17 beta-Estradiol prevents dysfunction of canine coronary endothelium and myocardium and reperfusion arrhythmias after brief ischemia/reperfusion

BACKGROUND

Brief myocardial ischemia is associated with myocardial and coronary endothelial dysfunction caused by oxygen free radicals released during reperfusion. Estrogen, known to have antioxidant activity, may prevent these complications.

METHODS AND RESULTS

We assessed the effect of 2 weeks of treatment with 17 beta-estradiol (E, 100 micrograms.kg-1.d-1, n = 12) or placebo (P, n = 15) on myocardial and coronary endothelial function during the first 2 hours of reperfusion in dogs subjected to 15 minutes of ischemia induced by occlusion of the left anterior descending coronary artery (LAD). Our results show that the incidence of ventricular arrhythmias significantly decreased in E (3 of 12) compared with P (11 of 15). Systolic shortening, significantly depressed in P during early reperfusion, was maintained at preischemic levels in E. During reperfusion, the increase in LAD flow to acetylcholine, attenuated in P (60 +/- 6%), was preserved in E endothelium. (151 +/- 28%) and was associated with increased serum nitrite/nitrate concentration. n-Pentane in exhaled gas in vivo, an index of lipid peroxidation, increased significantly during early reperfusion in P (from 9.1 +/- 1.9 to 41.6 +/- 13.0 ppb, P < .05) but not in E (23.0 +/- 6.9 ppb). In vitro, arterial segments from E generated significantly less superoxide anion after hypoxia/reoxygenation than those from P. Ischemic/reperfused LAD segments from E also revealed a better preservation of endothelium-dependent relaxation in vitro (maximum relaxation, 42 +/- 4% versus 24 +/- 4% in P; P < .05).

CONCLUSIONS

Estrogen protects against endothelial and myocardial dysfunction resulting from brief ischemia/reperfusion. This protection may relate to an antioxidant effect of estrogen.

Two Roles of Nonionic Surfactants on the Electrorheological Response

The influence of three nonionic surfactants (Brij 30, GMO, and GTO) on the electrorheological response of various alumina/silicone oil suspensions is investigated. The dependence of the dynamic yield stress on such variables as surfactant type and concentration, water and ion content, and electric field strength and frequency is reported. The prevalent feature common to all formulations is that the yield stress, tau0, initially increases with surfactant concentration, passes through a maximum, and then decreases with surfactant concentration. Below the maximum, the yield stress increases quadratically with the field strength, E, while above the maximum, yield stress increases slower than E2. The increase in the yield stress with surfactant concentration is due to surfactant-enhanced interfacial polarization, which may arise from increased proton transport via neighboring hydrogen bonds. The nonlinear behavior observed at large surfactant concentrations (i.e., tau0 $\not\propto$ E2) arises from field-induced phase separation of a surfactant-rich phase as opposed to field-dependent conductivity of a homogeneous continuous phase.

The effect of glucagon on spontaneous contractility of isolated pregnant uterine muscle

OBJECTIVE

To determine whether glucagon has relaxant effects on the spontaneous contractions of term pregnant human uterine smooth muscle in an isolated preparation.

METHODS

Myometrial specimens were excised from the upper incisional surface of the lower uterine segment in seven women during elective cesarean delivery. The muscle strips were suspended in tissue baths and isometric tension was recorded. After establishing rhythmic spontaneous contractions, glucagon reconstituted with distilled water or the accompanying diluent was added directly to the bath in a cumulative manner. In the second phase of the study, the effect of the diluent (1.6% glycerin with 0.2% phenol) alone on muscle contractility was evaluated.

RESULTS

Glucagon had no effect on uterine muscle concentrations when reconstituted with distilled water. However, glucagon reconstituted with the diluent decreased the contractile amplitude by 27 +/- 11% (mean +/- standard deviation, P < .01) and the frequency by 13 +/- 10% (P < .05) at a concentration of 20 micrograms/mL. At a cumulative concentration of 40 micrograms/mL, the reductions in amplitude and frequency were 65 +/- 13% (P < .001) and 18 +/- 14% (P < .01), respectively. The diluent at equivalent concentrations exerted relaxation similar to that produced by glucagon when reconstituted with the diluent. The relaxant effects were not different between the two solutions (P > .2, power 90%, alpha = .05).

CONCLUSION

These results suggest that relaxation of contractions was likely caused by the diluent rather than by glucagon. We conclude that glucagon does not have a direct relaxant effect on spontaneous contraction of isolated uterine muscle obtained from term pregnant uteri.

