A human donor (cadaveric) observation study of three needle placements in the piriformis muscle

OBJECTIVE

To compare the safety and accuracy of three dry needling locations in the piriformis muscle using human donors.

DESIGN

Observational dissection study of embalmed human donors.

METHODS

A licensed physical therapist of 17 years clinical experience and 5 years teaching dry needling placed three needles in a medial, midpoint, and lateral location of 14 piriformis muscles of seven embalmed human donors. Block dissection allowed for observation of tissues the needles traversed and recording of the structures that the needles pierced.

RESULTS

The lateral needle pierced piriformis in 3/14 trials, and contacted sciatic nerve in 0/14 trials. The medial needle pierced both piriformis and sciatic nerve in 11/14 trials. The midpoint needle pierced the piriformis in 11/14 trials, and contacted sciatic nerve in 3/14 trials. Fisher's Exact test (p < 0.001) found a nonrandom association between dry needle placement, and dry needle contact.

CONCLUSIONS

When dry needling the piriformis, a lateral approach can avoid the sciatic nerve, but cannot accurately pierce the piriformis tendon. Furthermore, while a midpoint and medial approach finds the piriformis muscle with the same accuracy, the midpoint location avoided the sciatic nerve more often.

COVID-19 recovery: tackling the 2-week wait colorectal pathway backlog by optimising CT colonography utilisation

AIM

To review the indications for computed tomography colonography (CTC) performed on patients referred via the 2-week wait colorectal pathway (2WWCP).

MATERIALS AND METHODS

A retrospective study was performed on all patients referred through the 2WWCP between October 2018 and September 2019. The referrals were audited against the National Institute for Health and Care Excellence (NICE) NG12/DG30 guidelines for referral to the 2WWCP, and against the Royal College of Radiologists (RCR) 2017 guidelines for CTC.

RESULTS

Over the study period, there were 1,707 2WWCP referrals, and 362 (21.2%) of these patients underwent CTC. The median age was 66 years, and 55% were female. Forty-six patients did not meet the NICE NG12/DG30 guidelines for referral to the 2WWCP, and a further 268, although meeting the NICE guidelines, did not meet the RCR 2017 guidelines for CTC. In total, only 13% of CTCs performed complied with both guidelines.

CONCLUSION

This audit demonstrated a significant opportunity to reallocate CTC resources in the recovery stage of the COVID-19 pandemic. To improve outcomes for colorectal cancer (CRC) in the UK, establishing a selective straight-to-test CTC 2WWCP should be considered. Documented consent detailing the risks and benefits of CTC versus colonoscopy should take place in order to assist the patient in making an informed choice.

The NLRP3 inflammasome mediates DSS-induced intestinal inflammation in Nod2 knockout mice

Crohn’s disease (CD) is a chronic disorder of the gastrointestinal tract characterized by inflammation and intestinal epithelial injury. Loss of function mutations in the intracellular bacterial sensor NOD2 are major risk factors for the development of CD. In the absence of robust bacterial recognition by NOD2 an inflammatory cascade is initiated through alternative PRRs leading to CD. In the present study, MCC950, a specific small molecule inhibitor of NLR pyrin domain-containing protein 3 (NLRP3), abrogated dextran sodium sulfate (DSS)-induced intestinal inflammation in Nod2^−/− mice. NLRP3 inflammasome formation was observed at a higher rate in NOD2-deficient small intestinal lamina propria cells after insult by DSS. NLRP3 complex formation led to an increase in IL-1β secretion in both the small intestine and colon of Nod2ko mice. This increase in IL-1β secretion in the intestine was attenuated by MCC950 leading to decreased disease severity in Nod2ko mice. Our work suggests that NLRP3 inflammasome activation may be a key driver of intestinal inflammation in the absence of functional NOD2. NLRP3 pathway inhibition can prevent intestinal inflammation in the absence of robust NOD2 signaling.

Impact of Body Mass Index (BMI) on the Effect of a Lactobacillus Rhamnosus GG (LGG)/Bifidobacterium Animalis Subspecies Lactis BB-12 (BB-12) Combination on Gut Microbiota (P20-023-19)

Objectives

This exploratory study builds upon an earlier study of probiotic supplementation1 to assess the effects of a probiotic combination (P) of LGG and BB-12 on human gut microbiota composition and function, and to uncover an association with BMI.

Methods

Healthy subjects ingested P for 21 days (n = 18, P group) or did not (n = 7, C group).

