The MAPP Room Memory Test: Examining Contextual Memory Using a Novel Computerized Test in Cognitively-Unimpaired Individuals with Autosomal Dominant Alzheimer's Disease

Contextual memory, the ability to remember spatial or temporal features related to an event, is affected in Alzheimer's disease (AD). There is a shortfall of tests that measure contextual memory. To evaluate visuospatial contextual memory, we developed a computerized cognitive test, the MAPP Room Memory Test, which requires participants to identify in which visual scene target items were previously presented. We hypothesized that cognitively-unimpaired carriers of an autosomal dominant AD mutation (Presenilin-1 E280A, n=15) would perform more poorly on this test than non-carrier family members (n=31). Compared to non-carriers, the carriers had significantly worse delayed room recognition. The results indicate that the MAPP Room Memory Test may be sensitive to subtle cognitive changes associated with risk of AD. Future studies with larger samples using the MAPP Room Memory Test and biomarkers are needed to examine whether this test may also be sensitive to the earliest pathological changes in preclinical AD.

Sex and hormonal status influence the anxiolytic-like effect of oxytocin in mice

Anxiety and depression are highly prevalent psychiatric disorders, affecting approximately 18% of the United States population. Evidence indicates that central oxytocin mediates social cognition, social bonding, and social anxiety. Although it is well-established that oxytocin ameliorates social deficits, less is known about the therapeutic effects of oxytocin in non-social contexts. We hypothesized that positive effects of oxytocin in social contexts are attributable to intrinsic effects of oxytocin on neural systems that are related to emotion regulation. The present study investigated the effect of intracerebroventricular (ICV) oxytocin administration (i.e., central action) on anxiety- and depression-like behavior in C57Bl/6J mice using non-social tests. Male and female mice received an ICV infusion of vehicle or oxytocin (100, 200, or 500 ng), then were tested in the elevated zero maze (for anxiety-like behavior) and the tail suspension test (for depression-like behavior). Oxytocin dose-dependently increased open zone occupancy and entries in the elevated zero maze and reduced immobility duration in the tail suspension test in both sexes. Oxytocin decreased anxiety and depression-like behavior in male and female mice. The observed effect of oxytocin on anxiolytic-like behavior appeared to be driven by the males. Given the smaller anxiolytic-like effect of oxytocin in the female mice and the established interaction between oxytocin and reproductive hormones (estrogen and progesterone), we also explored whether oxytocin sensitivity in females varies across estrous cycle phases and in ovariectomized females that were or were not supplemented with estrogen or progesterone. Oxytocin reduced anxiety-like behavior in female mice in proestrus/estrus, ovariectomized females (supplemented or not with estrogen or progesterone), but not females in metestrus/diestrus. Additionally, oxytocin reduced depression-like behavior in all groups tested with slight differences across the various hormonal statuses. These results suggest that the effect of oxytocin in depression- and anxiety-like behavior in mice can be influenced by sex and hormonal status.

Changing Faces: Factors Associated with the Intention to Pursue Plastic Surgery and Practice in Underserved Areas

Improving the number of plastic and reconstructive surgeons who provide care to patients in underserved communities is critical to achieving health equity. We aimed to identify factors associated with graduating medical students' intentions to pursue plastic surgery and practice in underserved areas.

Methods

De-identified data for US medical school graduates were obtained from the Association of American Medical Colleges for students who matriculated in academic years 2007-2008 and 2011-2012. Data collected included self-reported demographic and future practice intentions. Multivariate analysis was conducted to determine indicators of students' interest in plastic surgery, and their intention to practice in underserved areas.

Results

Of the 57,307 graduating US medical students in our cohort who completed the Graduation Questionnaire, 532 (0.9%) reported an intention to pursue plastic surgery. Hispanic [adjusted odds ratio (aOR): 1.45; 95% confidence interval (95% CI), 1.07-1.98] and multiracial (aOR: 1.59; 95% CI, 1.03-2.45) students were more likely to pursue plastic surgery compared with other surgical specialties. Among students interested in plastic surgery, compared with non-Hispanic White students, Black (aOR: 6.15; 95% CI, 1.96-19.26) students were more likely to report intention to practice in underserved areas. Students with community-engagement experiences were more likely to report intention to practice in underserved areas.

