Atrial Septal Defect Closure: Not Always Straightforward.

A nine-year old boy presented following a chest x-ray for COVID-19 infection that showed cardiomegaly. Transthoracic echocardiogram revealed a large atrial septal defect, dilated right heart, and normal function. Surgical repair was performed eight weeks after his COVID diagnosis. After weaning from cardiopulmonary bypass, pulmonary artery pressures were 2/3 systemic and ectopy was seen, requiring inotropes, nitric oxide, lidocaine, and amiodarone. He was discharged on postoperative day (POD) 5. On POD 6, he presented with acute right foot ischemia. Computed tomography showed a large aortic thrombus, requiring emergent thrombectomy. Coagulopathy workup was negative. Cardiac magnetic resonance imaging (CMR) and catheterization showed reduced biventricular function and diastolic dysfunction. Diuretics and ß blockers were started, with gradual improvement in left ventricular systolic function.

Regionalization or Access to Care? A Joint Pediatric Heart Care Program That Achieves Both: One Program-Two Sites.

Background: Regionalization of care for children with congenital heart disease has been proposed as a method to improve outcomes. This has raised concerns about limiting access to care. We present the details of a joint pediatric heart care program (JPHCP) which utilized regionalization and actually improved access to care. Methods: In 2017, Kentucky Children's Hospital (KCH) launched the JPHCP with Cincinnati Children's Hospital Medical Center (CCHMC). This unique satellite model was the product of several years of planning, leading to a comprehensive strategy with shared personnel, conferences, and a robust transfer system; "one program-two sites." Results: Between March 2017 and the end of June 2022, 355 operations were performed at KCH under the auspices of the JPHCP. As of the most recent published Society of Thoracic Surgeons (STS) outcome report (through the end of June 2021), for all STAT categories, the JPHCP at KCH outperformed the STS overall in postoperative length of stay, and the mortality rate was lower than expected for the case mix. Of the 355 operations, there were 131 STAT 1, 148 STAT 2, 40 STAT 3, and 36 STAT 4 operations, with two operative mortalities: an adult undergoing surgery for Ebstein anomaly, and a premature infant who died from severe lung disease many months after aortopexy. Conclusions: With a select case mix, and by affiliating with a large volume congenital heart center, the creation of the JPHCP at KCH was able to achieve excellent congenital heart surgery results. Importantly, access to care was improved for those children at the more remote location utilizing this one program-two sites model.

Differences in Cost of Care by Palliation Strategy for Infants With Ductal-Dependent Pulmonary Blood Flow.

BACKGROUND: In infants with ductal-dependent pulmonary blood flow, initial palliation with patent ductus arteriosus (PDA) stent or modified Blalock-Taussig (BT) shunt have comparable mortality but discrepant length of stay, procedural complication rates and reintervention burdens, which may influence cost. The relative economic impact of these palliation strategies is unknown. METHODS AND RESULTS: Retrospective study of infants with ductal-dependent pulmonary blood flow palliated with PDA stent (n=104) or BT shunt (n=251) from 2008 to 2015 at 4 centers of the Congenital Catheterization Research Collaborative. Inflation-adjusted inpatient hospital costs were calculated for first year of life using Pediatric Health Information System data. Costs derived from outpatient catheterizations not in Pediatric Health Information System were imputed. Costs were compared using propensity score-adjusted multivariable models, to account for baseline differences between groups. After propensity score adjustment, first year of life costs were significantly lower in PDA stent ($215 825 [190 644-244 333]) than BT shunt ($249 855 [230 693-270 609]) patients ( P=0.05). After addition of imputed costs, first year of life costs were not significantly different between PDA stent ($226 403 [200 274-255 941]) and BT shunt ($252 072 [232 955-272 759]) groups ( P=0.15). Patient characteristics associated with higher costs included: younger gestational age, genetic syndrome, noncardiac diagnoses, procedural complications, extracorporeal membrane oxygenation, duration of ventilation, intensive care unit and hospital length of stay and reintervention ( P≤0.02 for all). CONCLUSIONS: In this first multicenter comparative cost study of PDA stent or BT shunt as palliation for infants with ductal-dependent pulmonary blood flow, adjusted for baseline differences, PDA stent was associated with lower to equivalent costs over the first year of life. Combined with previous evidence suggesting clinical noninferiority, these findings suggest that PDA stent provides competitive health care value.

