Effect of CPAP therapy on daytime function in patients with mild sleep apnoea/hypopnoea syndrome

BACKGROUND

Continuous positive airway pressure (CPAP) is an effective treatment in patients with moderate and severe sleep apnoea/hypopnoea syndrome (SAHS), but the minimum illness severity at which patients obtain benefit from CPAP is unclear. A study was therefore undertaken to investigate whether CPAP improves symptoms and daytime function in patients with mild SAHS.

METHODS

Sixteen consecutively recruited patients with mild SAHS (5.0-14.9 apnoeas + hypopnoeas per hour slept and two or more symptoms of SAHS) participated in a prospective placebo controlled randomised crossover trial to assess the effects of CPAP on symptoms and daytime function. Patients spent four weeks on placebo and four weeks on CPAP, undergoing assessments of sleepiness, symptoms, cognitive performance, and well being on the last day of each treatment. Data from the placebo and CPAP assessments were compared.

RESULTS

The mean (SE) objective effective use of CPAP was 2.8 (0.7) hours per night. Significant improvements in symptom score (-1.7 (0.5), p < 0.01), mental flexibility (-14 (5) seconds, p = 0.02), and depression rating (-1.6 (0.8), p = 0.03) on CPAP were observed. However, no significant differences in subjective or objective sleepiness were found. Ten of the 16 patients preferred CPAP and opted to continue with this treatment, although this proportion was non-significant (p > 0.4). The eight patients with best CPAP use showed an additional CPAP related improvement in quality of life (-4.4 (1.8), p = 0.03). Those who complied better with CPAP therapy also had a higher average microarousal frequency (p < 0.01) and apnoea+hypopnoea index (p = 0.02) than the poorer compliers.

CONCLUSIONS

The results of this study provide evidence for improvements in symptoms and daytime function for patients with mild SAHS treated with CPAP.

The relationship of alcohol to injury in assault cases

Little is known about the precise role of alcohol in the escalation of interactions from threats into physical violence or its contribution to the risk of injury. Experimental studies indicate that intoxicated subjects (allegedly) give markedly higher electric shocks than sober subjects and are less sensitive to their cries of pain. However, few studies in a naturalistic setting have examined whether aggressive acts become more serious and result in higher injury rates when the assailants have been drinking than when they are sober. This chapter reviews the two bodies of research on the effects of alcohol on interpersonal aggression and violence; presents new data on the escalation of threatening interactions to assaults and the likelihood of victim injury given an assault, using data from the National Crime Victimization Survey for the years 1992 and 1993; and suggests future directions for research based on our findings that alcohol's impact on both escalation and injury differed according to the victim-assailant relationship.

Arousals and the sleep apnea/hypopnea syndrome

As daytime deficits in sleep apnea/hypopnea syndrome (SAHS) correlate poorly with earlier definitions of arousals, we investigated the relationship between microarousals and sleepiness in 63 patients with SAHS. There was a poor correlation between mean sleep latency and microarousal frequency. To determine whether arousals not detected by current definitions could account for some of the residual variance in normal subjects we used sound to induce "arousals" that were detected by rises in blood pressure but produced no visible EEG change. Such autonomic arousals produced an increase in sleepiness. We conclude that arousals not scored currently on polysomnography may contribute to the sleepiness of patients with SAHS.

Ambulatory blood pressure on and off continuous positive airway pressure therapy for the sleep apnea/hypopnea syndrome: effects in "non-dippers"

Ambulatory blood pressure (BP) monitoring was performed in 13 patients with the sleep apnea/ hypopnea syndrome (SAHS) during a randomized, placebo controlled crossover trial of the effects of continuous positive airway pressure (CPAP) therapy. BP was monitored at half-hourly intervals for a 24-hour period both on CPAP and on an oral placebo, each given for a minimum of 3 weeks. Objective effective CPAP use averaged 4.3 hours per night. Weight and anti-hypertensive medications remained stable over the study period. Systolic, diastolic and mean arterial BP for 24-hour, daytime and nighttime periods were not significantly different on placebo compared to CPAP. Those patients with no significant overnight fall in BP on placebo ("non-dippers") showed a significant improvement in daytime mean arterial BP on CPAP (98 +/- 4 mm Hg) compared to placebo (102 +/- 4 mm Hg; p = 0.01). These findings, in a well-controlled trial, suggest that BP is not reduced by CPAP in a heterogeneous group of SAHS patients, but it may be selectively improved in those patients most at risk for cardiovascular morbidity and mortality.