Fecal samples obtained at baseline (D_0) and after 21 days of supplementation (D_21) underwent 16S ribosomal RNA gene and shotgun metagenomics sequencing to characterize the bacterial and archaeal communities to the genus/species level and identify functional community genes.

Results

Following P ingestion, no global differences in microbiota community structure or relative gene abundance were detected. In targeted analyses, the abundances of LGG and BB-12 in the P group at D_21 increased in a statistically significant manner as the BMI decreased (Spearman correlation, P = 0.04 and P = 0.01, respectively). The relative abundance of LGG but not BB-12 appeared increased in P subjects at D_21 with BMI < 25 compared to BMI > 25 (P = 0.09). P group subjects with BMI < 25 demonstrated trends toward or statistically significant increases in the relative abundances of 5 genes involved with flagellar structure (KEGG orthologs K02422, P = 0.04; K03406, P = 0.06; K02407, P = 0.08; K02397, P = 0.08; K02396, P = 0.09) at D_21 compared to those with BMI > 25. No such differences were observed for the C group nor were there differences in relative gene abundance at D_0 in the P group with BMI < 25 vs BMI > 25.

Conclusions

We observed no global changes in the fecal microbial community structure or function with P ingestion in this sample of healthy persons. However, we did observe patterns suggestive of a potential link between BMI and the response of the gut microbiota to P. Although our results are based on a small number of subjects, they are in line with previous findings related to LGG supplementation and the expression of flagellar genes2. We agree with other recent reports that future studies would benefit from a detailed examination of the transcriptome, proteome and/or metabolome to better understand the potential impact of probiotics on the gut microbiota, and the mechanism of the effect of BMI.

Funding Sources

Pfizer Inc.

1337. SYN-004 (Ribaxamase) Protects the Gut Microbiome of Patients Treated With Ceftriaxone From Disruption and Reduces the Emergence of Antimicrobial Resistance

Background

When β-lactam antibiotics are administered intravenously, a significant portion of each dose can be excreted through the bile into the intestine. This excess antibiotic disrupts the balance of the gut microbiome making the recipient more susceptible to certain infections and can lead to the emergence of antimicrobial resistance. SYN-004 (ribaxamase) is an orally administered β-lactamase designed to be given with IV β-lactam antibiotics (penicillins and cephalosporins) to degrade excess antibiotics excreted into the upper GI tract before they can disrupt the gut microbiome and resistome.

Methods

During a Phase 2b, clinical study with ribaxamase which demonstrated a significant reduction in Clostridium difficile infection in patients receiving ceftriaxone + ribaxamase, longitudinal fecal samples were collected from the patients. DNA extracted from these samples was 16S rRNA and whole genome sequenced, and the sequences were analyzed for changes in the gut microbiome and resistome. Statistical analyses were performed to determine correlations between changes in the gut microbiome and resistome and clinical study data.

Results

Sequence analyses revealed that ribaxamase protected the integrity of the gut microbiome, including preventing enterococcal mono-domination (defined as &gt;30% of the microbiome being from one genus), and identified over 1,300 AMR genes in the gut resistome. LefSe analysis of the gut resistome identified a family of β-lactamases (CfxA) and vancomycin resistance genes which demonstrated a significant increase in placebo-treated vs. ribaxamase-treated patients from pre-to post-antibiotics. Analysis by qPCR supported both new acquisition of these genes and expansion of existing AMR pools. Further statistical analyses demonstrated significant correlations between changes in the gut resistome and clinical study parameters including β-lactamase gene frequency and study drug assignment, and efflux pump gene frequency and vancomycin resistance.

Conclusion

Taken together, these findings demonstrated that coadministration of ribaxamase with IV β-lactam antibiotics can protect the integrity of the gut microbiome and may help limit the emergence of AMR induced by these antibiotics.

Disclosures

J. Kokai-Kun, Synthetic Biologics, Inc.: Employee, Salary. C. Le, Synthetic Biologics, Inc.: Employee, Salary. K. Trout, Synthetic Biologics, Inc.: Employee, Salary. J. Sliman, Synthetic Biologics, Inc.: Employee, Salary.

Intestinal dysbiosis in preterm infants preceding necrotizing enterocolitis: a systematic review and meta-analysis

BACKGROUND

Necrotizing enterocolitis (NEC) is a catastrophic disease of preterm infants, and microbial dysbiosis has been implicated in its pathogenesis. Studies evaluating the microbiome in NEC and preterm infants lack power and have reported inconsistent results.