Comparison Between Patent Ductus Arteriosus Stent and Modified Blalock-Taussig Shunt as Palliation for Infants With Ductal-Dependent Pulmonary Blood Flow: Insights From the Congenital Catheterization Research Collaborative.

BACKGROUND: Infants with ductal-dependent pulmonary blood flow may undergo palliation with either a patent ductus arteriosus (PDA) stent or a modified Blalock-Taussig (BT) shunt. A balanced multicenter comparison of these 2 approaches is lacking. METHODS: Infants with ductal-dependent pulmonary blood flow palliated with either a PDA stent or a BT shunt from January 2008 to November 2015 were reviewed from the 4 member centers of the Congenital Catheterization Research Collaborative. Outcomes were compared by use of propensity score adjustment to account for baseline differences between groups. RESULTS: One hundred six patients with a PDA stent and 251 patients with a BT shunt were included. The groups differed in underlying anatomy (expected 2-ventricle circulation in 60% of PDA stents versus 45% of BT shunts; P=0.001) and presence of antegrade pulmonary blood flow (61% of PDA stents versus 38% of BT shunts; P<0.001). After propensity score adjustment, there was no difference in the hazard of the primary composite outcome of death or unplanned reintervention to treat cyanosis (hazard ratio, 0.8; 95% confidence interval [CI], 0.52-1.23; P=0.31). Other reinterventions were more common in the PDA stent group (hazard ratio, 29.8; 95% CI, 9.8-91.1; P<0.001). However, the PDA stent group had a lower adjusted intensive care unit length of stay (5.3 days [95% CI, 4.2-6.7] versus 9.19 days [95% CI, 7.9-10.6]; P<0.001), a lower risk of diuretic use at discharge (odds ratio, 0.4; 95% CI, 0.25-0.64; P<0.001) and procedural complications (odds ratio, 0.4; 95% CI, 0.2-0.77; P=0.006), and larger (152 mm2/m2 [95% CI, 132-176] versus 125 mm2/m2 [95% CI, 113-138]; P=0.029) and more symmetrical (symmetry index, 0.84 [95% CI, 0.8-0.89] versus 0.77 [95% CI, 0.75-0.8]; P=0.008] pulmonary arteries at the time of subsequent surgical repair or last follow-up. CONCLUSIONS: In this multicenter comparison of palliative PDA stent and BT shunt for infants with ductal-dependent pulmonary blood flow adjusted for differences in patient factors, there was no difference in the primary end point, death or unplanned reintervention to treat cyanosis. However, other markers of morbidity and pulmonary artery size favored the PDA stent group, supporting PDA stent as a reasonable alternative to BT shunt in select patients.

Lower liver transplant success in females: gender differences in metabolic response to global ischemia.

BACKGROUND: Research has shown that gender plays a significant role in the metabolic processes of different organs and that transplanting livers of females into male or female recipients has significantly higher failure rates. To understand why, this study examined whether gender differences exist in various metabolic responses of livers to ischemia. METHODS: The following metabolic liver parameters in Sprague-Dawley rats (male, n = 14; and female, n = 18) were examined; adenosine triphosphate (ATP) and lactate expressed as micromoles/g dry weight, and hydrogen ion content [H+] expressed as 10(-8) mol/L. In vivo liver biopsy specimens were compared with ischemic biopsy specimens at 3, 10, 15, 30, and 45 minutes (37 degrees C). RESULTS: In vivo female ATP values (9.9 +/- 0.8) were similar to males (9.8 +/- 0.9) and both had early, rapid decline during ischemia reaching 20% of baseline by 10 minutes of ischemia. In contrast, male liver lactate accumulation peaked by 3 minutes and at much lower levels (35 +/- 13), whereas female liver lactate peaked by 10 minutes at 71 +/- 11. For the rest of the ischemic period, female livers exhibited significantly (P < .05) greater lactate accumulation. Female liver H+ levels also increased to higher levels (55 +/- 10) than the male livers (37 +/- 7) and this pattern was significantly (P < .05) different from 10 minutes onward. CONCLUSIONS: Although livers of females ultimately have similar ATP profiles to livers of males, they experienced more rapid and greater degree of tissue lactate and H+ accumulation during ischemia. Therefore, female livers have increased acidosis during ischemia, which could adversely affect transplant outcome.