The effect of sleep fragmentation on daytime function

Patients with the sleep apnea/hypopnea syndrome suffer from impaired daytime function. This has been attributed to both sleep fragmentation and hypoxemia. To help understand which is casual, we studied the effects of sleep fragmentation alone on daytime function. Sixteen normal subjects were studied on two pairs of two nights. The first night of each pair was for acclimatization, and on the second the subject either slept undisturbed or had sleep fragmented with sound pulses every 2 min. Sound volume and duration was titrated to cause a return to theta or alpha rhythm on the EEG for at least 3 s. Study nights were followed by daytime testing of psychometric function and mood and by a multiple sleep latency test (MSLT) and a maintenance of wakefulness test (MWT). Total sleep time did not differ between study nights (400 +/- 20 SD min undisturbed, 396 +/- 24 min fragmented; p = 0.6). Fragmentation decreased sleep latency on both the MSLT (11 +/- 3, 7 +/- 2 min; p = 0.001) and the MWT (34 +/- 8, 24 +/- 10 min; p<0.001). Energetic arousal (22 +/- 4, 19 +/- 4; p = 0.005) and hedonic tone (29 +/- 4, 27 +/- 4; p = 0.05) decreased after fragmentation. Fragmentation impaired daytime function adjudged by the Trailmaking B (p = 0.05) and PASAT 4-s tests (p<0.03). One night of sleep fragmentation makes normal subjects sleepier during the day, impairs their subjective assessment of mood, and decreases mental flexibility and sustained attention.

The genetic defect in two well-studied cases of Bernard-Soulier syndrome: a point mutation in the fifth leucine-rich repeat of platelet glycoprotein Ib alpha

Bernard-Soulier syndrome (B-Ss) is a rare congenital bleeding disorder caused by abnormal giant platelets, thrombocytopenia, and defective glycoprotein (GP) Ib-V-IX, the adhesion receptor for von Willebrand factor (vWF). This report describes the molecular defect in two related individuals with well-established B-Ss whose platelets exhibit decreased GPIb-IX and normal GPV on their surfaces. The GPIb-V-IX genes of the two patients were analyzed by Southern blotting, hetero-duplex analysis, and polymerase chain reaction (PCR) amplification/sequencing. A point mutation was found in codon 129 of the GPIb alpha gene that results in the substitution of proline for leucine in the first position of the fifth leucine-rich glycoprotein repeat of the mature gene product. The mutation (CTC: leucine, wild-type to CCC: proline, mutant) eliminates a Sac I restriction site, facilitating analysis of the mutation in the propositi (both homozygotes), unaffected family members (8 heterozygotes and 8 wild-type), and 58 normal controls (116 wild-type alleles). The status of the genomes was confirmed by the sequencing of platelet cDNA. The mutation does not affect transcription of the Ib-IX genes, as estimated by PCR and Northern blot analysis, but it does inhibit surface expression of the receptor as assessed by transient transfection of mutant and wild-type GPIb alpha genes into mouse Ib beta-IX L cells. Many of the cells (43%) transfected with the normal gene express surface GPIb alpha, whereas untransfected cells and those transfected with the mutant gene lack surface GPIb alpha entirely. Patient platelets were tested both for vWF binding in the presence of ristocetin and for surface GPIb-IX expression. In these instances, despite their inability to agglutinate with ristocetin and vWF, patient platelets exhibit about 40% of normal vWF binding and 40% of normal Ib-IX surface antigens. The results suggest that the described mutation (GPIb alpha: Leu129 -> Pro) affects the conformation of the GPIb-V-IX receptor, alters its availability on platelet surfaces, and causes the observed Bernard-Soulier phenotype.

Does sleep enhance the effect of subanesthetic isoflurane on hypoxic ventilation?

