Assessment of cryogenic pretreatment for simulating environmental weathering in the formation of surrogate micro- and nanoplastics from agricultural mulch film

Microplastics (MPs) and nanoplastics (NPs) from mulch films and other plastic materials employed in vegetable and small fruit production pose a major threat to agricultural ecosystems. For conducting controlled studies on MPs' and NPs' (MNPs') ecotoxicity to soil organisms and plants and fate and transport in soil, surrogate MNPs are required that mimic MNPs that form in agricultural fields. We have developed a procedure to prepare MPs from plastic films or pellets using mechanical milling and sieving, and conversion of the resultant MPs into NPs through wet grinding, both steps of which mimic the degradation and fragmentation of plastics in nature. The major goal of this study was to determine if cryogenic exposure of two biodegradable mulch films effectively mimics the embrittlement caused by environmental weathering in terms of the dimensional, thermal, chemical, and biodegradability properties of the formed MNPs. We found differences in size, surface charge, thermal and chemical properties, and biodegradability in soil between MNPs prepared from cryogenically treated vs. environmentally weathered films, related to the photochemical reactions occurring in the environment that were not mimicked by cryogenic treatment, such as depolymerization and cross-link formation. We also investigated the size reduction process for NPs and found that the size distribution was bimodal, with populations centered at 50 nm and 150-300 nm, and as the size reduction process progressed, the former subpopulation's proportion increased. The biodegradability of MPs in soil was greater than for NPs, a counter-intuitive trend since greater surface area exposure for NPs would increase biodegradability. The result isassociated with differences in surface and chemical properties and to minor components that are readily leached out during the formation of NPs. In summary, the use of weathered plastics as feedstock would likely produce MNPs that are more realistic than cryogenically-treated unweathered films for use in experimental studies.

“Uroptysis!” – A case report of xanthogranulomatous pyelonephritis with nephrobronchial fistulation

Introduction and importance

Xanthogranulomatous pyelonephritis (XGP) is an uncommon complication of chronic urinary tract infection, classically secondary to a chronic obstructive uropathy, resulting in destruction of renal parenchyma and a non-functioning kidney (Jha and Aeddula, 2022 [1]). This is rarely associated with nephrobronchial fistulation, with few published case reports in the literature to date.

Case presentation

We present the rare case of a 42-year-old female who was admitted to an Irish tertiary urology centre with abdominal pain, elevated inflammatory markers and an obstructive uropathy on initial imaging, with a new diagnosis of XGP. Initial management was with targeted intravenous antimicrobial therapy, percutaneous nephrostomy and perinephric drain insertion. The subsequent discovery of a nephrobronchial fistula later complicated the case, warranting plan for interval nephrectomy and fistula repair following prolonged medical management. We discuss the initial presentation, workup and image-guided approach to management.

Clinical discussion

XGP is an uncommon sequela of chronic renal suppurative infection, and is usually associated with long-standing ureteric obstruction secondary to a staghorn calculus. Nephrobronchial fistulation is a rare complication of XGP, highlighting the significance of this case discussion.

Conclusion

XGP should be considered in cases of suspected chronic pyelonephritis and may rarely lead to nephrobronchial fistulation. In cases of known XGP and pleural empyema, nephrobronchial fistulation should be considered as part of the differential diagnosis.

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Xanthogranulomatous pyelonephritis is rare and associated with chronic upper urinary tract infection and obstruction.

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Nephrobronchial fistulation is a rare complication of xanthogranulomatous pyelonephritis.

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In cases of XGP and concurrent pleural empyema, a nephrobronchial fistula should be considered.

The scourge of knife crime: trends in knife-related assault managed at a major centre in South Africa

BACKGROUND

Knife wounds are common and represent a major burden to the South African healthcare system. This study reviews trends in spectrum, management and outcome of these injuries at a single trauma centre in KwaZulu-Natal(KZN).

METHOD

The regional hybrid electronic registry (HEMR) was reviewed for the period January 2013 - December 2018, and all patients who suffered a knife-related assault were identified and reviewed.

