Perceived Norms Influence Perceptions of Risk and Attitudes for Food Technologies

ObjectivesUnderstanding the factors that influence consumer attitudes and risk perception is critical for effective marketing of new food technologies. Many variables impact attitudes and risk perception. However, food technology research has largely focused on demographic variables, and often only single technologies (e.g., GMOs). Our goal was to determine how psychological variables differentially influence attitudes and risk perception for a range of food technologies: antibiotics, hormones, vaccines, GMOs, sustainability, and animal welfare technologies. We examined how attitudes and risk perception for these technologies related to four social psychological variables from the Theory of Planned Behavior (TPB): perceived norms, past behavior, familiarity, and perceived control. In addition, we measured general Food Technology Neophobia (FTN), Trust in Science (TIS), chemical reasoning (CR).Materials and MethodsParticipants (n = 394) provided demographics followed by TPB, attitude, and risk perception surveys for each of the six technologies. Then they completed FTN, TIS, and a CR survey measuring dose–response beliefs (DR), beliefs in unknown risks (UR), the role of risk in society (RS), and naturalness/knowledge of chemicals (NKC). Multiple regression analyses were used to test for associations among the survey measures.ResultsThe multiple regression models were all significant (p < 0.05). Variance accounted for (R2) ranged from 0.49 to0.69 (See Table 1 for summary). Perceived norms were the strongest predictor of attitudes and risk with higher values being associated with stronger attitudes (standardized betas ranging from 0.51 to 0.71) and lower risk perception (–0.54 to –0.40). There were a number of technology-specific associations, including familiarity increasing perceptions of risk for hormones, and NKC being primarily associated with animal welfare and sustainability technologies.ConclusionThe present findings show a critical role for perceived norms– a person’s perception that people they like also approve of or use a technology– across all technologies. This suggests that social factors like norms play a major role in consumer acceptance of food technologies. Other predictors varied in strength across technologies suggesting marketing may benefit from strategies tailored to specific technologies.Table 1Standardized betas (> 0.10 in bold) from selected coefficients of regression models predicting risk perceptions and attitudes (rows) for each technology (columns)

Evaluation and Safety Validation of Dehydrating Methods for Goat Meat in Rural Malawi

ObjectivesThis study was conducted to evaluate the dehydration methods of goat meat based in Malawi and the effects on food safety.Materials and MethodsGoat meat was prepared as ground, minced, and whole muscle strips. Samples were treated with 6% lemon juice marinade, 6% vinegar marinade, or salt rub. During phase 1, dehydration of the meat was performed with a solar dehydrator (n = 108), electric oven (n = 108) or drum oven (n = 108). Qualitative data on the three drying methods was collected from a panel of students from Mzuzu University, Malawi, on the practicality of each method in a local rural setting. Additionally, visual observations were conducted 30 d prior to drying for the presence of mold and insects to give an indication of shelf life. Phase 2 was performed at Texas Tech University in Lubbock, Texas where whole muscle strips of lamb were submerged in a five-strain Escherichia coli surrogate cocktail of Escherichia coli for 5 min, allowed 30 min for cell attachment, then dried using an electric and drum oven, replicating the dehydration procedure in Malawi. For each replicate (n = 2), attachment samples (n = 10), samples dried in the electric oven (n = 10) and samples dried in drum oven samples (n = 10) were aseptically plated on MacConkey agar with a TSA overlay and enumerated for E. coli.ResultsIn phase 1, mold growth was observed on 15.7% (34/216) of samples dried in the solar dehydrator and drum oven. Of those positive for mold, 32.4% (n = 11) were minced, and 67.6% (n = 23) were whole muscle strips. No samples dried using the electric oven displayed mold (0/108). No samples displayed insects. Based on qualitative data that was gathered, top reasons to dry goat meat using the drum oven include “not requiring electricity” and “drum ovens are a common piece of equipment in villages”. Top reasons against using a drum oven include “unequal distribution of heat” and “high level of oversight required during drying”. Top reasons to dry goat meat using electric oven include “fast drying time”, “uniform distribution of heat”, and “limited oversight required”. Top reasons against using electric oven to dry goat meat include “requiring electricity” and “low knowledge of electric oven operation in a community setting”. Top reasons to use the solar dehydrator to dry goat meat include “not requiring electricity or firewood” and “limited oversight required”. Top reasons against using the solar dehydrator to dry goat meat include “slow drying time” and “uneven heat distribution due to time of day and shadows”. In phase 2, a 5-log reduction was observed for all electric oven treatment replicates (100%, 2/2) and half drum oven (50%, 1/2) replicates. However, variation in the reduction of E.coli is a direct result of weather and fuel provided to the drum oven.ConclusionElectric drying oven displayed the most consistent results for shelf life and safety. However, in rural Malawi, dehydrating methods should be chosen on a case by case basis.

