ST-Segment Elevation Myocardial Infarction Caused by 5-Fluorouracil-Related Cardiotoxicity

5-Fluorouracil (5-FU) and its prodrug, capecitabine, are commonly used chemotherapeutic agents for solid tumor management. While these agents can present with adverse side effects such as nausea, vomiting, diarrhea, and myelosuppression, they can also, less commonly, cause cardiovascular toxicity. This toxicity may manifest as cardiac arrhythmias, myocarditis, heart failure, myocardial infarction, and even death. The management of 5-FU-related cardiotoxicity includes early recognition of symptom manifestation so that medication can be discontinued promptly and symptoms can be addressed appropriately. Here, we describe the case of a 72-year-old male who developed coronary vasospasm and ST-segment elevation myocardial infarction shortly after the initiation of chemotherapy with 5-FU.

Using the Flipped Classroom Model in Surgical Education: Efficacy and Trainee Perception

OBJECTIVE

To describe the feasibility, efficacy, and learner perception of the flipped classroom model for teaching conferences within surgical training programs.

DESIGN

For the flipped classroom conferences, video lectures were prepared by a faculty member, and sent to all attendees at least 2 days prior to lecture. The conference time was then spent going over cases and questions, rather than traditional lecture. We conducted a qualitative survey to assess learner's perceptions and pre-lecture quizzes to assess trainee preparedness.

SETTING

The comparison of pre-conference quizzes between flipped classroom and traditional models was carried out at Brooke Army Medical Center (BAMC) in San Antonio, TX, a tertiary care facility with a general surgery residency program. The survey was conducted at BAMC and within the Complex General Surgical Oncology fellowship program at University of Texas MD Anderson Cancer Center, where a flipped classroom model was similarly employed.

PARTICIPANTS

Surgical residents BAMC participated in pre-lecture quizzes. BAMC residents and MD Anderson fellows were invited to complete the online survey.

RESULTS

Lecture videos did not increase mean preparation time (1.53 vs. 1.46 hours without vs. with video, p = 0.858), but did increase mean quiz scores from 67% to 80% (p = 0.031) with 32/35 learners utilizing videos. Videos increased the proportion of learners who self-reported preparing at all from 42% to 95% (p = 0.28), and preparing for at least one hour for conference from 23% to 49% (p = 0.014). Of survey respondents, 90% said videos were very helpful, 90% would use them weekly if available, and 90% prefer this format to traditional lecture.

CONCLUSIONS

Utilization of a flipped classroom method was well received and preferred by surgical trainees, and it increased performance on pre-conference quizzes without increasing preparation time. Although creation of video lectures is work-intensive for lecturers, these results suggest it is more effective for learner preparation. These results could be generalizable to surgical residents nationwide as technology utilization increases in surgical education.

Drosophila female precopulatory behavior is modulated by ecdysteroids

The effect of ecdysteroid signaling on Drosophila female precopulatory behavior was investigated using two types of mutants with either globally reduced ecdysteroid availability or reduced expression of ecdysone receptors in fruitless neurons, known to control sexual behavior. While being courted by males, mutant females performed significantly less full ovipositor extrusion behavior to reject male copulation attempts. Ecdysteroid depleted females (ecdysoneless(1)) performed male-like courtship behaviors, including unilateral wing extension and song production with patterns very similar to male courtship song. These results support the hypothesis that ecdysteroids modulate female sexual behavior, perhaps acting as a regulator of sexual motivation, and as a component affecting the performance of sex specific behavior patterns.

Wnt/β-catenin pathway regulates bone morphogenetic protein (BMP2)-mediated differentiation of dental follicle cells

BACKGROUND AND OBJECTIVE

Bone morphogenetic protein 2 (BMP2)-induced osteogenic differentiation has been shown to occur through the canonical Wnt/βcatenin pathway, whereas factors promoting canonical Wnt signaling in cementoblasts inhibit cell differentiation and promote cell proliferation in vitro. The aim of this study was to investigate whether putative precursor cells of cementoblasts, dental follicle cells (murine SVF4 cells), when stimulated with BMP2, would exhibit changes in genes/proteins associated with the Wnt/β-catenin pathway.