Estrogen receptor immunocytochemistry in paraffin embedded tissues with ER1D5 predicts breast cancer endocrine response more accurately than H222Sp gamma in frozen sections or cytosol-based ligand-binding assays

BACKGROUND

Historically, estrogen receptor (ER) determinations have been made by the ligand-binding assay of tumor homogenates, primarily by the dextran-coated charcoal method (DCC). Immunocytochemical assays (ICA) for ER are more recent and have been executed mostly on frozen sections with the monoclonal antibody H222Sp gamma (H222). Lately, new monoclonal antibodies derived by recombinant ER technology have been developed that work well on paraffin embedded, formalin fixed tissue sections. However, there is little information as to whether such assays prognosticate endocrine response.

METHODS

Using antigen retrieval, the immunoglobulin G1 monoclonal antibody ER1D5, and the streptavidin-biotin detection system, 74 patients with breast cancer in whom endocrine response was known were assayed and the results compared with ER by DCC and ER by ICA in frozen section with H222.

RESULTS

ER1D5 in paraffin provided the highest correlation with endocrine response (Kendall's tau [r] = 0.57; P<0.001) whereas ER by DCC failed to correlate (r= -0.002; P<0.99). ER1D5 in paraffin correlated weakly though significantly with DCC (Kappa Statistic [K] = 0.204; P<0.02). H222 in frozen sections also correlated moderately with endocrine response (r = 0.34; P<0.001).

CONCLUSIONS

ER can be detected in routine tissue sections processed with antigen retrieval and ER1D5, and can be relied upon to provide accurate prognostic information regarding response to endocrine therapies in breast cancer patients.

Brain SPECT of Creutzfeldt-Jakob disease

SPECT imaging with I-123 IMP or Tc-99m HMPAO was performed in two patients with Creutzfeldt-Jakob disease to evaluate abnormalities in brain perfusion. In the first patient, there was decreased perfusion of the left frontal, parietal, and temporal lobes. CT and MRI were negative. In the second patient, there was patchy perfusion and slightly decreased perfusion of the right hemisphere. MRI revealed slight brain atrophy and bilateral high intensity areas in the basal ganglia on T2 weighted images. Subsequent SPECT imaging revealed severely decreased perfusion of the entire brain. Subsequent MRI demonstrated severe brain atrophy.

Cyst of accessory lacrimal gland

When a patient is presented with a subconjunctival cyst, it is not only hard to reveal its true nature clinically but also easy to rupture during excision. We experienced cases with cysts of the accessory lacrimal gland in two patients with subconjunctival cysts. They had lid swelling at initial presentation and underwent surgical excision of subconjunctival cysts located in superior portion of the upper tarsal plate. The lining of these cysts composed of ductal epithelia. Biochemical analyses for serum and cystic fluid were performed in one case, in which was found high Ig A titer in the cystic fluid. These cysts seemed to originate from the duct of Wolfring's accessory lacrimal gland, considering their anatomic locations and pathologic findings. Complete removal of the cyst is important, because recurrences have been reported in cases of incomplete removal or simple aspiration.

Effect of dantrolene sodium on contractility of isolated human uterine muscle

The administration of intravenous dantrolene in a parturient susceptible to malignant hyperthermia has been associated with post partum uterine atony. We examined the effect of dantrolene sodium for injection (Dantrium Intravenous) on spontaneous contractility of uterine smooth muscle from women in term pregnancy in an isolated preparation. Dantrolene sodium for injection at 5 microg/ml and 10 microg/ml had no effect on the spontaneous contractility of the uterine muscle preparations. At a cumulative concentration of 20 microg/ml, a mild depression (16 +/- 14%) in the frequency of spontaneous contractions was noted. However, a similar depression in the muscle preparations treated with mannitol suggests that the depression observed with the dantrolene was likely due to the mannitol that was included in the dantrolene formulation rather than to dantrolene sodium itself. We conclude that dantrolene sodium has no effect on the spontaneous contractility of uterine smooth muscle. The depression of uterine muscle activity observed with dantrolene for injection appears attributable to the mannitol.

Immunostaining for prostate cancer androgen receptor in paraffin identifies a subset of men with a poor prognosis

BACKGROUND

Knowledge of androgen receptor (AR) content could help predict hormone response and disease course in prostate cancer. However, determination of AR by biochemical assay is difficult. An immunohistochemical assay (ICA) would solve most difficulties and be especially useful if it could be performed on paraffinized tissue.

