The impact of time restricted eating on appetite and disordered eating in adults: A mixed methods systematic review

This mixed-methods systematic review evaluated the effect of Time Restricted Eating (TRE) on adult participants' experience of hunger, appetite, and disordered eating. PubMed, CINAHL Plus with Full Text, PscyINFO, and Web of Science were searched for quantitative and qualitative original research articles in human adults that had an intervention with a daily eating window of ≤12 h and outcome measures related to hunger, appetite, or disordered eating. Differences in quantitative measures during TRE and qualitative themes were summarized. Qualitative and quantitative data were synthesized by assessing for convergence and divergence. Sixteen studies were included. TRE was associated with higher appetite at bedtime, and lower or unchanged morning fasting appetite. Evening results were mixed. Disordered eating questionnaires were not different as a result of TRE except in one study that found TRE associated with lower hunger. Qualitative themes converged with these findings, however also showed fear of hunger, eating in the absence of hunger, and eating-related stressors. TRE did not result in major changes to appetite or disordered eating symptoms. Bedtime hunger was higher in TRE. Assessment of subtle alterations in eating behavior, such as eating in the absence of hunger, would be beneficial for future research and intervention design.

Determination of Dexamethasone in Milk by High Pressure Liquid Chromatography

A rapid and sensitive high pressure liquid chromatographic method for the analysis of dexamethasone (9α-fluoro-11β,17α,21-trihydroxy-16α-methylpregna-1,4-diene-3,20-dione) in milk has been developed. The corticosteroid can be quantitated at 20 ppb, with the limit of detectability estimated at 5 ppb. Recoveries ranged from 72 to 94%. After dexamethasone was injected into 5 Holstein-Friesian cows, no residues were found in milk, even after the first milking.

Cocaine-induced transmural myocardial infarction in a Yorkshire swine with normal coronary arteries: Evidence for microvascular and/or epicardial coronary artery spasm

Cocaine-induced myocardial infarction with normal coronary arteries is well documented in humans. The exact mechanism of action remains speculative. We report one case of cocaine-induced myocardial infarction with normal coronaries in one swine. Systemic hemodynamics and angiographic, electrocardiographic, echocardiographic, and histopathologic data are presented. Intravenous cocaine (1, 3, 10 mg/kg) produced significant decreases in mean arterial pressure, heart rate, stroke volume, coronary blood flow, and coronary reserve, whereas pulmonary artery diastolic pressure and coronary vascular resistances increased. Left anterior descending and left circumflex coronary artery cross-sectional area decreased by 31% and 64%, respectively, without localized vasospasm. Electrocardiographic changes occurred (3 mm ST elevation in leads II, III, AVF). Peak creatine phosphokinase was 17,220 IU/L. The echocardiogram revealed severe hypokinesis of the inferior wall and normal ventricular function. The animal survived the acute phase of the infarction and the swine was restudied 12 weeks later. Upon rechallenge, systemic and coronary hemodynamics shoved changes similar to those in the previous study. The swine developed ventricular fibrillation and expired after the 10 mg/kg cocaine dose. Macroscopic examination of the external surface of the heart revealed marked diffuse fibrosis in the posteroinferior and lateral left ventricular wall. Our data suggest that the infarct induced by cocaine may have resulted from severe vasoconstriction or spasm at the level of the microcirculation, and/or the epicardial coronary arteries, which shoved slight but significant narrowing throughout their lengths.

Somatostatin receptor gene expression in human ocular tissues: RT-PCR and immunohistochemical study

PURPOSE

Somatostatin (SST) analogues have been used to treat proliferative diabetic retinopathy, pseudotumor cerebri, thyroid orbitopathy, and cystoid macular edema. There is a paucity of published data in regards to cell-specific distribution of SST receptors (SSTR) in normal human eye tissues. Gene expression for all five known SSTRs in normal human ciliary body/iris, retina, choroid, and cultured retinal pigment epithelial (RPE) cells were studied.

METHODS

mRNA was isolated from human ocular tissues (iris/ciliary body, retina, and choroid) dissected from eight pairs of normal eyes (9-62 years) and from RPE cells grown in culture. RT-PCR was done for all five SSTRs in all analyzed tissues. Immunohistochemistry for SSTR1 and SSTR2 was performed on eight pairs of normal human eyes (28-74 years) imbedded in paraffin.

RESULTS

SSTR1 to 5 genes are expressed in retina, SSTR1 and SSTR2 genes in cultured RPE cells, and SSTR1, 2, and 4 in ciliary body and choroid. SSTR1 and SSTR2 immunoreactivity (-ir) was observed on a variety of cells within all analyzed tissues including cornea, iris, trabecular meshwork, Schlemm's canal, ciliary processes, ciliary muscle, retina, choroid, cultured RPE cells, and optic nerve.

CONCLUSIONS

SSTR genes are widely expressed in normal human eye tissues, with genes for SSTR1 and SSTR2 being the most widely expressed. Genes for all SSTRs are expressed in retina. SSTR1-ir and SSTR2-ir were observed in all analyzed ocular tissues. Detailed knowledge of SSTRs distribution and function in the human eye will result in a better understanding of their role in health and disease.

Chemical, physical, and environmental properties of pelleted newspaper compared to wheat straw and wood shavings as bedding for horses

Two experiments were conducted comparing pelleted recycled newspaper (PN) to wheat straw (S) and kiln-dried pine wood shavings (WS) as an animal bedding material. Adult horses housed 20 to 21 h/d in boxstalls served as the animal model for comparisons. In Exp. 1 eight boxstalls, each housing one horse, were each bedded with two types of PN (0.32 and 0.64 x 2.54 cm), S, and WS over four 5-d periods (replicated 4 x 4 Latin square). Initial amounts of bedding materials surpassed most commercial conditions, but stalls were cleaned daily of feces only and additional clean bedding was added as needed to maintain animal cleanliness, thus challenging the bedding properties of each material. In Exp. 2 nine boxstalls were bedded with PN (0.32 x 2.54 cm), S, and WS over three 14-d periods (three 3 x 3 Latin squares) during summer and autumn. Feces and wet spots were removed daily and clean bedding was added to reestablish working volume and simulate commercial conditions. In Exp. 1 and 2 daily additions of clean bedding varied (P < 0.05) with material (S > WS > PN). The higher water-holding capacity of PN and WS contributed to fewer bedding replacements. Usage of each material was greater (P < 0.05) during the autumn; PN had the greatest increase. Type of material and season also influenced bedding environment. Bedding pH increased (P < 0.05) with use and was highest in PN and lowest in S. Higher concentrations of breathable NH3 N were present in stalls bedded with PN and during autumn. Higher pH of used PN and decreased ventilation due to closed doors and windows during autumn were contributing factors. Season, type of bedding, and duration of its use affected (P < 0.05) numbers as well as species of microorganisms present in the breathing zone, nasal cavity, and on the leg of the horse. Clean and used WS contained greater (P < 0.05) quantities of particle fines, but with 5 d of use, particle fines in PN also increased. Quantities of breathable dust during cleaning of stalls varied (P < 0.05) with material and duration of its use; dust peaked at d 7 with PN but continued to decrease with S and to increase with WS through d 14. These data indicate that management of bedding materials varies with type of material and season of year. Use of PN as a bedding material has high potential.