MATERIAL AND METHODS

SVF4 cells were stimulated with BMP2, and the following assays were carried out: (i) Wnt/β-catenin pathway activation assessed by western blotting, β-catenin/transcription factor (TCF) reporter assays and expression of the lymphoid enhancer-binding factor-1 (Lef1), transcription factor 7 (Tcf7), Wnt inhibitor factor 1 (Wif1) and Axin2 (Axin2) genes; and (ii) cementoblast/osteoblast differentiation assessed by mineralization in vitro, and by the mRNA levels of runt-related transcription factor 2 (Runx2), osterix (Osx), alkaline phosphatase (Alp), osteocalcin (Ocn) and bone sialoprotein (Bsp), determined by quantitative PCR after treatment with wingless-type MMTV integration site family, member 3A (WNT3A) and knockdown of β-catenin.

RESULTS

WNT3A induced β-catenin nuclear translocation and up-regulated the transcriptional activity of a canonical Wnt-responsive reporter, suggesting that the Wnt/β-catenin pathway functions in SVF4 cells. Activation of Wnt signaling with WNT3A suppressed BMP2-mediated induction of cementoblast/osteoblast maturation of SVF4 cells. However, β-catenin knockdown showed that the BMP2-induced expression of cementoblast/osteoblast differentiation markers requires endogenous β-catenin. WNT3A down-regulated transcripts for Runx2, Alp and Ocn in SVF4 cells compared with untreated cells. In contrast, BMP2 induction of Bsp transcripts occurred independently of Wnt/β-catenin signaling.

CONCLUSION

These data suggest that stabilization of β-catenin by WNT3A inhibits BMP2-mediated induction of cementoblast/osteoblast differentiation in SVF4 cells, although BMP2 requires endogenous Wnt/β-catenin signaling to promote cell maturation.

Drosophila male courtship behavior is modulated by ecdysteroids

Temperature-dependent induction of ecdysteroid deficiency in the ecdysoneless mutant ecd(1) adult Drosophila melanogaster results in altered courtship behavior in males. Ecdysteroid deficiency brings about significantly elevated male-male courtship behavior including song production resembling that directed toward females. Supplementation with dietary 20-hydroxyecdysone reduces male-male attraction, but does not change motor activity, courtship patterns or attraction to females. These observations support the hypothesis that reduced levels of ecdysteroids increase the probability that male fruit flies will display courtship behaviors to male stimuli.

Measurement and repeatability of interrupter resistance in unsedated newborn infants

Interrupter resistance (R(int)) is a useful measure of airway caliber in young children, but has not been well characterized in infants-in whom there are concerns about the accurate measurement of driving pressure. This study aimed to assess the feasibility and repeatability of measuring R(int) in unsedated newborn infants, and to explore alternative algorithms for calculating driving pressure. R(int) measurement was attempted in 28 healthy term newborn infants during natural sleep using the MicroRint device. Paired R(int) measurements were achieved in 24 infants, but after screening of waveforms only 15 infants had at least 5 technically acceptable waveforms on both measurements. R(int) values obtained were comparable with reported values for airflow resistance in newborns using other methods. However, the repeatability coefficient (CR) was much higher than reported values in preschool children using standard back-extrapolation algorithms, with CR 2.47 KPa L(-1) sec (unscreened) and 2.93 KPa L(-1) sec (screened). Other algorithms gave only marginally better repeatability, with all CR values over 50% of the mean R(int) value. Using current commercially available equipment, R(int) is too poorly repeatable to be a reliable measurement of airflow resistance in newborn infants. Lower deadspace equipment is needed, but anatomical and physiological factors in the infant are also important.

Comparative analysis of antisense oligonucleotide sequences for targeted skipping of exon 51 during dystrophin pre-mRNA splicing in human muscle

Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene that result in the absence of functional protein. In the majority of cases these are out-of-frame deletions that disrupt the reading frame. Several attempts have been made to restore the dystrophin mRNA reading frame by modulation of pre-mRNA splicing with antisense oligonucleotides (AOs), demonstrating success in cultured cells, muscle explants, and animal models. We are preparing for a phase I/IIa clinical trial aimed at assessing the safety and effect of locally administered AOs designed to inhibit inclusion of exon 51 into the mature mRNA by the splicing machinery, a process known as exon skipping. Here, we describe a series of systematic experiments to validate the sequence and chemistry of the exon 51 AO reagent selected to go forward into the clinical trial planned in the United Kingdom. Eight specific AO sequences targeting exon 51 were tested in two different chemical forms and in three different preclinical models: cultured human muscle cells and explants (wild type and DMD), and local in vivo administration in transgenic mice harboring the entire human DMD locus. Data have been validated independently in the different model systems used, and the studies describe a rational collaborative path for the preclinical selection of AOs for evaluation in future clinical trials.

