Use of a topical Janus kinase inhibitor in immune checkpoint inhibitor-induced eczematous reaction: a case report

In this report, we describe the case of a 28-year-old female with bilateral breast cancer in the setting of a BRCA1 mutation, who presented to dermatology with an eczematous reaction, ultimately diagnosed as a cutaneous immune-related adverse event (cirAE) secondary to an immune checkpoint inhibitor (ICI), pembrolizumab. Our case report highlights a novel therapeutic option for an eczematous cirAE: the topical JAK 1/2 inhibitor, ruxolitinib. CirAEs can occur in up to 55% of patients on ICIs, a class of medications seeing rapidly increasing use in cancer therapy, and prior research has demonstrated that ICI-induced dermatitis may involve different pathways than traditionally observed in their spontaneous counterparts. Specifically, marked Th1 skewing is noted in ICI-induced dermatitis, as opposed to a predominant Th2 response which typically characterizes spontaneous atopic dermatitis. To our knowledge, this is the first case report in the literature discussing use of a topical JAK inhibitor, ruxolitinib, in the treatment of topical steroid-refractory cirAEs. Furthermore, as topical JAK inhibitors are thought to not carry the risks of systemic JAK inhibitors, including malignancy, ruxolitinib cream is a promising therapeutic option for this challenging patient population.

Clinical Experience of a Long-acting Pegylated Erythropoietin-Stimulating Agent in Pediatric Chronic Kidney Disease

OBJECTIVE

Management of anemia of chronic kidney disease (CKD) often includes subcutaneous or intravenous administration of erythropoietin-stimulating agents (ESAs). Mircera, a pegylated continuous erythropoietin receptor agonist, has a longer duration of action and requires less frequent administration than other ESAs. Pediatric experience with Mircera is limited. We retrospectively reviewed our long-term experience of Mircera in a national pediatric nephrology center.

METHODS

Patients were identified via an electronic patient record database. Data collected included demographics (sex, age, etiology of CKD, CKD stage, dialysis modality), dosing information, and laboratory data-hemoglobin (Hb), parathormone (PTH), ferritin, hematinics prior to commencing Mircera and all subsequent values associated with dose adjustments.

RESULTS

Seventy-seven patients aged 2 to 18 years, with CKD stages 2 to 5T had received at least 1 dose of Mircera, with 75 patients having sufficient data and a total of 1473 doses. No patients discontinued Mircera owing to adverse effects. One patient experienced a potential severe adverse drug reaction. Mircera was effective in improving or maintaining Hb ≥10.0 g/dL in most (58/75, 77.3%) patients. The median dose to achieve Hb ≥10.0 g/dL was 2.1 µg/kg/4 wk. Most doses (1039, 71.5%) were administered 4-weekly. The doses (161, 11.1%) that were administered 6-weekly remained efficacious. Thirty-two patients started Mircera with Hb <10.0 g/dL; 26 (81%) achieved Hb ≥10.0 g/dL within a median time of 4 months. Mircera was less effective if given every 8 weeks, or in the presence of hyperparathyroidism or hyperferritinemia.

CONCLUSION

Mircera appears safe and effective in pediatric patients with CKD.

Bortezomib-Induced Reticular Eruption in Patient with Multiple Myeloma

Bortezomib is the first proteasome inhibitor to treat a variety of malignancies and is currently part of the standard of care regimen for the initial treatment of patients with newly diagnosed multiple myeloma. While bortezomib is generally well tolerated, it has been associated with various side effects, which have limited its use in some patients. Here, we describe a unique case with histological confirmation of a reticular eruption that appeared at the site of a subcutaneous administration of bortezomib in a 62-year-old male who was newly diagnosed with IgG kappa multiple myeloma. A skin biopsy was performed, which revealed superficial perivascular dermatitis predominantly composed of lymphocytes with rare eosinophils. The patient was successfully treated with betamethasone dipropionate 0.05% cream. When consulted, dermatologists should advise the oncology team of multiple myeloma patients treated with bortezomib to maintain a high threshold before discontinuing the drug when a patient experiences an atypical, reticular rash following subcutaneous administration. Additionally, potent topical corticosteroids, such as betamethasone dipropionate 0.05% cream, should be considered in managing the cutaneous reticular eruptions related to bortezomib administration, in order to maintain an optimal treatment regimen for patients with multiple myeloma.