Effect of hypertension on reproductive organ weights in various strains of rats.

The testes of Wistar Kyoto (WKY) and Spontaneously Hypertensive (SHR) rats have been shown to have differences in regional vascular resistance. In addition, myocardial hypertrophy tends to be more pronounced and occur more frequently in WKY and SHR female rats than in their male counterparts. Therefore, we sought to determine whether hypertension had any effect on reproductive organs and whether this effect was the same among strains. We removed the testes or uterus from Sprague Dawley (SD; n = 30 male and 30 female), WKY (n = 23 male and 16 female), and SHR (n = 27 male and 34 female) rats, weighed these animals and organs, and calculated the reproductive organ:body weight ratio (mean +/- 1 standard deviation x 10-3 g). The testes:body weight ratio of WKY (6.5 +/- 0.8) animals was significantly (P= 0.05) less than those of SD (7.6 +/- 1.1) and SHR (8.0 +/- 0.5) rats. The uterus:body weight ratio of the SD rats (1.7 +/- 0.4) was significantly (P = 0.05) less than those of WKY (2.4 +/- 0.6) and SHR (2.3 +/- 0.6) rats. Compared with WKY rats, male SD rats had a higher testes:body weight ratio whereas female SD rats had a lower uterus: body weight ratio. Whereas the SHR testes:body weight ratio was significantly higher than that of WKY rats, this effect was not seen for the uterus: body weight ratio. The effect of hypertension on reproductive organs should be taken into consideration when choosing a species, gender, or organ for study. As well, data compared across genders or strains must be evaluated carefully to ensure valid comparisons.

Preischemic administration of ribose to delay the onset of irreversible ischemic injury and improve function: studies in normal and hypertrophied hearts.

Compared with normal hearts, those with pathology (hypertrophy) are less tolerant of metabolic stresses such as ischemia. Pharmacologic intervention administered prior to such stress could provide significant protection. This study determined, firstly, whether the pentose sugar ribose, previously shown to improve postischemic recovery of energy stores and function, protects against ischemia when administered as a pretreatment. Secondly, the efficacy of this same pretreatment protocol was determined in hearts with pathology (hypertrophy). For study 1, Sprague-Dawley rats received equal volumes of either vehicle (bolus i.v. saline) or ribose (100 mg/kg) before global myocardial ischemia. In study 2, spontaneously hypertensive rats (SHR; blood pressure approximately 200/130) with myocardial hypertrophy underwent the same treatment protocol and assessments. In vivo left ventricular function was measured and myocardial metabolites and tolerance to ischemia were assessed. In normal hearts, ribose pretreatment significantly elevated the heart's energy stores (glycogen), and delayed the onset of irreversible ischemic injury by 25%. However, in vivo ventricular relaxation was reduced by 41% in the ribose group. In SHR, ribose pretreatment did not produce significant elevations in the heart's energy or improvements in tolerance to global ischemia, but significantly improved ventricular function (maximal rate of pressure rise (+dP/dt(max)), 25%; normalized contractility ((+dP/dt)/P), 13%) despite no change in hemodynamics. Thus, administration of ribose in advance of global myocardial ischemia does provide metabolic benefit in normal hearts. However, in hypertrophied hearts, ribose did not affect ischemic tolerance but improved ventricular function.

Body weight and food intake profiles are modulated by sex hormones and tamoxifen in chronically hypertensive rats.