Infographics Influence Attitudes and Risk Perceptions for Food Technologies

ObjectivesFood technologies have facilitated a healthier, more efficient, and sustainable food supply. They nevertheless often face resistance from consumers. Compared to organic and traditional farming techniques, food produced with technologies tends to be associated with higher perceptions of risk, lower attitudes, and fewer perceived benefits. Countering resistance toward technologies poses a serious challenge because persuasive appeals have the potential to amplify preexisting attitudes instead of changing them. We tested six infographics for their ability to improve attitudes and risk perception toward six food technologies: hormones, antibiotics, GM crops, vaccines, sustainability technology, and animal welfare technology. Our objective was to determine whether these infographics would successfully shift perceived risk and attitudes toward these technologies.Materials and MethodsParticipants (n = 810) from English speaking countries (in North America, Europe, and Australia) were recruited from Amazon’s MTurk service. They answered a survey assessing their levels of risk perception and attitudes regarding each of the six food technologies, followed by a general food technology neophobia (FTN) survey. An experimental condition (n = 416) saw an infographic before answering questions about each technology and a control condition (n = 394) did not. Linear mixed effects models implemented in R were used to test risk and attitude differences among technologies and whether the infographics affected risk perception and attitudes.ResultsLinear mixed effects models revealed that there was a significant interaction between technology and condition for both risk: F(54040) = 5.068, p < 0.001, and attitudes: F(54040) = 26.34, p < 0.001. Overall, there was a tendency for risk perception to decrease (g = –.36, z = 6.89, p < 0.001) and attitudes to increase (g = .48, z = 9.38, p < 0.001), in the condition that saw the infographics. However, there were larger decreases in risk perception and increases in attitudes for hormones (risk: z = 5.05, p < 0.001; attitudes: z = 8.30, p < 0.001), GMOs (risk: z = 6.89, p < 0.001; attitudes: 13.21, p < 0.001), vaccines (risk: z = 6.45, p < 0.001; attitudes: z = 6.11, p < 0.001), and antibiotics (risk: 5.06, p < 0.001; attitudes: z = 7.83, p < 0.001), but smaller changes for sustainability (risk: z = 2.77, p = 0.03; attitudes: z = 2.89, p = 0.02) and animal welfare (risk: z = 4.91, p < 0.001; attitudes: z = 3.51, p = 0.003). Including FTN in the models did not affect the overall pattern of results, suggesting that the changes in risk perception and attitudes were not due to simply a general change in FTN.ConclusionOur results found that infographics provide a potential avenue for improving attitudes and risk perception for food technologies. Across six different infographics, we found attitudes and risk perception improved for hormones, antibiotics, vaccines, GMOs, sustainability technologies, and animal welfare technologies. These results are important because such persuasive appeals can often backfire, yet here we observed general improvement. In future studies it will be critical to examine how such attitude and risk perception changes relate to consumer behavior (e.g., willingness-to-pay), and which specific strategies in the infographics led to the improved attitudes.

