Secondary iron overload.

Transfusion therapy for inherited anemias and acquired refractory anemias both improves the quality of life and prolongs survival. A consequence of chronic transfusion therapy is secondary iron overload, which adversely affects the function of the heart, the liver and other organs. This session will review the use of iron chelating agents in the management of transfusion-induced secondary iron overload. In Section I Dr. John Porter describes techniques for the administration of deferoxamine that exploit the pharmacokinetic properties of the drug and minimize potential toxic side effects. The experience with chelation therapy in patients with thalassemia and sickle cell disease will be reviewed and guidelines will be suggested for chelation therapy of chronically transfused adults with refractory anemias. In Section II Dr. Nancy Olivieri examines the clinical consequences of transfusion-induced secondary iron overload and suggests criteria useful in determining the optimal timing of the initiation of chelation therapy. Finally, Dr. Olivieri discusses the clinical trials evaluating orally administered iron chelators.

Anthropometric facial analysis of the African American woman.

OBJECTIVE: To assess the differences in facial proportions between African American and Caucasian women. Differences within the African American population are sought. DESIGN: Anthropometric survey. PARTICIPANTS: Volunteer sample of African American women (N = 108), aged 18 through 30 years, with African American parents and no previous facial surgery or trauma. INTERVENTION: Photographs and 16 standard anthropometric measurements were taken in concordance with the 9 neoclassical canons. Results were compared with the North American white standard and the neoclassical canons, and an intragroup evaluation was performed. One-way analysis of variance, 99.7% confidence intervals, and t tests were used to test differences for significance. MAIN OUTCOME MEASURES: Anthropometric measures. RESULTS: Compared with white women, the following measurements were found to be significantly different (P<.003) in African American women: special head height was shorter; forehead height II was longer; nose length was shorter; lower face height was longer; height of the calva was shorter; forehead height I was longer; and ear length was shorter. In addition, most horizontal measures were wider, ie, eye-fissure width, nasal width, mouth width, and facial width. The nose and ear have greater angles of inclination. Of the 9 neoclassical canons, the orbital proportion was found to include the most proportional subjects (30.6%), followed by the nasoaural proportion (13.0%) and the nasofacial proportion (9.3%). Subcategorization based on nasal dorsal height yielded the most significantly different measures. CONCLUSIONS: African American female facial anthropometric measures, especially those of the horizontal dimension, differ significantly from those of young white subjects. The average African American woman does not fit the neoclassical standard of facial proportion.

Contribution of central ANG II to acute stress-induced changes in baroreflex function in young rats.

The aim of the present investigation was to characterize the baroreflex in weaned 23- to 25-day-old rats when maternal influences were no longer present. The relationship between mean arterial pressure (MAP) and heart rate (HR) was determined during baroreceptor loading with phenylephrine and baroreceptor unloading with sodium nitroprusside in conscious rats, first in the freely moving state and subsequently during acute stress. In unstressed rats, the slope of the relationship between MAP and HR was greater during baroreceptor loading than baroreceptor unloading. Acute stress significantly attenuated the slope of the response to baroreceptor loading but increased the slope of the response to baroreceptor unloading. Pretreatment with intracerebroventricular or intravenous losartan, an AT(1) receptor antagonist, or intracerebroventricular alpha-helical corticotropin-releasing hormone (alpha-hCRH), a receptor antagonist, before the stress significantly reduced the stress-induced attenuation of slope during baroreceptor loading. Hence, young postweaning rats can alter baroreflex function during acute stress in a manner that would favor increases in MAP. Even at this young age, a central action of ANG II and CRH contributes to these stress-induced adaptations.

Microvascular responses to endothelin in deoxycorticosterone acetate-salt hypertensive rats.

The objective of the present study was to determine if endothelin-1 played a role in the elevated peripheral resistance in deoxycorticosterone-acetate (DOCA)-salt hypertension. Radioimmunoassay showed that the concentration of endothelin-1 was higher in thoracic aorta of the DOCA-salt group than that of the control normotensive (CN) group. Responses of arterioles in the rat cremaster to endothelin-1 were also observed using in vivo closed circuit television microscopy. Microvascular sensitivity to endothelin-1 was decreased in the DOCA-salt group. In the presence of an endothelin type A (ET-A) receptor antagonist, low concentrations of endothelin-1 induced a significant vasoconstriction in the DOCA-salt group. In the presence of endothelin type B (ET-B) receptor antagonist, microvascular responses to endothelin-1 were attenuated in the DOCA-salt group. These results indicated that the increased tissue level of endothelin-1 may decrease the ET-A receptor-mediated vascular response to endothelin-1. However, the ET-B receptor-mediated vasoconstriction is potentiated during DOCA-salt hypertension.