After surgery, patients may receive little audiovisual stimulation and may sleep. Lack of audiovisual stimulation enhances the suppression of the hypoxic ventilatory response (HVR) by 0.1 minimum alveolar anesthetic concentration (MAC) isoflurane. Sleep also reduces the HVR and may thus increase the risk of hypoxia in patients at this time. We therefore measured the ventilatory response in volunteers to a sustained step hypoxic stimulus (mean arterial oxygen saturation [SaO2] 80% [SEM 0.3] for 20 min) in the presence of 0.1 MAC isoflurane, with subjects in the awake and asleep states. The behavioral states were studied in random order in nine male subjects. The combination of isoflurane and sleep significantly reduced (P < 0.05) normoxic ventilation (6.71 [0.39] vs 8.24 [0.29] L/min) and increased end-tidal PCO2 (PETCO2) (43.1 [0.5] vs 40.4 [0.8] mm Hg) compared with the awake state. However, ventilation was similar in the asleep and awake states during early (15.10 [1.35] vs 15.50 [1.61] L/min) and late (10.45 [0.97] vs 11.03 [0.99] L/min) hypoxia in the presence of isoflurane. Thus sleep did not reduce ventilation during hypoxia in the presence of isoflurane sedation. The increase in PETCO2 during sleep may have offset suppression of the HVR.

The effect of posture on airway caliber with the sleep-apnea/hypopnea syndrome

Snoring and sleep apnea are more common in the supine than seated position. We therefore studied the effect of posture on upper-airway caliber in normal subjects, snorers, and subjects with the sleep-apnea/hypopnea syndrome (SAHS). We measured upper-airway cross-sectional area by acoustic reflection in 110 SAHS patients (apnea/hypopnea index [AHI] > 15), 70 snorers without SAHS (AHI < 15), and 40 male controls matched for body-mass index (BMI) to the 40 SAHS patients. SAHS patients in the seated position had smaller upper-airway areas at the orophyngeal junction (OPJ) than either the snorers (p < 0.01) or the normal subjects (p < 0.02), but there were no differences between groups in airway cross-sectional areas in the supine or lateral recumbent positions. SAHS patients had significantly smaller decreases in OPJ area from the seated to either the supine (p < 0.001) or lateral recumbent (p < 0.001) positions than did the snorers. SAHS patients also had smaller (p < 0.05) decreases in OPJ area upon lying down than did the BMI-matched normal subjects. These data are compatible with SAHS patients defending their upper airway more upon lying down than do snorers or normal subjects.

Interaction of the effects of domperidone and sub-anaesthetic concentrations of isoflurane on the immediate and sustained hypoxic ventilatory response in humans

Twenty normal male subjects with brisk hypoxic ventilatory responses were recruited and ventilatory responses to sustained isocapnic hypoxia (SaO2 80.4 (SD 1.3)% for 20 min) were studied on separate days under four conditions: hypoxia alone, with or without domperidone, and 0.1 MAC of end-tidal isoflurane, with or without domperidone. Ventilatory variables were subjected to analysis of variance with estimation of the effects of isoflurane and domperidone, and their interaction. Isoflurane reduced the initial increase in ventilation significantly by 3.12 (95% confidence limits 1.69, 4.55) litre min-1 (P < 0.05) and domperidone increased the initial increase in ventilation by 1.78 (0.35, 3.21) litre min-1 (P < 0.05). Neither isoflurane nor domperidone affected the subsequent ventilatory decline. No interaction was found between these agents. These results confirm that 0.1 MAC of isoflurane suppressed the initial hypoxic ventilatory response but not the subsequent ventilatory decline when hypoxia was sustained. Domperidone offset the suppressive effect of isoflurane on the hypoxic ventilatory response but no interaction was detected.