Isotope analysis of human dental calculus δ13 CO3 2- : Investigating a potential new proxy for sugar consumption

RATIONALE

Dental calculus (mineralised dental plaque) is composed primarily of hydroxyapatite. We hypothesise that the carbonate component of dental calculus will reflect the isotopic composition of ingested simple carbohydrates. Therefore, dental calculus carbonates may be an indicator for sugar consumption, and an alternative to bone carbonate in isotopic palaeodiet studies.

METHODS

We utilised Fourier transform infrared attenuated total reflectance analysis to characterise the composition and crystallisation of bone and dental calculus before isotope analysis of carbonate. Using a Sercon 20-22 mass spectrometer coupled with a Sercon GSL sample preparation system and an IsoPrime 100 dual inlet mass spectrometer plus Multiprep device to measure carbon, we tested the potential of dental calculus carbonate to identify C₄ resources in diet through analysis of δ¹³ C values in paired bone, calculus and teeth mineral samples.

RESULTS

The modern population shows higher δ¹³ C values in all three tissue carbonates compared to both archaeological populations. Clear differences in dental calculus δ¹³ C values are observed between the modern and archaeological individuals suggesting potential for utilising dental calculus in isotope palaeodiet studies. The offset between dental calculus and either bone or enamel carbonate δ¹³ C values is large and consistent in direction, with no consistent offset between the δ¹³ C values for the three tissues per individual.

CONCLUSIONS

Our results support dental calculus carbonate as a new biomaterial to identify C₄ sugar through isotope analysis. Greater carbon fractionation in the mouth is likely due to the complex formation of dental calculus as a mineralized biofilm, which results in consistently high δ¹³ C values compared to bone and enamel.

Thromboprophylaxis in congenital nephrotic syndrome: 15-year experience from a national cohort

INTRODUCTION

Congenital nephrotic syndrome (CNS) is an ultra-rare disease associated with a pro-thrombotic state and venous thromboembolisms (VTE). There is very limited evidence evaluating thromboprophylaxis in patients with CNS. This study aimed to determine the doses and duration of treatment required to achieve adequate thromboprophylaxis in patients with CNS.

METHODS

From 2005 to 2018 children in Scotland with a confirmed genetic or histological diagnosis of CNS were included if commenced on thromboprophylaxis. The primary study endpoint was stable drug monitoring. Secondary outcomes included VTE or significant haemorrhage.

RESULTS

Eight patients were included; all initially were commenced on low-molecular weight heparin (enoxaparin). Four patients maintained therapeutic anti-Factor Xa levels (time 3-26 weeks, dose 3.2-5.07 mg/kg/day), and one patient developed a thrombosis (Anti-Factor Xa: 0.27 IU/ml). Four patients were subsequently treated with warfarin. Two patients maintained therapeutic INRs (time 6-11 weeks, dose 0.22-0.25 mg/kg/day), and one patient had two bleeding events (Bleed 1: INR 6, Bleed 2: INR 5.5).

CONCLUSIONS

Achieving thromboprophylaxis in CNS is challenging. Similar numbers of patients achieved stable anticoagulation on warfarin and enoxaparin. Enoxaparin dosing was nearly double the recommended starting doses for secondary thromboprophylaxis. Bleeding events were all associated with supra-therapeutic anticoagulation.

An ideal solution? Optimising pretreatment methods for artificially mummified ancient Egyptian tissues

RATIONALE

Although the analysis of skeletal remains dominates the study of ancient dietary stable isotopes, mummified bodies also allow short-term diet to be studied through the analysis of soft tissues. The application of resins, waxes and oils during mummification can affect the results obtained. This study assesses a range of methods for removing such substances from mummified tissue.