METHODS AND RESULTS

Our objectives were to perform a systematic review and meta-analyses of stool microbiome profiles in preterm infants to discern and describe microbial dysbiosis prior to the onset of NEC and to explore heterogeneity among studies. We searched MEDLINE, PubMed, CINAHL, and conference abstracts from the proceedings of Pediatric Academic Societies and reference lists of relevant identified articles in April 2016. Studies comparing the intestinal microbiome in preterm infants who developed NEC to those of controls, using culture-independent molecular techniques and reported α and β-diversity metrics, and microbial profiles were included. In addition, 16S ribosomal ribonucleic acid (rRNA) sequence data with clinical meta-data were requested from the authors of included studies or searched in public data repositories. We reprocessed the 16S rRNA sequence data through a uniform analysis pipeline, which were then synthesized by meta-analysis. We included 14 studies in this review, and data from eight studies were available for quantitative synthesis (106 NEC cases, 278 controls, 2944 samples). The age of NEC onset was at a mean ± SD of 30.1 ± 2.4 weeks post-conception (n = 61). Fecal microbiome from preterm infants with NEC had increased relative abundances of Proteobacteria and decreased relative abundances of Firmicutes and Bacteroidetes prior to NEC onset. Alpha- or beta-diversity indices in preterm infants with NEC were not consistently different from controls, but we found differences in taxonomic profiles related to antibiotic exposure, formula feeding, and mode of delivery. Exploring heterogeneity revealed differences in microbial profiles by study and the target region of the 16S rRNA gene (V1-V3 or V3-V5).

CONCLUSIONS

Microbial dysbiosis preceding NEC in preterm infants is characterized by increased relative abundances of Proteobacteria and decreased relative abundances of Firmicutes and Bacteroidetes. Microbiome optimization may provide a novel strategy for preventing NEC.

A phase II trial of low-dose estradiol in postmenopausal women with advanced breast cancer and acquired resistance to aromatase inhibition

BACKGROUND

High-dose oestrogen (HDE) is effective but toxic in postmenopausal women with advanced breast cancer (ABC). Prolonged oestrogen deprivation sensitises BC cell lines to estrogen and we hypothesised that third-generation aromatase inhibitors (AIs) would sensitise BCs to low-dose estradiol (LDE).

METHODS

A single-arm phase II study of LDE (2 mg estradiol valerate daily) in postmenopausal women with estrogen receptor-positive (ER+) ABC. The primary end-point was clinical benefit (CB) rate. If LDE was ineffective, HDE was offered. If LDE was effective, retreatment with the pre-LDE AI was offered on progression.

RESULTS

Twenty-one patients were recruited before the trial was closed early due to slow accrual; 19 were assessable for efficacy and toxicity. CB was seen in 5 in 19 patients (26%; 95% confidence interval 9.1-51.2%), all with prolonged SD (median duration 16.8 months; range 11.0-29.6). Treatment was discontinued for toxicity in 4 in 19 patients (21%) and 8 in 11 women without hysterectomy experienced vaginal bleeding (VB). After primary LDE failure, three patients received HDE and one achieved a partial response (PR). Following CB on LDE, four patients restarted pre-LDE AI and three achieved CB including one PR. Those with CB to LDE had a significantly longer duration of first-line endocrine therapy for ABC than those without (54.9 versus 16.8 months; p < 0.01) CONCLUSION: LDE is an effective endocrine option in women with evidence of prolonged sensitivity to AI therapy. LDE is reasonably well tolerated although VB is an issue. Re-challenge with the pre-LDE AI following progression confirms re-sensitisation as a true phenomenon.