Sex hormones and the selective estrogen receptor modulator tamoxifen affect food consumption and body weight in normotensive rats. This study investigated the effects of hormone manipulation and tamoxifen on weight gain and food intake in the presence of chronic systemic hypertension. Male and female spontaneously hypertensive rats (SHR) were either neutered or sham operated before puberty, and subgroups of neutered females received either estrogen replacement therapy (ERT) or tamoxifen at the age of 12 wk. Weekly body weight and food consumption were assessed, and food consumption was normalized to metabolic weight (g body(2/3)). Neutering reduced weight gain in males (P = 0.0001), but increased it in females (P < 0.0001). Both ERT and tamoxifen treatment prevented this increase in weight, with body weight dropping to levels of sham-operated rats for ERT, whereas rats given tamoxifen maintained greater body weights than sham-operated rats (P < 0.0001). This contrasts with previous work in normotensive females in which sham-operated and tamoxifen-treated females did not differ. Neutering reduced normalized food consumption relative to sham-operated rats in both males and females (P < 0.05). Although ERT returned it to normalized intakes of sham-operated rats, tamoxifen reduced normalized food consumption relative to that of both sham-operated and ERT groups. In hypertensive rats, body weight is modulated by sex hormones in both males and females, but in opposite directions. Both estrogen and tamoxifen exert immediate effects in females. Interestingly, the effect of tamoxifen on body weight appears to be greater in hypertensive than in normotensive rats.

A long-term stable normothermic cardiopulmonary bypass model in neonatal swine.

BACKGROUND: An appropriate animal model of cardiopulmonary bypass (CPB) is critical in order to study the morbidity and mortality in newborn children undergoing long-term cardiac surgery. Since this has been reported to be technically difficult, this paper describes a neonatal porcine CPB model (3 days old, n = 18) for up to 8 h to study long-term bypass. METHODS: After anesthesia, neonates had arterial/venous monitoring lines inserted, they were heparinized (300 IU/kg), the aorta was cannulated for arterial retroperfusion, and a two-stage venous drainage catheter was placed in the right atrium. A Medtronic Minimax Plus oxygenator and the bypass circuit were primed with donor blood and CPB was instituted. RESULTS: Line and mean arterial pressures were kept at 147.7 +/- 73 and 62.7 +/- 9 mm Hg, respectively. Myocardial (38.1 +/- 1.0 degrees C) and rectal temperatures (37.7 +/- 1.0 degrees C) were maintained. Heart rate was 184.8 +/- 34.5 bpm. Hematocrits were 29.6 +/- 6.0%, activated clotting time was sustained above 400 s throughout bypass, blood gas parameters were maintained in the normal range (pH, 7.39 +/- 0.1; PO(2), 123.1 +/- 65.2 mm Hg; PCO(2), 37.2 +/- 8.5 mm Hg; and HCO(3)(-), 21.5 +/- 3.6 mmol/L). CPB was terminated after 8 h and no visceral edema or other imbalances normally associated with swine on bypass were observed. CONCLUSIONS: Results demonstrate a model of stable long-term bypass in neonatal swine which can be used to study issues critical to children requiring surgical correction and CPB at a young age. Overall effects of surgery and bypass on these younger patients have yet to be explored and therefore a stable long-term normothermic model of CPB would allow the study of numerous parameters associated with this complicated procedure.

Sex hormones and the selective estrogen receptor modulator tamoxifen modulate weekly body weights and food intakes in adolescent and adult rats.

This study documented the effect of changes in male and female sex hormones and the selective estrogen receptor modulator (SERM) tamoxifen on weight gain and food consumption of rats from puberty to adulthood, and assessed whether age at onset of treatment affected outcome. In Study 1, male and female WKY rats were either neutered or sham-operated before puberty, and a subgroup of neutered females underwent estrogen replacement (ERT) at the age of puberty. In Study 2, subgroups of neutered females received either ERT or tamoxifen beginning well into the postpuberty period. Weekly body weight and food consumption were assessed, and food consumption was normalized to metabolic weight (body weight(0.67)). Neutering reduced the rate of weight gain in males (P < 0.05), but significantly increased it in females (P < 0.0001). ERT immediately reduced weight gain and prevented any further increase, resulting in weights below that of sham-operated females (P < 0.05). Tamoxifen prevented further weight gain and returned profiles to that of sham-operated females. Food consumption, normalized to metabolic weight, was similar in females and males, and both sexes showed a decrease through maturation to adulthood. Neutering decreased food consumption below that of sham-operated animals in both males and females (P < 0.05), and ERT returned it to sham levels. Despite the fact that tamoxifen had an effect on body weight similar to that of ERT, females receiving tamoxifen treatment consumed less food than both sham-operated and ERT females (P < 0.05). Weight gain is modulated by sex hormones in male and female rats, with both estrogen and tamoxifen exerting immediate effects in females, irrespective of the age at which treatment is initiated. Differences in food consumption do not appear to account for the effects of hormones and tamoxifen on body weight, suggesting that they exert a direct effect on overall body metabolism.