The influence of laser scribing on magnetic domain formation in grain oriented electrical steel visualized by directional neutron dark-field imaging

The performance and degree of efficiency of transformers are directly determined by the bulk magnetic properties of grain oriented electrical steel laminations. The core losses can be improved by post manufacturing methods, so-called domain refinement techniques. All these methods induce mechanical or thermal stress that refines the domain structure. The most commonly used technique is laser scribing due to the no-contact nature and the ease of integration in existing production systems. Here we show how directional neutron dark-field imaging allows visualizing the impact of laser scribing on the bulk and supplementary domain structure. In particular, we investigate the domain formation during magnetization of samples depending on laser treatment parameters such as laser energy and line distances. The directional dark-field imaging findings were quantitatively interpreted in the context with global magnetic hysteresis measurements. Especially we exploit the orientation sensitivity in the dark-field images to distinguish between different domain structures alignment and their relation to the laser scribing process.

Screening for cervical cancer in an African setting

OBJECTIVE

To estimate the proportion of women who were screened for cervical neoplasia with Papanicolaou (Pap) smears in 2002 in the Free State province of South Africa, and determine whether progress had been made since 1985.

METHODS

A cross-sectional survey was done using 1887 smears, which represented 5% of the 37,749 smears examined at the 7 laboratories serving the province in 2002.

RESULTS

Extrapolating the results to the census data for 2002, Pap smears were taken in 4.1% of the female population aged 15 to 65 years during that year. The rates were 18.8% for white women, most of whom use private medical services, and 2.6% for black women, almost all of whom use public medical services. In 1985, in a similar study found that 7.1% of the female population was screened with Pap smears, which means that cervical screening decreased by 42% over the 17 years (P< or =0.0001; 95% confidence interval, -3.1% to -2.9%).

CONCLUSION

In view of the deterioration of cervical screening services documented in this study, it seems unlikely that Pap smear screening will succeed in Africa.

Differential distribution of voltage-gated potassium channels Kv 1.1-Kv1.6 in the rat retina during development

The discharge behavior of neurons depends on a variable expression and sorting pattern of voltage-dependent potassium (Kv) channels that changes during development. The rodent retina represents a neuronal network whose main functions develop after birth. To obtain information about neuronal maturation we analyzed the expression of subunits of the Kv1 subfamily in the rat retina during postnatal development using immunocytochemistry and immunoelectron microscopy. At postnatal day 5 (P5) all the alpha-subunits of Kv1.1-Kv1.6 channels were found to be expressed in the ganglion cell layer (GCL), most of them already at P1 or P3. Their expression upregulates postnatally and the pattern and distribution change in an isoform-specific manner. Additionally Kv1 channels are found in the outer and inner plexiform layer (OPL, IPL) and in the inner nuclear layer (INL) at different postnatal stages. In adult retina the Kv 1.3 channel localizes to the inner and outer segments of cones. In contrast, Kv1.4 is highly expressed in the outer retina at P8. In adult retina Kv1.4 occurs in rod inner segments (RIS) near the connecting cilium where it colocalizes with synapse associated protein SAP 97. By using confocal laser scanning microscopy we showed a differential localization of Kv1.1-1.6 to cholinergic amacrine and rod bipolar cells of the INL of the adult retina.

Complications associated with cesarean section in HIV-infected patients

OBJECTIVE

To document complications associated with cesarean section in HIV-infected women.

METHOD

A cross-sectional study was done on 307 women who delivered by cesarean section. All these patients, irrespective of their HIV-status, were managed according to the same preset protocol.

RESULT

Of the 307 women, 59 (19%) were HIV-positive. The only significant differences were a higher prevalence of positive serology for syphilis (32% vs. 12%, P=0.0014) as well as more cases of post-operative endometritis in the HIV-positive group (24% vs. 7%, P=0.0003). Post-operative endometritis was documented in 44% of HIV-infected patients with a CD4 count below 400. However, the severity of endometritis, measured by antibiotic treatment and duration of hospital stay, was similar in the two groups. Overall, there was no difference in the duration of hospital stay, post-operative anemia, wound infection, birth weight and perinatal mortality between the two groups.