Studies on the platelet surface-associated von Willebrand factor

The contribution of platelets to the prevention and control of bleeding depends not only on the plasma and vessel wall von Willebrand (vW) factor, but also on the vW factor originating from platelets. Although platelet vW factor is mainly stored in the alpha-granules, small amounts of vW factor have been detected on the platelet surface under conditions without direct stimulation. This communication focuses on the small amount of vW factor associated with the surface of platelets. EDTA-washed platelets in a calcium-free medium containing prostaglandin E1 (PGE1) were exposed to anti-vW factor F(ab')2 fragments. The platelet-associated anti-vW factor antibodies were separated from the free fragments by gel chromatography. Normal platelets were compared to platelets from patients with Bernard Soulier syndrome, Glanzmann's thrombasthenia, and Hermansky-Pudlak syndrome. These experiments showed that, in the absence of extracellular calcium, vW factor can be detected on the surface of washed platelets independent of glycoproteins Ib and IIb-IIIa, and despite markedly reduced intracellular calcium content. This particular platelet surface expression of vW factor is probably the result of disturbing the platelet during the in vitro manipulation. von Willebrand factor is an extremely important element in the multiple molecular interactions required to stop and anchor the platelet in areas of high flow rates. Mechanical perturbation of platelets leading to surface expression of the vW factor helps increase its availability for such critical interactions.

Defects on SPECT "perfusion" images can occur due to abnormal segmental contraction

Technetium-99m-sestamibi images reflect tracer distribution at the time of injection. This "stay put" indicator allowed us to separate the effects of segmental left ventricular dysfunction per se versus myocardial blood flow on SPECT "perfusion" images in ten dogs.

METHODS

An electromagnetic flow probe and hydraulic occluder were placed on the LAD coronary artery. Sonomicrometry was used to measure segmental wall shortening. At peak myocardial blood flow induced by adenosine, 35-45 mCi 99mTc-sestamibi were injected without occlusion. At 1 hr postinjection, during normal contraction, 40-50 msec end-diastolic and end-systolic SPECT images (#1) were acquired to reflect normal myocardial blood flow distribution. Later, during total LAD occlusion, and without reinjection of isotope, another gated scan (#2) was acquired.

RESULTS

Coincident with abnormal contraction, large severe systolic defects [(28 +/- 5)% more severe compared to the baseline-scan #1; p < 0.01], and milder diastolic defects [(12 +/- 8)% more severe compared to the baseline-scan #1; p < 0.01] were observed during scan #2. Thus, abnormal contraction alone produced defects on SPECT images.

CONCLUSION

Accordingly, defects in myocardial perfusion images must be interpreted as representing the integrated result of the combination of blood flow and segmental contraction heterogeneity.

Improved outcome for high-risk acute myeloid leukemia patients using autologous bone marrow transplantation and monoclonal antibody-purged bone marrow

We have conducted a 9-year multicenter trial of autologous bone marrow transplantation (ABMT) for acute myeloid leukemia (AML). Remission BM was purged in vitro using monoclonal antibodies (MoAbs; PM-81, AML-2-23) and complement targeting myeloid differentiation antigens (CD15, CD14). In 1988, the preparative regimen changed from 60 mg/kg/d cyclophosphamide x 2 and fractionated total body irradiation (TBI) total dose, 1,200 cGy (Cy/fTBI), to 4 mg/kg/d busulfan x 4 and 60 mg/kg/d Cy x 2 (Bu/Cy2). Recent analysis (October 1, 1993) shows that the Bu/Cy2 regimen along with the same MoAb purging method yields an improved outcome. Seven first complete-remission (CR) (CR1), 45 second- or third-CR (CR2/3), and 11 first-relapse (R1) patients were treated with chemotherapy and TBI or chemotherapy alone followed by ABMT with MoAb-purged BM. Median age at ABMT for those patients in CR 2/3 and R1 patients was 36 years. Twenty-nine CR 2/3 and R1 patients were conditioned with Cy/fTBI, and 27 CR2/3 and R1 patients were conditioned with Bu/CY. Using the Kaplan-Meier method, the CY/fTBI, CR2/3, and R1 patients have a 3-year disease-free survival (DFS) of 21%. On the other hand, the Bu/Cy2, CR2/3, and R1 patients have a 3-year DFS of 48%. Nineteen CR2/3 and R1 patients relapsed post-ABMT. On analysis by conditioning regimen, those treated with Cy/fTBI have a 3-year relapse rate (RR) of 58%, whereas the patients conditioned with Bu/Cy2 have a 39% 3-year RR. Long-term DFS can be achieved in about 50% of patients with advanced remissions and relapsed AML using Bu/Cy2 with MoAb-purged BM.

