The correlation of non-invasive hemoglobin testing and lab hemoglobin in surgical patients: A systematic review and meta-analysis

BACKGROUND

The decision regarding intraoperative transfusion has traditionally been based on hemodynamic instability and estimated blood loss. We performed a systematic review to determine the validity of the oximetry method compared to standard of care for hemoglobin measurement.

METHODS

A systematic literature review was conducted, and several libraries were searched from inception to March 31,2023. The primary outcome was comparing the mean difference between laboratory-derived hemoglobin and non-invasive, point-of-care hemoglobin measurement. Subgroup analysis included comparing the mean difference in the pediatric population and among female patients.

RESULTS

A total of 276 studies were identified, and 37 were included. We found that the pooled mean difference varied qualitatively between adult and pediatric population (p value for heterogeneity <0.001). In adult populations, lab hemoglobin measurements were on average slightly higher than non-invasive measurements (mean difference = 0.23; 95% CI -0.13, 0.59), though there was greater heterogeneity across studies (I2 = 97%, p value = <0.001). In the pediatric population, most studies showed lab hemoglobin to be slightly lower (mean difference = -0.42; 95% CI -0.87 to 0.03).

CONCLUSIONS

In general, there was no clinically significant difference in mean hemoglobin among adult and pediatric populations. The percentage of female participants had no effect on the mean difference in hemoglobin.

Plasma tissue-type plasminogen activator is associated with lipoprotein(a) and clinical outcomes in hospitalized patients with COVID-19

Background

Patients with COVID-19 have a higher risk of thrombosis and thromboembolism, but the underlying mechanism(s) remain to be fully elucidated. In patients with COVID-19, high lipoprotein(a) (Lp(a)) is positively associated with the risk of ischemic heart disease. Lp(a), composed of an apoB-containing particle and apolipoprotein(a) (apo(a)), inhibits the key fibrinolytic enzyme, tissue-type plasminogen activator (tPA). However, whether the higher Lp(a) associates with lower tPA activity, the longitudinal changes of these parameters in hospitalized patients with COVID-19, and their correlation with clinical outcomes are unknown.

Objectives

To assess if Lp(a) associates with lower tPA activity in COVID-19 patients, and how in COVID-19 populations Lp(a) and tPA change post infection.

Methods

Endogenous tPA enzymatic activity, tPA or Lp(a) concentration were measured in plasma from hospitalized patients with and without COVID-19. The association between plasma tPA and adverse clinical outcomes was assessed.

Results

In hospitalized patients with COVID-19, we found lower tPA enzymatic activity and higher plasma Lp(a) than that in non-COVID-19 controls. During hospitalization, Lp(a) increased and tPA activity decreased, which associates with mortality. Among those who survived, Lp(a) decreased and tPA enzymatic activity increased during recovery. In patients with COVID-19, tPA activity is inversely correlated with tPA concentrations, thus, in another larger COVID-19 cohort, we utilized plasma tPA concentration as a surrogate to inversely reflect tPA activity. The tPA concentration was positively associated with death, disease severity, plasma inflammatory, and prothrombotic markers, and with length of hospitalization among those who were discharged.

Conclusion

High Lp(a) concentration provides a possible explanation for low endogenous tPA enzymatic activity, and poor clinical outcomes in patients with COVID-19.

Predicting risk of peripartum blood transfusion during vaginal and cesarean delivery: A risk prediction model

OBJECTIVE

The objective of this study is to develop a model that will help predict the risk of blood transfusion using information available prior to delivery.

STUDY DESIGN

The study is a secondary analysis of the Consortium on Safe Labor registry. Women who had a delivery from 2002 to 2008 were included. Pre-delivery variables that had significant associations with transfusion were included in a multivariable logistic regression model predicting transfusion. The prediction model was internally validated using randomly selected samples from the same population of women.

