Divergent selection for opsin gene variation in guppy (Poecilia reticulata) populations of Trinidad and Tobago.

The guppy is known to exhibit remarkable interindividual variations in spectral sensitivity of middle to long wavelength-sensitive (M/LWS) cone photoreceptor cells. The guppy has four M/LWS-type opsin genes (LWS-1, LWS-2, LWS-3 and LWS-4) that are considered to be responsible for this sensory variation. However, the allelic variation of the opsin genes, particularly in terms of their absorption spectrum, has not been explored in wild populations. Thus, we examined nucleotide variations in the four M/LWS opsin genes as well as blue-sensitive SWS2-B and ultraviolet-sensitive SWS1 opsin genes for comparison and seven non-opsin nuclear loci as reference genes in 10 guppy populations from various light environments in Trinidad and Tobago. For the first time, we discovered a potential spectral variation (180 Ser/Ala) in LWS-1 that differed at an amino acid site known to affect the absorption spectra of opsins. Based on a coalescent simulation of the nucleotide variation of the reference genes, we showed that the interpopulation genetic differentiation of two opsin genes was significantly larger than the neutral expectation. Furthermore, this genetic differentiation was significantly related to differences in dissolved oxygen (DO) level, and it was not explained by the spatial distance between populations. The DO levels are correlated with eutrophication that possibly affects the color of aquatic environments. These results suggest that the population diversity of opsin genes is significantly driven by natural selection and that the guppy could adapt to various light environments through color vision changes.

Cryptic MHC polymorphism revealed but not explained by selection on the class IIb peptide-binding region.

The immune genes of the major histocompatibility complex (MHC) are characterized by extraordinarily high levels of nucleotide and haplotype diversity. This variation is maintained by pathogen-mediated balancing selection that is operating on the peptide-binding region (PBR). Several recent studies have found, however, that some populations possess large clusters of alleles that are translated into virtually identical proteins. Here, we address the question of how this nucleotide polymorphism is maintained with little or no functional variation for selection to operate on. We investigate circa 750-850 bp of MHC class II DAB genes in four wild populations of the guppy Poecilia reticulata. By sequencing an extended region, we uncovered 40.9% more sequences (alleles), which would have been missed if we had amplified the exon 2 alone. We found evidence of several gene conversion events that may have homogenized sequence variation. This reduces the visible copy number variation (CNV) and can result in a systematic underestimation of the CNV in studies of the MHC and perhaps other multigene families. We then focus on a single cluster, which comprises 27 (of a total of 66) sequences. These sequences are virtually identical and show no signal of selection. We use microsatellites to reconstruct the populations' demography and employ simulations to examine whether so many similar nucleotide sequences can be maintained in the populations. Simulations show that this variation does not behave neutrally. We propose that selection operates outside the PBR, for example, on linked immune genes or on the "sheltered load" that is thought to be associated to the MHC. Future studies on the MHC would benefit from extending the amplicon size to include polymorphisms outside the exon with the PBR. This may capture otherwise cryptic haplotype variation and CNV, and it may help detect other regions in the MHC that are under selection.

Selection by parasites in spate conditions in wild Trinidadian guppies (Poecilia reticulata).

Gyrodactylids are ubiquitous fish parasites and yet, with the notable exception of Gyrodactylus salaris, few studies have reported the effect of these parasites on host survival in natural populations. Here, we assess the impact of the parasite load of gyrodactylids (G. turnbulli and G. bullatarudis) on the survival and migration of guppies (Poecilia reticulata) in their natural habitat of the Aripo River in Trinidad. The recapture rate of males declined by 19% with every additional parasite, a remarkably high figure given that the parasite load in this study ranged from zero to 20 worms. In addition, with an increased number of parasites, males were more prone to be recovered downstream. In contrast, no effect of parasitism was observed in females. The mean parasite load sharply declined after a series of flushing events during heavy seasonal downpours. The parasite load varied significantly between fish depending on their location in the river, and the size of the fish explained variation in parasite load between individuals. The present study indicates that tropical gyrodactylid parasites can play an important role in the ecology of natural fish populations, causing intense bouts of natural selection in guppies during heavy rains in the wet season.