Effect of continuous positive airway pressure treatment on daytime function in sleep apnoea/hypopnoea syndrome

Continuous positive airway pressure (CPAP) is the treatment of choice for the sleep apnoea/hypopnoea syndrome (SAHS); it is usually given with the aim of improving daytime cognitive function, mood, and sleepiness. However, its efficacy has not been validated by controlled trials. We have carried out a randomised, placebo-controlled, crossover study of objective daytime sleepiness, symptoms, cognitive function, and mood in a consecutive series of 32 SAHS patients with a median apnoea plus hypopnoea frequency of 28 (range 7-129) per hour slept. Patients were treated with 4 weeks each of CPAP and an oral placebo, which they were told might improve upper airway muscle function during sleep. Assessments on the last day of each treatment included a multiple sleep latency test and tests of symptom scores, mood profiles, and cognitive performance. The patients had significantly less daytime sleepiness on CPAP than during the placebo period (mean sleep latency 7.2 [SE 0.7] vs 6.1 [0.7] min, p = 0.03). There were also improvements with CPAP in symptom ratings (2.1 [0.2] vs 4.3 [0.3], p < 0.001), mood (p < 0.05 for several measures), and cognitive performance, which showed improved vigilance (obstacles hit in Steer Clear "driving" test 76 [5] vs 81 [6], p < 0.01), mental flexibility (trail-making B time 66 [5] vs 75 [5] s, p < 0.05), and attention (p < 0.05). Objectively monitored CPAP use averaged only 3.4 (0.4) hours per night, but this study provides evidence of improved cognitive performance even at this low level of CPAP compliance.

Compliance with CPAP therapy in patients with the sleep apnoea/hypopnoea syndrome

BACKGROUND

Continuous positive airway pressure (CPAP) therapy is the treatment of choice for the sleep apnoea/hypopnoea syndrome. Compliance with this relatively obtrusive therapy has not been well studied.

METHODS

Usage of CPAP was investigated in 54 patients with sleep apnoea/hypopnoea syndrome (median 36 (range 7-129) apnoeas + hypopnoeas/hour slept) over the first 1-3 months after starting CPAP therapy. In all cases CPAP usage was monitored by hidden time clocks that indicated for how long the machines were switched on--that is, the CPAP run time. In 32 patients the time at which the CPAP mask pressure was at the therapeutic level of CPAP pressure set for that patient--that is, the mask time--was also monitored. In all patients objective daytime sleepiness was assessed by multiple sleep latency before and after CPAP therapy.

RESULTS

The mean (SE) nightly CPAP run time was 4.7 (0.4) hours. There was no correlation between run time and severity of the sleep apnoea/hypopnoea syndrome as assessed by apnoea + hypopnoea frequency or multiple sleep latency, and no correlation between CPAP usage and improvement in multiple sleep latency. Thirty two patients in whom mask time was recorded had therapeutic CPAP pressures for 89% (3%) of their CPAP run times. Patients who experienced side effects from CPAP used their CPAP machines significantly less than those who did not.

CONCLUSIONS

Patients with sleep apnoea/hypopnoea syndrome used CPAP for less than five hours/night on average with no correlation between severity of sleep apnoea/hypopnoea syndrome and CPAP usage. Patients who complained of side effects used their CPAP therapy less. It is recommended that, as a minimum, CPAP run time should be regularly recorded in all patients receiving CPAP therapy.

Tyrosine-rich crystalloids in a fine needle aspirate of a polymorphous low grade adenocarcinoma of a minor salivary gland. A case report

Tyrosine-rich crystalloids were identified in a fine needle aspirate of a polymorphous low grade adenocarcinoma of a minor salivary gland. Such crystalloids have been described previously as occurring in tissue sections of both benign and malignant salivary gland neoplasms and in the fine needle aspirate of a pleomorphic adenoma. Their presence either in fine needle aspirates or tissue sections of salivary gland tumors should be interpreted only as an incidental and nonspecific finding and should not be used to support either a benign or malignant diagnosis.

