. Treatment of subclinical hypothyroidism reverses ischemia and prevents myocyte loss and progressive LV dysfunction in hamsters with dilated cardiomyopathy. Am J Physiol Heart Circ Physiol 289: H2409 -H2415, 2005. First published July 15, 2005; doi:10.1152/ajpheart.00483.2005.-Growing evidence suggests that thyroid dysfunction may contribute to progression of cardiac disease to heart failure. We investigated the effects of a therapeutic dose of thyroid hormones (TH) on cardiomyopathic (CM) hamsters from 4 to 6 mo of age. CM hamsters had subclinical hypothyroidism (normal thyroxine, elevated TSH). Left ventricular (LV) function was determined by echocardiography and hemodynamics. Whole tissue pathology and isolated myocyte size and number were assessed. TH treatment prevented the decline in heart rate and rate of LV pressure increase and improved LV ejection fraction. The percentage of fibrosis/necrosis in untreated 4-mo-old CM (4CM; 15.5 Ϯ 2.2%) and 6-mo-old CM (6CM; 21.5 Ϯ 2.4%) hamsters was pronounced and was reversed in treated CM (TCM; 11.9 Ϯ 0.9%) hamsters. Total ventricular myocyte number was the same between 4-and 6-mo-old controls but was reduced by 30% in 4CM and 43% in 6CM hamsters. TH treatment completely prevented further loss of myocytes in TCM hamsters. Compared with agematched controls, resting and maximum coronary blood flow was impaired in 4CM and 6CM hamsters. Blood flow was completely normalized by TH treatment. We conclude that TH treatment of CM hamsters with subclinical hypothyroidism normalized impaired coronary blood flow, which prevented the decline in LV function and loss of myocytes. thyroid hormones; remodeling; fibrosis; blood flow THE EFFECTS OF THYROID HORMONES (TH) on the cardiovascular system have been well studied. It is clear that both hypothyroidism and hyperthyroidism can lead to deleterious changes in cardiovascular function. Decreased TH levels have been reported in a variety of nonthyroidal illnesses (18), including congestive heart failure (12) and myocardial infarction (6). The decrease in TH levels also appears to be related to the severity of heart failure (12). This is not a minor point, because low 3,5,3'-triiodothyronine (T 3 ) concentrations are a strong, independent predictive marker of poor prognosis in cardiac patients and might represent a determining factor directly implicated in the evolution and prognosis of these conditions (14). Growing evidence also suggests that subclinical thyroid dysfunction might play an important role in heart failure (10, 21). This is highly relevant from a clinical standpoint because this patient group does not typically receive TH treatment.Development of heart failure is accompanied by a variety of neuroendocrine changes. Cardiac failure was shown to be associated with both a decline in circulating TH levels (11,17) and altered cardiac TH signaling, as evidenced by changes in myocardial expression of TH nuclear receptor isoforms (15,16). The observation that short-term TH administration improves cardiac performance, both in anim...

The hemolysin-determining plasmid pAD1 is a member of a widely disseminated family of highly conjugative elements commonly present in clinical isolates of Enterococcus faecalis. The determinants repA, repB, and repC, as well as adjacent iteron sequences, are believed to play important roles in pAD1 replication and maintenance. The repA gene encodes an initiator protein, whereas repB and repC encode proteins related to stability and copy number. The present study focuses specifically on repA and identifies a replication origin (oriV) within a central region of the repA determinant. A small segment of repA carrying oriV was able to support replication in cis of a plasmid vector otherwise unable to replicate, if an intact RepA was supplied in trans. We demonstrate that under conditions in which RepA is expressed from an artificial promoter, a segment of DNA carrying only repA is sufficient for stable replication in E. faecalis. We also show that RepA binds specifically to oriV DNA at several sites containing inverted repeat sequences (i.e., IR-1) and nonspecifically to single-stranded DNA, and related genetic analyses confirm that these sequences play an important role in replication. Finally, we reveal a relationship between the internal structure of RepA and its ability to recognize oriV. An in-frame deletion within repA resulting in loss of 105 nucleotides, including at least part of oriV, did not eliminate the ability of the altered RepA protein to initiate replication using an intact origin provided in trans. The relationship of RepA to other known initiator proteins is also discussed.pAD1 is a 60-kb, conjugative plasmid originally identified in Enterococcus faecalis DS16 (12,23,49). It encodes a cytolysin (hemolysin/bacteriocin) that contributes to virulence in animal models (8,37,40) and is one of numerous plasmids in E. faecalis that facilitate a response to peptide sex pheromones secreted by plasmid-free (recipient) bacteria. pAD1 responds to the pheromone cAD1 and represents a widely disseminated family of cytolysin plasmids commonly associated with clinical infections in humans (38) and which, for the most part, are members of the same incompatibility group (13,34). (For recent reviews, see references 9 and 10.)Nucleotide sequence data relating to plasmids from different incompatibility groups (e.g., pAD1, pAM373, pCF10, and pPD1) and responding to four different pheromones have shown that the regions associated with replication and maintenance are organized similarly; in all cases, this region is located adjacent to that involved in regulation of the pheromone response (9, 10). In the case of pAD1 the key determinants associated with plasmid maintenance are repA, repB, and repC (Fig. 1A). On the basis of sequence homology, repA is believed to encode the initiator of vegetative replication, whereas repB and repC most likely represent a partition system (50, 54). When a segment carrying these three determinants was cloned on an E. coli plasmid vector, it enabled the chimera to replicate in E. faecalis (52...