Gender-differences in myocardial adaptation to afterload in normotensive and hypertensive rats.

Echocardiographic studies suggest that women appear to exhibit a greater degree of myocardial hypertrophy in response to increased afterload than men. Therefore, gender differences and the role of estrogen and testosterone in the development of myocardial hypertrophy were studied in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Male and female rats were either surgically neutered or underwent a sham operation at 21 days of age. A subgroup of neutered females of each strain received 17beta-estradiol replacement. At 6 months, the heart weight-to-body weight ratio was assessed and correlated with systemic blood pressure. Compared with males, females had significantly smaller body and heart weights in both normotensive and hypertensive strains. Despite this, females consistently had significantly greater heart weight-to-body weight ratios. In females, neutering significantly lowered the heart weight-to-body weight ratio in WKY rats, which was returned to intact levels with estrogen replacement. Female SHR showed similar, but not statistically significant, responses. In males, neutering appeared to result in a higher heart weight-to-body weight ratio in WKY rats, but the opposite was seen in SHR. In addition, there was a significant correlation between arterial blood pressure and heart weight-to-body weight ratio (systolic r=0.45, P=0.0015: diastolic r=0.52, P=0.0002) in intact males and females of both strains, and for a given diastolic pressure, females always exhibited a greater heart weight-to-body weight ratio than males. Thus, a greater degree of myocardial hypertrophy in females appears to be related to the presence of estrogen in both normotensive and hypertensive rats. Females show a stronger relationship between heart/body weight and blood pressure than males, which occurred independent of the presence of estrogen.

Metabolic and functional response of neonatal pig hearts to the development of ischemic contracture: is recovery possible?

The potential for functional and metabolic recovery in neonatal hearts after the development of ischemic contracture remains controversial and undefined. This study documents post-ischemic recovery of metabolism and function in the in vivo neonatal heart after the development of onset and peak ischemic contracture. In piglets on cardiopulmonary bypass, hearts were reperfused after the development of either onset (TICo) or peak (TICp) ischemic contracture. Systolic (developed and systolic function, contractility) and diastolic (diastolic function, relaxation) performance was assessed throughout reperfusion. Biopsies were obtained at end-ischemia or end-reperfusion to assess metabolism. By end-ischemia, the metabolic profiles of both TICo and TICp hearts confirmed energy-store depletion and purine degradation that was quantitatively greater in TICp hearts. Hearts reperfused at TICo had consistent moderate impairment of developed function, contractility, diastolic function, and relaxation, whereas hearts reperfused at TICp had much more profound functional impairment. Diastolic function showed the worst functional recovery. In contrast, systolic function was not significantly altered in either study group and, thus, did not reflect the actual extent of injury. In addition, TICo hearts either did not further deplete or partially regenerated energy stores during reperfusion, whereas TICp hearts had further energy-store depletion and lactate accumulation. In summary, neonatal hearts reperfused after TICo maintained or partially restored energy stores and had significant but incomplete functional recovery. In contrast, further metabolic deterioration and profound functional impairment occurred with reperfusion after TICp, potentially indicating ongoing mitochondrial injury and compromised oxidative phosphorylation.

Does the degree of cyanosis affect myocardial adenosine triphosphate levels and function in children undergoing surgical procedures for congenital heart disease?