Common mechanistic themes for the powerstroke of kinesin-14 motors

Kar3Cik1 is a heterodimeric kinesin-14 from Saccharomyces cerevisiae involved in spindle formation during mitosis and karyogamy in mating cells. Kar3 represents a canonical kinesin motor domain that interacts with microtubules under the control of ATP-hydrolysis. In vivo, the localization and function of Kar3 is differentially regulated by its interacting stoichiometrically with either Cik1 or Vik1, two closely related motor homology domains that lack the nucleotide-binding site. Indeed, Vik1 structurally resembles the core of a kinesin head. Despite being closely related, Kar3Cik1 and Kar3Vik1 are each responsible for a distinct set of functions in vivo and also display different biochemical behavior in vitro. To determine a structural basis for their distinct functional abilities, we used cryo-electron microscopy and helical reconstruction to investigate the 3-D structure of Kar3Cik1 complexed to microtubules in various nucleotide states and compared our 3-D data of Kar3Cik1 with that of Kar3Vik1 and the homodimeric kinesin-14 Ncd from Drosophila melanogaster. Due to the lack of an X-ray crystal structure of the Cik1 motor homology domain, we predicted the structure of this Cik1 domain based on sequence similarity to its relatives Vik1, Kar3 and Ncd. By molecular docking into our 3-D maps, we produced a detailed near-atomic model of Kar3Cik1 complexed to microtubules in two distinct nucleotide states, a nucleotide-free state and an ATP-bound state. Our data show that despite their functional differences, heterodimeric Kar3Cik1 and Kar3Vik1 and homodimeric Ncd, all share striking structural similarities at distinct nucleotide states indicating a common mechanistic theme within the kinesin-14 family.

Kar3Vik1 uses a minus-end directed powerstroke for movement along microtubules

We have used cryo-electron microscopy (cryo-EM) and helical averaging to examine the 3-D structure of the heterodimeric kinesin-14 Kar3Vik1 complexed to microtubules at a resolution of 2.5 nm. 3-D maps were obtained at key points in Kar3Vik1's nucleotide hydrolysis cycle to gain insight into the mechanism that this motor uses for retrograde motility. In all states where Kar3Vik1 maintained a strong interaction with the microtubule, we found, as observed by cryo-EM, that the motor bound with one head domain while the second head extended outwards. 3-D reconstructions of Kar3Vik1-microtubule complexes revealed that in the nucleotide-free state, the motor's coiled-coil stalk points toward the plus-end of the microtubule. In the ATP-state, the outer head is shown to undergo a large rotation that reorients the stalk ∼75° to point toward the microtubule minus-end. To determine which of the two heads binds to tubulin in each nucleotide state, we employed specific Nanogold®-labeling of Vik1. The resulting maps confirmed that in the nucleotide-free, ATP and ADP+Pi states, Kar3 maintains contact with the microtubule surface, while Vik1 extends away from the microtubule and tracks with the coiled-coil as it rotates towards the microtubule minus-end. While many previous investigations have focused on the mechanisms of homodimeric kinesins, this work presents the first comprehensive study of the powerstroke of a heterodimeric kinesin. The stalk rotation shown here for Kar3Vik1 is highly reminiscent of that reported for the homodimeric kinesin-14 Ncd, emphasizing the conservation of a mechanism for minus-end directed motility.

A microfluidic microbial fuel cell array that supports long-term multiplexed analyses of electricigens

Microbial fuel cells (MFCs) are green energy technologies that exploit microbial metabolism to generate electricity. The widespread implementation of MFC technologies has been stymied by their high cost and limited power. MFC arrays in which device configurations or microbial consortia can be screened have generated significant interest because of their potential for defining aspects that will improve performance featuring high throughput characteristics. However, current miniature MFCs and MFC array systems do not support long-term studies that mimic field conditions, and hence, have limitations in fully characterizing and understanding MFC performances in varieties of conditions. Here, we describe an MFC array device that incorporates microfluidic technology to enable continuous long-term analysis of MFC performance at high throughput utilizing periodic anolyte/catholyte replenishment. The system showed 360% higher power output and 700% longer operating time when compared to MFC arrays without catholyte replenishment. We further demonstrate the utility of the system by reporting its successful use in screening microbial consortia collected from geographically diverse environments for communities that support enhanced MFC performance. Taken together, this work demonstrates that anolyte/catholyte replenishment can significantly improve the long-term performance of microfabricated MFC arrays, and support the characterization of diverse microbial consortia.

Kar3Vik1, a member of the kinesin-14 superfamily, shows a novel kinesin microtubule binding pattern

Kinesin-14 motors generate microtubule minus-end-directed force used in mitosis and meiosis. These motors are dimeric and operate with a nonprocessive powerstroke mechanism, but the role of the second head in motility has been unclear. In Saccharomyces cerevisiae, the Kinesin-14 Kar3 forms a heterodimer with either Vik1 or Cik1. Vik1 contains a motor homology domain that retains microtubule binding properties but lacks a nucleotide binding site. In this case, both heads are implicated in motility. Here, we show through structural determination of a C-terminal heterodimeric Kar3Vik1, electron microscopy, equilibrium binding, and motility that at the start of the cycle, Kar3Vik1 binds to or occludes two αβ-tubulin subunits on adjacent protofilaments. The cycle begins as Vik1 collides with the microtubule followed by Kar3 microtubule association and ADP release, thereby destabilizing the Vik1-microtubule interaction and positioning the motor for the start of the powerstroke. The results indicate that head-head communication is mediated through the adjoining coiled coil.