Importance of an intact growth hormone/insulin-like growth factor 1 axis for normal post-infarction healing: studies in dwarf rats

Treatment with GH attenuates remodeling and improves left ventricular function in the setting of experimental heart failure following coronary ligation. This study was designed to test the hypothesis that an intact GH/insulin-like growth factor 1 (IGF-1) axis is required for normal myocardial infarction healing. Myocardial infarction was induced by coronary ligation in GH-deficient dwarf rats and in age-matched controls. In dwarf rats, serum IGF-1 levels were reduced by 50%, and grow rate was 50% less than normal littermates, although no differences in myocardial IGF-1 messenger RNA levels were observed compared with controls. All rats underwent transthoracic echocardiography at baseline, 2 weeks, and 6 weeks after myocardial infarction. Left ventricular end-diastolic pressure was obtained by in vivo closed chest catheterization. At 6 weeks, both infarcted groups exhibited similar myocardial infarction size at transthoracic echocardiography and at morphometric histology. In both groups with myocardial infarction, there was significant left ventricular dilation and reduced systolic function. However, the extent of remodeling as assessed by the increase in end-diastolic dimension (%Delta + 36 +/- 5 vs. +19 +/- 4; P: < 0.01) and depression of function (%Delta fractional shortening -12 +/- 2 vs. -7 +/- 1; P: < 0.01) were both greater in the dwarf group. Furthermore, dwarf rats failed to develop compensatory hypertrophy of noninfarcted posterior wall (%Delta posterior wall +5 +/- 1 vs. +15 +/- 3; P: < 0.01). Therefore, pathologic left ventricular remodeling and functional loss following myocardial infarction is more marked in conditions of GH deficiency. An intact GH/IGF-1 axis appears necessary for a normal response to myocardial infarction injury in the rat.

Intraorbital rupture of a cavernous internal carotid artery aneurysm: therapeutic options

PURPOSE

To describe the use of an endovascular therapeutic technique in the management of a giant carotid cavernous aneurysm.

METHODS

We reviewed the clinical and neuroradiologic findings of a patient with an unusual case of carotid cavernous aneurysm and intraorbital rupture. The medical literature was searched for similar cases and to review the use of endovascular techniques.

RESULTS

The patient was treated by balloon occlusion of the left internal carotid artery.

CONCLUSIONS

Endovascular techniques can be used to treat complex giant cranioorbital cavernous aneurysms.

Echocardiographic assessment of cardiac morphology and function in mutant dwarf rats

Although the mutant dwarf rat has been proposed as a model of growth hormone (GH) deficiency, few studies have addressed its cardiovascular abnormalities. Therefore, the aim of the present study was to investigate cardiac structure and function in mutant dwarf rats in vivo before and after chronic GH administration, by means of transthoracic Doppler echocardiography. To this purpose, forty 90-day-old female dwarf rats were randomized to receive either GH treatment or placebo. Twenty age-and sex-matched Lewis rats (200-250 g) served as the control group. All rats underwent echocardiograms before receiving any drug and after 3 weeks of therapy. Echocardiographically detected left ventricular mass indexed to tibial length was reduced by 41% in dwarf rats compared to the control group. Such relative cardiac atrophy was also evident at the myocyte level, and was fully reversible after GH therapy. In contrast to the control group, dwarf rats also showed a reduction of left ventricular diastolic volumes normalized to tibial length and impaired cardiac performance as suggested by the reduction of cardiac index, abnormal stress-shortening relations, and a significant elevation of total peripheral vascular resistance. All these abnormalities were reversible upon GH therapy for 3 weeks. In conclusion, GH plays an important role in maintaining a normal cardiac structure and function. Since the observed changes are similar to those seen in GH-deficient men, the mutant dwarf rat represents a faithful animal model of GH deficiency.

Intersession repeatability of macular thickness measurements with the Humphrey 2000 OCT

PURPOSE

This study was designed to determine intersession repeatability of measurements of macular thickness made with a commercially available optical coherence tomography (OCT) system. The images that can be routinely acquired with the commercial instrument differ significantly in quality from the images in the literature, which have mostly been acquired on prototype systems.

METHODS

Multiple OCT images of the nasal macula were obtained from the right eye during three independent measuring sessions, using the Humphrey 2000 OCT system (Humphrey, San Leandro, CA). Twenty-six volunteers with no history of ocular disease participated in this investigation. Eyes in all subjects were undilated during scan acquisition. Scans were horizontal, 3 mm long, and through the fovea. Five scans were used from each session, for a total of 15 scans per subject. Retinal boundaries were automatically detected using custom software. Statistical software was used to calculate intersession and intrasession repeatability. Manual correction was performed on the automatically detected boundaries, and a second analysis was performed using these boundaries.

RESULTS

When no manual correction of boundaries was performed, there were no significant effects between different sessions (P = 0.529) or between different scans within the same session (P = 0.509). Average retinal thickness was found to be 274 +/- 17 microm for a 1-mm long region 0.75 mm from the fovea. Individual scan averages differed from overall patient averages by 0 +/- 4.3 microm (99% confidence interval, 11.2 microm).

CONCLUSIONS

OCT measurements of macular thickness made with the Humphrey 2000 OCT system are repeatable over different sessions with an expected variation of less than 11 microm (99% confidence interval).

Visual loss and central venous catheterization: cortical blindness and hemianopsia after inadvertent subclavian artery entry

A case of presumed embolic transient ischemic episodes and multifocal infarcts to the occipital and parietal cortices and the cerebellum of a young woman with ulcerative colitis is reported. These episodes were manifested by multifocal neurologic deficits including cortical blindness, visual hallucinations, and homonymous hemianopsia. They correlated with parenteral nutrition via a central line, presumed venous, but found to be in the subclavian artery. The complications of central venous lines are reviewed. The need for attention to neighborhood structures and unexpected symptoms, in view of the less well-recognized arterial embolic complications is emphasized.

Chronic N(G)-nitro-L-arginine methyl ester-induced hypertension : novel molecular adaptation to systolic load in absence of hypertrophy

BACKGROUND

Chronic N(G)-nitro-L-arginine methyl ester (L-NAME), which inhibits nitric oxide synthesis, causes hypertension and would therefore be expected to induce robust cardiac hypertrophy. However, L-NAME has negative metabolic effects on protein synthesis that suppress the increase in left ventricular (LV) mass in response to sustained pressure overload. In the present study, we used L-NAME-induced hypertension to test the hypothesis that adaptation to pressure overload occurs even when hypertrophy is suppressed.

METHODS AND RESULTS

Male rats received L-NAME (50 mg. kg(-1). d(-1)) or no drug for 6 weeks. Rats with L-NAME-induced hypertension had levels of systolic wall stress similar to those of rats with aortic stenosis (85+/-19 versus 92+/-16 kdyne/cm). Rats with aortic stenosis developed a nearly 2-fold increase in LV mass compared with controls. In contrast, in the L-NAME rats, no increase in LV mass (1. 00+/-0.03 versus 1.04+/-0.04 g) or hypertrophy of isolated myocytes occurred (3586+/-129 versus 3756+/-135 microm(2)) compared with controls. Nevertheless, chronic pressure overload was not accompanied by the development of heart failure. LV systolic performance was maintained by mechanisms of concentric remodeling (decrease of in vivo LV chamber dimension relative to wall thickness) and augmented myocardial calcium-dependent contractile reserve associated with preserved expression of alpha- and beta-myosin heavy chain isoforms and sarcoplasmic reticulum Ca(2+) ATPase (SERCA-2).