Conclusions

Diversity among medical trainees pursuing plastic and reconstructive surgery is critical for maintaining and expanding plastic surgery services rendered in underserved areas. These findings suggest that student demographics and experiences with community-engagement experiences are positive indicators of practicing in underserved communities.

Primary and secondary focal choroidal excavation morphologic phenotypes, associated ocular disorders and prognostic implications

AIMS

To characterise and classify the morphological, clinical and tomographic characteristics of focal choroidal excavation (FCE) lesions to determine their prognostic implications.

METHODS

36 eyes with FCE (32 patients) underwent multimodal imaging, including spectral domain optical coherence tomography and fundus autofluorescence. FCE lesions were classified into three subtypes: (1) type 1: myopic (central choroidal thickness: <100 µm), (2) type 2: suspected congenital (central choroidal thickness: 100-200 µm, without associated chorioretinal pathology) and (3) type 3: secondary or acquired (central choroidal thickness: >200 µm, with associated chorioretinal pathology).

RESULTS

80.6% of eyes were followed longitudinally (26.8±18.8 months). There were 9 type 1 FCEs (myopic), 8 type 2 FCEs (U-shaped, congenital) and 19 type 3 FCEs (V-shaped, secondary). Type 2 FCEs trended towards larger maximum widths (p=0.0563). Type 3 FCEs were associated with central serous chorioretinopathy or pachyvessels (47.4%), but were also seen in pattern dystrophy, geographic atrophy, inactive choroiditis, torpedo maculopathy and adult-onset vitelliform dystrophy. Choroidal neovascular membranes (CNVMs) were more prevalent in type 3 FCE (41.2% compared with 11.1% for type 1 FCE, p=0.251, and 0% for type 2 FCE, p=0.043).

CONCLUSIONS

The FCE types, stratified by central choroidal thickness, demonstrated distinct morphological characteristics and associated findings. The classification scheme held prognostic implications as type 3 FCE with V shapes were associated with other chorioretinal conditions and were more likely to develop CNVM.

Effect of the variation in the extracellular concentration of l-arginine in the physiology of Leishmania (Viannia) braziliensis and its susceptibility to some antileishmanial drugs

The knowledge about amino acid metabolism in trypanosomatids is a valuable source of new therapeutic targets. l-arginine is an essential amino acid for Leishmania parasites, and it participates in the synthesis of polyamines, a group of essential nutrients used for nucleic acids, proteins biosynthesis, and redox modulation necessary for proliferation. In the present study, we evaluated the effect of changes in the availability of this amino acid on promastigotes and intracellular amastigotes on U937 macrophages and showed that the absence of l-arginine in culture medium negatively influences the growth and infectivity of Leishmania (Viannia) braziliensis, causing a decrease in the percentage of the infected cells and parasite load tested through light microscopy. In addition, the absence of l-arginine resulted in the parasite's inability to regulate its reactive oxygen species (ROS) production, which persisted for up to 24 h by flow cytometry following the probe H2DCF-DA dye. Moreover, the differentiation of promastigote to amastigote in axenic culture was more significant at low concentrations of l-arginine suggesting that this depletion induces a stress environment to increase this transformation under axenic conditions. No association was established between the availability of l-arginine and the effectiveness of antileishmanial drugs. All these results confirm the importance of l-arginine in L. braziliensis life cycle vital processes, such as its replication and infectivity, as documented in other Leishmania species. Based on these results, we proposed that the l-arginine uptake/metabolism route is possible in exploring new antileishmanial drugs.

Subtotal content and geochemical fractionation of potential toxic elements in agricultural soils from Mocorito River basin in NW Mexico: environmental and health implications

Agricultural soils were collected from Mocorito river basin, to determine potentially toxic elements (PTEs) subtotal concentrations and geochemical fractionation, and evaluate their environmental and health risks. All sites showed low As and Cr concentrations. Subtotal concentrations (mg/kg) ranged between 6.8 and 25.6 for As, 1.9 and 2.5 for Cd and 22.5 and 55.1 for Cr. These values were classified as moderately contaminated for As, while a considerable contamination was presented for Cd and Cr. Geochemical partitioning revealed that PTEs are strongly linked with residual phase. Arsenic was associated with amorphous Fe-oxyhydroxides. Ecotoxicological indices showed from low (As and Cr) to considerable (Cd) potential ecological risk factors; potential non-carcinogenic risks by As, Cd and Cr, and potential carcinogenic risks by As and Cr. Lithogenic and anthropogenic sources were identified. Arsenic and Cr showed lithogenic influence, while Cd increased, caused by nearby activities, representing an environmental and health risk.