The use of fine needle aspiration cytology in the management of human immunodeficiency virus-related non-Hodgkin's lymphoma and Hodgkin's disease

We prospectively studied the utility of fine needle aspiration (FNA) to diagnose non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD) in patients with human immunodeficiency virus (HIV) infection and lymphadenopathy. Twenty-one patients with a clinical evidence of lymphoma underwent 24 FNA and site-specific tissue biopsies. Twenty-two of the 24 biopsy results were consistent with a malignant lymphoproliferative neoplasm: NHL (19 cases), HD (two cases), and T-cell lymphoma (one case). Two biopsies showed reactive lymphoid hyperplasia consistent with a clinical diagnosis of persistent generalized lymphadenopathy. There was an 87% correlation (21 of 24) between FNA and biopsy diagnoses. Eighteen of the 19 biopsy-confirmed NHL cases were diagnosed with FNA. Both cases of HD and the one T-cell lymphoma were also diagnosed with aspirate material. In conclusion, the FNA in HIV-infected individuals with suspected malignant lymphadenopathy is highly sensitive (95%). The FNA, when used in conjunction with the clinical appearance, is a useful tool in the management of HIV infection and lymphadenopathy.

Intracoronary papaverine but not adenosine reduces regional ventricular function

OBJECTIVES

Whether intracoronary papaverine or adenosine leads to reductions in regional left ventricular function was tested.

METHODS

Fifteen anaesthetised dogs were prepared to record aortic pressure, left ventricular pressure dP/dt, electrocardiogram, regional ventricular shortening, and phasic and mean left circumflex coronary blood flow, and to give intracoronary boluses of papaverine (2, 4, or 6 mg) or adenosine (0.37 and 1.87 mg).

RESULTS

Injected doses were chosen to mimic those given in the clinical setting. Papaverine (6 mg) reduced aortic pressure (mean 96(SD 17) to 89(18) mm Hg; p < 0.05), segmental shortening of the infused left circumflex zone (12(5) to 7(9)%; p < 0.05), and area of the pressure-length loop of the infused zone (120(71) to 53(47) mm.mm Hg; p < 0.05). Papaverine increased coronary blood flow (48(25) to 259(95) ml.min-1; p < 0.05), coronary vascular conductance (0.40(0.20) to 2.93(0.94) ml.mm Hg-1.min-1; p < 0.05), heart rate (88(27) to 100(28) beats.min-1; p < 0.05), and the segmental shortening (17(6) to 19(3)% p < 0.05) and area of the pressure-length loop (130(32) to 177(33) mm.mm Hg; p < 0.05) of the non-infused left anterior descending region. The hyperaemia elicited by papaverine was greater than that of reactive hyperaemia (p = 0.008). Papaverine also increased the QT interval corrected for heart rate (0.35(0.04) to 0.45(0.05) s; p < 0.05). When adenosine was given, coronary blood flow and coronary vascular conductance were increased to similar degrees as those during reactive hyperaemia (41(12) to 210(75) ml.min-1 and 0.46(0.14) to 2.43(0.83) mm Hg.ml-1.min-1, respectively; NS). No effects on segmental shortening or the area of the pressure-length loop in either zone were found. Also, adenosine had no effect on the QT interval.

CONCLUSIONS

These adverse effects of intracoronary papaverine have important implications in its use in patients, particularly in those in whom abnormal cardiac function already exists. Adenosine, on the other hand, seems to be without deleterious effects.

The special deterrent effects of a jail sanction on first-time drunk drivers: a quasi-experimental study

This study examines the special deterrent effects of alternative sanctions on first-time offenders convicted of driving while intoxicated (DWI). It uses a quasi-experimental design based on the fact that in Hennepin County, Minnesota, some judges did not comply with the judicial policy that mandated a two-day jail sentence for all first-time DWI offenders. Data were collected on all drunk driving cases adjudicated by two judges during an 11-month period. One judge was known to sentence few first offenders to jail; the other was reputed to sentence virtually all first offenders to jail. Of the 383 offenders sentenced by the two judges, 60 were, reconvicted within the 23-month follow-up period. Using judge as an indirect measure of the jail sanction, we found no statistically significant difference in the recidivism rates of persons sentenced by the "jail" and "no jail" judges. Nor did the sanction have a direct effect. After statistically controlling for offender characteristics and prior traffic record, there was no significant difference between those sentenced to a fine (large or small) with no jail and those who were given a two-day jail sentence plus a small fine. Thus, a two-day jail stay is found to be no more effective in deterring subsequent drunk driving by convicted first offenders than an alternative monetary sanction.