OBJECTIVE: The outcome of children with cyanosis after cardiac surgical procedures is inferior to that of children who are acyanotic. Animal studies indicated detrimental effects of chronic hypoxia on myocardial metabolism and function. We studied whether the presence or the degree of cyanosis adversely affected myocardial adenosine triphosphate, ventricular function, and clinical outcome in children. METHODS: Forty-eight children who underwent repair of tetralogy of Fallot were divided according to their preoperative saturation: group I, 90% to 100% (n = 14 patients); group II, 80% to 89% (n = 16 patients); and group III, 65% to 79% (n = 18 patients). Adenosine triphosphate was measured from right ventricular biopsy specimens taken before ischemia, at 15 minutes of ischemia, at end-ischemia, and at 15 minutes of reperfusion. Ejection fraction was measured by echocardiography. RESULTS: Even before surgical ischemia, compared with groups I and II, group III had lower preoperative ejection fraction (59% +/- 2.9% vs 67% +/- 1.7% and 68% +/- 1.0%; P <.01) and lower preischemic adenosine triphosphate levels (15.1 +/- 2.1 vs 19.1 +/- 1.9 and 21.4 +/- 1.5 micromol/g dry weight; P <.01). After 15 minutes of ischemia, group III had lower adenosine triphosphate levels (11.2 +/- 1.8 vs 14.77 +/- 2.3 and 17. 6 +/- 3.1 micromol/g dry weight; P <.01). With reperfusion, both cyanotic groups lost further adenosine triphosphate compared with partial recovery in the acyanotic group (-22% +/- 3.8%, -20% +/- 3. 1% vs +18% +/- 1.8%; P <.01). Children in group III had a more complicated postoperative course as evidenced by longer ventilatory support (85 +/- 25 hours vs 31 +/- 15 and 40 +/- 21 hours; P =.07), inotropic support (86 +/- 23 hours vs 38 +/- 12 and 36 +/- 4 hours; P <.01), and intensive care unit stay (160 +/- 35 hours vs 60 +/- 10 and 82 +/- 18 hours; P =.02). CONCLUSIONS: The degree of cyanosis adversely affects myocardial adenosine triphosphate, function, and clinical outcome of children who undergo cardiac operation. Children with cyanosis should be identified as a higher risk group that could be targeted for supportive interventions.

Extracellular calcium concentration affects susceptibility to global ischemic injury in newborn but not adult hearts.

BACKGROUND: Whether immaturity in calcium handling, that persists for a time after birth, could increase sensitivity to extracellular calcium and affect the development of global ischemic injury in the newborn heart is unknown. To address this, the impact of alterations in extracellular calcium concentration on newborn vs. adult development of myocardial injury due to ischemia was studied. METHODS: In Study 1, hearts of 3-day-old piglets and adult pigs were perfused with 1 of 3 different calcium concentrations: control (0.13 mmol/L); intermediate (2.23 mmol/L); high (4.44 mmol/L) before normothermic ischemia. In Study 2, newborn hearts were allocated to perfusion with or without the L-calcium channel antagonist verapamil before high (4.44 mmol/L) calcium exposure, followed by normothermic ischemia. Tolerance to ischemia was assessed by determining the time to irreversible injury in all hearts, and maximal intraventricular pressures at peak injury. RESULTS: In adults, altering calcium did not significantly affect tolerance to ischemia. In newborns, increasing calcium exposure resulted in significantly greater intraventricular pressures at maximal injury when compared with the control (low) calcium group (p<.05). As well, newborns exposed to high calcium had a significantly shorter time to the development of ischemic injury compared with the other groups (p<.05). Those newborn hearts pretreated with an L-calcium channel antagonist before the high calcium exposure did not exhibit this increased susceptibility to ischemic injury (p<.05). CONCLUSIONS: In contrast to adults, the development of ischemic injury in the newborn heart is affected by changes in extracellular calcium, that can be modified with an L-calcium channel antagonist. This information could be used to prolong the safe preservation time of newborn donor hearts harvested for transplantation, as well as to minimize postoperative ventricular dysfunction.

Special Feeding and Care of Senescent Spontaneously Hypertensive Rats.

This study investigated the impact of feeding methods on body weight of senescent female spontaneously hypertensive rats (SHRs) and showed that supplementing powdered feed was useful as they approached heart failure at 22 to 23 months of age. SHRs are genetically predisposed to systemic hypertension and will, with age, progress into complete heart failure resulting in death. Close to the time of heart failure, some rats experienced a loss of appetite and weight loss. It was postulated that either elevated blood pressure, age-associated health issues, or the effort required to access pelleted food prevented the rats from eating properly, resulting in malnutrition and weight loss. As they aged, the rats benefited from the addition of powdered food to ensure that body weights remained stable and to prevent malnutrition that could lead to premature death. Animals were fed commercially available rat chow pellets until they showed persistent signs of weight loss or a lack of interest in their food. At that time, the rats were also given powdered rat chow in shallow bowls to facilitate the eating and the digestion of their food. The rats were weighed weekly to confirm they consumed sufficient calories daily and to ensure that the change to the powdered chow was having the desired effect. Prior to being fed the powdered rat chow, the rats had shown signs of progressive weight loss. After starting the powdered chow, the rats either maintained or gained weight. This study shows that as the female SHR matures, special care and handling is key to maintaining body weights and good health. With only modest changes in routine (i.e., powdered food) and an attentive eye on the rats' daily activities, it was possible to maintain these senescent female SHRs in a healthy condition until the termination of the study or onset of heart failure.