Brain angiotensin type 1 receptor expression and function in the Zucker obese rat.

The Zucker obese rat is a model with predisposition for hypertension. There is evidence that angiotensin II (ANG II) may play a role in the maintenance of this hypertension. However, the potential role of brain ANG II in this regard has been largely unexplored. The aim of the present study was to compare the pressor response produced by i. c.v. injection of ANG II in Zucker obese and lean rats, and to determine if functional differences could be correlated to changes in brain AT1 receptor protein and/or mRNA expression. The Zucker obese rat had a significantly greater increase in blood pressure after i.c.v. injection of ANG II compared to the lean rat. AT1 receptor protein expression was greater in the brainstem, but not the hypothalamus, of the obese rat. These data raise the possibility that increased central responsiveness to ANG II may play a role in the predisposition of the Zucker obese rat to hypertension.

Prevalence of sinonasal symptoms in patients with HIV infection.

Infection with the human immunodeficiency virus (HIV) is increasing in prevalence, and disease patterns are changing as patient survival lengthens. The purpose of this cross-sectional epidemiological study was to assess the prevalence and severity of self-reported symptoms of otolaryngologic disease in a group of patients attending a general HIV outpatient clinic (n = 203), and to compare the prevalence of self-reported symptoms with a sample of patients without HIV infection (n = 100). Of the HIV-infected patients, 65% of patients had AIDS, 35% were HIV-positive, and the median CD4 count was 135. Although only 11% of patients had seen an otolaryngologist in the prior 6 months, the majority of patients (66%) reported the presence of sinonasal disease during that time. Allergic rhinitis (80%) and sinusitis (54%) were the most commonly reported sinonasal symptoms, and 44% regularly used nasal or sinus medications. Sinonasal disease severity was significantly higher than the self-reported severity of mouth/throat disease (p = 0.01), ear disease (p = 0.03), and neck/salivary disease (p = 0.01). Although patients' self-reported overall health status was associated (p = 0.02) with CD4 count, the severity of sinonasal symptoms was not associated (p = 0.93) with CD4 count. Similarly, sinonasal symptom severity did not differ between HIV-positive and AIDS patients (p = 0.45). In other words, sinonasal disease severity did not improve as general health status improved.

Chronic intracerebroventricular infusion of angiotensin II increases brain AT1 receptor expression in young rats.

The aim of the present study was to determine the effect of chronic intracerebroventricular infusion of angiotensin II (ANG II) on the expression of brain AT1 receptors in young (3-4 weeks) rats. One week of icv ANG II infusion produced a significant increase in brain AT1 receptor protein (Western blot) and mRNA (relative RT-PCR) expression. These data raise the possibility that ANG II may play a role in postnatal expression of brain AT1 receptors.

The effects of resorbable plates on rabbit ear cartilage.

BACKGROUND: When performing septorhinoplasty, deviated segments of septal cartilage can be straightened using cartilage or bone as splinting grafts. In some cases, autologous material is not available without an additional surgical procedure to harvest cartilage or bone. It is possible that resorbable plates can be used to splint and straighten deviated cartilage. Experience using bioresorbable rigid fixation devices on cartilage has been limited. OBJECTIVE: To examine early histopathologic changes of rabbit ear cartilage and adjacent soft tissue following implantation with bioresorbable plates. DESIGN: Nonrandomized, placebo-controlled trial. SUBJECTS: Twelve adult New Zealand white rabbits. MATERIALS AND METHODS: Ten adult New Zealand white rabbits (20 ears) underwent stenting of intact ear cartilage with LactoSorb plates (Lorenz, Jacksonville, Fla). Rabbits were killed 28 days after implantation, and the soft tissue, plates, and cartilage were harvested and prepared for histological examination. As controls, 2 rabbits (4 ears) underwent dissection and closure without stenting. RESULTS: Six rabbits experienced superficial skin breakdown on the ventral surface of the ear caused by excessive wound tension of the implant. The cartilage-plate interface and the surrounding soft tissues stenting the dorsal side of the ear remained free of inflammation or necrosis for all animals. Simple elevation of the perichondrium revealed no differences in the appearance of the cartilage between the control and test rabbits. CONCLUSIONS: Resorbable plates have no deleterious effects on cartilage during the first month of implantation. While short-term studies have documented the safety and efficacy of using bioresorbable plates, further studies are recommended.

