Structural and functional studies of the endothelial activation antigen endothelial leucocyte adhesion molecule-1 using a panel of monoclonal antibodies.

We have produced a panel of mAb to the endothelial activation Ag endothelial leucocyte adhesion molecule-1 (ELAM-1), using both a conventional immunization protocol and one involving immunosuppression. By constructing ELAM-1 mutants we have demonstrated that seven of these antibodies recognize epitopes within the lectin domain of ELAM-1 and that one binds within the complement regulatory protein domains. These studies also suggest that the EGF-like domain is important in maintaining the conformation of the neighbouring lectin domain. In functional studies, U937 cells bound to Cos cells expressing either ELAM-1 or ELAM-1 with the complement regulatory protein domains deleted. No adhesion was observed to Cos cells expressing ELAM-1 mutants lacking either the lectin or EGF-like domains. The fact that antibodies directed against the lectin domain can inhibit adhesion suggest that this domain is directly involved in cell binding.     

Estrogen induced changes in uterine sensitivity for the decidual cell reaction: Interactions between prostaglandin E2 and histamine or bradykinin

In rats receiving high doses of estrogen along with progesterone, the uterus is desensitized and does not respond to artificial stimuli with increased endometrial vascular permeability or decidualization. In addition, prostaglandin E₂ (PGE₂), the putative mediator of endometrial vascular permeability changes in sensitized uteri, is ineffective when given into the uterine lumen. The possibility that this inability of PGE₂ to increase endometrial vascular permeability may be related to the unavailability of hitamine of bradykinin was investigated. Rats were differentially sensitized for the decidual cell reaction by the daily injection of 2 mg progesterone with either 0.5 of 10 μg estrone for the 3 days preceding the unilateral intra-uterine injection of 50 μl phosphate buffered saline containing gelatin with or without 10 μg PGE₂ and with or without 1 mg histamine or 1 μg bradykinin. Prior to the intrauterine injection, all rats were treated with indomethacin to inhibit endogenous prostaglandin production. Endometrial vascular permeability changes were determined 8 h later by determining radioactivity levels in injected and non-injected uterine horns 15 min after the i.v. injection of ¹²⁵I-labelled bovine serum albumin. PGE₂ increased endometrial vascular permeability in rats receiving 0.5 μg estrone, but not in those receiving 10 μg. Histamine or bradykinin, alone or with PGE₂, did not affect endometrial vascular permeability in rats receiving either estrogen dose. The data suggest that the unresponsiveness of uteri from rats treated with high doses of estrogen is not simply due to the unavailability of bradykinin or histamine.     

Analysis of development and growth in a mutant of Physarum polycephalum with defective cytokinesis

Cultures of amoebae of the mutant strain ATS23 isolated from strain CLd of Physarum polycephalum contain multinucleate cells and cells with increased nuclear DNA content. Plasmodia derived from ATS23 clones show abnormal morphology and defective sporulation. All abnormalities are enhanced by high incubation temperature (31 °C). Genetic analysis suggested that all the abnormalities were caused by a single mutation, denoted hts-23. The kinetics of plasmodium formation were followed in cultures of apogamic amoebae carrying hts-23 and hts⁺ (wild type) respectively. Results indicated that, relative to wild type, hts-23 did not increase the rate of plasmodium formation. There was evidence that, in both mutant and wild-type strains, commitment to plasmodium development occurred in uninucleate cells. Analysis of cell pedigrees by time-lapse cinematography indicated that the primary abnormal event in cultures of hts-23 amoebae was failure of cytokinesis; an apparently complete cleavage furrow was formed but cell separation failed, resulting in a binucleate cell. This event occurred randomly in pedigrees in which the majority of divisions were completed normally; its frequency increased during incubation at 31 °C. All other abnormalities in hts-23 amoebal cultures could be attributed to this primary event, assuming that DNA synthesis continued in the absence of cytokinesis and that the binucleate cells underwent the amoebal type of “open” mitosis, allowing the possibility of spindle fusion. This implies that the acquisition of “closed” mitosis is an essential early step in plasmodium development.     

Interaction of radical anion probes with glucoamylase I from Aspergillus niger.

The radical anions (SCN)2.- and Br2.- produced during a pulse radiolysis of the respective potassium salts have been used to study the tryptophan residues of the glucoenzyme, glucoamylase I (EC 3.2.1.3.). At neutral pH, Br2.- reacted with the tryptophan residues of glucoamylase I as expected from previous studies of proteins and free amino acids. However, (SCN)2.- at neutral and high pH was surprisingly unreactive towards the native enzyme. Reaction did occur, however, between (SCN)2.- and glucoamylase from which one-third of the covalently bound carbohydrate had been removed, producing a tryptophyl radical. Reaction also occured between (SCN)2.- and glucoamylase I inactivated by treatment with sodium dodecyl sulphate, but the tryptophan residues were not involved. It is concluded from the results that two 'types' of tryptophan residues are found in glucoamylase I; both are attacked by Br2.- but only one type is attacked by (SCN)2.-.     