CONCLUSION

HIV-infected patients undergoing cesarean section are at increased risk for post-operative endometritis, but the severity of the infection is not different from that in HIV-negative patients.

Screening for cervical neoplasia in a developing country utilizing cytology, cervicography and the acetic acid test

OBJECTIVE

To compare three screening tests for cervical neoplasia.

METHOD

Women (6301) were screened simultaneously with cytology, cervicography and the acetic acid test (AAT). Biopsies were taken from the acetowhite lesions and every fifth seemingly normal cervix. Positive cases (both at screening and histology) were referred for colposcopy. The histology results served as the golden standard.

RESULTS

Cytology was positive in 1.7% of cases, cervicography in 10.7% and the AAT in 17.8%. The sensitivity of cytology was 19.3%, of cervicography 41.8% and the AAT 49.4%. Corresponding specificities were 99.3%, 78.8% and 48.5%. In 23% of biopsies showing cervical intraepithelial neoplasia (grade I--III), all three screening tests were negative. By combining the three tests, a sensitivity of 76.9% was achieved.

CONCLUSION

The sensitivity of cytology alone is not great enough for implementing as a screening test in a developing country where screening programs are often inadequate. Screening with a combination of tests, once or a few times per woman's life, is a more acceptable alternative since it allows for less screening events without sacrifying sensitivity.

Speculoscopy vs. the acetic acid test for cervical neoplasia

OBJECTIVE

To compare the specificity of speculoscopy and the acetic acid test (AAT).

METHODS

A randomized controlled trial was performed on 1150 women in a primary healthcare clinic. The main end-points were the sensitivity and specificity of speculoscopy and the AAT.

RESULTS

The mean age of the patients was 37.7 years in the speculoscopy group (n=545) and 37.5 years in the AAT group (n=605). Cervicography (the golden standard) was positive in 11.3% of the participants, speculoscopy in 20.4% and the AAT in 25.1%. The sensitivity, specificity and the kappa value for speculoscopy were 53.5%, 83.6% and 0.23, respectively. For the AAT, the corresponding figures were 51.1%, 77.3% and 0.15. No statistically significant differences were found between these two groups. Of clinical importance, however, was a finding that speculoscopy did not miss a single case of high grade squamous intra-epithelial lesion or cancer whilst the AAT missed five such lesions.

CONCLUSION

Speculoscopy could not be shown to have an improved specificity when compared with the acetic acid test. The low specificity of both the tests will result in the referral of too many patients for colposcopy.

Speculoscopy vs. the acetic acid test for cervical neoplasia

OBJECTIVE

To compare the specificity of speculoscopy and the acetic acid test (AAT).

METHODS

A randomized controlled trial was performed on 1150 women in a primary healthcare clinic. The main end-points were the sensitivity and specificity of speculoscopy and the AAT.

RESULTS

The mean age of the patients was 37.7 years in the speculoscopy group (n=545) and 37.5 years in the AAT group (n=605). Cervicography (the golden standard) was positive in 11.3% of the participants, speculoscopy in 20.4% and the AAT in 25.1%. The sensitivity, specificity and the kappa value for speculoscopy were 53.5%, 83.6% and 0.23, respectively. For the AAT, the corresponding figures were 51.1%, 77.3% and 0.15. No statistically significant differences were found between these two groups. Of clinical importance, however, was a finding that speculoscopy did not miss a single case of high grade squamous intra-epithelial lesion or cancer whilst the AAT missed five such lesions.

CONCLUSION

Speculoscopy could not be shown to have an improved specificity when compared with the acetic acid test. The low specificity of both the tests will result in the referral of too many patients for colposcopy.

Screening for cervical neoplasia during pregnancy

OBJECTIVE

To evaluate cytology as a screening method for cervical neoplasia in pregnancy and to compare it with cervicography and the acetic acid test (AAT).

METHODS

In a large antenatal clinic in South Africa, 842 women were screened utilizing cytology, cervicography and the acetic acid test simultaneously. The proportion of positive results of the different tests were compared and the agreement calculated by the kappa statistic.