The contoured auricular projection graft for nasal tip projection.

In all rhinoplasty surgery, the universal need exists to increase, decrease, or preserve existing tip projection. When proper tip projection is lacking, a variety of techniques are useful for improving projection. We describe a valuable technique for tip projection, particularly useful and indicated in the Asian rhinoplasty, African American rhinoplasty, and in certain revision rhinoplasties. In the past 15 years, the senior author (M.E.T.) has used the contoured auricular projection graft in selected patients for achieving satisfactory tip projection in patients with blunted tips. The aesthetic outcomes have been predictable, pleasing, and reliable for the long term. Precision pocket preparation for auricular conchal cartilage graft placement is key to symmetry and projection of the final outcome. The results yielded a rounded nasal tip that may be more natural-appearing in Asians, African Americans, and selected patients with revision rhinoplasty. The contoured auricular projection graft provides a highly useful graft for the nasal tip.

Role of cytoplasmic tail of the type 1A angiotensin II receptor in agonist- and phorbol ester-induced desensitization.

To investigate mechanisms underlying the agonist-induced desensitization of the type 1A angiotensin II receptor (AT1A-R), we have stably expressed in Chinese hamster ovary (CHO) cells the wild-type receptor and truncated mutants lacking varying lengths of the cytoplasmic tail. Assay of inositol 1,4,5-trisphosphate (IP3) formation in response to agonist demonstrated that the truncated mutants T318, T328, and T348 lacking the last 42, 32, or 12 amino acid residues, respectively, couple with Gq protein with an efficiency similar to that of full-length receptors, whereas coupling of Gq protein was abolished in the T310 truncated mutant devoid of the carboxyl-terminal 50 amino acids. Exposure of CHO/AT1A-R cells expressing the wild-type AT1A-R to angiotensin II resulted in rapid and dose-dependent homologous desensitization of receptor-mediated IP3 formation, which was independent of the receptor internalization. Mastoparan, an activator of G protein-coupled receptor kinase (GRK), induced desensitization of the AT1A-R. The agonist-induced desensitization of the receptor was largely prevented by heparin, a potent inhibitor of GRK, whereas it was only partially attenuated by a protein kinase C (PKC)-specific inhibitor. The homologous or heterologous desensitization of the receptor was greatly impaired in the truncated mutants T318 and T328, lacking the Ser/Thr-rich (13 or 12 Ser/Thr residues) cytoplasmic tail of the AT1A-R. Deletion of the last two Ser residues, including one PKC consensus site in the receptor tail, prevented only phorbol 12-myristate 13-acetate-induced desensitization by 30%. Moreover, we found an agonist-induced translocation of a heparin-sensitive kinase activity. The angiotensin II-stimulated heparin-sensitive kinase could phosphorylate a thioredoxin fusion protein containing the entire AT1A-R cytoplasmic tail (N295 to E359), which lacks consensus phosphorylation sites for GRK1, GRK2, and GRK3. The heparin-sensitive kinase may not be GRK2, GRK3, or GRK6 expressed in CHO/AT1A-R cells, since angiotensin II did not induce translocation of these receptor kinases. Potential Ser/Thr phosphorylation sites located between S328 and S347 in the cytoplasmic tail of AT1A-R seem to play a critical role in the heterologous and homologous desensitization of the receptor. A heparin-sensitive kinase other than GRK2, GRK3, or GRK6 may be involved in the agonist-induced homologous desensitization of the AT1A-R.

Immune enhancing effects of dehydroepiandrosterone and dehydroepiandrosterone sulphate and the role of steroid sulphatase.