Choroidal Neovascularization and Macular Hemorrhage: Real-World Experience During the New York City COVID-19 Lockdown

Purpose:

This work reviews ocular, systemic, and demographic factors contributing to presentation of choroidal neovascular membrane (CNVM)–associated macular hemorrhage after the New York City coronavirus disease 2019 (COVID-19) lockdown.

Methods:

A retrospective, consecutive case series was conducted of all established patients presenting with macular hemorrhage between March 22, 2020, and August 10, 2020.

Results:

Fourteen patients (mean age 82.2 years) were evaluated. Ten patients had active CNVMs, 1 had an inactive lesion that was last injected 2 years prior, and 3 had new conversions from nonexudative age-related macular degeneration. In the actively treated CNVM group there was a delay in expected follow-up from 50.4 days to 125 days. Eight patients with previously active CNVM (73%) had a history of prior macular hemorrhage. Eight patients (57%) were on some form of antiplatelet or anticoagulation therapy. Twelve patients (86%) had COVID-19–specific risk factors besides age, and all but 1 patient (93%) delayed care without discussion with a physician. Ten patients (71%) had more than 1 week of symptoms prior to presentation. Twelve patients (86%) had signs of CNVM on prior optical coherence tomography.

Conclusions:

Adequate documentation of potential risks for hemorrhage (particularly prior hemorrhage or presence of subclinical type 1 CNVM), as well as COVID-19–specific risk factors, would aid triage of clinic appointments in future lockdowns. High-risk patients would likely benefit from direct physician communication discussing their individual risk profiles to alleviate anxiety over clinic visits and communicate their risk of severe vision loss.

Cues conditioned to withdrawal and negative reinforcement: Neglected but key motivational elements driving opioid addiction

Opioid use disorder (OUD) is a debilitating disorder that affects millions of people. Neutral cues can acquire motivational properties when paired with the positive emotional effects of drug intoxication to stimulate relapse. However, much less research has been devoted to cues that become conditioned to the aversive effects of opioid withdrawal. We argue that environmental stimuli promote motivation for opioids when cues are paired with withdrawal (conditioned withdrawal) and generate opioid consumption to terminate conditioned withdrawal (conditioned negative reinforcement). We review evidence that cues associated with pain drive opioid consumption, as patients with chronic pain may misuse opioids to escape physical and emotional pain. We highlight sex differences in withdrawal-induced stress reactivity and withdrawal cue processing and discuss neurocircuitry that may underlie withdrawal cue processing in dependent individuals. These studies highlight the importance of studying cues associated with withdrawal in dependent individuals and point to areas for exploration in OUD research.

Focal Choroidal Excavation Expansion Following Treatment of Associated Choroidal Neovascular Membrane

The authors describe a case of a previously unreported phenomenon of focal choroidal excavation (FCE) expansion, in absence of inflammation, due to treatment of an associated choroidal neovascular membrane (CNVM). A patient with new type 2 CNVM, treated during 43 months of follow-up with aflibercept, experienced significant expansion of an FCE with conversion from nonconforming to conforming type. FCE is part of the pachychoroid spectrum and the regression of an associated CNVM during aflibercept treatment as seen in the authors' patient may elucidate the pathogenesis of some forms of focal choroidal excavation and their evolution over time. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:54-57.].

Viscostretch: A Novel Surgical Technique for Refractory Macular Holes

Purpose:

We present a novel technique of subretinal viscodissection for addressing refractory macular holes (MHs).

Methods:

A case report and surgical technique description are provided.