METHODS

An experimental mummification model following ancient Egyptian methods was created using a modern pig leg. Sub-samples of skin, muscle and bone were removed and coated with a range of substances used in Egyptian mummification. Four methods were used to clean these samples before the measurement of the carbon and nitrogen stable isotope ratios of their gelatinised collagen content using a ThermoFinnigan Flash Elemental analyser coupled to a DeltaPlus XL isotope ratio mass spectrometer via a ConFlo III interface.

RESULTS

The results showed that embalming materials can significantly affect dietary stable isotope ratios, and that these substances are most effectively removed using a mixture of polar and non-polar solvents. Results indicate that bone samples demineralised with HCl and skin samples produce more accurate results than bone samples demineralised with EDTA or muscle samples.

CONCLUSIONS

The choice of tissue and the preparation methods used can have a significant effect on the accuracy of stable isotope data obtained from mummified tissue, particularly when embalming materials are also present. A mixture of solvents appears to be a more effective cleaning agent than a single solvent. Demineralisation with HCl is preferable for well-preserved bone, as used in this study, but whether this is the case for more fragile, less well-preserved bone requires further study. Skin samples produce more consistent data than muscle, but visually distinguishing between these tissues is not simple on ancient mummies.

A portable magneto-optical trap with prospects for atom interferometry in civil engineering

The high precision and scalable technology offered by atom interferometry has the opportunity to profoundly affect gravity surveys, enabling the detection of features of either smaller size or greater depth. While such systems are already starting to enter into the commercial market, significant reductions are required in order to reach the size, weight and power of conventional devices. In this article, the potential for atom interferometry based gravimetry is assessed, suggesting that the key opportunity resides within the development of gravity gradiometry sensors to enable drastic improvements in measurement time. To push forward in realizing more compact systems, techniques have been pursued to realize a highly portable magneto-optical trap system, which represents the core package of an atom interferometry system. This can create clouds of 10⁷ atoms within a system package of 20 l and 10 kg, consuming 80 W of power.This article is part of the themed issue 'Quantum technology for the 21st century'.

Concomitant therapy for acne in patients with skin of color: a case-based approach

Acne affects individuals of all races and ethnicities. Patients with skin of color present a unique challenge, particularly due to the potential for post-inflammatory hyperpigmentation. Concomitant therapy is an appropriate strategy for this population, as demonstrated in the following case.

Trauma experience in the UK and Ireland: analysis of orthopaedic training using the FHI eLogbook

Surgical trainees routinely provide evidence of their training and operative experience for assessment. National comparative data on the number of procedures performed during training was previously unavailable in the UK. Since 2003 every trainee in Trauma and Orthopaedics (T&O) in the UK and Ireland has submitted data recording their operative experience electronically via the Faculty of Health Informatics (FHI) eLogbook. This provides detailed data on trainee, trainer, hospital and training programme performance. This data has been analysed for trauma surgery. By March 2007 there were 1053 T&O Specialist Registrars with operations logged. Trauma operations performed and uploaded during the previous 3 years have been included. Each trainee's work is analysed by 'year-in-training' (YIT, 1-6). Data on levels of supervision and potentially missed opportunities (where the trainee was present but assisted rather than performed the operation) was analysed. The mean number of trauma operations performed annually by trainees was 109, 120, 110, 122, 98 and 84 (total 643) for YIT 1-6, respectively. 22% of the operations at which a trainee was present were potentially missed opportunities. A high level of experience is gained in hip fracture surgery (121 operations performed), intramedullary nailing (38) and ankle (47) stabilisation over the 6 years of training. However, the mean number of tendon repairs (18), tension band wires (13), external fixators (12) and children's supracondylar fracture procedures (9) performed is low. We also report figures for complex fracture stabilisation. The eLogbook remains a powerful tool which can provide accurate information to support in-depth analysis of trainees, trainers, and training programmes. Based on this analysis, we suggest 'standard setting' to identify trainees performing fewer operations than required during their training. We have also established a baseline which can be used to identify the consequences of changes to length of training and working hours.