Steroid hormones, such as glucocorticoids (GC), influence immune and inflammatory responses through their suppressive actions. Recent evidence suggests that another steroid hormone, dehydroepiandrosterone (DHEA), provides an immunostimulatory influence opposing the effect of GC. DHEA circulates in its inactive sulphated form, DHEAS, requiring conversion to DHEA by a steroid sulphatase (SS) enzyme for biological activity. Therefore, inhibition of SS activity may affect immune responses, allowing endogenous GC effects to predominate. We have shown that administration of DHEA and DHEAS in contact sensitization (CS) augments ear swelling by 39 and 46% respectively (P < 0.001). DHEAS at doses of 0.5, 5 and 50 mg/kg reverses the inhibitory effect of corticosterone (5 mg/kg) (P < 0.01). In CS, CT2251 (SS inhibitor) at 10 and 0.1 mg/kg inhibited ear swelling by 61 and 38% (P < 0.05) respectively. In addition, it inhibited DHEAS-augmented responses by 49 and 35% respectively (P < 0.05), with no effect on DHEA-augmented responses. DHEAS reversed CT2251 inhibition of the CS response with complete reversal at 50 mg/kg (P < 0.05). DHEAS and CT2251 appear to affect cellular infiltration into the ear, since DHEAS increased the number of lymphocytes by 63.8% and macrophages by 107% (P < 0.001), whereas CT2251 at 0.1 mg/kg decreased the number of lymphocytes by 65% (P < 0.001) and macrophages by 80% (P < 0.001). DHEAS, CT2251 and dexamethasone had no effect on oedema in the ear. From our data we have shown that steroid hormones, such as DHEA, have the potential to act as immunostimulatory factors in vivo. Inhibiting the conversion of DHEAS to DHEA by SS enzyme leads to an anti-inflammatory effect.

Effect of intracerebroventricular and intravenous insulin on Fos-immunoreactivity in the rat brain.

The potential central neural substrate for the sympathoexcitatory effect of insulin was investigated in conscious rats using Fos expression as an index of neural activity. Fos immunoreactivity in the hypothalamus and brainstem was compared in rats infused with intracerebroventricular (i.c.v.) insulin or saline for 60 min. The insulin had no effect on Fos expression in any brain nuclei. Likewise, a 90-min intravenous infusion of insulin (euglycemic) had no effect on brain Fos immunoreactivity. However, when blood glucose was allowed to decrease, Fos expression did increase in the arcuate nucleus and in the brainstem. These data do not provide any evidence to support the idea that insulin can act within the central nervous system to increase sympathetic nervous outflow.

Vasodilator effect of insulin on the microcirculation of the rat cremaster muscle.

We recently showed that, in conscious rats, acute infusions of insulin (10-15 fold increase in plasma insulin) produced decreases in hindquarter vascular resistance, but only if, changes in sympathetic outflow were prevented with a ganglionic blocker. The aim of the present investigation was to determine if similar effects of insulin could be observed in a preparation that allowed direct visualization of striated muscle (cremaster) microvessels. Initial studies with topical application of insulin showed that third-order arterioles (A3), but not first- or second-order arterioles vasodilated in response to 800 microU/ml and 8 mU/ml of insulin. Systemic (euglycemic) infusion of insulin (6 mU/ml, but not 2 mU/ml) also increased A3 arteriole diameter in animals treated with a ganglionic blocker, but not in control rats. These data show that insulin can have a direct vasodilator effect on striated muscle microvessels if concomitant increases in sympathetic outflow are absent. However, the response was only present with supraphysiological doses of the hormone.

Dietary myo-inositol restores diabetic renal arteriolar reactivity to angiotensin II but not to norepinephrine.

OBJECTIVE: This study addresses the hypothesis that the diminished constriction of renal arterioles to angiotensin II (Ang II) and norepinephrine (NE) in diabetic rats is due to elevated activity in the polyol pathway. This activity results in reduced incorporation of myo-inositol into membrane phospholipids and impaired signal transduction. METHODS: The left ureter of female Wistar rats (140-160 g) was surgically ligated. Four to six weeks later, streptozotocin (50 mg/kg, i.p.) was injected in half of the rats in induce diabetes. Beginning on the day of streptozotocin injection, diabetic and nondiabetic rats were fed either a standard diet or a diet enriched with 1% myo-inositol. Seven to 10 days later, all rats were anesthetized and the hydronephrotic kidney was bisected and exteriorized in a bath for direct visualization of the renal microvasculature. The constrictor responses of interlobular, afferent, and efferent arterioles to Ang II or NE (applied to the bath) were directly quantitated by in vivo microscopy. RESULTS: Among diabetic rats, the myo-inositol-enriched diet significantly enhanced the constriction of interlobular, afferent, and efferent arterioles in response to Ang II, so that the responses to the peptide were almost completely restored to normal. Constriction to NE by interlobular arteries and afferent arterioles (but not efferent arterioles) was also significantly attenuated among diabetic rats fed the standard diet. However, unlike what was observed for Ang II, the myo-inositol-enriched diet did not enhance constriction to NE among diabetic rats. CONCLUSIONS: These data indicate that different mechanisms are responsible for decreased renal arteriolar constriction due to Ang II and NE in early diabetes. Diminished arteriolar constriction due to Ang II, but not to NE, may be linked to altered myo-inositol metabolism.