Sodium chloride, potassium chloride, and virulence in Listeria monocytogenes

Virulence, as determined in a mouse model, and the virulence factor activities of catalase, superoxide dismutase, and listeriolysin O were examined in a parental strain (10403S) and in a nonhemolytic mutant strain (DP-L224) of Listeria monocytogenes. The cells were propagated in media containing various concentrations of sodium chloride or potassium chloride. Strains 10403S and DP-L224 exhibited significant increases in catalase activity and listeriolysin O activity when grown in medium containing either salt at 428 mM. The superoxide dismutase activities for both strains increased when they were grown in medium containing either salt. The superoxide dismutase activity was significantly increased only when cells were propagated in medium containing no salt compared with that when they were propagated in medium containing either salt at 1,112 mM. In addition, the listeriolysin O activity was highest for cells propagated in medium containing KCl at 428 mM, while the activity was significantly less for cells propagated in medium containing NaCl at an equal concentration. Virulence was examined in mouse livers and spleens after intravenous infection, and approximate 50% lethal doses were determined after intragastric and intraperitoneal infection. Each method of infection indicated that listeriolysin O is required for virulence, while growth in salt-containing medium or the production of higher levels of catalase, superoxide dismutase, and listeriolysin O do not appear to enhance the virulence of L. monocytogenes.

Adenosine regulates coronary blood flow during increased work and decreased supply

Adenosine may mediate coronary vasodilation during work-related hyperemia and during ischemia. We tested whether adenosine blockade with 8-p-sulfophenyltheophylline (PSPT) prevented dobutamine-induced hyperemia or magnified the reductions in flow due to vasopressin. Control (n = 8) and test (n = 7) dogs received paired infusions of dobutamine (70 micrograms/min iv for 5 min). Test dogs received PSPT (10 mg/kg iv) between doses. In both groups, paired infusions elicited comparable increases in oxygen consumption. However, in test dogs, the hyperemia was reduced significantly. Thus adenosine mediates the hyperemia of dobutamine. Separately, control dogs (n = 9) received vasopressin (0.6 microgram ic over 5 min); test dogs (n = 7) received PSPT before vasopressin. Vasopressin maximally increased coronary resistance by 3 min; effects were gone by 10 min. With PSPT, coronary resistance was increased further and remained high beyond 10 min. Thus adenosine-mediated vasodilation moderates the severity and duration of ischemia. These results indicate the importance of adenosine in mediating coronary flow during increased demand and reduced supply.

Keratin intermediate filament expression in astrocytic neoplasms: analysis by immunocytochemistry, western blot, and northern hybridization

In this study, 29 formalin-fixed, paraffin-embedded astrocytic tumors were analyzed immunocytochemically with the antikeratin monoclonal antibodies Mak-6 and Cam 5.2 and a polyclonal antibody against glial fibrillary acidic protein (GFAP). Immunoreactivity for Mak-6 was present in 29 cases (100%) including six well-differentiated astrocytomas, nine anaplastic astrocytomas, and 14 glioblastomas multiforme. Cam 5.2 immunoreactivity was focally present in one case of GBM (4%) but was absent in the remaining 28 cases. All cases were immunoreactive with an antibody against GFAP. Cytokeratin (CK) expression was examined in extracts of four separate well-characterized astrocytoma cell lines by Western blotting with the monoclonal antibodies Mak-6, Cam 5.2, and anti-CK 18 and by Northern analysis using a cDNA probe for the human CK 18 gene. The Western blots revealed the presence of immunoreactive bands corresponding to CK numbers 14/15, 16, and 18 in extracts from all four cell lines and additional bands corresponding to CK 8 in 3/4 lines and CK 19 in 1/4 lines. Northern analysis detected CK 18 mRNA in extracts from 2/4 astrocytic cell lines. These findings demonstrate that CK immunoreactivity is frequent in astrocytic tumors and confirm through the molecular and biochemical analysis of CK 18 gene expression and of keratin intermediate filament proteins that the basis for CK immunoreactivity in astrocytic tumors is bona fide CK expression, not cross-reactivity with other antigens or artifact. The demonstration of CK expression by astrocytic neoplasms has important implications for pathologists involved in the diagnosis of poorly differentiated tumors.