EXPERIMENTAL DESIGN

AR was studied in paraffin sections from 90 men for whom endocrine response, survival (except one case), and/or biochemical AR was known. After Ag retrieval in a microwave oven, a polyclonal anti-AR Ab was used with the peroxidase antiperoxidase method. Results were semiquantified using a Histoscore (Hscore) and were correlated with biochemistry, endocrine response, and survival.

RESULTS

Only 15 patients were AR-negative. AR-ICA did not correlate with biochemistry, Gleason score, stage, or ethnicity but did correlate with endocrine response and survival. The average Histoscore was significantly lower in patients with progressive disease (p < 0.05). In a Cox's regression analysis of survival (mean follow-up = 30 months) AR-ICA was a significant predictor (p = 0.015). Risk of death was 2.5 times greater for a patient with a negative assay compared with one with a positive result.

CONCLUSIONS

Our data indicate that AR status by ICA may be a useful predictor of survival and endocrine response in prostate cancer. Further studies are needed to confirm these results because the assay could impact significantly on management.

Upper airway sleep-disordered breathing in women

OBJECTIVE

To investigate the various clinical presentations of sleep-disordered breathing in women.

DESIGN

A retrospective case-control study.

SETTING

A sleep disorders clinic.

PATIENTS

334 women, aged 18 years and older, seen between 1988 and 1993, who were diagnosed with upper airway sleep-disordered breathing. Controls were 60 women with insomnia and 100 men with sleep-disordered breathing.

MEASUREMENTS

Clinical, anatomic, and polygraphic information.

RESULTS

The mean lag time (+/- SD) in women between the appearance of symptoms and a positive diagnosis was 9.7 +/- 3.1 years; among participants 30 to 60 years of age, the duration of untreated symptoms differed (P < 0.001) between women and men. Sleep-disordered breathing was blamed for divorce or social isolation by 40% of the case patients. Abnormal maxillomandibular features were noted in 45% of the women with disordered breathing. Dysmenorrhea and amenorrhea (which disappeared after treatment with nasal continuous positive airway pressure) were reported in 43% of premenopausal women compared with 13% of persons in the control group of women with insomnia. Thirty-eight women (11.4%) with upper airway sleep-disordered breathing had a respiratory disturbance index of less than 5 and were significantly younger, had a smaller neck circumference, and had a lower body mass index than women with a respiratory disturbance index of 5 or more.

CONCLUSION

Physicians should revise their understanding of upper airway sleep-disordered breathing so that they notice women with certain craniofacial features, a low body mass index, a small neck circumference, and a respiratory disturbance index of less than 5. These revisions may enable more rapid diagnosis and treatment of women with sleep-disordered breathing.

Effects of estrogen on cardiovascular responses of premenopausal monkeys

Exogenous estrogen administration has been shown to reduce the risk of coronary heart disease in women. However, there are limited data in regard to the effects of estrogen on cardiovascular function and hemodynamics. This experiment sought to determine the effect of exogenous estrogen administration on systemic hemodynamic variables and cardiovascular responses to adrenergic and vasodilator agonists in premenopausal cynomolgus monkeys. Adult female monkeys were given weekly i.m. injections of 1) saline (control, n = 6), 2) estradiol cypionate (100 micrograms/kg, n = 6) or 3) estradiol cypionate (700 micrograms/kg, n = 5) for 6 weeks. A Swan-Ganz thermodilution catheter and arterial catheters were used to measure cardiovascular hemodynamic parameters in anesthetized monkeys before and during i.v. infusion of 1, 2, 4 and 8 micrograms kg-1 min-1 of isoproterenol, phenylephrine and nitroprusside. The high-dose estradiol group had a higher cardiac output index (0.6 +/- 0.1 versus 0.25 +/- 0.1 liter min-1 kg-1, mean +/- S.E.M.) and lower systemic vascular resistance index (628 +/- 160 versus 2630 +/- 872 dyne x cm-5 x sec-2 kg-1) than the control group at base line before infusion of agonists (P < .05). High-dose estradiol administration attenuated the mean arterial blood pressure, cardiac output and systemic vascular resistance changes in response to infusions of phenylephrine, isoproterenol and nitroprusside (P < .05 versus control). It was concluded that the administration of high-dose estradiol resulted in systemic arterial dilation, although changes in hemodynamic variables (systemic vascular resistance and cardiac output) were attenuated during adrenergic stimulation and vasodilation.