Knockdown of the Dnmt1s transcript using small interfering RNA in primary murine and bovine fibroblast cells

RNA interference (RNAi) has rapidly developed into one of the most widely applied technologies in molecular and cellular research, and although young, is now an essential experimental tool. The versatility of RNAi, especially in mammalian species, lends to its potential applications in a wide array of fields. Without having to genetically manipulate the genome, the ability to selectively reduce the level of a specific transcript using small interfering RNA (siRNA) molecules has great appeal in studying reprogramming issues in somatic cell nuclear transfer (SCNT) embryos. In such embryos, the aberrant expression of the somatic isoform of Dnmt1 (Dnmt1s), the enzyme responsible for maintaining DNA methylation in all somatic cells, has been implicated as one factor in the improper reprogramming of the donor genome. In the present study, the ability to develop a method allowing for the knockdown, or reduction, of Dnmt1s in primary fibroblast cells, like those commonly used as karyoplast donors in SCNT studies, was investigated in primary murine and bovine fibroblast cells as well as in a compromised cell line (NIH/3T3). Two Dnmt1s-specific siRNA candidates were designed and tested. Using optimized conditions, these siRNAs were transiently transfected into the cells with total RNA and nuclear protein being collected. A 56.5% knockdown in Dnmt1s was achieved in the compromised and primary murine cells whereas Dnmt1s was reduced by 15.4% in the primary bovine cells. A reduction in Dnmt1s mRNA did not correspond to a reduction in protein as determined by immunodetection of Western blots. Overall, this study demonstrated the ability of siRNA to knockdown Dnmt1s mRNA in primary fibroblast donor cells. In order to substantially increase the efficiency while decreasing the anomalies seen in SCNT, novel techniques, like the one proposed, are needed to assist the oocyte's ability to reprogram a differentiated genome.

Comparison of patient dose from imaging protocols for dental implant planning using conventional radiography and computed tomography

OBJECTIVES

To compare the radiation doses from imaging protocols for dental implant planning either using conventional radiography only (dental panoramic radiography (DPR), cephalometry and linear cross-sectional tomography) or involving computed tomography (CT).

METHODS

Organ absorbed doses were measured using a female Rando anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosemeters (TLD). Standard mandibular protocols for dental implant planning were followed using either a conventional dental radiographic unit (PM 2002 CC Planmeca, Helsinki, Finland) or CT scanner (Excel Twin Elscint, Haifa, Israel). Organ absorbed and effective doses were calculated. Effective dose was calculated using two approaches, one based on the ICRP method which excludes the salivary tissue from the remainder organs (designated E(exc)), and the other with its inclusion (E(inc)).

RESULTS

The greatest individual organ doses for any examination were measured in the salivary tissue. E(exc) for panoramic, cephalometric and cross-sectional tomography using DPR was 0.004 mSv, 0.002 mSv and 0.002 mSv, respectively, whereas with CT it was 0.314 mSv. The value of E(inc) calculated using these data was between two and five times E(exc).

CONCLUSIONS

E(inc) greatly increases the apparent radiation burden, especially with high dose procedures. CT techniques can provide excellent images, but at the cost of increased radiation detriment. DPR with a cross-sectional tomography facility may give adequate clinical information at a greatly reduced dose.

Comparison of patient dose from imaging protocols for dental implant planning using conventional radiography and computed tomography

OBJECTIVES

To compare the radiation doses from imaging protocols for dental implant planning either using conventional radiography only (dental panoramic radiography (DPR), cephalometry and linear cross-sectional tomography) or involving computed tomography (CT).