CONCLUSIONS

When the expected compensatory hypertrophic response is suppressed during L-NAME-induced hypertension, severe chronic pressure overload is associated with a successful adaptation to maintain systolic performance; this adaptation depends on both LV remodeling and enhanced contractility in response to calcium.

Abnormal cardiac function in the streptozotocin-induced non-insulin-dependent diabetic rat: noninvasive assessment with doppler echocardiography and contribution of the nitric oxide pathway

OBJECTIVES

We sought to evaluate in vivo and in vitro left ventricular (LV) geometry and function in streptozotocin-induced diabetic rats and the possible role of the nitric oxide (NO) pathway.

BACKGROUND

Diabetes results in cardiac dysfunction; however, the specific abnormalities are unknown. Because decreased NO contributes to abnormal vascular function in diabetics, we hypothesized that NO pathway abnormalities may contribute to diabetic cardiomyopathy.

METHODS

Control rats and those with non-insulin-dependent diabetes mellitus (NIDDM) underwent echocardiography, hemodynamic assessment, isolated heart perfusion and measurement of exhaled NO and LV endothelial constitutive nitric oxide synthase (ecNOS).

RESULTS

Diabetic rats had increased LV mass (3.3 +/- 0.6 vs. 2.6 +/- 0.3 g/g body weight [BW], p < 0.001) and cavity dimensions (diastolic 2.0 +/- 0.1 vs. 1.8 +/- 0.2 cm/cm tibial length [TL], p < 0.05). Diabetic rats had prolonged isovolumic relaxation time (IVRT) (40 +/- 8 vs. 26 +/- 6 ms, p < 0.0001), increased atrial contribution to diastolic filling (0.47 +/- 0.09 vs. 0.30 +/- 0.08 m/s, p < 0.0001), and elevated in vivo LV end-diastolic pressure (7 +/- 6 vs. 2 +/- 1 mm Hg, p = 0.04). Diabetic rats had increased chamber stiffness. Shortening was similar in both groups, despite reduced meridional wall stress in diabetics, suggesting impaired systolic contractility. Exhaled NO was lower in diabetic rats (1.8 +/- 0.2 vs. 3.3 +/- 0.3 parts per billion, p < 0.01) and correlated with Doppler LV filling. The ecNOS was similar between the groups.

CONCLUSIONS

Diabetic cardiomyopathy is characterized by LV systolic and diastolic dysfunction, the latter correlating with decreased exhaled NO. The NO pathway is intact, suggesting impaired availability of NO as contributor to cardiomyopathy.

Cardiovascular abnormalities in transgenic mice with reduced brown fat: an animal model of human obesity

BACKGROUND

A new model of murine obesity has recently been developed through transgenic ablation of brown adipose tissue that manifests typical metabolic complications of obesity, including insulin resistance and non-insulin-dependent diabetes mellitus. The cardiovascular phenotype has not been defined.

METHODS AND RESULTS

Transthoracic echocardiography, aortic catheterization, isolated whole-heart studies, and morphometric histology defined cardiac structure and function in 30 transgenic mice with reduced brown fat and 30 matched wild-type controls. Obesity was indicated by a 77% increase in body weight and was accompanied by elevated systemic pressures (mean aortic blood pressure 85+/-1 versus 66+/-2 mm Hg; P<0.01), left ventricular dilation and hypertrophy (mass/body weight 4.0+/-0.2 versus 2.7+/-0.3 mg/g; P<0.01), and high cardiac output (cardiac index 3.2+/-0.4 versus 2.4+/-0.1 mL x kg(-1) x min(-1); P<0.01). Baseline functional parameters assessed in vitro were not different, but after imposition of zero-flow ischemia, significant relaxation impairment developed in obese mice. Although morphometrically determined myocyte diameters were similar, the percentage of interstitial fibrosis was significantly increased in transgenic mice compared with wild-type controls (7.5+/-2% versus 4. 2+/-0.2%; P<0.01).

CONCLUSIONS

Transgenic ablation of brown adipose tissue is associated not only with obesity but also with systemic hypertension, left ventricular hypertrophy with eccentric remodeling and fibrosis, and high cardiac output, a unique constellation of findings strikingly similar to that seen in human obesity. Mice with reduced brown fat may serve as a new model for the cardiovascular morbid complications associated with obesity in humans.

Left atrial appendage anatomy and function: short term response to sustained atrial fibrillation

OBJECTIVE

To determine whether there is significant atrial or atrial appendage enlargement or functional remodelling as a result of one to two months of sustained atrial fibrillation, a duration similar to that experienced by patients undergoing warfarin anticoagulation before elective cardioversion.

METHODS

To test the hypothesis that left atrial and left atrial appendage enlargement develop as a result of short term atrial fibrillation, serial anatomical and functional indices were measured using transoesophageal echocardiography (TOE) in 20 patients with recent onset atrial fibrillation (14 men, six women; mean (SEM) age 67 (2) years). Serial TOE was performed 2.5 months apart in patients with sustained atrial fibrillation.

RESULTS

There was no significant change in left atrial area (23.7 cm(2) to 24.1 cm(2), p = 0.98); length (5.7 cm to 5.7 cm, p = 0.48); width (5.2 cm to 5.2 cm, p = 0. 65); volume (83 cm(3) to 87 cm(3), p = 0.51) or left atrial appendage area (7.9 cm(2) to 8.1 cm(2), p = 0.89); length (4.6 cm to 4.5 cm, p = 0.8); or width (2.5 to 2.4 cm, p = 0.87). Peak left atrial appendage velocity ejection (0.2 m/s to 0.2 m/s, p = 0.57), and presence of severe spontaneous echo contrast in the left atrial appendage (n = 15 (75%) to n = 13 (72%)) were also not significantly different. There was no correlation between changes in left atrial or left atrial appendage dimensions.

CONCLUSIONS

In the setting of sustained atrial fibrillation, significant left atrial and left atrial appendage functional and anatomical remodelling do not occur with atrial fibrillation of a duration similar to that used for conservative anticoagulation in preparation for cardioversion.

Gender differences in postinfarction left ventricular remodeling

OBJECTIVE

Previous studies suggest that gender affects the adaptive responses of the heart to some forms of cardiac overload. It is unknown whether gender influences left ventricular (LV) remodeling after myocardial infarction (MI).

METHODS

We performed transthoracic echocardiographic-Doppler examinations in age-matched male (n = 17) and female (n = 16) rats before, and 1 and 6 weeks after transmural MI or sham surgery.

