CT findings of renal cell carcinoma of clear type (RCCCT) and to determine if there are characteristic morphologic features in RCCCT with respect to tumor size, architectural patterns, and pathologic stage. The CT scans of 35 patients with RCCCT were reviewed retrospectively. The CT findings (tumor size, attenuation patterns, presence of calcifications, encapsulation, margins of neoplasms, venous involvement by neoplasms) were correlated with tumor size, architectural patterns, and pathologic staging. Of the 35 neoplasms, 28 (80 %) were solid, 4 (11 %) were papillary, and 3 (9 %) were cystic. Complete encapsulation was more frequent in lower pathologic stages (40 % in stages 1 and 2 vs 0 % in stages 3 and 4; p < 0.05). Venous involvement was less frequent with completely encapsulated neoplasms (0 of 10, 0 %) than with incompletely or nonencapsulated neoplasms (8 of 25, 32 %; p < 0.05). Encapsulated RCCCT are more likely to have lower pathologic stage. Nonencapsulated neoplasms are more likely to have a higher pathologic stage.

Cervical spondylotic myelopathy treated with corpectomy: technique and results in 44 patients

Forty-four patients with cervical spondylotic myelopathy who underwent a ventral surgical approach were evaluated with respect to the results of surgery. The neurological status of the patients was categorized according to the modified Japanese Orthopedic Association scale (0-18). Three patients had a functional score of 8, one patient 9, five patients 10, five patients 11, seven patients 12, seven patients 13, seven patients 14, and nine patients had a functional score of 15, preoperatively. Twenty-three patients underwent a one-level corpectomy, 15 patients a two-level corpectomy, and six patients underwent a three-level corpectomy. Forty-one (93.1%) of the 44 patients underwent ventral cervical plate fixation. Complications among the 44 patients included graft-and instrumentation-related complications in seven cases, iliac crest donor-site infection in three cases, and respiratory complications in three cases. The follow-up periods ranged between 7 and 60 months (mean 42.3 months). Overall, the fusion rate was 97.72%. Three patients showed no functional change (6.8%), two patients were worse (4.5%), and 39 patients (88.6%) showed functional improvement in their score between +1 and +6 points (mean 2.16 points). There was no statistically significant difference in the functional improvement score in patients younger or older than 60 years old. The mean improvement in the functional score was found to be +2.857 ± 1.352, +2.400 ± 1.454, and +0.5000 ± 1.871 following one-level corpectomy, two-level, and three-level corpectomies, respectively. There were statistically significant differences in the neurological improvement observed between patients with one-level corpectomy and three-level corpectomy (p < 0.01), as well as between those with two-level and three-level corpectomy (p < 0.05). There was no statistically significant difference in the neurological outcome between patients with one-level and two-level corpectomy (p > 0.05). The results of this study demonstrate a high rate of solid bone fusion and a high rate of functional (neurological) improvement. Five patients underwent reoperation, predominantly for instrumentation failure. The use of instrumentation dictates careful consideration of the risk/benefit ratio associated with its use in each case.

Acute effects of thyroid hormone on vascular smooth muscle

The enhanced cardiovascular hemodynamics associated with triiodo-L-thyronine (T3) treatment is in part mediated by a decrease in systemic vascular resistance. To determine the molecular mechanisms for the vasoactive properties of T3, we studied primary cultures of aortic endothelial and vascular smooth muscle (VSM) cells. Active tension development by the VSM cells was measured by deformation lines within a siloxane matrix on which the cells were grown. Exposure to T3 (10(-10) M) resulted in cellular relaxation within 10 min. Hormone binding studies to purified VSM cell plasma membranes identified two binding sites specific for T3 with Kd of 1 x 10(-11) and 6.1 x 10(-8) M. L-Thyroxine and reverse T3 did not compete for the L-T3 binding sites. To determine an intracellular signaling pathway of T3 action, cAMP and cGMP content were measured in VSM cell cultures treated with T3. No quantitative changes were observed in a time frame known to cause VSM cell relaxation. The level of myosin light chain phosphorylation is a major determinant of smooth muscle contraction. Thus, treatment of VSM cells with isoproterenol, a vasodilator, caused a significant decrease in radiolabeled phosphate incorporation into the myosin light chains, whereas T3 had no effect on phosphorylation of these proteins. Primary cultures of vascular endothelial cells exposed to T3 showed no nitric oxide production as measured by cellular cGMP content and nitrite release, suggesting that T3 acted directly on the VSM cell to cause vascular relaxation.