RESULTS

The mean age of the women was 27 years, and 12.5% smoked. Cytological smears were abnormal (low-grade squamous intra-epithelial lesion and higher degrees of abnormality) in 1.4% of cases, cervicography in 6.3% and the AAT in 14.3% (P = 0.5400). Kappa values were as follows: cytology vs. cervicography 0.01, cytology vs. AAT 0.0 and cervicography vs. AAT 0.2.

CONCLUSIONS

As a result of cytology's rather low yield and the small measure of agreement between the tests, cytology should be supplemented by an additional screening test in pregnancy.

Successful total correction of complete atrioventricular canal, total anomalous pulmonary venous drainage and unroofed coronary sinus in an infant

An infant with complete atrioventricular canal, total anomalous pulmonary venous drainage into the left superior vena cava and an unroofed coronary sinus successfully underwent total correction. A homograft vein was used to connect the proximal left superior vena cava to the right atrium and can be recommended when other methods of correction of unroofed coronary sinus cannot be used.

Linked pacing after heterotopic heart transplantation with concurrent left ventricular reduction of the native heart

A 30-year-old man with dilated cardiomyopathy underwent heterotopic heart transplantation, concurrently with surgical reduction of the native left ventricle, a mitral valvuloplasty, and an apical thrombectomy. Postoperatively, the patient had hemodynamic instability that was refractory to conventional medical therapy. Temporary sequential pacing of the 2 hearts was used to induce timed counterpulsation, which resulted in marked hemodynamic improvement. To the best of our knowledge, this case involves the 1st report in the English-language literature of clinical usage of paced, linked counter-pulsation to treat acute hemodynamic compromise early after heterotopic heart transplantation.

Change of isoforms' spectra of alpha-L-fucosidase from human skin fibroblasts in intracellular storage of nonhydrolyzable substances

The effect of exogenous and endogenous products storage in lysosomes on the activity and multiple forms of alpha-L-fucosidase from human skin fibroblasts was investigated. It was shown that sucrose load, modelling intralysosomal accumulation of nonhydrolyzable products, causes certain changes in secretion level of alpha-L-fucosidase and multiple forms' spectra of the intracellular and secreted enzymes. These changes were different for the enzyme from embryonal and postnatal normal fibroblasts. Some changes of secreted alpha-L-fucosidase isoforms' spectra were found in fibroblasts from a patient with Fabry's disease, characterized by the intralysosomal storage of di- and trihexosylceramides. The alterations of isoforms' profiles in Fabry fibroblasts at the early and late accumulation stages were similar to those in sucrose-loaded embryonal and postnatal fibroblasts, respectively. It is proposed that intralysosomal accumulation of nonhydrolyzable compounds influences the alpha-L-fucosidase posttranslational processing.

Electrical properties of mammalian lens epithelial gap junction channels

PURPOSE

To establish an "electrical fingerprint" for the gap junction channels between mammalian lens epithelial cells.

METHODS

The double whole cell patch clamp technique was applied to isolated cell pairs obtained from mouse lens epithelium and a continuous cell line of lens epithelial cells derived from the sheep lens (SLE 2.1).

RESULTS

The junctional conductance in mouse lens epithelial cells and in cultured SLE 2.1 cells was found to be moderately voltage dependent. SLE 2.1 cells were analyzed in more detail. The voltage dependence could be described by a Boltzmann distribution with Vo = +/- 63.1 mV and Gmin = 0.34. In cell pairs that exhibited spontaneously low junctional conductance, single channel events could be distinguished. Single gap junction channel currents had a linear current-voltage relationship. A frequency histogram of single channel conductances from eight cell pairs had three major peaks of 35, 60 and 97 pS.

CONCLUSION

The electrical properties of gap junction channels between mammalian lens epithelial cells were virtually identical to those previously reported for transfected cell lines expressing connexin43. The authors' physiological data are therefore in agreement with molecular studies that have identified connexin43 as the major connexin of lens epithelial cells.