Enterococcus faecalis plasmid pAD1 is a 60-kb conjugative, low-copy-number plasmid that encodes a mating response to the peptide sex pheromone cAD1 and a cytolytic exotoxin that contributes to virulence. Although aspects of conjugation have been studied extensively, relatively little is known about the control of pAD1 maintenance. Previous work on pAD1 identified a 5-kb region of DNA sufficient to support replication, copy control, and stable inheritance (K. pAD1 is representative of a large and globally disseminated family of conjugative plasmids in Enterococcus faecalis. It is a 60-kb, low-copy-number (one to four copies per chromosome) element that encodes a mating response to the peptide sex pheromone cAD1. It also determines a virulence-related cytolytic (hemolysin/bacteriocin) exotoxin, as well as resistance to UV light. (For recent reviews of pheromone-responding plasmids, see references 6, 7, and 8.) Although aspects of conjugation have been studied extensively, much less is known about the control of pAD1 replication and maintenance. A previous investigation of pAD1 identified a 5-kb region of DNA able to support replication, copy control, and stable inheritance, and it was found that three determinants, designated repA, repB, and repC, were necessary for normal maintenance (46). Data suggested that RepA (336 amino acids) was involved in replication initiation whereas RepB (281 amino acids) and RepC (123 amino acids) were involved in maintaining copy number and stability. As illustrated in Fig. 1, the repA and repB determinants diverge and are separated by a series of iterons, whereas repC is immediately downstream of, and probably transcribed together with, repB. The iterons correspond to two groups of octanucleotide repeats with the sequence TAGTARRR: 13 iterons and 12 iterons are separated by a 75-bp AT-rich (80%) "spacer." There are also three tandemly arranged iterons located downstream of repC.ERecently, the pAD1 replication initiator (RepA) and the origin of vegetative replication (oriV) were identified and characterized (15). It was found that repA alone, under an artificial promoter, was sufficient for replication when cloned on a plasmid devoid of replication ability. The chimera maintained itself at a high copy number (20 to 30 copies per chromosome), in contrast to the low copy number of intact pAD1. In addition, the replication origin was found to be located within a 170-bp segment of repA, which alone could facilitate replication in cis as long as RepA was provided in trans. RepA was also found to bind specifically to several sites containing inverted-repeat sequences within oriV and bound nonspecifically to singlestranded DNA (15).Whereas RepA alone was able to support replication, the high-copy-number repA chimera was not highly stable in that after 30 generations of unselected growth in broth about 60% of the cells were observed to have lost the plasmid (15); an efficient partitioning system was clearly missing. Good candidates for components of a partition system in the intact pAD1 are...

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Ketoacidosis is a metabolic condition that occurs as a result of an insufficient amount of insulin. The lack of insulin results in an increased release of glucose from the liver and an excess of ketone bodies as a result of the breakdown of adipose tissue. This occurs when carbohydrates are unable to be properly processed for needed energy requirements during cellular metabolism. Ketoacidosis is commonly linked to diabetes mellitus. Diabetes mellitus is a condition where the body is unable to produce the proper amount of insulin or is unable to effectively respond to insulin stimulation. Excessive alcohol use can damage the pancreas, reducing insulin secretion. Other conditions such as pneumonia or urinary tract infections can trigger the release of counter-regulatory hormones that may contribute to the decrease in insulin's activity and secretion. Symptoms of diabetic ketoacidosis often include nausea and vomiting, increased thirst and urine production, hyperglycemia, abdominal pain, shortness of breath, confusion, headache, general weakness, fatigue and increased heart rate. If left untreated, diabetic ketoacidosis can lead to more serious complications including circulatory collapse, decreased blood potassium levels, infection and cerebral edema. The following case study presents a complex condition of ketoacidosis associated with a bacterial infection compounded by the patient's history of alcohol abuse.