RESULTS

During the period under review, a total of 2117 patients suffered a knife-related assault. Regions injured were as follows: head 445, neck 572, face 258, chest 939, abdomen 649, pelvic/urogenital 49, upper limb 418, and lower limb 105. The median ISS was 9 (4-10). Imaging comprised 1242 chest X-rays, 315 abdominal X-rays, 162 abdominal ultrasounds/ FAST, and 929 CT scans of which 634 were CT angiograms. A total of 783 (37%) patients required an operation. The rate of laparotomy was 447/649 (69%) and of thoracotomy/sternotomy/thoracoscopy 95/939 (10%). The rate of vascular exploration for upper and lower limb vascular injury was 101/523 (19%). Mortality was 49/2117 (2.3%)..

CONCLUSION

Although our clinical outcomes over this period appear to be consistent, suggesting a familiarity with managing knife-related trauma, the persistently high rate of knife-related injury suggests that we have failed to develop a preventative strategy to try and reduce this scourge.

178 Evaluation of polar body extrusion following exposure of cattle oocytes to different concentrations of ethylene glycol cryoprotectant

Cryoprotectant (CPA) toxicity has been recognised as a critical barrier to further advancement of cattle oocytes. Furthermore, CPA at high concentration might be toxic to oocytes, leading to osmotic shock and cell death (Arav et al. 1993). Selection of quality oocytes among a heterogeneous pool is mostly done subjectively. The use of Brilliant Cresyl Blue (BCB) stain for oocyte selection before ethylene glycol (EG) CPA toxicity test on cattle oocytes might be a useful tool. The objectives of this study were to elucidate the toxicity of EG penetrating CPA to cattle oocytes and the effectiveness of BCB on oocyte selection. Ovaries from cows of unknown reproductive status were collected from the local slaughterhouse and transported in warmed (37°C) saline water to the laboratory within 2h of slaughter. The oocytes (n=374) were exposed to 26mM BCB for 90min at 38.5°C under an atmosphere of 5% CO2. The other oocytes (n=450) were not exposed to BCB solution or CPA (positive control: no BCB and no CPA exposure). Oocytes were classified as BCB positive (+) with a varying degree of blue cytoplasm or BCB negative (−) with no blue cytoplasm. Oocytes were exposed in EG at different CPA concentrations as follows: Toxicity test 1 (TT1) was 0, 5, 10, and 15%, followed by exposure to TT2 as follows: 10, 20, and 30% (stepwise increased CPA). The oocytes were then invitro matured (IVM) as per treatment groups for 22h. After maturation, oocytes were removed from the maturation medium and denuded of granulosa cells by vortexing. The polar body extrusion was evaluated with the aid of Oosight Imaging System (Hamilton Thorne) connected to an inverted research microscope. Treatment means were compared using Fisher protected t-test least significant difference. There was a drastic decline of oocytes with polar body extrusion as CPA concentration increased (P<0.05): 40.5% (positive control, no BCB and no CPA exposure), 33.3% [(control, CPA exposure (EG 5 + 10%)], 23.1% [BCB− with CPA toxicity test (EG 5 + 10%)], 12.5% [(BCB− with CPA toxicity test (EG 10 + 20%)] and 4.9% [(BCB− with CPA toxicity test (EG 15 + 30%)]. The BCB+ groups (EG 5 + 10% and EG 10 + 20%) had significantly more oocytes with polar body extrusion (68.9% and 51.9%) compared with the positive control (40.5%), respectively (P<0.05). In conclusion, higher EG cryoprotectant concentrations compromise oocyte polar body extrusion following IVM. We recommend that BCB be used for selection of suitable oocytes before the CPA toxicity test because of its ability to stain larger and more competent oocytes from cattle.

Mechanical formation of micro- and nano-plastic materials for environmental studies in agricultural ecosystems