Osteoporosis in Health and Disease: A Dermatologist's Perspective

Osteoporosis affects more than 75 million people in the United States, Asia, and Europe. Osteoporosis results from a combination of genetic and environmental factors that contribute to peak bone mass and the rate of bone loss. These factors include medications, diet, race, sex, lifestyle, and physical activity. The management of osteoporosis can be complicated by simultaneous treatment of other diseases. For dermatologists, the use of long-term oral corticosteroids for the management of immunobullous and blistering diseases is of particular importance. Although these treatment modalities are potentially lifesaving for patients, the side effects can be dangerous. This article examines the pathophysiology, clinical course, and treatments for osteoporosis and the special considerations that arise when managing patients using corticosteroids.

Large mammal turnover in Africa and the Levant between 1.0 and 0.5 Ma

Faunal change at the Early-Middle Pleistocene boundary in Europe has long been a topic for discussion. However, analyses of large mammal turnover at this time in Africa have been lacking, largely because of the low number of sites dated to this interval. Recent work, particularly in the last 10 years, has resulted in a much larger published sample of sites and we synthesize these data in this paper. In our multivariate (TWINSPAN) analyses of African and Levantine large mammal faunas we found that localities were subdivided by geographic regions, not by age. There were some small-scale changes with the appearance or extinction of particular taxa, but there was no large-scale turnover such as that seen in Europe. The Levant was included as a possible route for faunal interchange with east Africa, but no similarities were found between these areas. It therefore appears that the modern zoogeographic separation of the Levant and north Africa into the Palaearctic region and sub-Saharan Africa into the African region can be traced back to at least the Early-Middle Pleistocene boundary.

Differential deficits in expression recognition in gene-carriers and patients with Huntington's disease

Previous studies in symptomatic patients and asymptomatic gene-carriers of Huntington's disease (HD) reported a differential deficit in the recognition of facial expressions of disgust. This impairment may point to involvement of the basal ganglia in the recognition of disgust. In this study, we compared the performance of 20 patients with symptoms of HD, 20 gene-carriers of HD and 20 healthy controls on two tests of facial expressions in order to further investigate the role of the basal ganglia in disgust recognition. Recognition of fear, rather than disgust, was most severely impaired in the patients, who were also impaired at recognising expressions of anger, disgust and sadness. Direct testing for a differential deficit in disgust at the group level (and at the level of individual HD cases) revealed that the patients were in fact significantly more impaired on the other negative expressions than on disgust. The gene-carriers were not impaired on any expression, although there was a trend for the gene-carriers to be poorer at recognising fearful faces than the controls. We argue that the expression recognition performance of the patients and gene-carriers simply reflects differences in task difficulty, rather than dysfunction of any mechanisms dedicated to specific emotions. In contrast to previous studies in patients or gene-carriers of HD, our findings provide no evidence for a role of the basal ganglia in the recognition of disgust and cast doubt on whether results from HD patients and gene-carriers can be used in support of a double dissociation between recognition of disgust and fear.

Experience with an XML/HTTP-based federative approach to develop a hospital-wide clinical information system

The authors present a two-year experience with an approach aimed at federating applications into a component-based hospital-wide clinical information system. Recognizing the need for better integration, clearer separation of knowledge from applications, as well as the necessity to respect and integrate the diversity of roles in a healthcare network, a strategy was implemented that included the development of a shared vision, organizational changes to promote appropriation at all levels, and the elaboration and maintenance of a common architecture and terminology by an instrumental technical group. Choices for federative technologies were in part based on their level of acceptance and potential to evolve. XML was used as the syntactic framework and HTTP as the transfer protocol. Within twelve months, the shared vision was developed, the architecture was specified, the key central components implemented, incorporated into the applications, and applications teams started producing shareable services using XML and HTTP.

Rapid prenatal diagnosis of chromosome aneuploidies by interphase fluorescence in situ hybridization: a one-year clinical experience with high-risk and urgent fetal and postnatal samples

OBJECTIVES

To evaluate the clinical utility of rapid prenatal and postnatal detection of common chromosome aneuploidies by interphase fluorescence in situ hybridization (FISH) analysis with DNA probes.