RESULTS

Of 156,572 deliveries, 5,463 deliveries (3.5%) required transfusion. Women who had deliveries requiring transfusion were more likely to have a number of comorbidities such as preeclampsia (6.3% versus 4.1%, OR 1.21, 95% CI 1.08-1.36), placenta previa (1.8% versus 0.4%, OR 4.11, 95% CI 3.25-5.21) and anemia (10.6% versus 5.4%, OR 1.30, 95% CI 1.21-1.41). Transfusion was least likely to occur in university teaching hospitals compared to community hospitals. The c statistic was 0.71 (95% CI 0.70-0.72) in the derivation sample. The most salient predictors of transfusion included type of hospital, placenta previa, multiple gestations, diabetes mellitus, anemia, asthma, previous births, preeclampsia, type of insurance, age, gestational age, and vertex presentation. The model was well-calibrated and showed strong internal validation.

CONCLUSION

The model identified independent risk factors that can help predict the risk of transfusion prior to delivery. If externally validated in another dataset, this model can assist health care professionals counsel patients and prepare facilities/resources to reduce maternal morbidity.

Association of prehospital antiplatelet therapy with survival in patients hospitalized with COVID-19: A propensity score-matched analysis

PURPOSE

Coronavirus disease 2019 (COVID-19) is associated with hypercoagulability and increased thrombotic risk. The impact of prehospital antiplatelet therapy on in-hospital mortality is uncertain.

METHODS

This was an observational cohort study of 34 675 patients ≥50 years old from 90 health systems in the United States. Patients were hospitalized with laboratory-confirmed COVID-19 between February 2020 and September 2020. For all patients, the propensity to receive prehospital antiplatelet therapy was calculated using demographics and comorbidities. Patients were matched based on propensity scores, and in-hospital mortality was compared between the antiplatelet and non-antiplatelet groups.

RESULTS

The propensity score-matched cohort of 17 347 patients comprised of 6781 and 10 566 patients in the antiplatelet and non-antiplatelet therapy groups, respectively. In-hospital mortality was significantly lower in patients receiving prehospital antiplatelet therapy (18.9% vs. 21.5%, p < .001), resulting in a 2.6% absolute reduction in mortality (HR: 0.81, 95% CI: 0.76-0.87, p < .005). On average, 39 patients needed to be treated to prevent one in-hospital death. In the antiplatelet therapy group, there was a significantly lower rate of pulmonary embolism (2.2% vs. 3.0%, p = .002) and higher rate of epistaxis (0.9% vs. 0.4%, p < .001). There was no difference in the rate of other hemorrhagic or thrombotic complications.

CONCLUSIONS

In the largest observational study to date of prehospital antiplatelet therapy in patients with COVID-19, there was an association with significantly lower in-hospital mortality. Randomized controlled trials in diverse patient populations with high rates of baseline comorbidities are needed to determine the ultimate utility of antiplatelet therapy in COVID-19.

Association between heart failure and perioperative outcomes in patients undergoing non-cardiac surgery

AIMS

Heart failure (HF) affects ∼5.7 million US adults and many of these patients develop non-cardiac disease that requires surgery. The aim of this study was to determine perioperative outcomes associated with HF in a large cohort of patients undergoing in-hospital non-cardiac surgery.

METHODS AND RESULTS

Adults ≥18 years old undergoing non-cardiac surgery between 2012 and 2014 were identified using the Healthcare Cost and Utilization Project National Inpatient Sample. Patients with HF were identified by ICD-9 diagnosis codes. The primary outcome was all-cause in-hospital mortality. Multivariable logistic regression models were used to estimate associations between HF and outcomes. A total of 21 560 996 surgical hospitalizations were identified, of which 1 063 405 (4.9%) had a diagnosis of HF. Among hospitalizations with HF, 4.7% had acute HF, 11.3% had acute on chronic HF, 27.8% had chronic HF, and 56.2% had an indeterminate diagnosis code that did not specify temporality. In-hospital perioperative mortality was more common among patients with any diagnosis of HF compared to those without HF [4.8% vs. 0.78%, P < 0.001; adjusted odds ratio (aOR) 2.15, 95% confidence interval (CI) 2.09-2.22], and the association between HF and mortality was greatest at small and non-teaching hospitals. Acute HF without chronic HF was associated with 8.0% mortality. Among patients with a chronic HF diagnosis, perioperative mortality was greater in those with acute on chronic HF compared to chronic HF alone (7.8% vs. 3.9%, P < 0.001; aOR 1.78, 95% CI 1.67-1.90).