Release of microplastics (MPs) and nanoplastics (NPs) into agricultural fields is of great concern due to their reported ecotoxicity to organisms that provide beneficial service to the soil such as earthworms, and the potential ability of MPs and NPs to enter the food chain. Most fundamental studies of the fate and transport of plastic particulates in terrestrial environments employ idealized MP materials as models, such as monodisperse polystyrene spheres. In contrast, plastics that reside in agricultural soils consist of polydisperse fragments resulting from degraded films employed in agriculture. There exists a need for more representative materials in fundamental studies of the fate, transport, and ecotoxicity of MPs and NPs in soil ecosystems. The objective of this study was therefore to develop a procedure to produce MPs and NPs from agricultural plastics (a mulch film prepared biodegradable polymer polybutyrate adipate-co-terephthalate (PBAT) and low-density PE [LDPE]), and to characterize the resultant materials. Soaking of PBAT films under cryogenic conditions promoted embrittlement, similar to what occurs through environmental weathering. LDPE and cryogenically-treated PBAT underwent mechanical milling followed by sieve fractionation into MP fractions of 840 μm, 250 μm, 106 μm, and 45 μm. The 106 μm fraction was subjected to wet grinding to produce NPs of average particle size 366.0 nm and 389.4 nm for PBAT and LDPE, respectively. A two-parameter Weibull model described the MPs' particle size distributions, while NPs possessed bimodal distributions. Size reduction did not produce any changes in the chemical properties of the plastics, except for slight depolymerization and an increase of crystallinity resulting from cryogenic treatment. This study suggests that MPs form from cutting and high-impact mechanical degradation as would occur during the tillage into soil, and that NPs form from the MP fragments in regions of relative weakness that possess lower molecular weight polymers and crystallinity.

Potassium channel gene associations with joint processing speed and white matter impairments in schizophrenia

Patients with schizophrenia show decreased processing speed on neuropsychological testing and decreased white matter integrity as measured by diffusion tensor imaging, two traits shown to be both heritable and genetically associated indicating that there may be genes that influence both traits as well as schizophrenia disease risk. The potassium channel gene family is a reasonable candidate to harbor such a gene given the prominent role potassium channels play in the central nervous system in signal transduction, particularly in myelinated axons. We genotyped members of the large potassium channel gene family focusing on putatively functional single nucleotide polymorphisms (SNPs) in a population of 363 controls, 194 patients with schizophrenia spectrum disorder (SSD) and 28 patients with affective disorders with psychotic features who completed imaging and neuropsychological testing. We then performed three association analyses using three phenotypes - processing speed, whole-brain white matter fractional anisotropy (FA) and schizophrenia spectrum diagnosis. We extracted SNPs showing an association at a nominal P value of <0.05 with all three phenotypes in the expected direction: decreased processing speed, decreased FA and increased risk of SSD. A single SNP, rs8234, in the 3' untranslated region of voltage-gated potassium channel subfamily Q member 1 (KCNQ1) was identified. Rs8234 has been shown to affect KCNQ1 expression levels, and KCNQ1 levels have been shown to affect neuronal action potentials. This exploratory analysis provides preliminary data suggesting that KCNQ1 may contribute to the shared risk for diminished processing speed, diminished white mater integrity and increased risk of schizophrenia.

Microscopic relaxations in a protein sustained down to 160K in a non-glass forming organic solvent

BACKGROUND

We have studied microscopic dynamics of a protein in carbon disulfide, a non-glass forming solvent, down to its freezing temperature of ca. 160K.

METHODS

We have utilized quasielastic neutron scattering.

RESULTS

A comparison of lysozyme hydrated with water and dissolved in carbon disulfide reveals a stark difference in the temperature dependence of the protein's microscopic relaxation dynamics induced by the solvent. In the case of hydration water, the common protein glass-forming solvent, the protein relaxation slows down in response to a large increase in the water viscosity on cooling down, exhibiting a well-known protein dynamical transition. The dynamical transition disappears in non-glass forming carbon disulfide, whose viscosity remains a weak function of temperature all the way down to freezing at just below 160K. The microscopic relaxation dynamics of lysozyme dissolved in carbon disulfide is sustained down to the freezing temperature of its solvent at a rate similar to that measured at ambient temperature.

CONCLUSIONS

Our results demonstrate that protein dynamical transition is not merely solvent-assisted, but rather solvent-induced, or, more precisely, is a reflection of the temperature dependence of the solvent's glass-forming dynamics.

GENERAL SIGNIFICANCE

We hypothesize that, if the long debated idea regarding the direct link between the microscopic relaxations and the biological activity in proteins is correct, then not only the microscopic relaxations, but also the activity, could be sustained in proteins all the way down to the freezing temperature of a non-glass forming solvent with a weak temperature dependence of its viscosity. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo.

Effect of antimicrobial peptide on the dynamics of phosphocholine membrane: role of cholesterol and physical state of bilayer

Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fall in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol% melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Their importance lies in the fact that many membrane processes, including signaling and energy transduction pathways, are controlled to a great extent by the lateral diffusion of lipids in the membrane. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol% cholesterol. Our measurements indicate that the destabilizing effect of the peptide melittin on membranes can be mitigated by the presence of cholesterol. This study might provide new insights into the mechanism of action of antimicrobial peptides and their selective toxicity towards foreign microorganisms.