Effects of isoflurane on regional coronary blood flow and myocardial tissue pressure in chronically instrumented dogs

BACKGROUND

The effects of isoflurane on distribution of transmural blood flow and transmural intramyocardial tissue pressure (IMP) were studied in chronically instrumented dogs, to address following aims: (1) to evaluate the direct effects of isoflurane on transmural blood flow distribution in the absence of compounding effects of baseline anesthetics, acute surgery, and indirect effects caused by changes in systemic blood pressures and heart rate--factors that were not well controlled in the past studies; (2) to examine the relation between transmural myocardial perfusion pressure and concurrent changes in transmural blood flow distribution during isoflurane anesthesia; and (3) to evaluate the effects of isoflurane on transmural myocardial oxygen supply-demand relation.

METHODS

Dogs were allowed to recover at least 1 week after surgery for instrumentation. Blood flow of the left anterior descending coronary artery and subendocardial and subepicardial blood flows, regional IMPs, regional segmental dimension, heart rate, aortic pressure and left ventricular pressure were measured while dogs were awake and during 1.3% isoflurane anesthesia, with and without correction of heart rate and aortic pressure. Concurrently regional myocardial perfusion pressure, regional myocardial stroke work, and systolic pressure time index were calculated, based on direct measurements of IMP in subendocardium and subepicardium.

RESULTS

Without correction of aortic pressure, neither left anterior descending coronary artery flow nor transmural blood flow distribution was altered with isoflurane. When aortic pressure and heart rate were corrected to the awake values, left anterior descending coronary artery flow increased (37 +/- 2%) and the increase was preferentially distributed to subendocardium, resulting in a shift in transmural blood flow. The subendocardial/subepicardial blood flow ratio increased from 1.2 +/- 0.3 to 1.4 +/- 0.4 (p, 0.05). The transmural blood flow changes were closely related to changes in regional myocardial perfusion pressure ratio between subendocardium and subepicardium (r = 0.76, P < 0.001). Concurrent with marked increases in blood flow (55 +/- 4% increase), regional myocardial stroke work and systolic pressure time index of subendocardium were decreased more than 50% with isoflurane, resulting in a favorable subendocardial oxygen supply-demand balance.

CONCLUSIONS

Isoflurane is a coronary vasodilator and redistributes blood flow in favor of subendocardium and depresses subendocardial work when heart rate and aortic pressure are controlled. These changes in regional myocardial blood flow, regional myocardial stroke work, and systolic pressure time index appear to be a result of changes in regional IMP.

Management of exposed hydroxyapatite orbital implants

BACKGROUND

Porous coralline hydroxyapatite orbital implants have gained significant popularity for use in anophthalmic sockets. Several reports have noted increased rates of early implant exposure.

METHODS

Six patients with exposure complications of primary hydroxyapatite implants after enucleation or evisceration were studied.

RESULTS

The hydroxyapatite implant exposures occurred 2 to 8 weeks after implantation. Magnetic resonance imaging scans with gadolinium enhancement obtained in two patients demonstrated a "cold" zone anteriorly with failure of fibrovascular ingrowth in the region of anterior exposure. Several different surgical procedures were used to regain implant coverage, including freshening the edge of the conjunctival defect and observing for spontaneous closure, burring away the anterior surface of the hydroxyapatite implant, and placing autogenous free tissue grafts of hard-palate mucosa or thin dermis-fat graft over the exposed hydroxyapatite. Repeated exposure after free graft was noted in several patients, and three of the six patients followed have an intact surface but very thin conjunctiva overlying hydroxyapatite spicules.

CONCLUSION

Although small areas of hydroxyapatite exposure (< 3 mm) may close spontaneously, larger defects do not tend to close spontaneously and should be actively managed. Based on our experience, optimal results are obtained with free autogenous tissue grafts combined with burring of the anterior hydroxyapatite surface. Steps should be taken at the time of primary implantation to minimize implant exposure, including choosing appropriately sized implants and obtaining careful coverage with good vascularized tissue under minimal tension.

Functional recovery of stunned myocardium is greater with halothane than fentanyl anaesthesia in dogs

We have compared the effects of halothane or fentanyl on recovery of regional myocardial function in the postischaemic ventricle in dogs. The animals were followed for 120 min during reperfusion after 15-min of occlusion of the left anterior descending coronary artery. After 120 min of reperfusion, the fentanyl group had recovered only 54% and 50% of regional contractility and systolic shortening (P < 0.05), respectively, compared with halothane (63% and 86%). Intramyocardial tissue pressure was less than baseline 60 min after reperfusion in the fentanyl group (P < 0.05), whereas the halothane group had returned to control values. We conclude that halothane is more effective than fentanyl in attenuating regional myocardial dysfunction associated with transient episodes of ischaemia.