Results:

In this technique, standard pars plana vitrectomy with internal limiting membrane peeling (unless previously peeled) is performed. A cohesive ophthalmic viscosurgical device (OVD) is injected through the MH, focally detaching the parafoveal retinal tissue around the hole. The OVD is removed at the conclusion of the air-fluid exchange. We provide an example of a recurrent 833-µm MH that was successfully closed despite failing initial surgery. There was no retention of subretinal OVD, and anatomic closure was achieved in this patient with a refractory MH.

Conclusions:

In refractory holes with adhesions at the MH base, this technique mobilizes the adjacent retinal tissue and uses the air’s surface tension to facilitate closure. Surgeons can consider using this technique as part of their MH arsenal.

Sulfonylureas attenuate electrocardiographic ST-segment elevation during an acute myocardial infarction in diabetics

OBJECTIVES

The aim of this study was to determine whether sulfonylureas attenuate ST-segment elevation in diabetics during acute myocardial infarction (AMI).

BACKGROUND

Sulfonylureas block adenosine triphosphate-sensitive potassium channels found in the pancreas and heart. Animal studies have demonstrated that opening of these cardiac channels results in ST-segment elevation during AMI, and pretreatment with sulfonylureas blunts these ST-segment changes.

METHODS

We performed a retrospective study of diabetic patients hospitalized with AMI over a four-year period in Framingham, Massachusetts. Electrocardiograms obtained on arrival were analyzed for standard ST-segment criteria for thrombolytic therapy (>1 mm in two or more contiguous leads). Results were compared between the study group (40 patients taking sulfonylureas) and control group (48 patients taking alternative hypoglycemic agent).

RESULTS

Demographics were similar for both groups apart from a female preponderance in the study group. A significantly higher percentage of patients in the study group did not meet ST-segment criteria for thrombolytic therapy as compared with the control group (53% vs. 29%, p = 0.02). This difference was most prominent in patients with peak creatinine phosphokinase levels between 500 and 1,000 mg/dl (86% vs. 22%, p = 0.04). The magnitude of ST-segment elevation and the frequency of thrombolytic therapy were significantly lower in the sulfonylurea group than in the control group (1.1 +/- 1.0 mm vs. 2.1 +/- 2.7 mm, p = 0.02 and 20% vs. 40%, p = 0.04, respectively).

CONCLUSIONS

Sulfonylurea therapy appears to attenuate the magnitude of ST-segment elevation during an AMI, resulting in failure to meet criteria for thrombolytic therapy and as a consequence leading to inappropriate withholding therapy in this subset of diabetic patients.

Cataleptic postures in thalamic hemorrhage: case report

We report a case of catalepsy associated with thalamic hemorrhage. A 72 year-old hypertensive woman had acute onset of right-sided weakness and speech disturbances. She was on anticoagulants because of aortic valve replacement. When postures were imposed, the patient maintained the left upper limb raised for several minutes, even in uncomfortable or bizarre positions. A CT scan of the head revealed a left thalamic hemorrhage. Cataleptic postures have been reported in few cases with acute stroke.

Differences in stroke subtypes among natives and caucasians in Boston and Buenos Aires

BACKGROUND AND PURPOSE

Several issues regarding ethnic-cultural factors, sex-related variation, and risk factors for stroke have been described in the literature. However, there have been no prospective studies comparing ethnic differences and stroke subtypes between populations from South America and North America. It has been suggested that natives from Buenos Aires, Argentina, may have higher frequency of hemorrhagic strokes and penetrating artery disease than North American subjects. The aim of this study was to validate this hypothesis.

METHODS

We studied the database of all consecutive acute stroke patients admitted to the Ramos Mejia Hospital (RMH) in Buenos Aires and to the Beth Israel Deaconess Medical Center (BIMC) in Boston, Massachusetts, from July 1997 to March 1999. Stroke subtypes were classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. All information on patients (demographic, clinical, and radiographic) was recorded prospective to the assessment of the stroke subtype.

RESULTS

Three hundred sixty-one and 479 stroke patients were included at RMH and BIMC stroke data banks, respectively. Coronary artery disease was significantly more frequent in BIMC (P:<0.001), whereas tobacco and alcohol intake were significantly more frequent in RMH (P:<0.001). Intracerebral hemorrhage (P:<0.001) and penetrating artery disease (P:<0.001) were significantly more frequent in the RMH registry, whereas large-artery disease (P:<0.02) and cardioembolism (P:<0.001) were more common in the BIMC data bank.