DESIGN

Four hundred and seventy-seven high-risk and/or urgent amniotic fluid, chorionic villus and fetal and postnatal blood samples were prospectively examined by FISH with probes specific for chromosomes 13, 18, 21, X, and Y and results were reported within 48 hours. All FISH results were followed by conventional chromosome analysis, if possible.

SETTING

Cytogenetic service laboratory at the tertiary referral center, Rigshospitalet in Copenhagen.

MAIN OUTCOME MEASURES

The fraction of clinically significant chromosome aneuploidies that was detected by FISH analysis, and the fraction of terminations that was based on FISH and ultrasound results rather than on conventional cytogenetic results.

RESULTS

The FISH assay detected 76% of the clinically significant chromosome abnormalities as determined by subsequent cytogenetic analysis. Seventy-two percent of the terminations of the chromosomally abnormal pregnancies were based on FISH and ultrasound results rather than on conventional cytogenetic results.

CONCLUSION

FISH analysis is a clinically useful adjunctive tool to conventional pre- and postnatal cytogenetic analysis. The assay rapidly detects the majority of clinically significant chromosome abnormalities, thus facilitating difficult pre- and postnatal clinical decisions.

Patients' perceptions of the Odstock Dropped Foot Stimulator (ODFS)

OBJECTIVE

To determine the perceived benefit, pattern and problems of use of the Odstock Dropped Foot Stimulator (ODFS) and the users' opinion of the service provided.

DESIGN

Questionnaire sent in a single mailshot to current and past users of the ODFS. Returns were sent anonymously.

SETTING

Outpatient-based clinical service.

SUBJECTS

One hundred and sixty-eight current and 123 past users with diagnoses of stroke (CVA), multiple sclerosis (MS), incomplete spinal cord injury (SCI), traumatic brain injury (TBI) and cerebral palsy (CP).

INTERVENTION

Functional electrical stimulation (FES) to correct dropped foot in subjects with an upper motor neuron lesion, using the ODFS.

MAIN OUTCOME MEASURES

Purpose-designed questionnaire.

RESULTS

Return rate 64% current users (mean duration of use 19.5 months) and 43% past users (mean duration of use 10.7 months). Principal reason cited for using equipment was a reduction in the effort of walking. Principal reasons identified for discontinuing were an improvement in mobility, electrode positioning difficulties and deteriorating mobility. There were some problems with reliability of equipment. Level of service provided was thought to be good.

CONCLUSION

The ODFS was perceived by the users to be of considerable benefit. A comprehensive clinical follow-up service is essential to achieve the maximum continuing benefit from FES-based orthoses.

Gain of 9p in the pathogenesis of polycythemia vera

Polycythemia vera (PV) is a clonal stem cell disorder characterized by excessive erythrocyte production, resulting in absolute erythrocytosis. No specific structural chromosomal abnormalities have been reported in PV to date. We have observed two cases of PV with an extra i(9)(p10) as the sole anomaly, and FISH analysis using a 9p-specific chromosome microdissection probe showed that two other PV patients previously identified as having an add(18p) and an add(1p) as the primary changes actually carried a der(18)t(9;18)(p12;p11.2) and a der(1)t(1;9)(p12;p12), respectively. The same FISH assay was employed to evaluate domain signals on interphase cells of 15 more cases of PV with normal karyotypes and five normal controls. Two patients were observed with a significant increase in the percentage of cells with three domain signals. Our results strongly indicate that an additional i(9)(p10) is a new and recurrent primary chromosome anomaly in PV, and, in consideration of trisomy 9 being one of the most common anomalies in PV, amplification of a gene or genes on 9p, but not on 9q, may play a crucial role in the pathogenesis of PV.

Investigation and modelling of the surface dose from linear accelerator produced 6 and 10 MV photon beams

The radiation reaction from the surface dose to a patient's skin is clinically important as an indicator of tolerance to treatment and is frequently the most visible side-effect from external beam radiotherapy. To quantify surface dose, its build-up was investigated in a solid water phantom over a range of field sizes, source to skin distances, wedge angles and beam shaping conditions. These data were analysed and used to produce an empirical model of the effect of these factors which predicted surface dose to within 5% under test conditions. The effects of changing treatment techniques was investigated by comparing fixed to dynamic wedges, and multileaf collimator (MLC) with alloy blocks. It was found that the MLC reduced the surface dose relative to alloy blocks but that dynamic wedges made no change relative to open fields. Fixed wedges reduced the relative surface dose as a consequence of beam hardening. It is hoped that routine clinical use of the model to calculate skin dose will increase awareness of situations in which the skin sparing effect of modern linear accelerators may be compromised.