METHODS

Organ absorbed doses were measured using a female Rando anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosemeters (TLD). Standard mandibular protocols for dental implant planning were followed using either a conventional dental radiographic unit (PM 2002 CC Planmeca, Helsinki, Finland) or CT scanner (Excel Twin Elscint, Haifa, Israel). Organ absorbed and effective doses were calculated. Effective dose was calculated using two approaches, one based on the ICRP method which excludes the salivary tissue from the remainder organs (designated E(exc)), and the other with its inclusion (E(inc)).

RESULTS

The greatest individual organ doses for any examination were measured in the salivary tissue. E(exc) for panoramic, cephalometric and cross-sectional tomography using DPR was 0.004 mSv, 0.002 mSv and 0.002 mSv, respectively, whereas with CT it was 0.314 mSv. The value of E(inc) calculated using these data was between two and five times E(exc).

CONCLUSIONS

E(inc) greatly increases the apparent radiation burden, especially with high dose procedures. CT techniques can provide excellent images, but at the cost of increased radiation detriment. DPR with a cross-sectional tomography facility may give adequate clinical information at a greatly reduced dose.

Evaluation of a new percutaneous dilatational tracheostomy set apparatus

Percutaneous tracheostomy is a well established technique used primarily to assist weaning from mechanical ventilation on many intensive care units. We report our experiences of a total of 36 procedures performed with the new Blue Rhino Percutaneous Tracheostomy Introducer Set developed by Ciaglia. The technique was successful in all cases and was simpler and quicker to perform than with the earlier Ciaglia percutaneous tracheostomy set. Difficulties were encountered when using Shiley tracheostomy tubes. Significant complications included one posterior wall tear and one tracheal cartilage ring fracture.

Risk perception and communication: recent developments and implications for anaesthesia

This review begins by outlining the history of probability theory, exposing cultural differences between scientists and lay people in the way risks are viewed. The basic principles of the science of risk perception are described, and the various methods of communicating risk in health care, both verbal and numerical, are then discussed critically. These concepts are then applied to the practice of anaesthesia. Risk perception may affect anaesthetists' choice of career and may be involved in the genesis and evolution of critical incidents; we also discuss possibilities for training in risk perception issues. The place of risk communication in informed consent and its ethical implications are discussed.

Gender, socioeconomic development and health-seeking behaviour in Bangladesh

In efforts to reduce gender and socioeconomic disparities in the health of populations, the provision of medical services alone is clearly inadequate. While socioeconomic development is assumed important in rectifying gender and socioeconomic inequities in health care access, service use and ultimately, outcomes, empirical evidence of its impact is limited. Using cross-sectional data from the BRAC-ICDDR,B Joint Research Project in Matlab, Bangladesh, this paper examines the impact of membership in BRAC's integrated Rural Development Programme (RDP) on gender equity and health-seeking behaviour. Differences in health care seeking are explored by comparing a sample of households who are BRAC members with a sample of BRAC-eligible non-members. Individuals from the BRAC member group report significantly less morbidity (15-day recall) than those from the non-member group, although no gender differences in the prevalence of self-reported morbidity are apparent in either group. Sick individuals from BRAC member households tend to seek care less frequently than non-members. When treatment is sought, BRAC members rely to a greater extent on home remedies, traditional care, and unqualified allopaths than non-member households. While reported treatment seeking from qualified allopaths is more prevalent in the BRAC group, non-members use the para-professional services of community health care workers almost twice as frequently. In both BRAC member and non-member groups, women suffering illness report seeking care significantly less often than men. The policy and programmatic implications of between group and gender differences in care seeking are discussed with reference to the literature.

Natural transfer of helminths of marine origin to freshwater fishes with observations on the development of Diphyllobothrium alascense