Sex differences in response to dietary manipulation in rats with hypertension and myocardial hypertrophy.

Studies of the effect of sex on the metabolic state of rats with chronic hypertension and concomitant myocardial hypertrophy were conducted. Female and male spontaneously hypertensive rats (SHRs) with early myocardial hypertrophy (5.5 mo old) were used. Serum fatty acids, liver glycogen, and myocardial glycogen were measured at baseline and after the rats were deprived of food for 24 h. The metabolic effects of progressive myocardial hypertrophy in females were assessed in additional groups of female SHRs (5.5 or 12 mo old) under the following conditions: control, food deprived, or food deprived and refed with equienergetic lipid-rich (38.9% of total energy) or carbohydrate-rich (76.5% of total energy) diets. Despite no differences in serum fatty acids, females had significantly higher baseline myocardial glycogen and liver glycogen concentrations than males. In response to food deprivation, females continued to have significantly higher myocardial glycogen and fatty acid concentrations than males, whereas there were no sex differences in liver glycogen, which was depleted in both males and females. Older hypertensive females had higher baseline fatty acid concentrations and lower liver glycogen concentrations than younger females, whereas there were no differences in myocardial glycogen. Food deprivation doubled fatty acid concentrations, depleted liver glycogen, and increased myocardial glycogen in both age groups. In both age groups, fatty acid concentrations and liver glycogen did not return to baseline values after food deprivation and refeeding. In both age groups, fatty acid concentrations increased further after the lipid-rich diet whereas liver glycogen concentrations returned to approximately 50% of baseline values after the carbohydrate-rich diet. Refeeding with either diet did not significantly increase myocardial glycogen further. Thus, the metabolic response to dietary manipulation was influenced by both sex and, in females, progressive pathology.

Comparative evaluation of an immunofluorescent antibody test, enzyme immunoassay and western blot for the detection of HIV-1 antibody.

Screening blood and blood products for human immunodeficiency virus type 1 (HIV-1) antibody is predominantly performed by enzyme immunoassay (EIA), and results must be confirmed by the more immunospecific Western blot (WB) assay. This study evaluated an HIV immunofluorescent antibody (IFA) test relative to WB assay for use in confirming EIA designated HIV-1 antibody-positive sera. Specimens from seroconversion and CDC panels as well as clinical specimens obtained for routine EIA HIV-1 antibody screening were evaluated. Results with 209 specimens indicated that sensitivity and specificity of the Fluorognost-HIV assay were equivalent relative to WB. In addition, the Fluorognost-HIV IFA test was faster and easier to perform than the WB assay, and unlike the WB assay was not prone to indeterminate results.

Evaluation of a rapid latex agglutination test for detection of group B streptococci in vaginal specimens.

A rapid latex agglutination test (Bactigen Group B Streptococcus Cervical Screen) for detection of group B streptococci in cervical-vaginal specimens was evaluated using two different slide systems, the traditional serologic slide and capillary action track (Trak) slide. Culture was used as reference method. A total of 344 cervical-vaginal specimens were tested. The group B streptococci carrier rate was found by culture to be 10.8%, 56.8% of these specimens being heavily colonized. The sensitivity and specificity of the latex agglutination test in heavily colonized specimens was 95.2% and 99.3% for the serologic and track slides respectively. The overall sensitivity, including lightly colonized specimens, was 62.2%. The positive predictive value was 92% for both slide systems, and the negative predictive value 95.4% and 95.6% for the serologic and track slides respectively. The latex agglutination test, used with either slide, provides a rapid and effective method for identification of specimens heavily colonized with group B streptococci. The track slide may provide a convenient alternative to serologic slides since it does not require rotation.