RESULTS

Following large MI (male = 45 +/- 1% LV circumference vs. female = 48 +/- 4%, p = NS), both male and female rats developed progressive LV dilatation. Infarctions caused a similar degree of global and regional LV systolic dysfunction in males and females. Male rats had significant increases in the thickness of the noninfarcted posterior wall by 6 weeks after MI. However, posterior wall thickness did not change in the infarcted female rats. Average myocyte diameter in the noninfarcted region of the heart was also greater in male than female MI rats. The combination of increased cavity size with little change in wall thickness resulted in a greater decline in relative wall thickness in the female rats compared to the males. Male rats with MI showed progressively restricted LV diastolic filling as assessed by transmitral Doppler recordings. Female rats had less of an increase in the ratio of early to late transmitral velocities and less of an increase in the E wave deceleration rate after MI.

CONCLUSIONS

Female rats showed a different pattern of LV remodeling than males with less of an increase in thickness of the noninfarcted portions of the left ventricle than males, but comparable LV cavity enlargement and systolic dysfunction. Despite similar infarct size, females developed less pronounced abnormalities of LV diastolic filling. We hypothesize that the gender-related differences in postinfarction LV remodeling may contribute to the different LV filling patterns, and might ultimately relate to differences in clinical outcome.

Effects of propranolol treatment on left ventricular function and intracellular calcium regulation in rats with postinfarction heart failure

1. Chronic treatment with beta-adrenergic blocking agents can improve survival in patients with heart failure. The mechanisms underlying the beneficial effects and whether these effects are generalizable to ischaemic heart failure are unresolved. 2. We performed echocardiographic-Doppler examinations in rats (n=28) 1 and 6 weeks after myocardial infarction (MI) or sham surgery. Rats were randomized to no treatment or propranolol (500 mg/l in drinking water) after the first echocardiogram. Isometric contractions and intracellular Ca transients were recorded simultaneously in noninfarcted left ventricular (LV) papillary muscles. 3. Untreated MI rats had significant LV dilatation (10.6+/-0.4* vs 8.9+/(-0.3) mm, MI vs control), impaired systolic function (fractional shortening=11+/-2* vs 38+/-2%), and a restrictive LV diastolic filling pattern. MI rats receiving propranolol had similar LV chamber sizes (10.6+/(-0.5) mm) and systolic function (13+/(-2%). The propranolol treated animals had higher LV end-diastolic pressures (27+/-2* vs 20+/(-3 mmHg) and a more restricted LV diastolic filling pattern (increased ratio of early to late filling velocities and more rapid E wave deceleration rate). Contractility of papillary muscles from untreated MI rats was depressed (1.6+/(-0.3) vs 2.4+/(0.5 g mm(-2). In addition, Ca transients were prolonged and the inotropic response to isoproterenol was blunted. Propranolol treatment did not improve force development (1.6+/(-0.3 g mm(-2) or the duration of Ca transients during isoproterenol stimulation. 4. Chronic propranolol treatment in rats with postinfarction heart failure did not improve LV remodeling or systolic function. LV diastolic pressures and filling patterns were worsened by propranolol. Treatment also did not produce appreciable improvement in contractility, intracellular Ca regulation or beta-adrenergic responsiveness in the noninfarcted myocardium.

Suck and spit, don't blow: orbital emphysema after decompression surgery

PURPOSE

To describe the occurrence of vision-threatening orbital emphysema in patients awakening from orbital decompression surgery and to assess risk factors and preventive measures.

DESIGN

Small noncomparative case series.

PARTICIPANTS

Three patients undergoing bilateral orbital two-wall decompression experienced significant orbital emphysema associated with persistent coughing and Valsalva at the time of extubation.

INTERVENTION

In two patients, symptoms resolved with simple observation, whereas one patient required sedation, topical anesthesia around the endotracheal tube, and needle decompression of trapped air.

MAIN OUTCOME MEASURES

Visual acuity, pupils, visual fields, and sensorimotor examination.

RESULTS

No patient experienced a permanent deficit of visual or sensorimotor function.

CONCLUSIONS

Acute orbital emphysema can occur after orbital decompression surgery despite the large bony opening created. Violent coughing spells at the time of extubation are more common in patients with a history of heavy tobacco use and may be causative. Opening the periorbita may be another specific predisposing risk factor. Knowledge of this dangerous phenomenon, along with appropriate perioperative management, may prevent this complication from occurring.

Gender differences in molecular remodeling in pressure overload hypertrophy

OBJECTIVES

The objective of this study was to examine gender differences in left ventricular (LV) function and expression of cardiac genes in response to LV pressure overload due to ascending aortic stenosis in rats.

BACKGROUND

Clinical studies have documented gender differences in the pattern of adaptive LV hypertrophy. Whether these differences result from intrinsic differences in molecular adaptation to pressure overload between men and women, or are related to other factors is not known.

METHODS

Male (n = 8) and female (n = 8) Wistar rats underwent ascending aortic stenosis and were studied 6 weeks after banding with gender-matched control rats (male n = 7; female n = 7). The LV contractile reserve was examined in isolated hearts from each group. We compared LV messenger ribonucleic acid (mRNA) levels of atrial natriuretic factor (ANF), beta-myosin heavy chain, sarcoplasmic reticulum Ca2+-adenosine triphosphatase (ATPase) and Na+-Ca2+ exchanger. Reverse transcriptase polymerase chain reaction was used to identify estrogen receptor transcript in cardiac myocytes and LV tissue.

RESULTS

The magnitude of LV hypertrophy (LVH) and systolic wall stress were similar in male and female animals with LVH. Male LVH hearts demonstrated a depressed contractile reserve; in contrast, contractile reserve was preserved in female LVH hearts. The expression of beta-myosin heavy chain and ANF mRNA was greater in male versus female LVH hearts. Sarcoplasmic reticulum Ca2+-ATPase mRNA levels were depressed in male LVH but not in female LVH compared with control rats, and Na+-Ca2+ exchanger mRNA levels were increased similarly in both male and female LVH hearts. Estrogen receptor transcript was detected in both adult male and female cardiac myocytes and LV tissue.

CONCLUSIONS

There are significant gender differences in the LV adaptation to pressure overload despite a similar degree of LVH and systolic wall stress in male and female rats. There is the potential for estrogen signaling through the adult myocyte estrogen receptor in both male and female rats to contribute to gender differences in gene expression in pathologic hypertrophy.

Diagnosis of polycystic ovary syndrome

The clinical features of polycystic ovary syndrome (PCOS) include hirsutism and irregular menses, which are the results of ovarian hyperandrogenism and chronic, unopposed estrogen secretion. The discovery that most women with PCOS are insulin-resistant and have compensatory hyperinsulinemia, with increased risk for type 2 diabetes mellitus, designates this condition as a reproductive-metabolic disorder. That the symptoms of PCOS may be mimicked by other endocrine disorders of the ovary and adrenal glands warrants careful evaluation to exclude these associated conditions.

Hypertrophic remodeling: gender differences in the early response to left ventricular pressure overload

OBJECTIVES

To identify gender differences in left ventricular remodeling, hypertrophy, and function in response to pressure overload due to ascending aortic banding in rats.

BACKGROUND

Gender may influence the adaptation to pressure overload, as women with aortic stenosis have greater degrees of left ventricular hypertrophy and better left ventricular function than men.