Aeromonas popoffii sp. nov., a mesophilic bacterium isolated from drinking water production plants and reservoirs

We examined the taxonomic position of seven Aeromonas isolates, recovered from Flemish and Scottish drinking water production plants and reservoirs, which were previously recognized by numerical analysis of genomic AFLP fingerprints as members of an unknown Aeromonas taxon that most closely resembled the species Aeromonas bestiarum (DNA hybridization group [HG] 2). The new phenotypic and DNA-DNA hybridization data obtained in this study show that the A. bestiarum-like strains constitute a separate Aeromonas species, for which the name Aeromonas popoffii sp. nov. is being proposed. The new species exhibited an internal DNA relatedness ranging from 79 to 100% and was 22 to 63% related to the type or reference strains of other Aeromonas spp. The highest DNA binding values were determined with A. bestiarum (51 to 63%), followed by Aeromonas hydrophila sensu stricto (HG1; 50 to 60%) and Aeromonas salmonicida (HG3; 39 to 55%). Although fingerprints generated by ribotyping and cellular fatty acid analysis often were highly similar, minor differences between the respective fingerprints were of significance for the differentiation of A. popoffii from its closest taxonomic neighbors, HG1, HG2, and HG3. Phenotypically, all seven strains of A. popoffii were positive for acid and gas production from D-glucose and glycerol, growth in KCN broth, arginine dihydrolase, DNase, Voges-Proskauer reaction, and resistance to vibriostatic agent O/129 and ampicillin but displayed negative reactions for production of urease, tryptophan deaminase, ornithine decarboxylase, and lysine decarboxylase (LDC). None of the strains displayed strong hemolytic activity. The lack of D-sucrose fermentation and LDC production and the ability to utilize DL-lactate as the sole energy and carbon source were useful characteristics for the biochemical separation of A. popoffii from A. bestiarum. Other Aeromonas spp. could be differentiated phenotypically from the new species by at least two features. The chromosomal G+C content of A. popoffii ranges from 57.7 to 59.6 mol%. Strain LMG 17541 is proposed as the type strain.

Do protective devices prevent needlestick injuries among health care workers?

OBJECTIVES

To determine the effectiveness and direct of two protective devices-a shielded 3 ml safety syringe (Safety-Lok; Becton Dickinson and Co., Becton Dickinson Division, Franklin Lakes, N.J.) and the components of a needleless IV system (InterLink; Baxter Healthcare Corp., Deerfield, Ill.)--in preventing needlestick injuries to health care workers.

DESIGN

Twelve-month prospective, controlled, before-and-after trial with a standardized questionnaire to monitor needlestick injury rates.

SETTING

Six hospital inpatient units, consisting of three medical units, two surgical units (all of which were similar in patient census, acuity, and frequency of needlesticks), and a surgical-trauma intensive care unit, at a 900-bed urban university medical center.

PARTICIPANTS

All nursing personnel, including registered nurses, licensed practical nurses, nursing aides, and students, as well as medical teams consisting of an attending physician, resident physician, interns, and medical students on the study units.

INTERVENTION

After a 6-month prospective surveillance period, the protective devices were randomly introduced to four of the chosen study units and to the surgical-trauma intensive care unit.