Parents exposed to warming produce offspring lower in weight and condition

The parental environment can alter offspring phenotypes via the transfer of non‐genetic information. Parental effects may be viewed as an extension of (within‐generation) phenotypic plasticity. Smaller size, poorer physical condition, and skewed sex ratios are common responses of organisms to global warming, yet whether parental effects alleviate, exacerbate, or have no impact on these responses has not been widely tested. Further, the relative non‐genetic influence of mothers and fathers and ontogenetic timing of parental exposure to warming on offspring phenotypes is poorly understood. Here, we tested how maternal, paternal, and biparental exposure of a coral reef fish (Acanthochromis polyacanthus) to elevated temperature (+1.5°C) at different ontogenetic stages (development vs reproduction) influences offspring length, weight, condition, and sex. Fish were reared across two generations in present‐day and projected ocean warming in a full factorial design. As expected, offspring of parents exposed to present‐day control temperature that were reared in warmer water were shorter than their siblings reared in control temperature; however, within‐generation plasticity allowed maintenance of weight, resulting in a higher body condition. Parental exposure to warming, irrespective of ontogenetic timing and sex, resulted in decreased weight and condition in all offspring rearing temperatures. By contrast, offspring sex ratios were not strongly influenced by their rearing temperature or that of their parents. Together, our results reveal that phenotypic plasticity may help coral reef fishes maintain performance in a warm ocean within a generation, but could exacerbate the negative effects of warming between generations, regardless of when mothers and fathers are exposed to warming. Alternatively, the multigenerational impact on offspring weight and condition may be a necessary cost to adapt metabolism to increasing temperatures. This research highlights the importance of examining phenotypic plasticity within and between generations across a range of traits to accurately predict how organisms will respond to climate change.     

Measuring the unknown: An estimator and simulation study for assessing case reporting during epidemics

The fraction of cases reported, known as ‘reporting’, is a key performance indicator in an outbreak response, and an essential factor to consider when modelling epidemics and assessing their impact on populations. Unfortunately, its estimation is inherently difficult, as it relates to the part of an epidemic which is, by definition, not observed. We introduce a simple statistical method for estimating reporting, initially developed for the response to Ebola in Eastern Democratic Republic of the Congo (DRC), 2018–2020. This approach uses transmission chain data typically gathered through case investigation and contact tracing, and uses the proportion of investigated cases with a known, reported infector as a proxy for reporting. Using simulated epidemics, we study how this method performs for different outbreak sizes and reporting levels. Results suggest that our method has low bias, reasonable precision, and despite sub-optimal coverage, usually provides estimates within close range (5–10%) of the true value. Being fast and simple, this method could be useful for estimating reporting in real-time in settings where person-to-person transmission is the main driver of the epidemic, and where case investigation is routinely performed as part of surveillance and contact tracing activities.     

Effect of clinician information sessions on diagnostic testing for Chagas disease

BackgroundChagas disease is a potentially life-threatening neglected disease of poverty that is endemic in continental Latin America. Caused by Trypanosoma cruzi (T. cruzi), it is one of six parasitic diseases in the United States targeted by the Centers for Disease Control as a public health problem in need of action. An estimated 300,000 people are infected with T. cruzi in the United States (US). Although its morbidity, mortality and economic burden are high, awareness of Chagas disease is lacking among many healthcare providers in the US. The purpose of this analysis is to determine if the number of diagnostic tests performed at a community health center serving an at-risk population for Chagas disease increased after information sessions. A secondary aim was to determine if there was a difference by provider type, i.e., nurse practitioner vs. physician, or by specialty in the number of patients screened.Methodology/Principal findingsWe conducted a retrospective data analysis of the number of Chagas serology tests performed at a community health center before and after information sessions for clinicians. A time series analysis was conducted focusing on the Adult and Family Medicine Departments at East Boston Neighborhood Health Center (EBNHC). Across all departments there were 1,957 T. cruzi tests performed before the sessions vs. 2,623 after the sessions. Interrupted time series analysis across departments indicated that testing volume was stable over time prior to the sessions (pre-period slope = +4.1 per month; p = 0.12), followed by an immediate shift after the session (+51.6; p = 0.03), while testing volume remained stable over time after the session (post-period slope = -6.0 per month; p = 0.11).Conclusion/SignificanceIn this study, Chagas testing increased after information sessions. Clinicians who began testing their patients for Chagas disease after learning of the importance of this intervention added an extra, potentially time-consuming task to their already busy workdays without external incentives or recognition.     

Protein kinase C delta null mice exhibit structural alterations in articular surface,intra-articular and subchondral compartments

IntroductionStructural alterations in intra-articular and subchondral compartments are hallmarks of osteoarthritis, a degenerative disease that causes pain and disability in the aging population. Protein kinase C delta (PKC-δ) plays versatile functions in cell growth and differentiation, but its role in the articular cartilage and subchondral bone is not known.MethodsHistological analysis including alcian blue, safranin O staining and fluorochrome labeling were used to reveal structural alterations at the articular cartilage surface and bone–cartilage interface in PKC-δ knockout (KO) mice. The morphology and organization of chondrocytes were studied using confocal microscopy. Glycosaminoglycan content was studied by micromass culture of chondrocytes of PKC-δ KO mice.ResultsWe uncovered atypical structural demarcation between articular cartilage and subchondral bone of PKC-δ KO mice. Histology analyses revealed a thickening of the articular cartilage and calcified bone–cartilage interface, and decreased safranin O staining accompanied by an increase in the number of hypertrophic chondrocytes in the articular cartilage of PKC-δ KO mice. Interestingly, loss of demarcation between articular cartilage and bone was concomitant with irregular chondrocyte morphology and arrangement. Consistently, in vivo calcein labeling assay showed an increased intensity of calcein labeling in the interface of the growth plate and metaphysis in PKC-δ KO mice. Furthermore, in vitro culture of chondrocyte micromass showed a decreased alcian blue staining of chondrocyte micromass in the PKC-δ KO mice, indicative of a reduced level of glycosaminoglycan production.ConclusionsOur data imply a role for PKC-δ in the osteochondral plasticity of the interface between articular cartilage and the osteochondral junction.

Electronic supplementary material

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