CONCLUSIONS

Penetrating artery disease and intracerebral hemorrhage were the most frequent stroke subtypes in natives from Buenos Aires. Lacunar strokes and intracerebral hemorrhage were more frequent among Caucasians from Buenos Aires than Caucasians from Boston. Poor risk factor control and dietary habits could explain these differences.

Relationship between red cell folate and cervical intraepithelial neoplasia and cervical human papillomavirus infection

OBJECTIVE

The aim of this study was to determine the relationship between red cell folate levels and the presence of cervical intraepithelial neoplasia (CIN) or cervical human papillomavirus infection (HPV) (or both). For that purpose, we designed a case-control study.

MATERIALS AND METHODS

One hundred three asymptomatic women who were between the ages of 20 and 76 and attending the gynecological clinic of the Military Hospital in Bogota, Colombia, were selected. Their mean age was 37.9 years. Inclusion criteria combined a colposcopic examination and a cervicovaginal Papanicolaou smear; accordingly, patients were divided into women without CIN or HPV (55 women, the control group) and women with CIN or HPV (or both) (48 women, the study group). Red cell folate levels were determined by radioimmunoassay.

RESULTS

Statistically significant differences in folate levels were found between cases [2.55 ng/ml; standard deviation, 0.75; 95% confidence interval, 2.34-2.73] and controls (2.96 ng/ml; standard deviation, 0.77; 95% confidence interval, 2.75-3.14; p < .008). The odds ratio between the folate levels and CIN or HPV (or both) was 0.49 (p = .01). Red cell folate levels of the individuals participating in this study were not found to be associated with parity, the use of oral contraceptives, cigarette smoking, or age.

CONCLUSIONS

High red cell folate levels appear to provide a protective effect against the development of CIN or HPV (or both).

Climate and vegetation history of the midcontinent from 75 to 25 ka: A speleothem record from crevice cave, missouri, USA

Four Missouri stalagmites yield consistent overlapping records of oxygen and carbon isotopic changes and provide a climate and vegetation history with submillennial resolution from 75 to 25 thousand years ago (ka). The thorium-230-dated records reveal that between 75 and 55 ka, the midcontinental climate oscillated on millennial time scales between cold and warm, and vegetation alternated among forest, savanna, and prairie. Temperatures were highest and prairie vegetation peaked between 59 and 55 ka. Climate cooled and forest replaced grassland at 55 ka, when global ice sheets began to build during the early part of Marine Oxygen Isotope Stage 3.

Further studies on HTLV-I associated myelopathy in Argentina

We report 10 HTLV-I virus seropositive subjects, eight of them with HTLV-I associated myelopathy (HAM), two of them also infected with HIV as well as two asymptomatic HTLV-I+ relatives of two unrelated patients. HTLV-I is endemic in several tropical areas, where it causes different neurological diseases. Only few patients have been reported in our country since 1994. We studied 8 patients, who fulfilled the clinical criteria for chronic spastic paraplegia, and 2 other non-symptomatic HTLV-I seropositive relatives, with electromyography (EMG), motor and sensory conduction velocities (NCV), somatosensory, visual and brainstem auditory evoked potentials (SSEP, VEP and BAEP), Magnetic Resonance Images (MRI) and cerobrospinal fluid (CSF) analysis. The latter was carried out only in seven symptomatic patients. In every case positive ELISA tests for HTLV-I/II were confirmed by Western Blot. The two asymptomatic persons were clinically and electromyographically assessed, one of them was also submitted to SSEPs studies. Three patients were males. Patient's ages ranged from 5 to 65 years old. All symptomatic patients showed muscular weakness, spasticity with pyramidal signs and sphincter disturbances. Five of them had paresthesias and 2 had burning pain on their feet. The EMGs and the NCVs were normal in 7 patients and in the 2 asymptomatic ones. SSEPs, obtained by stimulating the posterior tibial nerves, were impaired in 7 patients and in the asymptomatic person who received the procedure. The 7 symptomatic patients who underwent lumbar puncture had positive tests for HTLV-I in CSF, 3 out of these 7 patients had also high protein levels and 4 had increased number of lymphocytes. In 2 patients intrathecal IgG production could also be demonstrated. MRI were normal in 7 patients and in the 2 asymptomatics, the exception being a female who had bilateral hyperintense lesions in cerebral white matter in T2. In conclusion, tropical spastic paraparesis is apparently a rare disorder in Argentina. However, some cases have been reported recently. Most probably, its prevalence is currently underestimated. Its diagnosis should be considered in every patient with progressive spastic paraplegia.