Effect of insulin on regional vascular resistances in conscious rats.

In the rat, but not in humans and other mammals, chronic administration of insulin produces hypertension. The present aim was to determine the effect of acute insulin infusion on regional vascular resistances and to determine the neurogenic contribution to the response. Conscious rats were infused with insulin (2 or 6 mU/min) before and after ganglionic blockade with chlorisondamine (5 mg/kg). The low dose of insulin produced an increase in arterial pressure and hindquarter vascular resistance; the high dose produced a gradual decrease in arterial pressure and renal resistance. After ganglionic blockade, the hindquarter vasoconstriction produced by the low dose was abolished. The high dose of insulin produced both hindquarter and renal vasodilation. Thus the low dose of insulin had a selective neurogenic vasoconstrictor effect in rat skeletal muscle vascular beds. With higher doses, direct vasodilatory effects in both skeletal muscle and renal vascular beds appeared. This greater sensitivity of the sympathoexcitatory effects of insulin in rats may explain the ability of chronic insulin infusions to increase blood pressure in this species.

Reduced renal microvascular reactivity to angiotensin II in diabetic rats.

OBJECTIVE: Renal hyperfiltration in early diabetes is often correlated with increased renal blood flow, reflecting dilation of resistance arterioles. This loss of arteriolar tone has been associated with an impaired reactivity to angiotensin II (Ang II). This study determined if outer cortical arterioles (preglomerular and/or postglomerular) of diabetic rats exhibit a diminished reactivity to Ang II and established if renal vascular prostaglandins account for the diminished responsiveness. METHODS: The constriction of renal microvessels to Ang II (applied to the kidney bath) was quantitated in hydronephrotic kidneys of diabetic rats (7-10 days after streptozotocin treatment) and nondiabetic rats by in vivo videomicroscopy. RESULTS: Interlobular, afferent, and efferent arterioles of diabetic rats were found to be less reactive to Ang II than arterioles of nondiabetic rats. Indomethacin, added to the bath to inhibit renal vascular prostaglandin synthesis, enhanced the interlobular and efferent arteriolar reactivity to the peptide among diabetic rats. Yet, after indomethacin treatment, the afferent and efferent arterioles of diabetic rats were still less reactive than control arterioles to Ang II. CONCLUSIONS: We conclude that the blunted reactivity of afferent and efferent arterioles to Ang II among diabetic hydronephotic kidneys cannot be fully explained by the influence of renal vascular-derived dilator prostaglandins.

Effect of intrahypothalamic insulin on sympathetic nervous function in rats drinking a high-sucrose solution.

Hyperinsulinemia has been associated with increased sympathetic nervous activity. However, direct injection of insulin into the hypothalamus of anesthetized rats produces sympatho-inhibition. This discrepancy could be due to confounding effects of anesthesia or insulin resistance on central neural function. The effect of injecting saline or insulin (3.0 or 30 mU) into the ventromedial hypothalamus on mean arterial pressure, heart rate, and renal nerve activity (RNA) was investigated in conscious rats and in rats anesthetized with urethan or pentobarbital. Insulin decreased RNA in conscious rats but had no effect in pentobarbital-anesthetized rats. In urethan-anesthetized rats with hyperglycemia, the insulin increased RNA. Drinking a 10% sucrose solution enhanced the sympathoexcitatory effect of insulin in the urethan-anesthetized rats but had no effect in the other two groups. The sucrose solution did not affect insulin sensitivity in any group; however, urethan anesthesia did produce insulin resistance. These data show that central effects of insulin are sensitive to anesthesia and do not support a sympathoexcitatory role for insulin in the ventromedial hypothalamus of conscious rats, at least in relation to the renal sympathetic nerves.

Humanization of an antibody directed against IgE.

IgE antibodies bind to specific high-affinity receptors on mast cells, leading to mast cell degranulation and release of mediators, such as histamine, which produce symptoms associated with allergy. Hence, anti-IgE antibodies that block binding of IgE to its high-affinity receptor are of potential therapeutic value in the treatment of allergy. These antibodies must also not bind to IgE once it is bound to the receptor because this would trigger histamine release. This study describes the humanization of a murine antibody, MaE11, with these characteristics. Variants of the humanized antibody were evaluated to probe the importance of framework residues on antibody binding and to determine which charged residues in the CDR interacted with IgE. We found that only five changes in human framework residues were required to provide for binding comparable to that of the original murine antibody.