Functional, angiographic and intracoronary Doppler flow characteristics in symptomatic patients with myocardial bridging: effect of short-term intravenous beta-blocker medication

OBJECTIVES

We sought to define the effects of short-term beta-adrenergic blocking medication on intracoronary flow characteristics, clinical symptoms and angiographic diameter changes in patients with severe myocardial bridging of the left anterior descending coronary artery.

BACKGROUND

Controversy exists regarding the pathophysiology, clinical relevance and optimal therapy in symptomatic patients with myocardial bridges because antianginal drugs have not been systematically tested.

METHODS

In 15 symptomatic patients with myocardial bridging of the left anterior descending coronary artery, maximal lumen diameter reductions were evaluated by quantitative coronary angiography. There were no angiographic signs of coronary artery disease. Coronary blood flow velocities (using a 0.014-in. [0.035 cm] Doppler guide wire) were measured at rest, during atrial pacing and during intravenous administration of a short-acting beta-blocker (esmolol, 50 to 500 micrograms/kg body weight per min) with continuous atrial pacing.

RESULTS

The maximal angiographic systolic lumen diameter reduction within the myocardial bridges was 83 +/- 9% at rest, with a persistent diastolic diameter reduction of 41 +/- 11% (mean +/- SD). Short-term intravenous beta-blocker therapy decreased the diameter reduction during both systole (from 83 +/- 9% to 62 +/- 11%) and diastole (from 41 +/- 11% to 30 +/- 9%, both p < 0.001). The average diastolic peak flow velocity was higher within the myocardial bridges (33 +/- 13 cm/s) than the proximal (26 +/- 13 cm/s) and distal bridges (17 +/- 4 cm/s, both p < 0.001). During tachypacing, average diastolic peak flow velocity increased within the bridged segments to 63 +/- 21 cm/s versus 29 +/- 12 cm/s in the proximal and 20 +/- 4 cm/s in the distal bridges (both p < 0.001). Beta-receptor blockade produced a return to baseline values (average diastolic peak flow velocity within bridge 35 +/- 16 cm/s, p < 0.001). ST segment changes and symptoms were abolished with beta-blocker administration.

CONCLUSIONS

In patients with myocardial bridges, administration of short-acting beta-blockers during atrial pacing alleviates anginal symptoms and signs of ischemia. This effect was mediated by a reduction of vascular compression and maximal flow velocities within the bridged coronary artery segment.

Thyroid hormone and hemodynamic regulation of beta-myosin heavy chain promoter in the heart

Thyroid hormone exerts marked effects on cardiovascular function. Expression of cardiac alpha- and beta-myosin heavy chain (MHC) isoforms can be altered in response to thyroid hormone as well as by hemodynamic changes imposed on the heart. The molecular mechanisms that mediate these changes are not completely known. We studied the contractile and thyroid hormone responsiveness of the betaMHC promoter in both cultured cardiac myocytes and in vivo by direct DNA transfer. Using transient transfection of neonatal rat cardiomyocytes, the activities of recombinant reporter plasmids containing betaMHC 5'-flanking sequences terminating at positions -2250, -1145, -670, and -354 were decreased significantly in cultures containing L-T3 (50 nM). Similar deletion analysis showed that 5'-flanking regions terminating within -2250 to -151 bp were contractility responsive; however, deletion to position -126 attenuated this response. In vivo betaMHC promoter activity, determined by injecting the recombinant plasmid into the myocardium, was significantly higher by 2-fold in hyperthyroid than in euthyroid ventricles (2.47 +/- 0.41 vs. 1.33 +/- 0.25 luciferase/ chloramphenicol acetyltransferase; P<0.05). Increased ventricular workload, produced by aortic coarctation for 5 days, resulted in ventricular hypertrophy (heart/body weight, 4.05 +/- 0.19 vs. 3.42 +/- 0.16 mg/g; P < 0.02) and a 3.4-fold increase in betaMHC messenger RNA content. However, betaMHC promoter activity in vivo was not significantly different between rats experiencing aortic coarctation and sham-operated rats (1.49 +/- 0.41 vs. 0.96 +/- 0.27 luciferase chloramphenicol acetyltransferase, respectively) and was similar to that in euthyroid animals. These results show that betaMHC promoter activity is T3 responsive in cultured myocytes and in vivo, but that the increase in betaMHC messenger RNA observed in the in vivo pressure overloaded myocardium cannot be explained entirely by transcription control mechanisms.