RESULTS

Forty-seven needlesticks were reported throughout the entire study period, 33 in the 6 months before and 14 in the 6 months after the introduction of the protective devices. Nursing staff members who were using hollow-bore needles and manipulating intravenous lines accounted for the greatest number of needlestick injuries in the pre-intervention period. The overall rate of needlestick injury was reduced by 61%, from 0.785 to 0.303 needlestick injuries per 1000 health care worker-days after the introduction of the protective devices (relative risk = 1.958; 95% confidence interval, 1.012 to 3.790; p = 0.046). Needlestick injury rates associated with intravenous line manipulation, procedures with 3 ml syringes, and sharps disposal were reduced by 50%; however, reductions in these subcategories were not statistically significant. No seroconversions to HIV-1 or hepatitis B virus seropositivity occurred among those with needlestick injuries. The direct cost for each needlestick prevented was $789.

CONCLUSIONS

Despite an overall reduction in needlestick injury rates, no statistically significant reductions could be directly attributed to the protective devices. These devices are associated with a significant increase in cost compared with conventional devices. Further studies must be concurrently controlled to establish the effectiveness of these devices.

Supernumerary chromosome marker (1) in a developmentally delayed child

A 15-month-old boy with mild developmental delay and several minor anomalies was found to be mosaic 46,XY/47,XY ,+mar(1). The marker r(1) was a small de novo ring identified by FISH with a painting type DNA probe.

Exogenously administered alpha-bungarotoxin binds to embryonic chick spinal cord: implications for the toxin-induced arrest of naturally occurring motoneuron death

Administration of alpha-bungarotoxin and other curare-like drugs during embryogenesis arrests motoneuron death which normally occurs in the spinal cord from day 6 to day 10 of embryogenesis. The accepted explanation is that such motoneuron rescue is mediated by inhibition of neuromuscular transmission following the blockade of nicotinic cholinoceptors at the neuromuscular junction. In this study we investigated a further possibility, namely that motoneuron rescue might also involve the blockade of alpha-bungarotoxin-sensitive sites within the spinal cord. The kinetic profile of [125I]alpha-bungarotoxin binding was examined in the brachial and lumbar regions of chick spinal cord at embryonic day 15. Binding was specific and apparently saturable within the range 1-34 nM reaching a maximum after 45 min. Specific binding involved a single class of non-interacting sites with a KD of 8.0 nM and a Bmax of 106 +/- 12 fmol/mg of protein. Nicotine displaced specific [125I]alpha-bungarotoxin binding in a concentration-dependent manner. Furthermore, specific binding dissociated slowly in the absence of nicotine. Autoradiographs localizing [125I]alpha-bungarotoxin binding in embryonic spinal cord revealed that, at embryonic day 15, specific toxin binding sites could be detected throughout the gray matter. In contrast, at embryonic day 6, the ventral horn contained the majority of specific binding sites. Exogenously administered [125I]alpha-bungarotoxin reached and bound to nicotine-sensitive sites in the spinal cord at embryonic day 7. To conclude, these data demonstrate that central nicotine-sensitive sites which bind [125I]alpha-bungarotoxin in a saturable and specific manner were present at the beginning of the critical motoneuron death phase of neurogenesis and that they were accessible to exogenously administered toxin. It is proposed that the [125I]alpha-bungarotoxin binding characterized here is to a class of putative alpha-bungarotoxin-sensitive nicotinic cholinoceptors. These studies raise the possibility that alpha-bungarotoxin blockade of such putative nicotinic cholinoceptors within the spinal cord may contribute to toxin-induced arrest of naturally occurring motoneuron death.

The swab rack--an outdated ritual

The risk of Theatre Staff becoming infected from blood borne viruses such as HIV and Hepatitis B is steadily increasing. Sir David Cox's report (1988) predicted that the number of people infected with HIV by the end of 1987 would be between 20,000 and 50,000. Although these predictions are now thought to be more accurately estimated between 12,000 and 26,000, the number of people developing Aids is still expected to rise at an alarming rate. The precautions taken within the Theatre Department to reduce this risk are becoming transparently inadequate. It is no longer sufficient--or acceptable practice--to only be vigilant in avoiding blood contamination if the patient falls within a certain 'high risk' category. A happily married, middle aged woman may also be a virus carrier, particularly considering the long dormancy the HIV virus can exhibit before being detectable. It must be assumed that everyone is a potential carrier and the same precautionary measures taken for every patient, regardless of their past history, or present appearance.