CONCLUSION

In patients hospitalized for non-cardiac surgery, HF was common and was associated with increased risk of perioperative mortality. The greatest risks were in patients with acute HF.

P935Effect of hypertension and systolic blood pressure on cardiovascular and limb outcomes in patients with symptomatic peripheral artery disease: the EUCLID trial

Background

Hypertension is a risk factor for major adverse cardiac events (MACE) in patients with symptomatic peripheral artery disease (PAD).

Purpose

The effects of a history of hypertension and baseline systolic blood pressure (SBP) on MACE and major adverse limb events (MALE), including acute limb ischemia and major amputation, were evaluated in the Examining Use of tiCagreLor In paD (EUCLID) trial.

Methods

EUCLID randomized 13,885 patients with PAD and found no benefit of ticagrelor compared with clopidogrel on risk of MACE or MALE. The median duration of follow up was approximately 30 months. This post hoc, subgroup analysis evaluated the effects of hypertension history at baseline on the hazard for MACE and MALE. An adjusted restricted cubic spline regression analysis evaluated the association of SBP with MACE and MALE.

Results

A clinical history of hypertension was present in 10,857 (78%) patients at baseline and these patients were more likely to be older, female, white or African American, and reside in North America compared with the 3026 without hypertension. Hypertension was associated with a higher prevalence of concomitant cardiovascular diseases, polyvascular disease, diabetes, and prior coronary interventions. MACE occurred at a rate of 4.63 events/100 pt-yrs in participants with hypertension and 3.64 events/100 pt-yrs in participants without hypertension, (adjusted hazard ratio [aHR] 0.94, 95% CI 0.82–1.08; p=0.38). MALE occurred at a rate of 1.11 events/100 pt-yrs in those with hypertension and 1.38 events/100 pt-yrs in those without hypertension (p=0.054) (aHR 0.93 (95% CI 0.73, 1.18) p=0.55. The adjusted spline model for MACE and SBP demonstrated a significantly non-linear relationship with a HR 1.08 (95% CI 1.01, 1.15), p=0.0275 for every 10-unit decrease <135 mmHg SBP and HR 1.11 (1.06, 1.16), p<0.0001 for every 10-unit increase >135 mmHg (figure). There was no association between baseline SBP and MALE events.

Conclusions

A history of hypertension was not associated with a higher adjusted hazard for MACE or MALE in participants with PAD. In contrast, SBP at baseline was associated with increased risk of MACE at values both above and below 135 mmHg.

Acknowledgement/Funding

EUCLID was sponsored by AstraZeneca

Report on Implementation, Use, and Sustainability of a Labor Epidural Service in Georgetown, Guyana

BACKGROUND

The use of epidural analgesia for laboring women is generally unavailable at public hospitals in Guyana despite favorable utilization rates in private institutions. In 2014, a healthcare team completed a targeted mission aimed at neuraxial analgesia training of providers at the preeminent public hospital in Georgetown, Guyana. This study evaluates the impact of the training, including provider attitudes, use, and barriers.

METHODS

A prospective, mixed methods study of all obstetric, nursing, and anesthesiology providers at Georgetown Public Hospital Corporation was completed. Quantitative assessment of the posttraining use of epidural analgesia at 2 and 6 months was documented. Provider surveys were distributed anonymously at 2 months posttraining. Targeted interviews were completed from a random sampling of providers at 6 months; qualitative analysis of interviews formulated the basis for reporting limitations and barriers.

RESULTS

Providers surveyed included 7 anesthesia providers and 24 obstetrics providers. Respondents believed Guyanese women should be offered epidural analgesia (93%), epidurals could be performed safely (87%), and Guyana has the resources necessary for routine use (81%). In assessing epidural knowledge, anesthesia providers achieved 60% correct response rate compared to 84% among obstetrics providers. Nurse anesthetists placed 16 epidurals following training. However, placement ceased after 2 months. The largest barriers to placement were unavailable anesthesia staff (63%), lack of supplies (16%), and insufficient nursing staff to monitor patients with epidurals (11%).