Infective stages of helminths of 5 species that occur as adults in marine mammals were found in burbot, Lota lota (L.) (Gadidae), from the lower Kuskokwim River (southwestern Alaska): Diphyllobothrium alascense Rausch et Williamson, 1958; Pyramicocephalus phocarum (Fabricius, 1780); Corynosoma strumosum (Rudolphi, 1801); Corynosoma semerme (Forsell, 1904); and Pseudoterranova decipiens (Krabbe, 1878). Some larval stages were obtained also from smelt, Osmerus mordax dentex Steindachner, an anadromous fish important as prey of burbot. Burbot, which are freshwater fish, could become paratenic hosts of those helminths by means of at least 3 interactions: by consuming marine fishes in brackish waters at river mouths, by feeding on marine fishes that enter lower reaches of rivers, or by preying on anadromous fishes as they migrate up rivers. Consumption of burbot by people may result in infection by helminths of marine origin; of those recorded, only P. decipiens may be significantly pathogenic. Attempts to rear P. phocarum in dogs were unsuccessful. Plerocercoids of D. alascense, of very small size and found only in the gastric lumen of burbot, readily infected dogs. For study of their development, strobilae were obtained at intervals of 48 hr to 32 days postinfection. In heavy infections, some strobilae developed slowly, while others underwent rapid development.

Limitations in working memory: implications for language development

In this study, the proposal that individual differences in spoken language acquisition may be due to limitations in short-term memory abilities was investigated within a working memory framework. The relationship speech production skills and working memory abilities was examined in two groups of 4-year-old children, matched for non-verbal ability but who had either relatively good or poor non-word repetition skills. Children with better non-word repetition skills produced speech that comprised a wider repertoire of words, on average longer utterances and a greater range of syntactic constructions than did children with relatively poor non-word repetition skills. The significant association found between these indices of language development and verbal short-term memory span assessed with non-spoken recall, suggested that this relationship was not merely due to the common output requirements of the language and memory tasks. Inconsistent associations between language performance and two tasks of visuo-spatial short-term memory precluded firm conclusions being drawn regarding the specificity of the relationship to the phonological domain. Cognitive mechanisms that may underlie the association between spoken language development and working memory skills are discussed.

An oligonucleotide-ligation assay for the differentiation between Cyclospora and Eimeria spp. polymerase chain reaction amplification products

An oligonucleotide-ligation assay (OLA) was developed and compared to a restriction fragment length polymorphism (RFLP) test for distinguishing between 294-bp polymerase chain reaction (PCR) amplification products of the 18S rRNA gene from Cyclospora and Eimeria spp. The PCR/OLA correctly distinguished between three Cyclospora, three E. tenella, and one E. mitis strains and the ratio of positive to negative spectrophotometric absorbance (A490) values for each strain ranged from 4.086 to 15.280 (median 9.5). PCR/OLA provides a rapid, reliable, spectrophotometric alternative to PCR/RFLP.

Survival of Anisakis simplex in microwave-processed arrowtooth flounder (Atheresthes stomias)

The purpose of this study was to define the relationship between survival and temperature of nematodes of the species Anisakis simplex in microwave-processed arrowtooth flounder (Atheresthes stomias). Ten fillets (each 126 to 467 g, 0.5 to 1.75 cm thick), with an average of five larvae of Anisakis simplex per fillet, were processed to target temperatures on high (100%) power using a commercial 700-W microwave oven. Fillets were neither covered nor rotated and had a temperature probe inserted to two-thirds depth into the thickest portion. After the fillet was digested using a 1% pepsin solution, the viability of nematodes was determined by viewing them under a dissecting microscope. Survival rates were 31% at 140 degrees F (60 degrees C), 11% at 150 degrees F (65 degrees C), 2% at 160 degrees F (71 degrees C), 3% at 165 degrees F (74 degrees C), and 0% at 170 degrees F (77 degrees C). Microwave processing of standardized fillet "sandwiches," 14 cm long, 4.5 cm wide, and approximately 1.75 cm high, each of which was preinoculated with 10 live nematodes, resulted in no survival at either 160 degrees F or 170 degrees F. Using ultraviolet light to detect both viable and nonviable nematodes in fillet sandwiches as an alternative method to pepsin digestion resulted in survival rates of 1% at 140 degrees F (60 degrees C), 3% at 145 degrees F (63 degrees C), and 0% at 150 degrees F (65 degrees C). Smaller fillet sandwiches, which most likely had fewer cold spots during microwave processing, required 150 degrees F (65 degrees C), whereas larger whole fillets required 170 degrees F (77 degrees C) to kill larvae of Anisakis simplex. The parasites were most likely inactivated by a thermal mechanism of microwave treatment. Damage to the nematodes was often evident from ruptured cuticles that were no longer resistant to digestive enzymes. The high hydrostatic pressure and low chloride content of the pseudocoelomic fluid probably contributed greatly to the damage incurred by the larvae.