High-pressure dynamics of hydrated protein in bioprotective trehalose environment

We present a pressure-dependence study of the dynamics of lysozyme protein powder immersed in deuterated α,α-trehalose environment via quasielastic neutron scattering (QENS). The goal is to assess the baroprotective benefits of trehalose on biomolecules by comparing the findings with those of a trehalose-free reference study. While the mean-square displacement of the trehalose-free protein (hydrated to dD2O≃40 w%) as a whole, is reduced by increasing pressure, the actual observable relaxation dynamics in the picoseconds to nanoseconds time range remains largely unaffected by pressure--up to the maximum investigated pressure of 2.78(2) Kbar. Our observation is independent of whether or not the protein is mixed with the deuterated sugar. This suggests that the hydrated protein's conformational states at atmospheric pressure remain unaltered by hydrostatic pressures, below 2.78 Kbar. We also found the QENS response to be totally recoverable after ambient pressure conditions are restored. Small-angle neutron diffraction measurements confirm that the protein-protein correlation remains undisturbed. We observe, however, a clear narrowing of the QENS response as the temperature is decreased from 290 to 230 K in both cases, which we parametrize using the Kohlrausch-Williams-Watts stretched exponential model. Only the fraction of protons that are immobile on the accessible time window of the instrument, referred to as the elastic incoherent structure factor, is observably sensitive to pressure, increasing only marginally but systematically with increasing pressure.

Dynamics of lysozyme and its hydration water under an electric field

The effects of a static electric field on the dynamics of lysozyme and its hydration water are investigated by means of incoherent quasi-elastic neutron scattering (QENS). Measurements were performed on lysozyme samples, hydrated respectively with heavy water (D2O) to capture the protein dynamics and with light water (H2O), to probe the dynamics of the hydration shell, in the temperature range from 210 < T < 260 K. The hydration fraction in both cases was about ∼ 0.38 gram of water per gram of dry protein. The field strengths investigated were respectively 0 kV/mm and 2 kV/mm (~2 × 10(6) V/m) for the protein hydrated with D2O and 0 kV and 1 kV/mm for the H2O-hydrated counterpart. While the overall internal protons dynamics of the protein appears to be unaffected by the application of an electric field up to 2 kV/mm, likely due to the stronger intra-molecular interactions, there is also no appreciable quantitative enhancement of the diffusive dynamics of the hydration water, as would be anticipated based on our recent observations in water confined in silica pores under field values of 2.5 kV/mm. This may be due to the difference in surface interactions between water and the two adsorption hosts (silica and protein), or to the existence of a critical threshold field value Ec ~2-3 kV/mm for increased molecular diffusion, for which electrical breakdown is a limitation for our sample.

Common features in the microscopic dynamics of hydration water on organic and inorganic surfaces

The microscopic dynamics of hydration water exhibits some universal features that do not depend on the nature of the hydrated surface. We show that the hydration level dependence of the dynamic transition in the mean squared atomic displacements measured by means of elastic neutron scattering is qualitatively similar for hydration water in inorganic and organic hosts. The difference is that the former are 'rigid', whereas the dynamics of the latter can be enhanced by the motions of the hydration water. The overall hydration level appears to be the main parameter governing the magnitude of the mean squared atomic displacements in the hydration water, irrespective of the details of the hydrated host.

Small heat shock proteins and α-crystallins: dynamic proteins with flexible functions

The small heat shock proteins (sHSPs) and the related α-crystallins (αCs) are virtually ubiquitous proteins that are strongly induced by a variety of stresses, but that also function constitutively in multiple cell types in many organisms. Extensive research has demonstrated that a majority of sHSPs and αCs can act as ATP-independent molecular chaperones by binding denaturing proteins and thereby protecting cells from damage due to irreversible protein aggregation. As a result of their diverse evolutionary history, their connection to inherited human diseases, and their novel protein dynamics, sHSPs and αCs are of significant interest to many areas of biology and biochemistry. However, it is increasingly clear that no single model is sufficient to describe the structure, function or mechanism of action of sHSPs and αCs. In this review, we discuss recent data that provide insight into the variety of structures of these proteins, their dynamic behavior, how they recognize substrates, and their many possible cellular roles.