Cryo-electron tomography for structural characterization of macromolecular complexes

Cryo-electron tomography (cryo-ET) is an emerging 3-D reconstruction technology that combines the principles of tomographic 3-D reconstruction with the unmatched structural preservation of biological matter embedded in vitreous ice. Cryo-ET is particularly suited to investigating cell-biological samples and large macromolecular structures that are too polymorphic to be reconstructed by classical averaging-based 3-D reconstruction procedures. This unit aims to make cryo-ET accessible to newcomers and discusses the specialized equipment required, as well as relevant advantages and hurdles associated with sample preparation by vitrification and cryo-ET. Protocols describe specimen preparation, data recording and 3-D data reconstruction for cryo-ET, with a special focus on macromolecular complexes. A step-by-step procedure for specimen vitrification by plunge freezing is provided, followed by the general practicalities of tilt-series acquisition for cryo-ET, including advice on how to select an area appropriate for acquiring a tilt series. A brief introduction to the underlying computational reconstruction principles applied in tomography is described, along with instructions for reconstructing a tomogram from cryo-tilt series data. Finally, a method is detailed for extracting small subvolumes containing identical macromolecular structures from tomograms for alignment and averaging as a means to increase the signal-to-noise ratio and eliminate missing wedge effects inherent in tomographic reconstructions.

GTPgammaS microtubules mimic the growing microtubule end structure recognized by end-binding proteins (EBs)

Microtubule plus-end-tracking proteins (+TIPs) localize to growing microtubule plus ends to regulate a multitude of essential microtubule functions. End-binding proteins (EBs) form the core of this network by recognizing a distinct structural feature transiently existing in an extended region at growing microtubule ends and by recruiting other +TIPs to this region. The nature of the conformational difference allowing EBs to discriminate between tubulins in this region and other potential tubulin binding sites farther away from the microtubule end is unknown. By combining in vitro reconstitution, multicolor total internal reflection fluorescence microscopy, and electron microscopy, we demonstrate here that a closed microtubule B lattice with incorporated GTPγS, a slowly hydrolyzable GTP analog, can mimic the natural EB protein binding site. Our findings indicate that the guanine nucleotide γ-phosphate binding site is crucial for determining the affinity of EBs for lattice-incorporated tubulin. This defines the molecular mechanism by which EBs recognize growing microtubule ends.

Cryo-electron tomography of microtubule-kinesin motor complexes

Microtubules complexed with molecular motors of the kinesin family or non-motor microtubule associated proteins (MAPs) such as tau or EB1 have been the subject of cryo-electron microcopy based 3-D studies for several years. Most of these studies that targeted complexes with intact microtubules have been carried out by helical 3-D reconstruction, while few were analyzed by single particle approaches or from 2-D crystalline arrays. Helical reconstruction of microtubule-MAP or motor complexes has been extremely successful but by definition, all helical 3-D reconstruction attempts require perfectly helical assemblies, which presents a serious limitation and confines the attempts to 15- or 16-protofilament microtubules, microtubule configurations that are very rare in nature. The rise of cryo-electron tomography within the last few years has now opened a new avenue towards solving 3-D structures of microtubule-MAP complexes that do not form helical assemblies, most importantly for the subject here, all microtubules that exhibit a lattice seam. In addition, not all motor domains or MAPs decorate the microtubule surface regularly enough to match the underlying microtubule lattice, or they adopt conformations that deviate from helical symmetry. Here we demonstrate the power and limitation of cryo-electron tomography using two kinesin motor domains, the monomeric Eg5 motor domain, and the heterodimeric Kar3Vik1 motor. We show here that tomography does not exclude the possibility of post-tomographic averaging when identical sub-volumes can be extracted from tomograms and in both cases we were able to reconstruct 3-D maps of conformations that are not possible to obtain using helical or other averaging-based methods.