Template preparation for PCR and RFLP of amplification products for the detection and identification of Cyclospora sp. and Eimeria spp. Oocysts directly from raspberries

Raspberries were epidemiologically associated with cyclosporiasis outbreaks during 1996 and 1997. The 18S rRNA genes of Cyclospora cayetanensis and several species of a closely related genus, Eimeria, were sequenced and primers for a nested PCR developed in a previous study. The ability to distinguish amplified products of Cyclospora sp. from those of Eimeria spp. is important for testing food and environmental samples. Therefore, an RFLP analysis of amplified products was used to differentiate Cyclospora cayetanensis from Eimeria spp. PCR inhibitors and the low levels of Cyclospora oocysts present in raspberries make template preparation for PCR challenging. Several approaches for PCR template preparation from raspberry samples were evaluated. Template preparation methods using various washing and concentration steps, oocyst disruption protocols, resin matrix treatment, DNA precipitation, and/or the addition of nonfat dried milk solution to a PCR using modified primers were evaluated first with oocysts of Eimeria tenella then refined with oocysts of C. cayetanensis. Approximately 10 E. tenella oocysts per PCR or approximately 19 C. cayetanensis oocysts per PCR were detected with the optimized template preparation method. The addition of 20 microliters of raspberry wash sediment extract and nonfat dried milk solution did not inhibit the amplification of DNA from as few as 10 E. tenella and 25 C. cayetanensis oocysts in a 100-microliter PCR. The nucleotide sequences of C. cayetanensis and the Eimeria spp. are 94 to 96% similar in the amplified region, but the amplification products from the two genera were distinguished using an RFLP analysis with the restriction enzyme MnlI.

Occurrence and morphological comparisons of Campula oblonga (Digenea: Campulidae), including a report from an atypical host, the thresher shark, Alopias vulpinus

New host records for Campula oblonga Cobbold, 1858 from the common dolphin, Delphinus delphis L., and from the thresher shark, Alopias vulpinus (Bonnaterre), are reported herein. Campulids have not been reported previously from a host that was not a marine mammal. The excellent condition and small size of the gravid specimen and the diet and natural history of the thresher shark lead us to conclude that the digene was acquired from the consumption of infected fish. Specimens of C. oblonga from these 2 hosts and from harbor porpoises, Phocoena phocoena (L.), and from Dall's porpoises, Phocoenoides dalli (True), are compared, and a wide variation in ranges and values for characters is noted. The synonymy of Campula folium Ozaki, 1935 with C. oblonga is further supported by the apparent effect of the host on the size of the trematodes. Due to the degree of variation in measurements and the numerous factors that may impact these values, we recommend the use of qualitative morphologic characters for the identification of C. oblonga.

Parasites of fish and risks to public health

A multitude of parasites have been reported in fish, but only a few species are capable of infecting humans. The most important of the helminths acquired by humans from fish are the anisakid nematodes (particularly Anisakis simplex and Pseudoterranova decipiens), cestodes of the genus Diphyllobothrium and digenetic trematodes of the families Heterophyidae, Opisthorchiidae and Nanophyetidae. Seafood-associated infections by acanthocephalans are rarely reported in humans. All of the helminths mentioned above are associated with social-cultural and behavioural factors, in particular the consumption of raw or undercooked seafood. Measures can be taken during harvesting, processing or post-processing (e.g., by the consumer) to mitigate the risks of infection. The seafood industry and government authorities can apply various programmes to reduce these risks, including good manufacturing practices (GMPs) and hazard analysis and critical control point (HACCP) systems. Such measures may include avoiding particular harvest areas, sizes of fish, or even particular species of fish. The method of capture, handling and storage of the catch can directly affect the quality of the seafood with regard to the presence and numbers of parasites. The extent of processing--including heading and gutting, candling and trimming--and the type of product derived (fresh, frozen, salted or pickled) can all contribute to the control of the risks posed by helminths. The most effective means of killing the parasites are either freezing or heat inactivation.

Case report. Spontaneous regression of a radiolucency associated with an ectopic mandibular third molar

A dentigerous cyst is the most common cause of a pericoronal radiolucency involving an impacted mandibular third molar. Spontaneous regression of such a lucency is reported in a patient who failed to attend for surgical enucleation. Factors promoting bony healing of cysts are discussed with reference to previous case reports.