Differential expression of two gap junction proteins in corneal epithelium

Two distinct gap junction proteins (connexins) are expressed in rat corneal epithelium in a way which parallels cellular differentiation processes in this tissue. Connexin43 is restricted predominantly to the basal cells of the corneal epithelium and is present in significantly reduced amounts compared to the situation in the adjacent conjunctival epithelium. In contrast, a gap junction protein recognized by antibodies against MP70 which is the ovine homolog of mouse connexin50, is strongly expressed in the corneal epithelium and is present in the basal cells, wing cells and surface cells. While the functional significance of this differential expression of corneal epithelial connexins has yet to be established, the corneal epithelium is the third avascular tissue besides lens and heart valves which expresses a gap junction protein recognized by anti-MP70 antibodies.

Differential expression of gap junction connexins in endocrine and exocrine glands

We have investigated the expression of three gap junction proteins and their corresponding mRNAs by secretory cells of a variety of endocrine and exocrine rat glands. By immunostaining cryostat sections (indirect immunofluorescence) with antibodies against connexins (Cx) 26, 32, and 43 and by hybridizing total glandular RNA (Northern blot) with cRNAs for these proteins, we have found that several endocrine glands (pituitary, parathyroid, pancreatic islets, and adrenal) express Cx43, variable levels of Cx26, and no Cx32, whereas several exocrine glands (lacrimal gland, salivary glands, pancreas, prostate, and seminal vesicle) express high levels of Cx32 and variable levels of Cx26, but no Cx43. Thus, different sets of proteins comprise the gap junctions of endocrine and exocrine glands. Together with the findings that an endocrine gland (thyroid) that discharges secretory products extracellularly before releasing them in the vascular compartment expresses both Cx43 and Cx32 and that an exocrine gland (preputial gland) that has a pheromonal role expresses Cx43, these observations suggest that the differential expression of gap junction connexins may be required to specify the endocrine or exocrine differentiation of a secretory cell.

Characterization of gap junctional communication-deficient mutants of a rat liver epithelial cell line

To understand the mechanism(s) regulating gap junctional communication, we isolated gap junctional intercellular communication-deficient (GJIC-) mutant clones of a rat liver epithelial cell line, WB F-344, which is hypoxanthine-guanine phosphoribosyl transferase deficient (HGPRT-). The cells were exposed to a mutagenesis regimen and cocultured with the wild type HGPRT+ cells. Four GJIC- and one positive clones were characterized in the present study. Northern analysis of RNA isolated from both mutant and parental cells showed a single RNA species of about 3.0 kb which hybridized to connexin43 (Cx43) cDNA. Western blot analysis confirmed the expression of this junctional protein in all these clones. However, in the GJIC- clones the slowest migrating band corresponding to a hyperphosphorylated form, P2, of Cx43 protein (approximately 46 kDa) was absent suggesting that loss of this phosphorylated form of Cx43 may be involved in the failure of the mutants to establish cell-cell communication. Immunofluorescence analysis of the mutants did not reveal any differences in the distribution and localization of Cx43 between GJIC+ and GJIC- clones suggesting that the loss of phosphorylation did not affect the membrane association of this protein. Taken together, these data suggest that one mechanism for the loss of communication in these GJIC- mutants may be the consequence of a change in the intrinsic phosphorylation state of Cx43 protein.

Expression of different connexin genes in rat uterus during decidualization and at term