Mosaic structure of foot-and-mouth disease virus genomes

The results of a simple pairwise-scanning analysis designed to identify inter-serotype recombination fragments, applied to genome data from 156 isolates of Foot-and-mouth disease virus (FMDV) representing all seven serotypes, are reported. Large numbers of candidate recombinant fragments were identified from all parts of the FMDV genome, with the exception of the capsid genes, within which such fragments are infrequent. As expected, intertypic fragment exchange is most common between geographically sympatric FMDV serotypes. After accounting for the likelihood of intertypic convergence in highly conserved parts of the FMDV genome, it is concluded that intertypic recombination is probably widespread throughout the non-structural genes, but that recombination over the 2B/C and 3B/C gene boundaries appears to be less frequent than expected, given the large numbers of recombinant gene fragments arising in these genes.

CT in pseudomyxoma peritonei: a review of 17 cases

AIM

To describe the computed tomography (CT) findings in pseudomyxoma peritonei.

MATERIALS AND METHOD

Two observers independently and retrospectively reviewed the CT images of 17 consecutive patients (nine women, eight men, mean age 53 years) with histologically proven pseudomyxoma peritonei.

RESULTS

Six patients had small volume disease where pseudomyxoma peritonei was present in focal collections in the peritoneal cavity. Eleven had large volume disease that completely, or almost completely, filled the peritoneal cavity. Pseudomyxoma peritonei is characterized by low attenuation mucinous ascites on CT. Areas of high attenuation, septae and calcification are seen more commonly within it as the volume of disease increases. The pattern of accumulation of pseudomyxoma peritonei follows the normal flow of peritoneal fluid. It initially seeds at sites of relative stasis and as large volume disease develops it fills the remaining spaces in the peritoneal cavity and pressure effects dominate imaging. Pseudomyxoma peritonei may extend into hernial orifices or the pleural cavity.

CONCLUSION

Pseudomyxoma peritonei is difficult to diagnose clinically. However, the pattern of accumulation of disease is predictable and can be recognized on CT.

Spleen stromal cells support haemopoiesis and in vitro growth of dendritic cells from bone marrow

Long-term stroma-dependent cultures from murine spleen have been previously shown to support dendritic cell (DC) development in vitro. Secondary cultures have now been established using a splenic stromal cell layer overlaid with cells from different lymphoid sites. Cells resembling DCs can be generated in vitro from unfractionated murine lymphoid cells in the absence of added growth factors. Bone marrow (BM) cultures are the most successful but some cultures have been derived from spleen and thymus. Large numbers of mononuclear cells with dendritic morphology can be generated from BM within 2 weeks and cell production in many cultures has been maintained for at least 6 months. A significant proportion of cells binds antibodies specific for DC markers. No lymphoid cells, mast cells or granulocytes are detectable in culture by antibody and histochemical staining and light and electron microscopy. As with cells generated in primary cultures, cells grown in secondary cultures are equally potent stimulators of both syngeneic and allogeneic mixed lymphocyte reactions, confirming their function as antigen-presenting cells. They are also capable of endocytosing and presenting protein antigen to the D10.G4.1 Th2 clone and to unprimed T cells. This study confirmed the presence of DC precursors in multiple lymphoid sites which can be induced to proliferate in the presence of a spleen stromal cell monolayer. The secondary culture system provides an ideal in vitro model for investigation of the development of DC from different tissue sites. It also provides a stable and continuous resource of cells for further studies on DC development.