METHODS

Fifty-two weanling rats underwent ascending aortic banding (16 males, 18 females), or sham surgery (9 males, 9 females). At 6 and 20 weeks, rats underwent transthoracic echo Doppler studies, and closed-chest left ventricular pressures with direct left ventricular puncture. Perfusion-fixed tissues from eight rats were examined morphometrically for myocyte cross-sectional area and percent collagen volume.

RESULTS

At 6 weeks after aortic banding, left ventricular remodeling, extent of hypertrophy, and function appeared similar in male and female rats. At 20 weeks, male but not female rats showed an early transition to heart failure, with onset of cavity dilatation (left ventricular diameter=155% vs. 121% of same-sex sham), loss of concentric remodeling (relative wall thickness=102% vs. 139% of sham), elevated wall stress (systolic stress=266% vs. 154% of sham), and diastolic dysfunction (deceleration of rapid filling=251% vs. 190% of sham). Left ventricular systolic pressures were higher in female compared with male rats (186+/-20 vs. 139+/-13 mm Hg), while diastolic pressures tended to be lower (14+/-4 vs. 17+/-4 mm Hg).

CONCLUSIONS

Gender significantly influences the evolution of the early response to pressure overload, including the transition to heart failure in rats with aortic stenosis.

Prolonged exercise alters cardiac chronotropic responsiveness in endurance athletes

OBJECTIVE

To determine whether exhaustive exercise alters cardiac adrenergic chronotropic responsiveness in endurance-trained athletes.

METHODS

Fifteen athletes were studied prospectively 2-4 days before and within 3.3 hours after completing the Hawaii Ironman Triathlon (3.9 km swim, 180.2 km bike, 24.2 km run). Increasing intravenous boluses of isoproterenol were given until the rise in heart rate was > 30 bpm (n = 3-6 doses). A log dose heart rate response curve was constructed, and the dose required to increase heart rate by 15 and 25 bpm estimated. Left ventricular size and function were also assessed by echocardiography.

RESULTS

After race finish, left ventricular volume (98 vs 83 cc), ejection fraction (56 vs 46%) and diastolic filling (3.86 vs 3.12 edv/sec) were reduced (all p < 0.01). Resting heart rate rose from 54 +/- 7 bpm to 70 +/- 10 bpm. The isoproterenol dose required to increase heart rate by 15 bpm rose from 0.6 to 1.7 micrograms by 25 bpm rose from 1.8 to 4.0 micrograms, both p < 0.01. The linear relationship between change in heart rate and log isoproterenol dose was preserved.

CONCLUSIONS

Cardiac chronotropic responsiveness is reduced following an Ironman triathlon.

Combined venous lymphatic malformations of the orbit (so-called lymphangiomas). Association with noncontiguous intracranial vascular anomalies

OBJECTIVE

The authors present seven cases of orbital combined venous lymphatic vascular malformations (CVLVM) (lymphangioma) with evidence of noncontiguous intracranial vascular anomalies.

DESIGN

The study design was a review.

MAIN OUTCOME MEASURES

Radiologic studies of 25 patients with combined venous lymphatic vascular malformations were evaluated for noncontiguous intracranial vascular anomalies. Features of the intracranial anomalies and orbital lesions, their clinical presentation, and prognosis are described.

RESULTS

Seven patients (28%) had associated noncontiguous intracranial vascular anomalies. Intracranial hemorrhage occurred in one of these patients. The intracranial anomalies had radiologic characteristics of developmental venous anomalies (DVAs). Diffuse orbital lesions with superficial and deep components (7/7), orbital bony expansion (7/7), and intraconal and extraconal components (4/7) were most common. They involved the inferior orbital fissure and extended into the pterygopalatine fossa in five patients. Involvement of the superior orbital fissure was noted in all seven patients with extension into the middle cranial fossa in three patients. At birth, these patients generally had a visible superficial component and then had episodes of sudden proptosis associated with deep orbital hemorrhages. Visual outcome was poor (20/200 or less) in four (57%) of seven cases. Anterior extension into soft tissues of the face and forehead and other associated vascular lesions, such as palatal involvement, were relatively common. In contrast, CVLVMs (lymphangiomas) without noncontiguous intracranial vascular anomalies were more anterior, less diffuse, less likely to extend into the soft tissues of the face, have associated vascular lesions, or have a poor visual outcome.

CONCLUSIONS

Orbital CVLVMs (lymphangiomas) may be associated with noncontiguous intracranial vascular anomalies that may bleed. This association with intracranial DVAs has not been reported previously. The intracranial vasculature should be evaluated prospectively in these lesions, especially if they are diffuse.

Consequences of growth hormone deficiency on cardiac structure, function, and beta-adrenergic pathway: studies in mutant dwarf rats

To evaluate GH's role in cardiac physiology and its interrelationship with the beta-adrenergic system, we studied GH-deficient dwarf (dw/dw) and control rats in 4 groups of 20 each: dwarf group receiving placebo, dwarf-GH group receiving 2 mg/kg GH, dwarf-GH-propranolol group receiving 2 mg/kg GH and 750 mg/liter propranolol, and a control group of Lewis rats receiving placebo. Dwarf rats showed reduced left ventricular weight and myocyte cross-sectional area, and impaired cardiac performance in vitro. Left ventricular pressure-volume curves showed a shift upward and leftward, indicating reduced distensibility. These abnormalities reversed after GH treatment regardless of concomitant propranolol administration. Although isoproterenol responsiveness was reduced in dwarf rats, there were no differences in beta-adrenergic receptor density, affinity, Na+,K+-adenosine triphosphatase activity, or adenylyl cyclase activity. In summary, myocyte size, cardiac structure, myocardial contractility, and distensibility are abnormal in GH deficiency. The effects of GH are not mediated by the beta-adrenergic pathway, which, in turn, is unaffected by changes in the GH-insulin-like growth factor I axis. Thus, GH plays a regulatory role in normal cardiac physiology that is independent of the beta-adrenergic system.

Left ventricular hypertrophy in athletes

Left ventricular wall thickness >1.3 cm, septal-to-posterior wall ratios > 1.5, diastolic left ventricular size >6.0 cm, and eccentric or concentric remodeling are rare in athletes. Values outside of these cutoffs in an athlete of any age probably represent a pathologic state.

Acquired dynamic left ventricular outflow tract obstruction complicating acute anterior myocardial infarction: serial echocardiographic and clinical evaluation

We describe three cases of dynamic outflow obstruction complicating acute anterior myocardial infarction. Serial echocardiography suggests the intraventricular gradient results from basal hyperkinesis, the latter being a reciprocal response to the apical wall motion abnormality.

Growth hormone attenuates early left ventricular remodeling and improves cardiac function in rats with large myocardial infarction

OBJECTIVES

We sought to investigate the cardiac effects of growth hormone (GH) administration during the early phase of pathologic remodeling in a rat model of large myocardial infarction (MI).

BACKGROUND

Recent evidence suggests that exogenous administration of GH evokes a hypertrophic response and increases left ventricular (LV) function in vivo in rats with normal or chronically failing hearts. We hypothesized that these effects would attenuate ventricular remodeling early after MI.