Nonsteric factors dominate binding of nitric oxide, azide, imidazole, cyanide, and fluoride to the rhizobial heme-based oxygen sensor FixL

BACKGROUND

The FixL protein is a heme-based sensor. Binding of oxygen to a unique heme domain inhibits a kinase domain of the type found in two-component regulators. Oxygen association is slow, but the dissociation rate is comparable to that of myoglobins. We have probed the size and chemistry of the FixL heme pocket by measuring the affinites, on rates and off rates for a wide variety of ferric heme ligands. Cyanide, but not fluoride, regulates the kinase activity. To examine how the sensory heme domain interacts with the kinase, we asked how the presence of the kinase domain affects ligand binding.

RESULTS

The affinities of ferric FixL for heme ligands follow the same trend as their pKa values: cyanide > 4-methyl imidazole > imidazole > fluoride > azide >> thiocyanate. The association rates follow the reverse trend. Striking differences from myoglobin include a 6-fold greater affinity for, and faster binding to, the bulky ligand imidazole, a 14-fold faster on rate for nitric oxide, a 2 800-fold lower affinity for azide, and a complete failure to bind thiocyanate. The presence of the kinase domain does not alter the affinity or binding kinetics of the high-spin ligand fluoride, but affects the off rates of other ligands. The EPR spectrum shows a characteristic pentacoordinate nitrosyl heme, indicating that the Fe-His bond in FixL is strained.

CONCLUSIONS

The importance of ligand deprotonation to the on rates and the fact that large ligands bind readily indicate that the heme pocket is open and apolar. Ligand basicity strongly influences the strength of binding. The destabilization of inhibitory ligands by the presence of the kinase domain is consistent with a 'load' imposed by coupling to the inactivating mechanism.

[Living with diabetes: an ethnographic study]

The purpose of this study was to learn the experience of diabetic clients who live health-disease phenomena in an outpatient service of endocrinology in a school hospital. The objective of the research was to obtain a comprehensive view of their way of thinking their practices and their feelings lived during treatment. I adopted SPRADLEY's ethnographic methodology which includes: participant observation and ethnographic interview which are carried out simultaneously. Symbolic interactionism was also a strategy to clarify the themes, the validation of domains pointed out to the central theme: "The disease came to stay". The diseases metaphor emerged from this cultural universe as dangerous, impossible that destroys and stays. The disease is lived as a illness that provokes different feelings like sadness, panic, pain and death. The emic knowledge obtained from this ethnographic research gave to nursing practice important episthemologic and onthologic bases.

Force and acid-base state of turtle cardiac tissue exposed to combined anoxia and acidosis

We measured contractile force of ventricular strips form the turtle Chrysemys picta bellii exposed to 1 h of combined anoxia and acidosis (pH 7.0) at 20 degrees C. Strips either beat spontaneously (self-paced) or in response to electrical stimulation (paced at 12, 24, or 36 beats/min). Tissue [lactate] and intracellular pH (pHi) were measured in control strips and at the end of anoxia-acidosis. In self-paced strips, at normal extracellular Ca2+ concentration ([Ca2+]o) (1 mM), both rate and force fell significantly after 1 h of anoxia-acidosis to 54 and 17.1%, respectively, of control values. Increased [Ca2+]o to 10 mM at 30 min had a small but significant positive effect on both rate and force. Contractile force of paced strips also fell progressively during anoxia-acidosis, but the decrease varied directly with pacing frequency. Under all cases of anoxia-acidosis, pHi fell significantly from the control value of 7.53; in paced strips, acidosis was most severe at 36 beats/min (pHi 6.75), and in self-paced strips, pHi (approximately 6.85) was independent of [Ca2+]o. Based on this and previous work, we conclude that combined anoxia-acidosis, similar to that observed in vivo after prolonged anoxic submergence, profoundly depresses cardiac function. Both hypercalcemia and bradycardia improve performance in this extreme state, but these effects are not as great as when anoxia and acidosis occur alone.