CONCLUSIONS

A 1-week mission achieved widespread Guyanese provider acceptance despite a lack of previous experience. However, barriers proved insurmountable to achieving a sustainable, independently functioning epidural analgesia program.

Increased Prevalence of Moderate and Severe Peripheral Arterial Disease in the American Indian (AI)/Alaskan Native (AN) Population; a Study of 96,000 AI/AN

BACKGROUND

Peripheral arterial disease (PAD) disproportionally affects racial groups in the United States. Few studies have analyzed the rates of PAD in the American Indian (AI)/Alaskan Native (AN) population. In this article, we compare the prevalence of PAD in the AI/AN as compared with white and nonwhite Americans.

METHODS

The study data were provided by Life Line Screening (Independence, OH). The cohort consists of self-referred individuals who paid for vascular screening tests. Mild-to-moderate and severe PAD were defined as having an ankle-brachial index (ABI) in at least one extremity of < 0.9 and < 0.5, respectively. Univariate and multivariate analyses were performed to compare the rates of PAD between AI/AN, Caucasians, and nonwhites.

RESULTS

The original sample for which this study was obtained included 3,444,272 people. Of this group there was a predominance of females 64.5% (2,221,555) compared with 35.5% (1,222,716) males. The Native American/AN population was 2.8% of the sample (96,440). In our univariate analysis AI/AN had the highest rates of mild-moderate and severe PAD when compared with whites (odds ratio [OR] 1.78 and 2.14, respectively) and nonwhites (OR 1.52 and 1.82, respectively). We then controlled for atherosclerotic risk factors in our multivariate analysis, and the AI/NA cohort had persistently higher rates of both moderate and severe PAD compared with whites (OR 1.32 and 1.40) but not compared with nonwhites (OR 0.95 and 0.92).

CONCLUSIONS

Here we present the largest epidemiology study of PAD in AI/AN to date. AI/NA people have disproportionately high rates of both mild to-moderate and severe PAD when compared with whites and nonwhite Americans. After controlling for atherosclerotic risk factors the rates of PAD remain high for AI/NA when compared with whites but not when compared with nonwhites. While it is possible that a combination of diet and lifestyle choices are responsible for the high rates of PAD in this population, genetic factors may be involved as well, and deserve further investigation. Optimal medical management may help to prevent the complications of PAD in this patient population.

Genetic testing in patients with acute coronary syndrome undergoing percutaneous coronary intervention: a cost-effectiveness analysis

BACKGROUND

The CYP2C19 genotype is a predictor of adverse cardiovascular events in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) treated with clopidogrel.

OBJECTIVES

We aimed to evaluate the cost-effectiveness of a CYP2C19*2 genotype-guided strategy of antiplatelet therapy in ACS patients undergoing PCI, compared with two 'no testing' strategies (empiric clopidogrel or prasugrel).

METHODS

We developed a Markov model to compare three strategies. The model captured adverse cardiovascular events and antiplatelet-related complications. Costs were expressed in 2010 US dollars and estimated using diagnosis-related group codes and Medicare reimbursement rates. The net wholesale price for prasugrel was estimated as $5.45 per day. A generic estimate for clopidogrel of $1.00 per day was used and genetic testing was assumed to cost $500.

RESULTS

Base case analyses demonstrated little difference between treatment strategies. The genetic testing-guided strategy yielded the most QALYs and was the least costly. Over 15 months, total costs were $18 lower with a gain of 0.004 QALY in the genotype-guided strategy compared with empiric clopidogrel, and $899 lower with a gain of 0.0005 QALY compared with empiric prasugrel. The strongest predictor of the preferred strategy was the relative risk of thrombotic events in carriers compared with wild-type individuals treated with clopidogrel. Above a 47% increased risk, a genotype-guided strategy was the dominant strategy. Above a clopidogrel cost of $3.96 per day, genetic testing was no longer dominant but remained cost-effective.

CONCLUSIONS

Among ACS patients undergoing PCI, a genotype-guided strategy yields similar outcomes to empiric approaches to treatment, but is marginally less costly and more effective.