Sudden blowout rupture of the myocardium after infarction: urgent management. Report of four cases.

Blowout rupture of the myocardium is intended to describe a syndrome of sudden hemodynamic deterioration after myocardial infarction. Characterized by abrupt hypotension, cardiac tamponade, or electromechanical dissociation, it is an emergency of the first order with no time for cardiac catheterization. Frequently one must make the diagnosis and race for the operating room almost simultaneously. We have managed four such patients, one with a ruptured false aneurysm and three patients with acute rupture of recently infarcted myocardium. All patients were placed on femoro-femoral bypass initially and all survived operation. Two patients died in the hospital of irreversible brain damage and two are long-term survivors. A high index of suspicion, a well-coordinated operating team, and a willingness to take the bold step to the operating room, frequently on the basis of clinical judgment alone, are necessary to salvage patients with this syndrome.

Lysis of a left ventricular thrombus with recombinant tissue plasminogen activator.

A 23-year-old woman with peripartum cardiomyopathy presented with a 2.1 x 2.5-cm pedunculated, mobile, left ventricular thrombus and evidence of systemic embolization. Due to the patient's poor left ventricular function, thrombectomy was not a viable option. Treatment with high-dose IV heparin was initially utilized but was unsuccessful as the thrombus appeared to enlarge on echocardiography. An accelerated weight-adjusted dose of recombinant tissue plasminogen activator (rt-PA) successfully lysed the thrombus without evidence of embolization. Although rt-PA has been used for primary lysis of high-risk ventricular thrombi, this is the first documentation of successful lysis of a left ventricular thrombus in a patient with peripartum cardiomyopathy.

Total anomalous pulmonary venous connection: surgical correction in a 66-year-old man.

A cyanotic, debilitated 66-year-old man was referred as an emergency because of embolic arterial occlusion of the left lower extremity. Subsequent investigation revealed total anomalous pulmonary venous connection. Complete surgical correction was accomplished. Despite a difficult postoperative hospital course, more than 3 years after operation he continues to experience improved quality of life with better exercise tolerance, freedom from further emboli and symptomatic arrhythmias, and no need for his previously routine phlebotomies.

Surgical experience with left ventricular free wall rupture.

BACKGROUND: Autopsy studies reveal that left ventricular free wall rupture (LVFWR) accounts for 7% to 24% of deaths after myocardial infarction. The condition occurs up to 10 times more often than papillary muscle or interventricular septal rupture. A high index of suspicion must be maintained to differentiate LVFWR from infarct extension, cardiogenic shock, pulmonary embolus, and even Dressler's syndrome. METHODS: Since 1980, we have operated on 18 patients with LVFWR. Fourteen patients had experienced "blow-out" rupture associated with cardiogenic shock. Four patients had "stuttering" ruptures, a less spectacular occurrence. Echocardiography was the most important diagnostic tool. Repair was performed, usually using infarctectomy and direct suture closure. RESULTS: Eleven patients (61%) died after operation, 4 patients as a result of rerupture 1 to 12 hours after operation. Recently, we have used a "patch/glue" technique to repair ruptures in 2 patients. We believe this technique is superior to direct suture closure in preventing rerupture. There have been 7 long-term survivors (39%) from 6 months to 15 years. CONCLUSIONS: Left ventricular free wall rupture is not always sudden and dramatic. Yet, the operating staff must be willing to race to the operating room even with the patient in full resuscitation. Echocardiography is the most sensitive and efficient diagnostic tool. All rupture sites should be aggressively repaired, possibly combining direct suture and patch/glue techniques.

HCFA's consumer information commitment.

This article provides examples of how the Health Care Financing Administration is providing Medicare and Medicaid beneficiaries with information that will allow them to become more active participants in decisions affecting their health and well-being. The article emphasizes how HCFA has incorporated a beneficiary-centered focus and social marketing techniques in its consumer information activities. The work described in this article represents a cross section of the innovative and excellent work being done by staff throughout the Agency and by our partners and agents in meeting the information needs of beneficiaries.

The Medicare experience with end-stage renal disease: trends in incidence, prevalence, and survival.