METHODS

Fifty-eight male rats underwent sham operation (n = 19) or had induced MI (n = 39). The day after the operation, the infarcted rats were randomized to receive 3 weeks of treatment with GH, 3 mg/kg body weight per day (n = 19) or placebo (n = 20). Echocardiography, catheterization and isolated whole heart preparations were used to define cardiac structure and function.

RESULTS

Growth hormone caused hypertrophy of the noninfarcted myocardium in a concentric pattern, as noted by higher echocardiographic relative wall thickness at 3 weeks and by morphometric histologic examination. Left ventricular dilation was reduced in the GH-treated versus placebo group (echocardiographic LV diastolic diameter to body weight ratio 2.9 +/- 0.1 vs. 3.5 +/- 0.2 cm/kg; p < 0.05). In vivo and in vitro cardiac function was improved after GH treatment. Despite elevated insulin-like growth factor-1 (IGF-1) serum levels in GH-treated rats, myocardial IGF-I messenger ribonucleic acid was not different among the three groups, suggesting that an increase in its local expression does not appear necessary to yield the observed effects.

CONCLUSIONS

These data demonstrate that early treatment of large MI with GH attenuates the early pathologic LV remodeling and improves LV function.

Photographic documentation of the loss of medullated nerve fibers of the retina in uncontrolled primary open angle glaucoma

PURPOSE

We report the first case of retinal myelin loss associated with uncontrolled primary open angle glaucoma (POAG).

METHODS

The clinical features, visual fields, and serial disc photos documenting the changes are described. The literature regarding this phenomenon in other forms of optic neuropathy and the specific implications in glaucoma patients are discussed.

RESULTS

A 75-year-old black man with POAG had medullated nerve fibers of the retina bilaterally abutting the optic discs inferonasally. Optic disc appearance and visual fields were stable over 6 years. The patient was then lost to follow-up for 2 years and returned with elevated intraocular pressures (IOPs), visual acuity and field loss, progressive optic disc damage, peripapillary atrophy, and disappearance of retinal myelin on the left greater than the right. Retinal myelin loss occurred in areas of nerve fiber layer dropout.

CONCLUSIONS

Loss of medullated nerve fibers in the retina occurs secondary to anterograde axonal degeneration as a nonspecific response to any form of optic atrophy. The apparent paucity of glaucoma patients with retinal myelin may be due to late referral rather than any inherent protective effect of retinal myelin against elevated IOP.

Evaluation of left atrial appendage anatomy and function in recent-onset atrial fibrillation by transesophageal echocardiography

Data regarding left atrial (LA) and LA appendage anatomy and function among patients with newly recognized atrial fibrillation (AF) who have not received long-term warfarin are currently unknown. To identify echocardiographic indexes which characterize those at increased risk for thrombus formation, we analyzed transesophageal echocardiographic studies in 100 consecutive patients with newly recognized AF (duration 2.6 +/- 0.3 week) who had not received long-term warfarin. Fourteen percent of patients had LA thrombi. LA thrombi were associated with larger LA appendages, more depressed LA appendage outflow velocities, and a higher prevalence of severe spontaneous LA contrast. Patients with spontaneous contrast had larger LA and LA appendage anatomy and lower LA appendage ejection velocity. Among patients presenting with their first episode of AF, greater LA appendage ejection and filling velocities and smaller LA and LA appendage sizes were seen among those with AF of <2 weeks duration compared with those with AF of >2 weeks. Thus, patients with recent onset AF and LA thrombi or spontaneous echo contrast have more dilated LA and LA appendage anatomy, and more depressed LA appendage systolic function. Data from patients with their first episode of AF suggests that AF is associated with rapid LA remodeling.

Tumors arising in the palpebral lobe of the lacrimal gland

PURPOSE

Tumors arising in the palpebral lobe of the lacrimal gland are uncommon. There have been only eight reported patients, all of whom had pleomorphic adenomas. The authors present another six patients with primary palpebral lobe tumors.

METHODS

The clinical presentation, computed tomographic, and pathologic findings of these six patients were reviewed.

RESULTS

Tumor types include three pleomorphic adenomas, one well-differentiated adenoid cystic carcinoma, one carcinoma in pleomorphic adenoma, and one carcinoma ex pleomorphic adenoma. All six patients presented with a painless mass in the upper outer eyelid without significant displacement of the globe, but the superficial location of these lesions led to early detection. The tumors were localized to the lacrimal gland, predominantly anterior to the orbital rim. In all six patients, the involved palpebral lobe was removed, five via a direct anterior subcutaneous approach and one by superolateral orbitotomy. In two patients (adenoid cystic carcinoma and carcinoma ex pleomorphic adenoma), repeat surgery via superolateral orbitotomy was necessary to achieve complete removal of the lacrimal gland and surrounding tissue. No recurrences were detected during follow-up (range, 6 months to 7 years; mean, 26 months).

CONCLUSION

Palpebral lobe tumors of the lacrimal gland are more common and consist of a greater variety of histologic types than previously described. In our series, these tumors comprise 17% of all epithelial lacrimal gland lesions. These are the first reported cases of malignancy in this location. A longer follow-up period is necessary to determine the true recurrence rate of these tumors.

Long-term captopril treatment improves diastolic filling more than systolic performance in rats with large myocardial infarction

OBJECTIVES

This study sought to determine the effects of long-term angiotensin-converting enzyme (ACE) inhibition on left ventricular (LV) diastolic filling in postinfarction heart failure.

BACKGROUND

Long-term treatment with ACE inhibitors is beneficial in experimental animals and patients with heart failure. Because this treatment typically produces only small improvements in LV systolic function, we hypothesized that improvements in LV diastolic filling might contribute to the overall beneficial effects of ACE inhibitors after myocardial infarction (MI).

METHODS

We performed transthoracic echocardiographic-Doppler examinations in rats 1 and 6 weeks after transmural MI or sham operation. Rats with MI were randomized to no treatment (n = 10) or captopril (2 g/liter in drinking water, n = 8) after the baseline echocardiogram.

RESULTS

Six weeks after MI, untreated rats had significant LV dilation compared with sham-operated rats (LV diastolic dimension [mean+/-SEM] 10.7 +/- 0.3 vs. 8.5 +/- 0.3 mm, p < 0.05). Rats with untreated MI also had impaired fractional shortening (9 +/- 1% vs. 34 +/- 2%, p < 0.05) and depressed systolic thickening of the noninfarcted posterior wall (3% +/- 3% vs, 65 +/- 9%, p < 0.05). Rats with MI showed progressively restricted LV diastolic filling as assessed by transmitral Doppler recordings. At 6 weeks, peak early filling velocity (E) was increased (97 +/- 3 vs. 77 +/- 2 cm/s, p < 0.05), E wave deceleration was more rapid (23 +/- 3 vs. 12 +/- 1 m/s2, p < 0.05), isovolumetric relaxation time was decreased (18 +/- 1 vs. 24 +/- 1 ms, p < 0.05), and late filling velocity was lower (26 +/- 7 vs. 34 +/- 1 cm/s, p < 0.05) in rats with MI versus sham-operated rats. Compared with rats with untreated MI, rats receiving captopril had similar LV diastolic dimensions (10.5 +/- 0.35 vs. 10.7 +/- 0.35 mm), slightly higher fractional shortening (16 +/- 2% vs. 9 +/- 1%, p < 0.05 [captopril MI vs. untreated MI]) and unchanged posterior wall thickening (49 +/- 12% vs. 37 +/- 3%, p = 0.3). In contrast, captopril almost completely normalized diastolic filling abnormalities (E velocity 82 +/- 5 cm/s, p < 0.05 [captopril MI vs. untreated MI]; E wave deceleration rate 15 +/- 2 m/s2, p < 0.05 [captopril MI vs. untreated MI]; isovolumetric relaxation time 20 +/- 1 ms).