Centrifugation speed affects light transmission aggregometry

BACKGROUND

Light transmission aggregometry (LTA) is considered the gold standard for investigating platelet activity ex vivo. However, LTA protocols are not standardized, and differences in LTA procedure are a potential source of variance in results. Centrifugation speed is an essential component of platelet preparation in LTA, has yet to be standardized, and may affect platelet aggregation results. We sought to investigate the effect of relative centrifugal force (RCF) intensity on LTA results.

METHODS

Ten healthy controls had venous blood drawn and centrifuged at 150, 200, 300, and 500 g for 10 min. Cell counts in whole blood and platelet-rich plasma (PRP) were measured using a hematology analyzer. LTA was performed using 1.0 μm adenosine diphosphate (ADP) and 0.4 μm epinephrine as an agonist. Aggregation (%) was compared at 60, 120, 180, and 300 s and at maximum aggregation.

RESULTS

Centrifugation speed was associated with decreasing platelet count (P < 0.001) and decreasing mean platelet volume (P < 0.001) in PRP. Maximum aggregation decreased with increasing speeds for ADP 1.0 μm (150 g- 89%, 200 g- 93%, 300 g- 71%, 500 g- 17%; P < 0.001). Similar findings were noted at 120 s (150 g- 69%, 200 g- 50%, 300 g- 35%, 500 g- 12%; P < 0.001), 180 s (150 g- 82%, 200 g- 74%, 300 g- 44%, 500 g- 13%; P < 0.001), and 300 s (150 g- 85%, 200 g- 88%, 300 g- 55%, 500 g- 14%; P < 0.001). Consistently, platelet aggregation in response to epinephrine 0.4 μm decreased significantly with increasing centrifuge RCF at 60, 120, 180, 300 s and at maximum aggregation (P < 0.05 for each comparison).

CONCLUSION

Our data demonstrate the importance of centrifugation speed in the interpretation of LTA results, supporting the need for standardization of centrifugation RCF in LTA protocols.

Mean platelet volume as a predictor of cardiovascular risk: a systematic review and meta-analysis

AIM

To determine whether an association exists between mean platelet volume (MPV) and acute myocardial infarction (AMI) and other cardiovascular events. Platelet activity is a major culprit in atherothrombotic events. MPV, which is widely available in clinical practice, is a potentially useful biomarker of platelet activity in the setting of cardiovascular disease.

METHODS AND RESULTS

We performed a systematic review and meta-analysis investigating the association between MPV and AMI, all-cause mortality following myocardial infarction, and restenosis following coronary angioplasty. Results were pooled using random-effects modeling. Pooled results from 16 cross-sectional studies involving 2809 patients investigating the association of MPV and AMI indicated that MPV was significantly higher in those with AMI than those without AMI [mean difference 0.92 fL, 95% confidence interval (CI) 0.67-1.16, P < 0.001). In subgroup analyses, significant differences in MPV existed between subjects with AMI, subjects with stable coronary disease (P < 0.001), and stable controls (P < 0.001), but not vs. those with unstable angina (P = 0.24). Pooled results from three cohort studies involving 3184 patients evaluating the risk of death following AMI demonstrated that an elevated MPV increased the odds of death as compared with a normal MPV (11.5% vs. 7.1%, odds ratio 1.65, 95% CI 1.12-2.52, P = 0.012). Pooled results from five cohort studies involving 430 patients who underwent coronary angioplasty revealed that MPV was significantly higher in patients who developed restenosis than in those who did not develop restenosis (mean difference 0.98 fL, 95% CI 0.74-1.21, P < 0.001).

CONCLUSIONS

Elevated MPV is associated with AMI, mortality following myocardial infarction, and restenosis following coronary angioplasty. These data suggest that MPV is a potentially useful prognostic biomarker in patients with cardiovascular disease. Whether the relationship is causal, and whether MPV should influence practice or guide therapy, remains unknown.

Mean platelet volume as a predictor of cardiovascular risk: a systematic review and meta-analysis

AIM

To determine whether an association exists between mean platelet volume (MPV) and acute myocardial infarction (AMI) and other cardiovascular events. Platelet activity is a major culprit in atherothrombotic events. MPV, which is widely available in clinical practice, is a potentially useful biomarker of platelet activity in the setting of cardiovascular disease.