The expression of different connexin genes (cx26, cx32, cx37, cx43) that code for the protein subunits of gap junctions, was investigated in various uterine tissues during the estrous cycle of nonpregnant rats, in pregnant rats at decidualization and at term. Connexin gene expression was studied at the mRNA level by Northern blot hybridization and at the protein level by immunocytochemistry. In gap junctions from uterine epithelium, stroma, or myometrium, connexin 26 and/or connexin 43 are much more abundant than connexins 32 and 37. The expression of connexin 26 and 43 appears to be modulated by maternal steroid hormones. High expression of these connexins is found in developing decidual cells by day 7 to 8 post coitum; furthermore, coexpression of connexins 26 and 43 in myometrium is observed just before delivery on day 21 post coitum. In both the decidua and the myometrium, the connexin 26 protein appears to be distributed in lower abundance than connexin 43. In uterine epithelium only connexin 26 is expressed throughout all of the reproductive phases investigated. The enhanced expression of this gene correlates with higher levels of maternal estrogen both in the proestrus/estrus phase and at term. The distinct spatial and temporal pattern of expression of connexins 26 and 43 in different uterine tissues suggests a physiological role for these proteins during embryo implantation and subsequent contraction of the uterus at birth.

Relationship of the multiple forms of human alpha-D-galactosidase and alpha-D-fucosidase in the normal and in Fabry's disease

Activities and multiple forms of alpha-D-galactosidase of human kidney and liver in the normal and in Fabry's disease were comparatively studied using alpha-D-galactoside and alpha-D-fucoside as substrates. By isoelectric focusing alpha-D-galactosidase was shown to exist in multiple forms, one of which possesses both alpha-D-galactosidase and alpha-D-fucosidase activity. In Fabry's disease, caused by a deficiency of alpha-D-galactosidase A, we found only one form of alpha-D-galactosidase, which corresponded to form B (alpha-N-acetylgalactosaminidase) and was also able to split alpha-D-fucoside. Thus, in Fabry's disease the alpha-D-fucosidase profile was virtually unchanged, as compared with the normal. The results obtained indicate that the alpha-D-fucosidase activity is due to the action of alpha-D-galactosidase B, encoded for by an autosomal gene of chromosome 22. We suppose these data could be confirmed by revealing the significant reduction of the alpha-D-fucosidase activity in patients with alpha-N-acetylgalactosaminidase deficiency.

Differential expression of three gap junction proteins in developing and mature brain tissues

By using antibodies directed against gap junction proteins of liver (connexins 26 and 32) and heart (connexin 43), we have localized immunoreactivity to specific cell types in frozen sections of adult rodent brains. Connexin 32 reactivity was found in oligodendrocytes and also in a few neurons, whereas reactivity to connexins 26 and 43 was localized to leptomeningeal cells, ependymal cells, and pineal gland. Immunoreactivity with antibodies to connexin 43 also occurred in astrocytes. Furthermore, during embryonic and postnatal maturation of brain tissues, gap junction proteins were differentially expressed. Connexins 43 and 26 predominated in the neuroepithelium of embryonic brains, whereas connexin 32 was virtually absent. Between 3 and 6 weeks after birth, connexin 26 largely disappeared from immature brain; this time course corresponded to the increased expression of connexin 32. Expression of connexin 43 remained high throughout embryonic and postnatal development. These findings demonstrate that gap junction expression in the brain is diverse, with specific cell types expressing different connexins; this cell-specific distribution may imply differences in the function of these intercellular channels in different loci and developmental stages.

Monocyte bone degradation: in vitro analysis of monocyte activity in patients with juvenile rheumatoid arthritis

We examined the ability of the mononuclear phagocyte in vitro to degrade 45Ca-labeled bone particles to determine whether this assay allowed us to monitor disease activity in patients with juvenile rheumatoid arthritis. The monocytes from patients with juvenile rheumatoid arthritis receiving no anti-erosive therapy (n = 10) degraded significantly more bone than did cells obtained from normal controls (n = 10, P less than 0.001) or patients with juvenile rheumatoid arthritis receiving either gold thioglucose (n = 4, P less than 0.001) or D-penicillamine (n = 6, P less than 0.005). In two patients monitored for either 8 or 11 months, results of monocyte assays were found to parallel the clinical course. We conclude that in vitro monocyte bone degradation assays may provide a means of assessing joint activity in patients with juvenile rheumatoid arthritis. Further, this study and others indicate that mononuclear phagocytes are capable of causing erosive changes.