Effects of fibronectin on the interaction of polymorphonuclear leukocytes with unopsonized and antibody-opsonized bacteria

Fibronectin (Fn) affects the interaction of polymorphonuclear leukocytes (PMNLs) with certain bacteria. Fn alone enhanced the response, in a chemiluminescence (CL) assay, of PMNLs to Staphylococcus aureus (P less than .05) and Staphylococcus epidermidis (P less than .01) but had no effect on type III, group B streptococci (GBS) or Escherichia coli. When GBS or E. coli were first preopsonized in antibody, Fn significantly enhanced the CL response of PMNLs (P less than .05). The intracellular metabolic inhibitor NaN3 but not the extracellular scavengers superoxide dismutase or human serum albumin inhibited Fn-enhanced CL; this fact suggests that enhancement of the respiratory burst by Fn is an intracellular event. We used an acridine orange-crystal violet monolayer assay to examine the effects of Fn on ingestion and intracellular killing of bacteria by PMNLs. Fn alone promoted uptake and killing of S. aureus (P less than .01) and S. epidermidis (P less than .05) by PMNLs but did not enhance monolayer phagocytosis of GBS or E. coli, unless these bacteria were preopsonized in antibody (P less than .01).

Laboratory evaluation of stain-length passive dosimeters for monitoring of vinyl chloride and ethylene oxide

The effects of vapor concentration in the range of 1.2 to 5.1 ppm (vinyl chloride) and 8.3 to 29.1 ppm (ethylene oxide) on the response of new stain-length passive dosimeters were evaluated separately in a dynamic exposure chamber. The vinyl chloride dosimeter was prepared with a permanganate impregnated blend of Chromosorb W and silica gel, while a silica gel-coated plastic strip (TLC plate) impregnated with dichromate was used to detect ethylene oxide. The use of a TLC plate as the inert support allowed us to reduce the amount of reagent loaded per length of tube, thus significantly enhancing in the sensitivity of the unit, which was necessary for accurately detecting ethylene oxide at these low concentrations. At the vinyl chloride exposure of 8 ppm-hrs the length of stain was 0.76 cm and the 95% confidence interval about this point was +/- 1.4 ppm-hrs (18%). For the ethylene oxide dosimeter the length of stain at the exposure of 80 ppm-hrs was 0.90 cm and the 95% confidence interval about this point was +/- 16 ppm-hrs (20%). Although some shortening of the stain was noted at low relative humidity (26%) in the vinyl chloride device, no effect on the dosimeter response was observed over the range of relative humidity of 35 to 96%. The ethylene oxide dosimeter response was not affected by relative humidity in the range of 28 to 90%. The use of a TLC plate as the inert support of the colorimetric reagent has proven to be an excellent means of improving the sensitivity of these stain-length passive dosimeters.(ABSTRACT TRUNCATED AT 250 WORDS)

Stain length passive dosimeter for monitoring of carbon monoxide

A new passive dosimeter for the personal monitoring of carbon monoxide exposure in the workplace has been developed. This new type of sampling device does not require follow-up analysis of the collected sample to determine the exposure. Rather, the time-weighted average concentration is determined directly from the length of a colored stain which is produced instantaneously during the exposure period in a specially prepared indicator tube. The colored stain length is a function of both contaminant concentration and exposure time. The effects of carbon monoxide concentration in the range of 0.5 T TLV to 2.0 X TLV on the response of the dosimeter were evaluated in a dynamic exposure chamber. In this range of concentration, plots of stain length against exposure collapsed onto a single curve. At the TLV exposure the stain length was 2.1 cm and the 95% confidence interval about this point was +/- 17%. Relative humidity in the range of 26 to 92% and face velocity in the range of 0.01 to 1.0 m/s (2 to 200 fpm) did not significantly affect the dosimeter response. These data were fitted to the appropriate model equation with a correlation coefficient of 0.968. By eliminating the need for follow-up analysis, this stain length dosimeter significantly reduces the cost of monitoring. The instantaneous readout eliminates the delay between exposure and quantification, enabling more careful control of the workplace environment.