Ocular and systemic side effects of brimonidine 0.2% eye drops (Alphagan®) in children

INTRODUCTION

Brimonidine 0.2% (Alphagan) is a topical alpha-2 agonist widely used as an antihypertensive. There have been occasional reports of systemic adverse effects in children including apparent central nervous system depression. There are few data available on the overall safety of brimonidine 0.2% in children.

METHODS

Computerised pharmacy records were used to identify all children who had been prescribed brimonidine 0.2% in our eye department between August 1999 and June 2001, and their notes were reviewed.

RESULTS

In all, 23 patients were identified from pharmacy records and 22 sets of notes were recovered and reviewed. The mean age at commencement of treatment was 8 years (range 0-14 years). In all, 10 (46%) were treated in one eye and 12 (54%) in both. Brimonidine 0.2% was taken for a mean 14 months (range 1 day-75 months). A total of 14 (64%) patients were already taking a topical beta-blocker when brimonidine 0.2% was commenced and a further four (18%) were being treated with another topical hypotensive agent. Of the 22 patients, six (27%) had to stop brimonidine 0.2% because of adverse side effects (two because of local irritation/allergy, two because of tiredness, and two because of fainting attacks).

DISCUSSION

Many topical hypotensive agents are not licensed for use in children and few safety data are available. In this study, 18% of children had systemic adverse effects sufficient to necessitate stopping the drug. It is possible that educational impairment may have passed unnoticed in others. Larger studies are required to investigate this further.

'Get it on' in the millennium

Over the Christmas and New Year period the Health Education Authority launched a sexual health promotion campaign aimed at increasing the awareness of and reducing the incidence of sexually transmitted infections (STIs) and unwanted pregnancy. We undertook a study to assess the effect of this campaign locally in 2 genitourinary medicine (GUM) clinics. From our study we concluded the following: (1) Although rarely performed, it is possible to assess the effectiveness of health promotion campaigns. (2) Genitourinary medicine clinics provide a good forum for the assessment of such campaigns. (3) The information obtained from such assessments can be valuable for effective targeting of future campaigns.

Fluctuating silicate:nitrate ratios and coastal plankton food webs

Marine diatoms require dissolved silicate to form an external shell, and their growth becomes Si-limited when the atomic ratio of silicate to dissolved inorganic nitrogen (Si:DIN) approaches 1:1, also known as the "Redfield ratio." Fundamental changes in the diatom-to-zooplankton-to-higher trophic level food web should occur when this ratio falls below 1:1 and the proportion of diatoms in the phytoplankton community is reduced. We quantitatively substantiate these predictions by using a variety of data from the Mississippi River continental shelf, a system in which the Si:DIN loading ratio has declined from around 3:1 to 1:1 during this century because of land-use practices in the watershed. We suggest that, on this shelf, when the Si:DIN ratio in the river decreases to less than 1:1, then (i) copepod abundance changes from >75% to <30% of the total mesozooplankton, (ii) zooplankton fecal pellets become a minor component of the in situ primary production consumed, and (iii) bottom-water oxygen consumption rates become less dependent on relatively fast-sinking (diatom-rich) organic matter packaged mostly as zooplankton fecal pellets. This coastal ecosystem appears to be a pelagic food web dynamically poised to be either a food web composed of diatoms and copepods or one with potentially disruptive harmful algal blooms. The system is directed between these two ecosystem states by Mississippi River water quality, which is determined by land-use practices far inland.

Early lesion of mystacial vibrissae in rats results in an increase of somatostatin-labelled cells in the somatosensory cortex

Recent studies in the developing cortex have shown that during the first 2 postnatal weeks somatostatin (SRIF)-containing neurons appear in greater numbers. After this time their numbers decline significantly probably due to cell death (Cavanagh and Parnavelas 1988). In this study we report changes in the distribution of SRIF-labelled cells in the somatosensory cortex of adult rats following unilateral lesions of mystacial vibrissae at birth. Specifically, we observed that the side contralateral to the lesion contained a significantly greater number of labelled cells compared to the ipsilateral side. We suggest that the decline in cell numbers observed during normal development is reduced following early deafferentation.

The stellate layer and rhythmic contractions of the Oryzias latipes embryo

The objective of this study was to determine which cells in the medaka (Oryzias latipes) embryo participate in the rhythmic contraction waves that propagate slowly across the yolk sac throughout most of embryonic development. To facilitate observation of the cells, we inhibited the contractions temporarily by incubating the embryos with o-nitrobenzylacetate, n-heptanol, or n-octanol. After we washed out the inhibitor, isolated cells in a subepithelial layer (similar to the stellate layer in Fundulus heteroclitus) began to pulse. Stellate cells are much smaller than cells in the surface epithelium (enveloping layer) and are present throughout the developmental period during which the contractions occur, stage 14 to stage 26. We conclude that the active force for the rhythmic contraction waves is provided by cells in the stellate layer and that cells in the enveloping layer are passively deformed by the contraction of cells in the closely apposed stellate layer.