Discrimination of three parallel pathways of lactate transport in the human erythrocyte membrane by inhibitors and kinetic properties

The transmembrane movements of lactate and other monocarboxylate anions in mammalian erythrocytes have been claimed, by virtue of their sensitivity to SH-reagents, to involve a transfer system different from the classical anion system (Deuticke, B., Rickert, I. and Beyer, E. (1978) Biochim. Biophys. Acta 507, 137-155). Inhibition of monocarboxylate transfer by SH-reagents, however, was incomplete to an extent varying for different monocarboxylates. The transport component insensitive to SH-reagents has now been shown to involve (a) the classical anion-exchange system, as demonstrated by sensitivity to specific disulfonate inhibitors, and (b) nonionic diffusion, as indicated by the characteristic pH- and concentration dependency of this component and its stimulation by aliphatic alcohols. Under physiological conditions about 90% of total lactate movement proceed via the specific system, 5% via the classical anion-transfer system, 5% by nonionic diffusion. These three components of lactate exchange differ in their activation energies. The specific lactate system mediates net fluxes almost as fast as exchange fluxes, in marked contrast to the classical anion-exchange system which mediated halide exchange much faster than halide net movements. The underlying mechanism, for maintenance of electroneutrality, is an OH- -antiport or an H+ -symport as indicated by the particular response of lactate net fluxes to changes of intra- or extracellular pH.

[Etomidate and suxamethonium. The duration of relaxation and pseudocholinesterase activity. A clinical experimental study (author's transl)]

In ten health volunteers general anaesthesia was induced with etomidate (0.3 mg per kg body weight) and continued with NWO/O2 inhalation. Together with etomidate, suxamethonium (1.5 mg per kg body weight) was given simultaneously and the same dose reinjected as soon as the original muscle tone had returned completely. At equal intervals after the first and second injection the pseudocholinesterase was spectrophotometrically measured. No significant alteration of the enzyme activity was detectable at any time. Etomidate therefore does not inhibit the pseudocholinesterase. The two phases of relaxation were registered with the "finger-twitch" method and their duration compared. Etomidate did not prolong the time of relaxation after suxamethonium.

Reversible inhibition of anion exchange in human erythrocytes by an inorganic disulfonate, tetrathionate

Tetrathionate (S4O6--) markedly inhibits anion exchange across the human erythrocyte membrane. This phenomenon has been studied in order to obtain further insight into the mechanism of action of reversible inhibitors, in particular disulfonate inhibitors, of anion exchange. Anion fluxes were measured by tracer techniques at equilibrium. The following results were obtained: Tetrathionate, although an inorganic compound, inhibits the self-exchange of sulfate and of divalent organic anions (oxalate, malonate) noncompetitively at Ki values (less than or equal to 0.5 mM) as yet only observed for amphiphilic inhibitors. The inhibitor is effective only from the outside of the cell. The inhibition is temperature-dependent, Ki increasing by a factor of 5 between 5 and 35 degrees C, and instantaneously and fully reversible. The presence of small monovalent anions (fluoride, bromide, chloride, nitrate, acetate) counteracts inhibition by tetrathionate to a varying and concentration-dependent extent, divalent anions have only a minor effect at high concentrations. Chloride exchange is also inhibited, while glycolate and lactate fluxes are much less sensitive or almost insensitive, in agreement with their alleged transfer by a different transport system. Tetrathionate is unique in its inhibitory action, its structural congeners, peroxodisulfate (S2O8--) and ethanedisulfonate (C2H4S2O6--) are much less effective. The results can be interpreted by assuming that tetrathionate inhibits the movement of anions via the inorganic anion exchange system by binding--in a 1 : 1 stoichiometry--to inhibitory "modifier sites", for which it competes with other anions. These sites are located only on the exofacial surface of the membrane. The high affinity of tetrathionate is probably due to a local excess of pi electrons in the region of its central disulfide bond. These may stabilize the binding by their ability to form electron donor-acceptor complexes with membrane sites, thus compensating for the absence of a hydrophobic binding domain in tetrathionate.