CONCLUSIONS

Long-term captopril treatment in rats with a large MI modestly limits LV remodeling and the development of systolic dysfunction but markedly improves the restrictive diastolic filling abnormalities that are seen in untreated rats.

Adverse effects of bone wax in surgery of the orbit

The goal of this article is to establish the incidence and scope of adverse reactions to bone wax in a large orbital surgical series. We report two patients with bone wax granulomas of the orbit as a remote surgical complication. These are the first reported cases of adverse reactions to bone wax in the ophthalmic literature. A chart review was conducted on all patients from the University of British Columbia Orbit Clinic that had surgery with temporary or permanent removal of orbital bone. Two patients with bone wax granulomas were identified. In one case, intraoperative cultures grew Staphylococcus aureus, confirming that the wax may indeed act as a nidus for infection. No cases of pseudoarthrosis have occurred. This syndrome of chronic granulomatous giant cell foreign body inflammation has characteristic clinical, radiologic, and histopathologic features. The literature regarding adverse reactions to bone wax is reviewed, and specific implications for orbital surgery are discussed.

Sex differences in cytosolic androgen receptors in gonadectomized male and female rats

The purpose of this experiment was to determine if there are sex differences in cytosolic androgen receptors (AR) in individual brain nuclei. Bilateral 500 mu diameter samples from 300 mu thick frozen brain sections were micropunched from males and females 2-3 weeks following gonadectomy. Tissue samples were taken from 12 brain nuclei: lateral septum, bed nucleus of the stria terminalis, medial preoptic nucleus, anterior hypothalamic area, arcuate nucleus, corticomedial nucleus of the amygdala, lateral preoptic area, parietal cortex, medial nucleus of the amygdala, dorsomedial nucleus of the hypothalamus, ventromedial nucleus of the hypothalamus, and dorsal hippocampus. Cytosolic ARs were found in brain regions involved in the neuromodulation of androgen dependent responses. These data suggest that behavioral differences in male reproductive responses may be the sexually dimorphic distribution of androgen receptor containing neurons.

Differential cardiac effects of growth hormone and insulin-like growth factor-1 in the rat. A combined in vivo and in vitro evaluation

BACKGROUND

Despite their increasing clinical use and recent evidence that growth hormone (GH) and insulin-like growth factor-1 (IGF-1) target the heart, there has been no systematic investigation of the effects of GH and IGF-1 on the cardiovascular system.

METHODS AND RESULTS

Sixty normal but growing adult female rats were randomized to receive 4 weeks of treatment with GH (3.5 mg.kg-1.d-1), IGF-1 (3 mg.kg-1.d-1), a combination of the two, or placebo. Transthoracic echocardiograms were performed at baseline and at 2 weeks and 4 weeks of treatment. After the final echocardiography, rats underwent either closed-chest left ventricular (LV) catheterization or Langendorff perfusion studies. Myocyte diameter and interstitial tissue fraction were assessed by morphometric histology. Echocardiographic and ex vivo data demonstrated a LV hypertrophic response in all three groups of treated animals that was most marked in the GH group, which alone exhibited a concentric growth pattern (relative wall thickness, 0.52 versus 0.42 to 0.44 in the other groups; P < .001). At 4 weeks, cardiac index was significantly higher and total systemic vascular resistance was lower in all groups of treated animals than in control animals (both P < .001), whereas arterial blood pressure did not differ significantly. All indexes of in vivo and in vitro cardiac function were higher in GH- and IGF-1-treated rats than in control animals, whereas combination therapy yielded a blunted effect. Myocyte diameter was increased in all three treated groups without an increase in interstitial tissue.

CONCLUSIONS

Exogenous administration of GH and IGF-1 in the normal adult rat induces a cardiac hypertrophic response without development of significant fibrosis. Cardiac performance is increased both in vivo and in the isolated heart.

Prolonged exercise alters beta-adrenergic responsiveness in healthy sedentary humans

To examine whether beta-adrenergic desensitization occurs after prolonged exercise, echocardiograms, heart rate responses to isoproterenol, plasma catecholamines, and circulating lymphocyte beta-adrenergic receptors were examined in 10 sedentary normal subjects at rest and after brief (10 min) and exhaustive (mean duration 95 min) cycle exercise. Resting end-diastolic volume and ejection fraction were significantly reduced after exercise (from 120 +/- 34 to 100 +/- 26 ml and from 60 +/- 0.4 to 54 +/- 0.6%, respectively; both P < 0.05). The amount of isoproterenol needed to increase heart rate 15 and 25 beats/min increased in a dose- (exercise duration) related fashion, and the increase in amount of isoproterenol needed after prolonged exercise was closely related to the decrease in ejection fraction (r2 = 0.67, P = 0.004). Circulating lymphocyte beta-receptor density and affinity, agonist binding, and adenylylcyclase levels were unchanged with prolonged exercise. In conclusion, prolonged exercise in sedentary normal subjects resulted in reduced cardiac chronotropic responsiveness to isoproterenol that was not reflected in peripheral lymphocyte beta-adrenergic-receptor downregulation.

Primary ductal adenocarcinoma of the lacrimal gland

PURPOSE

To their knowledge, the authors report the first recognized case of ductal adenocarcinoma of the lacrimal gland (histologic equivalent of salivary duct carcinoma). Primary adenocarcinoma of the lacrimal gland is rare and has been described generically. In contrast, primary adenocarcinomas of the major and minor salivary glands are much more common and have been classified into histopathologic subtypes that have different clinical characteristics and outcomes.

METHODS

A 68-year-old man presented with a 6-month history of a painless mass in the right upper outer eyelid. The authors describe the clinical, radiologic, and histopathologic features of this case and review the lacrimal gland literature.

RESULTS

A modified en bloc orbitectomy was performed, and postoperative radiotherapy was administered. The patient was alive and well without evidence of tumor recurrence 10 months after surgery.

CONCLUSION

The World Health Organization classification of salivary adenocarcinomas (1991) provides a framework for further insight into the presentation and biologic behavior of the less common lacrimal carcinomas.

Serial echocardiographic-Doppler assessment of left ventricular geometry and function in rats with pressure-overload hypertrophy. Chronic angiotensin-converting enzyme inhibition attenuates the transition to heart failure

BACKGROUND

Although chronic pressure overload may progress to left ventricular (LV) failure, the pathophysiology of this transition is not well understood. In addition, the effects of chronic angiotensin-converting enzyme (ACE) inhibition on this transition are largely undefined.