Seasonal variations in energy balance among agriculturalists in central Mali: compromise or adaptation?

OBJECTIVE

This paper considers whether seasonal variations in the energy balance of adult agriculturalists in Central Mali exceed acceptable risk, or whether they represent a short-term adaptive response without functional consequence.

DESIGN

Prospective/longitudinal study design.

SETTING

Agricultural village in rural Mali.

SUBJECTS

From a total population of 166 adults aged > or = 16 years, two cohorts of 63 men and 73 non-pregnant women with complete records were retained for analysis.

INTERVENTIONS

Over a 12-month period, monthly anthropometry and biweekly retrospective assessments of morbidity were made on every adult in the sample. Direct measures of household food consumption were collected twice in harvest, dry and rainy seasons respectively. Continuous 15-h observations of time-use and work intensity were conducted on a sub-sample of active adults and used to calculate mean seasonal energy expenditure.

RESULTS

Energy balance as measured by body mass index (BMI; kg/m2) declines significantly in the rainy season (P < 0.01), corresponding to a seasonal weight loss of 2-3 kg. A similar seasonal trend in % body fat (P < 0.0001) suggests that most of this loss represents adipose tissue. A rainy season increase in arm muscle area (AMA) implies that there is no seasonal compromise in lean tissue. Among men and women with BMI > 18.5, seasonal fat loss is significantly greater than their leaner counterparts. Considering the likely determinants of variations in energy balance, an increase in the duration and incidence of adult morbidity is observed; however, no significant intercorrelations exist between it and seasonal nutritional indices. Comparing trends in energy expenditure and intake, a disturbance in energy homeostasis is apparent as energy expenditure increases in the rainy season relative to constant household food consumption across seasons. While seasonal variations in energy expenditure are not as dramatic in the female sample, they appear to have less opportunity to recover from so-called 'heavy' levels of expenditure experienced in successive dry and rainy seasons. Periods of 'light' activity in both harvest and dry seasons provide the male sample with a reasonable length of time in which to reconstitute energy stores after the physical demands of the rainy season.

CONCLUSIONS

In the year of study, the modest loss of body fat recorded in the rainy season (< 5% body mass) represents a successful physiological response to energy imbalance, and is unlikely to compromise adult productive and reproductive function.

Morphological changes in cultured human periodontal ligament cells exposed to dental materials

The cytotoxicity of a range of dental restorative cements was assessed by continuous observation of cultures with inverted microscopy and by light microscopic study of fixed preparations, using an in vitro model with cultured test cells derived from human periodontal ligament. The sequential morphological changes observed over a seven day period showed different degrees of cell loss and patterns of injury in response to different restorative materials, reflecting primarily either nuclear or cytoplasmic damage. Attempts at recovery were frequently identified as the culture period was extended and were characterized by recolonization of denuded areas of the culture well. It was concluded that differing dental cements damage cells through a variety of mechanisms and that the test cells exhibit differing degrees of susceptibility to injury. Assays based on short-term cultures may overestimate cytotoxicity by not allowing for cell recovery from reversible injury or repopulation of monolayers by proliferation of resistant cells.

Ultrastructural changes in cultured human periodontal ligament cells exposed to dental materials

The cytopathic effects of a range of dental restorative cements were examined by electron microscopy using an in vitro model with cultured test cells derived from human periodontal ligament. Monolayers were fixed and processed in situ after 2, 24, and 48 h exposure. Many cells showed lysis after two hours exposure consistent with immediate acute injury. Cultures subsequently recovered, reflecting different susceptibilities of cells to injury, and at later stages showed distinct patterns of cell damage in response to different restorative materials. These were related primarily to either cytoplasmic or nuclear damage and to changes resembling apoptosis.

Phonological working memory and speech production in preschool children

This study investigates whether phonological working memory is associated with spoken language development in preschool children. Assessments were made of speech corpora taken from 3-year old children grouped in terms of their phonological memory abilities. Both quantitative and qualitative indices of the children's spontaneous speech output were taken in a structured play session. Significant differences were found, with children of good phonological memory abilities producing language that was more grammatically complex, contained a richer array of words, and included longer utterances than children of poor phonological memory abilities. The possible mechanisms by which phonological working memory skills are linked to the production of speech are considered.