Inhomogeneity of gated and ungated SPECT technetium-99m-sestamibi bull's-eyes in normal dogs: comparison with thallium-201

By computer simulation, we have previously hypothesized, independent of the isotope imaged, that differences in view-to-view resolution and attenuation patterns predictably cause count density distortions in SPECT images. We tested the simulation predictions for both ECG-gated and ungated SPECT 99mTc-sestamibi and SPECT 201Tl myocardial perfusion images in normal dogs. In agreement with the predictions of the computer model, distortions in SPECT 99mTc-sestamibi myocardial perfusion images are virtually equivalent to SPECT 201Tl, dependent on the exact SPECT acquisition orbit and markedly different for a posterior 180 degrees acquisition arc compared to an anterior 180 degrees acquisition arc. Furthermore, ungated and gated SPECT 99mTc-sestamibi images show similar count inhomogeneities. These results suggest that little is to be gained from a 360 degrees acquisition with SPECT 99mTc-sestamibi, and that image distortions from gated or ungated SPECT 99mTc images with 180 degrees orbits will be similar to those in SPECT 201Tl images.

Comparison of single-photon emission computed tomographic (SPECT) myocardial perfusion imaging with thallium-201 and technetium-99m sestamibi in dogs

OBJECTIVES

The purpose of the present study was to compare single-photon emission computed tomographic (SPECT) myocardial images of technetium-99m (Tc-99m) sestamibi and thallium-201 (Tl-201) isotopes in the same dog undergoing partial coronary occlusion during pharmacologic vasodilation.

BACKGROUND

To date, no controlled study has been reported comparing SPECT Tc-99m sestamibi with SPECT Tl-201 imaging during stress with anatomic and physiologic standards.

METHODS

Mongrel dogs were anesthetized with chloralose and instrumented to record left anterior descending coronary blood flow and aortic pressure. Partial coronary occlusion with a hydraulic cuff reduced coronary vascular conductance, which is equal to the coronary blood flow normalized to aortic pressure during peak vasodilation with intravenous adenosine. Each dog received 5 mCi of Tl-201, then 30 mCi of Tc-99m sestamibi during partial coronary occlusion at peak vasodilation. Tomographic myocardial imaging was performed in a 180 degrees anterior arc scan for 33.5 min, first with Tl-201, and later, without moving the dog, for 33.5 min with Tc-99m sestamibi. Postmortem staining defined the region underperfused because of its dependence on the artery that was partially occluded.

RESULTS

In seven dogs with moderate reduction in coronary blood flow, coronary vascular conductance decreased with partial coronary occlusion (47 +/- 12%) during Tl-201 imaging and (47 +/- 8%, p = NS) during Tc-99m sestamibi imaging. The underperfused region was 23.9 +/- 6.4% of total left ventricular mass. Counts in the defects were 39% higher (0.86 +/- 0.08 of normal counts) for Tc-99m sestamibi than for Tl-201 (0.64 +/- 0.09 of normal counts, p < 0.001), and the defect on SPECT Tc-99m sestamibi images occupied only a fraction (0.37 +/- 0.30) of the area of the defect on the Tl-201 images of the same dog. Bull's-eye displays constructed from the pathologic slices showed that the Tl-201 defect size was closer to the underperfused region of the left ventricular mass determined pathologically than was the Tc-99m sestamibi defect size. In four additional dogs a severe, near total coronary occlusion was created during Tl-201 and Tc-99m sestamibi administration. In these dogs, similar defect contrast (0.55 +/- 0.12 vs. 0.62 +/- 0.09, p = NS) and areas (0.18 +/- 0.07 vs. 0.18 +/- 0.11, p = NS) were observed with Tl-201 and Tc-99m sestamibi, respectively.

CONCLUSIONS

Tomographic myocardial imaging with Tc-99m sestamibi during moderately severe partial coronary occlusion underestimated the area of the defect relative to Tl-201 or to the pathologic reference standard in dogs. Defect contrast was sharper with tomographic myocardial Tl-201 than with tomographic myocardial Tc-99m sestamibi during moderately severe partial coronary occlusion.