METHODS AND RESULTS

We performed a systematic review and meta-analysis investigating the association between MPV and AMI, all-cause mortality following myocardial infarction, and restenosis following coronary angioplasty. Results were pooled using random-effects modeling. Pooled results from 16 cross-sectional studies involving 2809 patients investigating the association of MPV and AMI indicated that MPV was significantly higher in those with AMI than those without AMI [mean difference 0.92 fL, 95% confidence interval (CI) 0.67-1.16, P < 0.001). In subgroup analyses, significant differences in MPV existed between subjects with AMI, subjects with stable coronary disease (P < 0.001), and stable controls (P < 0.001), but not vs. those with unstable angina (P = 0.24). Pooled results from three cohort studies involving 3184 patients evaluating the risk of death following AMI demonstrated that an elevated MPV increased the odds of death as compared with a normal MPV (11.5% vs. 7.1%, odds ratio 1.65, 95% CI 1.12-2.52, P = 0.012). Pooled results from five cohort studies involving 430 patients who underwent coronary angioplasty revealed that MPV was significantly higher in patients who developed restenosis than in those who did not develop restenosis (mean difference 0.98 fL, 95% CI 0.74-1.21, P < 0.001).

CONCLUSIONS

Elevated MPV is associated with AMI, mortality following myocardial infarction, and restenosis following coronary angioplasty. These data suggest that MPV is a potentially useful prognostic biomarker in patients with cardiovascular disease. Whether the relationship is causal, and whether MPV should influence practice or guide therapy, remains unknown.

Activity in human frontal cortex associated with spatial working memory and saccadic behavior

We examined, with event-related fMRI, two hypotheses about the organization of human working memory function in frontal cortex: (1) that a region immediately anterior to the frontal eye fields (FEF) (superior frontal cortex, SFC) is specialized for spatial working memory (Courtney, et al., 1998); and (2) that dorsolateral prefrontal cortex (PFC) plays a privileged role in the manipulation of spatial stimuli held in working memory (Owen, et al., 1996; Petrides 1994). Our delayed-response task featured 2-D arrays of irregularly arranged squares that were highlighted serially in a random sequence. The Forward Memory condition required maintenance of the spatio-temporal sequence, the Manipulate Memory condition required reordering this sequence into a new spatially defined order, the Guided Saccade condition required saccades to highlighted squares in the array, but no memory, and the Free Saccade condition required self-paced, horizontal saccades. The comparison of fMRI signal intensity associated with 2-D saccade generation (Guided Saccades) versus fMRI signal intensity associated with the delay period of the working memorials condition revealed no evidence for greater working memory-related activity than saccade-related activity in SFC in any individual subject, nor at the level of the group, and greater 2-D saccade than delay-period activity in three of five subjects. These results fail to support the hypothesis that spatial working memory-related activity is represented preferentially in a region of SFC anterior to the FEF (Courtney, et al., 1998). The comparison of maintenance versus manipulation of spatio-temporal information in working memory revealed significantly greater activity associated with the latter in dorsolateral PFC, but not in ventrolateral PFC or in SFC. These results suggest that the delay-related function of SFC is limited to the maintenance of spatial information, and that this region does not support the nonmnemonic executive control functions supported by dorsolateral PFC. These results also indicate that the preferential recruitment of dorsolateral PFC for the manipulation of information held in working memory applies to tasks employing spatial stimuli, as well as to tasks employing verbal stimuli (D'Esposito, et al., 1999); Petrides et al., 1993; Postle et al., 1999).