METHODS AND RESULTS

To examine changes in LV structure and function during the transition to heart failure, rats with LV hypertrophy due to banding of the ascending aorta (LVH, n = 22) and age-matched sham-operated rats (n = 6) were studied 6, 12, and 18 weeks after aortic banding. Two-dimensionally guided transthoracic M-mode echocardiograms and transmitral Doppler spectra were recorded for assessment of LV geometry and systolic and diastolic functions. LVH rats were randomized to no treatment (n = 10) or treatment with the ACE inhibitor fosinopril (50 mg/kg per day, n = 12) after the baseline echocardiogram. Six weeks after banding, LVH rats had increased LV wall thickness with normal cavity dimensions and supranormal endocardial systolic shortening. However, midwall shortening was mildly depressed, and a restrictive diastolic filling pattern was present. After 18 weeks of untreated pressure overload, LV wall thickness was unchanged, but cavity dilation, a fall in endocardial shortening, and further deterioration of diastolic filling were evident. In contrast to untreated LVH rats, the fosinopril-treated rats showed no change in LV diastolic cavity dimension, and systolic and diastolic functions did not deteriorate or improved. Closed chest LV systolic pressures at 18 weeks were not different in LVH or LVH-fosinopril rats (197 versus 198 mm Hg), although end-diastolic pressure was higher in the untreated rats (18 versus 11 mm Hg). Calculated LV systolic wall stress was lower in fosinopril-treated than untreated LVH rats. The severity of LV diastolic filling abnormalities correlated strongly with operating LV chamber stiffness (r = .88, P < .0001).

CONCLUSIONS

This model of pressure overload is characterized initially by concentric LV hypertrophy with compensated LV chamber performance; however, markedly abnormal diastolic filling is present. The transition from compensated hypertrophy to early failure is heralded by LV dilation, impairment of systolic function, and progression of the abnormalities in LV filling. Chronic ACE inhibition in rats with supravalvular aortic banding (1) does not change in vivo LV systolic pressure but prevents increased LV cavity size and increased LV wall stress and (2) attenuates impairment of (or improves) both systolic and diastolic functions. The effects of fosinopril could be explained in part by inhibition of an intracardiac renin-angiotensin system.

Determination of sulfadimethoxine withdrawal time from milk. Part I: Dosing, sampling, and assay

This study was undertaken to determine whether present regulations for discarding milk from cows treated with sulfadimethoxine (SDM) can be supported by modern analytical methodology. Two groups of milking cows (10 in first group; 11 in the second) were treated orally with SDM at the recommended dose levels for 5 days. The SDM concentration in the milk was determined with 4 methods (Charm Inhibition Assay [CIA], Charm II, enzyme linked immunosorbent assay, and liquid chromatography) during the treatment and the subsequent withdrawal periods. The results of the 4 assays were compared.

Muscarinic receptors on human eccrine sweat gland in aging and Alzheimer's disease

Age and Alzheimer's disease-related changes have been reported in the peripheral cholinergic system controlling sweating. We present (1) evidence of a high affinity muscarinic receptor localized on human eccrine sweat gland and (2) muscarinic receptor concentrations on eccrine gland samples from 22 patients with probable Alzheimer's disease of various degrees of dementia, 8 age-matched controls, and 11 young controls. Muscarinic receptors were measured using autoradiography with 3H-NMS as ligand. We found no evidence of changes related to aging or Alzheimer's disease in the overall concentration of receptors or in the amount of gland showing binding. Nor was there any correlation between the degree of dementia as measured by the Global Deterioration Scale or the Mini-Mental State Exam and 3H-NMS binding. In conclusion, we find no evidence that previously reported sweat gland functional changes associated with aging and Alzheimer's disease are reflected in changes in eccrine gland muscarinic receptor density.

Impaired left atrial mechanical function after cardioversion: relation to the duration of atrial fibrillation

OBJECTIVES

We hypothesized that the time course of the recovery of atrial systolic function may be related to the duration of atrial fibrillation before cardioversion and sought to study noninvasively the recovery of left atrial mechanical function utilizing serial transthoracic Doppler studies.

BACKGROUND

Recovery of atrial mechanical function may be delayed for several weeks after successful cardioversion of atrial fibrillation to sinus rhythm.

METHODS

After successful cardioversion, 60 patients with atrial fibrillation of brief (< or = 2 weeks, 17 patients), moderate (> 2 to 6 weeks, 22 patients) or prolonged (> 6 weeks, 21 patients) duration were followed up with serial transmitral pulsed Doppler echocardiography immediately (60 patients) and at 24 h (45 patients), 1 week (41 patients), 1 month (31 patients) and > 3 months (30 patients) after cardioversion.

RESULTS

Atrial mechanical function is greater immediately and at 24 h and 1 week after cardioversion in patients with "brief" compared with "prolonged" atrial fibrillation. In all groups, atrial mechanical function increases over time, ultimately achieving similar levels. Full recovery of atrial mechanical function, however, is achieved within 24 h in patients with brief atrial fibrillation, within 1 week in patients with moderate-duration atrial fibrillation and within 1 month in patients with prolonged atrial fibrillation.

CONCLUSIONS

Recovery of left atrial mechanical function is related to the duration of atrial fibrillation before cardioversion. These findings have important implications for assessing the early hemodynamic benefit of successful cardioversion.

In vivo assessment of LV mass in mice using high-frequency cardiac ultrasound: necropsy validation

Left ventricular (LV) mass is an important descriptor of cardiac status that increases with normal aging and may be affected by a variety of disease processes. There are currently limited noninvasive techniques that permit accurate determination of in vivo LV mass in very small animals, such as the mouse, a frequently used model for cardiac research. We sought to evaluate the ability of high-frequency (7.0 or 7.5 MHz), two-dimensional (2-D) guided M-mode echocardiography to estimate in vivo LV mass in the mouse. Fifteen adult mice weighing 22-45 g were studied, including six young adult (2- to 3-mo-old), two adult (12- to 14-mo-old), and seven senescent (18- to 20-mo-old) animals. Resting heart rate varied up to 450 beats/min. Anterior wall, inferior wall, and end-diastolic dimensions were measured, and echocardiographic LV mass (LVMe) was calculated using an uncorrected cube approximation. Autopsy LV mass was determined within 4 h of echocardiographic examination. Autopsy LV mass ranged from 88 to 211 mg. LV chamber dimensions included anterior wall (1.0 +/- 0.2 mm), inferior wall (1.1 +/- 0.3 mm), and end-diastolic dimension (3.7 +/- 0.5 mm). There was a very good correlation between LVMe (x) and autopsy LV mass (y):y = 0.96x - 7, r = 0.94, standard error of the estimate = 18 mg, P < 0.001. This correlation was stronger than that for autopsy LV mass and body weight (r = 0.70) or age (r = 0.74), indexes which until now were the only noninvasive correlates available for this very small animal model. We conclude that, despite the rapid heart rate and small size of the mouse heart, these results demonstrate the potential of high-frequency 2-D guided M-mode transthoracic echocardiography for the in vivo assessment of LV dimensions and mass in the mouse and may prove useful for cardiac research on aging and cardiomyopathies.