Review: dendritic cell immunotherapy for melanoma

Melanoma is a particularly aggressive malignant tumour of the skin that is influenced by genetic, environmental and physiological elements. Since current therapy for melanoma is limited and associated with high toxicity and side effects, development of alternative approaches is imperative. The importance of dendritic cells (DCs) in immunity against tumours is now well established. DC immunotherapy for melanoma is possible but must be considered in terms of effectiveness and clinical viability. The source of DCs to be used in adoptive therapy as well as the nature and method of delivery of the priming antigen are important factors. The most suitable DC appears to be cells derived by culture from hemopoietic progenitor cells (HPC) in bone marrow or DC progenitors in peripheral blood. Generation of an effective anti-tumour immune response will be dependent upon the presentation of multiple melanoma-specific antigens by both major histocompatibility complex (MHC) class I and class II molecules and stimulation of both tumour-specific cytotoxic T lymphocytes (Tc) and T helper type 1 (Thl) cells. Different techniques for delivery of the priming antigen offer different advantages. DCs can be pulsed with peptide, protein or tumour cell lysate, transfected with viral vectors or naked nucleic acid and tumour/DC hybridomas can also be generated. Repeated antigen administration into neighbouring lymph nodes appears to be the most effective method for promoting a systemic anti-tumour response. Adjuvant therapies can also enhance immune responses and lead to total tumour clearance. The importance of DC immunotherapy in clinically different stages of disease will also be an important consideration.

Cloning and analysis of the genes for a novel electron-transferring flavoprotein from Megasphaera elsdenii. Expression and characterization of the recombinant protein

The genes that encode the two different subunits of the novel electron-transferring flavoprotein (ETF) from Megasphaera elsdenii were identified by screening a partial genomic DNA library with a probe that was generated by amplification of genomic sequences using the polymerase chain reaction. The cloned genes are arranged in tandem with the coding sequence for the beta-subunit in the position 5' to the alpha-subunit coding sequence. Amino acid sequence analysis of the two subunits revealed that there are two possible dinucleotide-binding sites on the alpha-subunit and one on the beta-subunit. Comparison of M. elsdenii ETF amino acid sequence to other ETFs and ETF-like proteins indicates that while homology occurs with the mitochondrial ETF and bacterial ETFs, the greatest similarity is with the putative ETFs from clostridia and with fixAB gene products from nitrogen-fixing bacteria. The recombinant ETF was isolated from extracts of Escherichia coli. It is a heterodimer with subunits identical in size to the native protein. The isolated enzyme contains approximately 1 mol of FAD, but like the native protein it binds additional flavin to give a total of about 2 mol of FAD/dimer. It serves as an electron donor to butyryl-CoA dehydrogenase, and it also has NADH dehydrogenase activity.

Psychiatric morbidity in sentenced segregated HIV-positive prisoners

In this comparative study with a control group of prisoners, psychiatric morbidity was measured in two groups of sentenced prisoners, each group completing the GHQ-30 and 21-item Beck Depression Inventory (BDI). Group 1 consisted of 40 segregated HIV-positive prisoners and group 2 a matched control group in the main prison who had no history of HIV seropositivity. All members of group 1 had a history of intravenous drug abuse. The mean GHQ-30 and BDI scores were significantly higher in group 1, and 90% of group 1 were psychiatric 'cases' compared with just over 42% of group 2. Levels of psychiatric morbidity present in a third group, consisting of HIV-positive prisoners who had not been segregated (prison authorities were unaware of their seropositivity) are an interesting pointer for further research.

Adenovirus 12 and dermatitis herpetiformis

Previous studies have shown that A-gliadin, a major gluten-derived peptide known to activate the gluten-sensitive enteropathy (GSE) of coeliac disease (CD), and the non-structural E1B peptide produced during early lytic gastrointestinal infection with human adenovirus type 12 (AD12) share an identical twelve amino acid sequence. It is suggested that immunological cross reactivity between these two peptides may play an important role in the pathogenesis of CD. As a milder but histologically identical GSE is found in the majority of patients with dermatitis herpetiformis (DH), a condition also thought to be caused by dietary gluten, we postulated that AD12 may also be involved in the pathogenesis of DH. To test this we assayed sera from 40 patients with DH and 18 healthy controls for AD12-neutralizing antibodies as evidence of past viral exposure. Detectable AD12 antibodies (titre of 13 or higher) were found in only 15% (6/40) of DH patients, compared with 27.8% (5/18) controls (not significant). These findings do not support a causative role for AD12 in the pathogenesis of DH.

Blunted prolactin responses to d-fenfluramine in sociopathy. Evidence for subsensitivity of central serotonergic function

Using a neuroendocrine probe we studied nine male offenders in a forensic hospital, convicted of murder, with a diagnosis of antisocial personality disorder, who had been behaviourally 'quiescent' for varying periods and who had not recently been abusing drugs. Nine healthy age-matched men also participated. All subjects received 30 mg d-fenfluramine (d-FEN), a 5-HT releasing agent, orally, after an overnight fast, and serial samples for prolactin estimation were taken hourly for five hours. Responses were significantly impaired in the patients, suggesting a subsensitivity of certain 5-HT systems in antisocial personality disorder, regardless of recent or ongoing behavioural disturbance.