Behavioral and neurophysiological correlates of episodic coding, proactive interference, and list length effects in a running span verbal working memory task

Updating refers to (1) discarding items from, (2) repositioning items in, and (3) adding items to a running working memory span. Our behavioral and fMRI experiments varied three factors: trial length, proactive interference (PI), and group integrity. Group integrity reflected whether the grouping of items at the encoding stage was violated at discarding. Behavioral results were consistent with the idea that updating processes have a relatively short refractory period and may not fatigue, and they revealed that episodic information about group context is encoded automatically in working memory stimulus representations. The fMRI results did not show evidence that updating requirements in a task recruit executive control processes other than those supporting performance on nonupdating trials. They did reveal an item-accumulation effect, in which signal increased monotonically with the number of items presented during the trial, despite the insensitivity of behavioral measures to this factor. Behavioral and fMRI correlates of PI extended previous results and rejected an alternative explanation of PI effects in working memory.

Functional neuroanatomical double dissociation of mnemonic and executive control processes contributing to working memory performance

We used event-related functional MRI to investigate the neural bases of two categories of mental processes believed to contribute to performance of an alphabetization working memory task: memory storage and memory manipulation. Our delayed-response tasks required memory for the identity and position-in-the-display of items in two- or five-letter memory sets (to identify load-sensitive regions) or memory for the identity and relative position-in-the-alphabet of items in five-letter memory sets (to identify manipulation-sensitive regions). Results revealed voxels in the left perisylvian cortex of five of five subjects showing load sensitivity (as contrasted with alphabetization-sensitive voxels in this region in only one subject) and voxels of dorsolateral prefrontal cortex in all subjects showing alphabetization sensitivity (as contrasted with load-sensitive voxels in this region in two subjects). This double dissociation was reliable at the group level. These data are consistent with the hypothesis that the nonmnemonic executive control processes that can contribute to working memory function are primarily prefrontal cortex-mediated whereas mnemonic processes necessary for working memory storage are primarily posteriorly mediated. More broadly, they support the view that working memory is a faculty that arises from the coordinated interaction of computationally and neuroanatomically dissociable processes.

Antibodies to chondroitin sulfate C: a new detection assay and correlations with neurological diseases

Antibodies to chondroitin sulfate C (ChS C) have been previously associated with sensory axonal neuropathy. Investigation of these antibodies has, however, been limited by the lack of a sensitive and reliable test for their detection. We developed a new enzyme-linked immunoassorbent assay (ELISA), where biotinylated ChS C was made to adhere to avidin-coated microwells. The new ELISA showed a much greater sensitivity than other currently available ELISAs for detection of anti-ChS C antibodies. A total of 480 sera (466 patients and 14 normal volunteers) were tested at increasing dilutions for anti-ChS C antibody activity. Normal subjects had IgM anti-ChS C antibody titers of up to 3,200 and mildly elevated titers of 6,400 were seen in a variety of diseases. Eleven patients had titers of 12,800 or higher. These included seven patients with sensory axonal neuropathy, three with amyotrophic lateral sclerosis and one with corticobasal ganglionic degeneration. These studies indicate that anti-ChS antibodies do occur in patients with axonal sensory neuropathy, but are not limited to that disease.

The mandibular repositioning device: role in the treatment of obstructive sleep apnea

The role of oral appliances in the routine treatment of obstructive sleep apnea (OSA) is not well defined. This prospective study attempts to clarify the clinical role of a specific oral appliance, the mandibular repositioning device (MRD). This study evaluated the demographic, polysomnographic, and cephalometric radiographic findings predictive of treatment success or failure with the MRD. Twenty-nine patients were diagnosed with mild to severe OSA by nocturnal polysomnography. The majority of these patients were intolerant to nasal continuous positive airway pressure (CPAP) and all were fitted with a MRD. Twenty-three of these patients were compliant initially with MRD use and received post-treatment nocturnal polysomnogrpahy at a mean of 104 days after receiving the device. The respiratory disturbance index (RDI) decreased with MRD use (37 +/- 23 versus 18 +/- 20 events/hour, p < 0.001), and 16 of the 23 patients (69%) were considered responders (decrease in RDI > or = 50% and posttreatment RDI < or = 20). Measurements of subjective and objective daytime sleepiness, nocturnal oxygen desaturation, and snoring were all improved with MRD use. A pre-treatment RDI > 40 was present in four of the seven (67%) non-responders. Age, body mass index, and cephalometric radiographic measurements were not predictive of treatment outcome. Sixteen of 23 patients (70%) continue to use the MRD after 3.4 +/- 0.7 years. This study suggests that the MRD is useful in the long-term treatment of patients with OSA of mild to moderate severity.