Mechanisms of chemoprevention by dietary dehydroisoandrosterone. Inhibition of lymphopoiesis

The ingestion of dehydroisoandrosterone (DHA), a naturally occurring steroid, inhibits the development of autoimmunity, neoplasias, and other disorders of rodents. Potential mechanisms of action include (1) the induction of peroxisomal proliferation and (2) the conversion of DHA to androgens. We evaluated the immune system of mice fed DHA. Dietary DHA had no significant effect on antibody responses, cutaneous sensitivity reactions, natural killer activity, or graft-versus-host reactions. However, a decrease in lymphoid organ cellularity and an absence of splenic germinal centers were observed. We assessed progenitor cell activity in irradiated mice by evaluating the repopulation of marrow and lymphoid organs. Dehydroisoandrosterone feeding resulted in an inhibition of lymphopoiesis but not myelopoiesis. Clofibrate, another peroxisomal proliferator, failed to inhibit lymphocyte repopulation after irradiation. Androgen-non-responsive Tfm/Y mice were as susceptible as control mice to the inhibitory effects of DHA on lymphopoiesis. Thus DHA itself may act on lymphoid progenitor cells and/or the microenvironment.

AIDS vaccine research in the UK

The UK Medical Research Council initiated a Directed Programme, aimed at developing vaccines for prevention and drugs for treatment of HIV infection and AIDS, in April 1987. This is a single collaborative research programme encompassing work in about 100 UK laboratories together with a small number in Europe and the USA. The third annual workshop for the programme, held at the University of Sheffield in September 1989, which brought together nearly 400 scientists, technical staff and students, as well as representatives of other national AIDS research programmes, showed that the Directed Programme is now well established and productive, making important contributions to the worldwide effort to control AIDS.

Follicular thyroid tumours: a study of laminin and type IV collagen in basement membrane and endothelium

Immunocytochemical stains for laminin and type IV collagen can be used as markers for basement membrane and vascular endothelium. Thirty four follicular thyroid lesions were examined using these techniques to investigate two aspects: firstly, the relation between the extent of invasion and the integrity of basement membrane; secondly, whether the techniques could enhance the detection of tumour vascular invasion. The results showed that although basement membrane was lost in widely invasive tumours, preservation was seen in most but not all encapsulated tumours. The potential for improved recognition of vascular invasion was also found.

A report of three cases of Yersinia reactive arthritis

Three cases of reactive arthritis associated with Yersinia enterocolitica bowel infection are reported. In one case Y. enterocolitica was cultured from stools while all three exhibited a significant increase in serum antibody titres to Y. enterocolitica. These are believed to be the first reports of Yersinia reactive arthritis in Australia. Synovial membrane biopsy in one case revealed a mixed inflammatory cell infiltrate the appearance of which was quite dissimilar to that of rheumatoid arthritis (RA). Mononuclear cells of the peripheral blood, but not the synovial fluid from another patient had reduced functional activity compared to RA patients as determined by response to phytohemagglutinin stimulation and allogeneic responses. Large numbers of HLA-DR and acid phosphatase positive macrophages were also found in the synovial fluid of this patient. The reason for joint involvement in Y. enterocolitica reactive arthritis is unknown and further work is necessary.

Streptococcal pharyngitis. Evaluation of a new diagnostic kit for clinic and office use

One hundred sixty-eight children with upper respiratory infections were screened for beta-hemolytic streptococcal pharyngitis. A recently developed throat culture kit was processed in comparison with the conventional blood agar plate using a duplicate swab technique. Kits and plates were examined independently. Three individuals with no previous bacteriologic experience were allowed to interpret results of the culture kit after receiving instructions for approximately 15 minutes on three consecutive days. The interpretations of two of these individuals approached 95% accuracy, and those of the third individual surpassed this rate. The kit appears to be at least equal to the conventional blood agar plate in supporting the growth of beta-hemolytic streptococci. Moreover, its selective nature allows the nontechnical office staff to interpret results of the cultures promptly and accurately with a minimum of instruction.