This article presents a detailed account of the incidence, prevalence, and survival experience of people with end-stage renal disease (ESRD) covered by Medicare. The number of new entrants into the ESRD program has risen since its inception. This increase is greatest for people whose cause of renal failure is primary hypertensive disease or diabetic nephropathy. The program incidence rates for black people is 2.8 times that of white people. Incidence is highest for persons 65 to 69 years of age. Total patient survival is 44 percent 5 years after renal failure onset. Total Medicare enrollment for ESRD quadrupled between the years 1974 and 1981.

A data-driven approach to improving the care of in-center hemodialysis patients.

Health care providers, patients, the end stage renal disease (ESRD) networks, and HCFA have developed the ESRD Health Care Quality Improvement Program (HCQIP) in an effort to assess and improve care provided to ESRD patients. Currently, the ESRD HCQIP focuses on collecting information on quality indicators (QIs) for treatment of anemia, delivery of adequate dialysis, nutritional status, and blood pressure control for adult in-center hemodialysis patients. QIs were measured in a national probability sample of ESRD patients, and interventions and evaluations of the interventions are beginning. The ESRD HCQIP illustrates a way to mobilize the strengths of the public and private sectors to achieve improved care for special populations.

Distal bypass for limb salvage in very elderly patients.

During the last 3 1/2 years, 40 bypasses to a tibial or peroneal artery (distal bypass) were performed for severe leg ischemia in 34 patients who were 80 years of age or older (range, 80-91; mean, 85). The operative mortality rate was 5 per cent. Cumulative life-table limb salvage rates for the 40 extremities were 91 per cent at 1 year and 81 per cent at 3 years. Graft patency rates at 1 and 3 years were 88 per cent and 56 per cent, respectively. Survival rates for the 36 patients were 91 per cent and 58 per cent at 1 and 3 years, respectively. Among 134 patients younger than 80 years who underwent 142 distal bypasses during the same 3 1/2-year period, no operative deaths occurred. In this younger group, cumulative life-table rates at 1 and 3 years were 89 per cent and 89 per cent, respectively, for limb salvage, 86 per cent and 85 per cent, respectively, for graft patency, and 93 per cent and 78 per cent, respectively, for survival. There were no statistically significant differences in these figures for the younger group when compared with corresponding figures for the older group. Among the 36 very elderly patients who underwent distal bypass for limb salvage, 24 patients (67%) with 25 revascularized limbs are alive and have a salvaged, functional extremity after follow-up as long as 41 months (mean, 21 months). These results suggest that an aggressive approach using distal bypass is warranted for limb salvage in very elderly patients.

Managing serum phosphate in haemodialysis patients: time for an innovative approach?

BACKGROUND/OBJECTIVES: Hyperphosphataemia, a common biochemical abnormality in chronic kidney disease, poses significant management challenges. This study aims to determine whether the reasons for this are multifactorial; including poor dietary knowledge, poor adherence to a low phosphate diet and phosphate-binding medications and the impact of age on these parameters. SUBJECTS/METHODS: In order to compare serum phosphate and other associated parameters to the UK Renal Association Clinical Practice Guidelines 2010 an audit and service evaluation questionnaire was carried out in May 2011 on 130 haemodialysis outpatients attending the Plymouth Dialysis Unit. RESULTS: Fifty-three percent of patients had serum phosphate within the target range of 1.1-1.7 mmol/l, 77% and 85% had serum calcium and parathyroid hormone within target ranges, respectively. Younger patients (18-45 years) were significantly less likely to have serum phosphate within range χ(2) (2, n=124)=18.77, P<0.001. Despite better knowledge of their own phosphate levels (P=0.005), phosphorus-rich foods (P<0.001), symptoms of hyperphosphataemia (P<0.001) and increased use of Renal Patient View (P=0.002), <65 years old had significantly higher phosphate levels than those >65 years (P<0.001). No significant associations were found between phosphate control and the following factors: gender, timing of dialysis shift, years on dialysis or dialysis adequacy. CONCLUSIONS: In this population, despite better knowledge, younger patients have worse phosphate control than older patients. Using the same dietary education techniques may not be suitable for all ages, more innovative approaches supported by skilled health professionals are needed to motivate and engage with younger patients to promote self-management and adherence.