Hepatitis B screening in a northern Irish mental handicap institution: relevance to hepatitis B vaccination

The current DHSS guidelines on immunisation against hepatitis B in mental handicap hospitals recommend vaccination for personnel at risk directly involved in patient care (who may have direct contact with patients or their body fluids) and for new admissions into institutions where the incidence is known to be high. We report a serological survey of hepatitis B markers in over 99% of the residents of a large mental handicap hospital. Of 720 patients tested only one carried hepatitis surface antigen. This patient was anti-HBe positive. Only 4.5% of the residents carried any hepatitis marker. These results do not suggest the need for a local vaccination programme for patients or staff.

Skin blood flow changes and tissue deformations produced by cylindrical indentors

Since skin blood flow as a function of applied pressure depends on many factors, one may find different curves within each group of subjects, making separation of groups difficult. A dimensional analysis has been out which indicates that the percent decrease in skin blood flow associated with external loading is primarily a function of only three variables: the ratios of bone depth and bone diameter to indentor diameter, and percent compression of the tissue overlying the bone. The load itself is found to be unimportant. It is concluded that measurement of bone depth, bone diameter, and tissue deformation are more important than pressure measurements. Measurements of skin displacement and average indentor pressure for four male subjects indicate that tissue stiffness increases with age, regardless of disability, so that higher pressures are required to produce the same displacement in older subjects.

Development and evaluation of a universal contoured cushion

A new wheelchair seat cushion has been developed which reduces the ischaemia producing forces and redistributes them to the more tolerant areas of the posterior thighs and lateral gluteal muscles. The cushion is fabricated of foam materials and designed to stabilise the pelvis and promote proper spinal-pelvic alignment. Pressure measurements were recorded at the skin cushion interface for 66 subjects while seated on the cushion in their own wheelchair. The cushion was considered effective if maximum interface pressures recorded were: coccyx: less than 20 mmHg, ischii: less than 65 mmHg, trochanters: less than 70 mmHg, and posterior thighs: less than 80 mmHg. The cushion was considered ineffective if the interface pressure at any one location exceeded these criteria. The cushion was found effective for 52 of the subjects. The cushion was more effective (90 per cent versus 58 per cent) for subjects without certain skeletal deformities (pelvic obliquity, bony resections). Eighty-three per cent of the respondents who were followed on the cushion reported that they preferred the cushion to their previous cushions with improved posture, balance and comfort being the most commonly cited reasons. This study has shown the cushion to be a preferred alternative to other commercially available wheelchair cushions for those who are paraplegic.

Aetiology of chronic constrictive pericarditis

In a consecutive series of 32 cases of chronic constrictive pericarditis treated by pericardiectomy during the past 25 years, four were attributable to rheumatoid disease, two to trauma, one to sarcoidosis, and four, at a maximum, to tuberculosis. In the remaining 21 cases of undetermined aetiology there was no evidence of tuberculosis. It appears, therefore, that tuberculosis was not a common cause of chronic constrictive pericarditis during the period under review, which included the 1950s and early 1960s when tuberculosis was widespread.

Problems in the management of patients with artificial valves during pregnancy

During the past 15 years, 12 patients with prosthetic valves were treated during 18 pregnancies in the four Dublin maternity hospitals. These patients were on long-term anticoagulants and their pregnancies were reviewed to assess the problems associated with anticoagulation. One baby had warfarin embryopathy, six pregnancies ended in spontaneous abortions and there were two intrauterine deaths. On the basis of the findings a policy on the most appropriate anticoagulant regimen in such cases was formulated.

Haemodynamic effects of pregnancy in patients with heart failure

Four patients, who were maintained on a constant regimen of treatment, developed congestive cardiac failure during pregnancy. They were examined regularly and carefully during the course of pregnancy to assess the progress of their failure. All four demonstrated unequivocal improvement during the third trimester attributable to obstruction of the inferior vena cava restricting venous return to the right side of the heart. This resulted in a fall in venous pressure in the neck and the resulting fall in right ventricular output could be very valuable in patients with left ventricular failure.