The product of the KIN1 locus in Saccharomyces cerevisiae is a serine/threonine-specific protein kinase

The catalytic domain (30 kDa) of all protein kinases can be aligned for maximum homology, thereby revealing both invariant and highly conserved residues. The KIN1 locus from Saccharomyces cerevisiae was isolated by hybridization to a degenerate oligonucleotide encoding the conserved protein kinase domain, DVWSFG. The predicted amino acid sequence revealed significant homology to the catalytic domain of protein kinases. Using antibodies raised against a bacterial LacZ/KIN1 fusion protein, we have identified by immunoprecipitation the yeast KIN1 gene product as a 145,000 dalton protein (p145KIN1). In exponentially growing yeast cells, the KIN1 protein is phosphorylated primarily on serine residues. The gene product of KIN1 was shown to be a serine/threonine-specific protein kinase in immune complexes, as determined by the transfer of label from [gamma-32P]ATP to either pp145KIN1 or to an exogenously added substrate, alpha-casein. The optimal metal ion concentration in this assay was 20 mM-MnCl2. Subsequent phosphoamino acid analysis of the radiolabelled product, pp145KIN1, demonstrated that this autophosphorylation was specific for serine/threonine residues. There is no apparent difference between wild-type cells and cells containing a disrupted KIN1 gene. The biochemical characterization of protein kinases in simple eukaryotes such as yeast will aid us in determining the role of phosphorylation in cellular growth and physiology.

Cerebral asymmetries and interhemispheric processes

Those who attempt to characterize the functions of the cerebral hemispheres tend, broadly speaking, to do so either in terms of structural specializations or of different information-processing modes. Often little attention is paid to the possible importance, in determining the outcome of experiments in this field, of interhemispheric processes. An experiment is described which concurrently studies hemispheric response differences and interhemispheric processes. Sets of dot patterns are learned, each made up of an original and three distortions of the original. The degree of distortion is systematically changed and is quantified in terms of information theory. Subjects then examine pairs of patterns and decide whether they belong to the 'same' family, i.e. an original and one of its distortions, or 'different', i.e. a pattern previously learned and a completely new one. Manual response times are recorded for 'same' and 'different' responses and functions plotted of response latencies against degree of pattern distortion. The pairs of patterns are presented under three different conditions. Either both patterns in one visual field (unilateral condition), one pattern in each visual field (bilateral condition) or the patterns one above the other straddling the vertical meridian (central condition). Response latencies are shortest for the bilateral condition, next shortest for the unilateral condition and slowest for the central condition. Models which may account for these results are examined and one crucially involving changed information transmission rates with increasing distortion of patterns to be compared is found to provide the most parsimonious explanation of the results from all three experimental conditions.

Human chromosome 2 rod/ring mosaicism: probable origin by prezygotic breakage and intrachromosomal exchange

A 5-year-old male with mild mental retardation showed a chromosomal rearrangement involving duplication of part of 2q (2q33.3 leads to 2wter) in 70% of metaphases from peripheral blood; the remaining 30% of cells had a rearrangement of chromosome 2 in the form of a ring, viz., r(2)(2p25.2 leads to 2q33.2). Both configurations appeared to be missing a tiny portion of 2p (p25.3 leads to pter). All metaphases examined from cultured skin fibroblasts from the child had the abnormal rod configuration of chromosome 2; none had the ring. The pattern of the 2q duplication/2p deletion in the rod is that expected if there were an inversion in a No. 2 in one of the parents. Q-, G-, and R-banding studies, however, revealed both parents to be chromosomally normal. Furthermore, the finding of an inversion would not explain the origin of the ring. The most probable explanation is that neither parent is mosaic for an inversion, but that the rod and ring configurations arose simultaneously from a de novo, prezygotic or early zygotic exchange in a No. 2, either between complementary DNA strands in G1 or by intrachromosomal exchange in S or G2. Differential selection against cells with the ring chromosome in blood and skin probably occurred during subsequent embryological development. Cytoplasmic malate dehydrogenase (MDH1) was excluded from the terminal band of 2p (i.e., 2p25.3) by deletion mapping.