Stabilization of helical peptides by mixed spaced salt bridges

Whether or not surface salt bridges have a strong stabilizing effect on the native structure in proteins remains uncertain. Previous studies of model peptides have shown that salt bridges spaced at i,i +4 along the chain are more stabilizing than those spaced at i,i +3, with a preference for the order acid-base rather than base-acid from N to C terminus. An analysis of the effect of spacing the ion pairs in short helical peptides is presented, in which acidic and basic side chains spaced two or three residues apart alternate along the chain. The mixed spacing proves to be stabilizing relative to pure spacings. A control peptide in which salt bridges were spaced uniformly three residues apart proved to form a beta-sheet structure rather than alpha-helix. This is due to formation of a silk-like apolar face consisting of alanine side chains; the mesoscopic structure formed by these sheets can be imaged by scanning microscopy.

Poly(adenosine diphosphoribose) polymerase in peripheral blood leukocytes from normal donors and patients with malignancies

A two-color flow cytometric technique was developed to analyze poly(ADP-ribose) polymerase (PADPRP) in different individuals as a function of different physiological or pathological conditions and to establish the basis for determining whether enzyme deficiency may predispose to degenerative or malignant disorders. Peripheral blood granulocytes were devoid of enzyme activity, whereas mononuclear cells had variable amounts. PADPRP was highest in B cells, intermediate in T cells, and lowest in monocytes. This pattern of enzyme distribution and relative enzyme content of different types of cells was remarkably constant in normal subjects. In a series of 66 normal donors there was no significant biological variation in enzyme content as a function of age, race, or sex. The mean PADPRP values in peripheral blood mononuclear cells from 81 random patient samples obtained from an ambulatory oncology clinic did not differ significantly from normal subjects. However, groups of patients with breast cancer, lymphocytic malignancies, and esophageal cancer were observed to have below normal levels for peripheral blood mononuclear cell PADPRP.

Cyclosporine induces abnormal facial bone growth in children: a preliminary study

Using cephalometric radiography, facial bony structure of a group of pediatric renal transplant recipients immunosuppressed with cyclosporine (CsA) and prednisone was studied and compared with a control group of children. A pattern of abnormal facial growth was demonstrated on cephalometry in eight of nine transplant recipients receiving CsA. The abnormalities included shortening of posterior facial height and increased anterior facial height with a deep mandibular plane angle. There was also an absolute shortening in the mandibular body and mandibular retrognathia. These findings may be consistent with inhibition of mandibular condylar growth inhibiting the anteroinferior growth of the mandible. Similar changes were present in two children with end-stage renal disease and none of the remaining nine control patients (P less than 0.01, chi-squared analysis). The affected area appears to be the lower third of the face. The role of CsA in affecting facial bony growth in children needs to be evaluated further.

Alveolar atrophy and decreased skeletal mass of the radius

Using absorptiometry, the bone calcium mass (BCM) at two different sites of the radius was measured in 12 male patients referred for vestibuloplasty of the mandible. The most distal site contained both cortical and cancellous bone while the other site contained cortical bone only. The BCM values were compared with those for normal patients of the same age. The patients with mandibular atrophy all had less bone in the radius than their age-matched controls (p less than 0.01). This is indicative of a systemic factor or factors operating both in the mandible and in the radius. The examination prior to oral surgery should therefore include an evaluation for diseases causing general bone loss.

Adenoid cystic carcinoma of the parotid gland: report of case

A case of adenoid cystic carcinoma of the parotid gland is reported, in which the initial symptom was facial paresthesia. Pathologic features, treatment, and prognosis of the tumor have been discussed.

Interpositional bone graft augmentation of the atrophic mandible: a preliminary report

The mandible is sectioned in an oblique direction and an iliac crest graft is placed between the fragments for augmentation of an atrophied mandible. The technique was used in 12 patients; follow-up examinations included serial panoramic radiographs and recording of changes in mandibular height. A 10% to 27% loss of the height gained occurred between three and 12 months postoperatively.