Cytotoxicity studies of dental restorative materials using human periodontal ligament cells in vitro

A model that simulates conditions of clinical practice in vivo and allows extended exposure of test cells to test substances, was evaluated in vitro by screening the toxicity of seven dental restorative cements. Millipore filter discs, 0.45 micron pore size, or preserved dentine slices were used as diffusion barriers between test cells and test substances. Cytotoxicity was assessed by estimating cell loss from monolayers and by evaluating cytopathic changes in cultured cells. After 24 h exposure to the test materials results were in general agreement with reported observations from similar studies. However, extended exposure to composite resins gave rise to severe cytotoxicity, which has not been reported previously. In addition, monitoring of cultures by inverted microscopy demonstrated attempts at recovery in damaged monolayers with viable cells migrating and proliferating into areas of earlier cell loss. This supports observations in vivo of transient pulpal injury associated with the corresponding materials.

Do young children rehearse? An individual-differences analysis

The issue of whether young children rehearse in auditory memory tasks was investigated across a series of three studies comparing individual differences in articulation rates and memory spans. Applying the principles of the working-memory model, children with faster rates of speaking should have superior memory spans if they engage in rehearsal. Two of the experiments, with 4-year-old children, failed to establish any significant association between articulation rate and memory span, although both the memory span and articulation rate procedures were found to be highly reliable in this age group. A third experiment confirmed that, as expected, articulation rates and memory spans were significantly associated with one another in adult subjects. The results indicate that, contrary to recent theories of children's short-term-memory development, 4-year-old children do not engage in subvocal rehearsal during auditory memory span tasks.

Symptomatic and asymptomatic salivary duct abnormalities in Darier's disease: a sialographic study

Symptoms of obstructive sialadentis have been occasionally reported as a feature of Darier's disease. Parotid sialograms of three patients with confirmed Darier's disease and histories suggestive of salivary obstruction revealed dilatation with periodic strictures and indentations affecting the main ducts. Similar parotid sialograms in three Darier's disease patients with no symptoms attributable to their salivary glands revealed seepage of contrast media associated with the secondary and tertiary ducts. These findings suggest that salivary glands may be more commonly involved in Darier's disease than previous reports indicate.

Cultural and morphological characteristics of human periodontal ligament cells in vitro

Primary cell lines from explants of human periodontal ligament were established in vitro to assess their suitability as test cells in a biocompatibility assay. They were maintained over nine passages. The constituent fibroblast-like cells (F-cells) were monitored throughout by light and electron microscopy. Although F-cells from several different donors displayed stable and consistent growth characteristics, after the ninth subculture changes in the fine structure suggested that some cells were undergoing differentiation or senescence. It is therefore recommended that cells from earlier passages be used in in vitro biocompatibility assays.

Effect of amphotericin B on human periodontal ligament cells cultured in vitro

Three micrograms of amphotericin B/ml nutrient medium markedly inhibited the monolayer outgrowth of cells from explants of human periodontal ligament. Amphotericin B (1.5 microgram/ml) retarded outgrowth with morphological evidence of cell injury. The addition of 3 micrograms/ml amphotericin B to existing monolayers initially caused disruption of the majority of cells but those which survived then proliferated. Thus, routine use of amphotericin B is contra-indicated in tissue culture of human periodontal ligament.

Detection of macrophages and the characterization of Fc receptor-bearing cells in the mouse decidua, placenta and yolk sac using the macrophage-specific monoclonal antibody F4/80

A mouse macrophage-specific rat monoclonal antibody, F4/80, has been used to detect directly macrophages in short term cultures of mouse decidua, fetal placenta and yolk sac and to investigate the identity of Fc receptor (FcR) bearing cells in these tissues. We find that a significant proportion of FcR positive cells in decidual, placental and yolk sac tissues are macrophages as defined by the expression of the macrophage marker, F4/80 antigen. Macrophages may act as immunocompetent cells near to the maternal-fetal interface and play a significant role in the mechanism of the transfer of passive immunity from mother to fetus across the mouse yolk sac.