Impacts of Covid-19 on mental health service provision in the Western Cape, South Africa: The MASC study

In the context of an already large treatment gap in South Africa, this study aimed to examine how Covid-19 and the related lockdown measures affected the availability, accessibility, quality, and continuity of mental health services in the Western Cape province in South Africa. A mixed-methods design was employed, using narrative surveys, quantitative surveys, and qualitative semi-structured interviews, with 17 public mental health providers, and secondary data from the District Health Information System. We analysed and combined the data using descriptive statistics, template analysis and methodological triangulation. Results showed that Covid-19 and the lockdowns had negative impacts on mental health service provision at all levels of care, such as reduced access to services, increased stigma and discrimination, disrupted medication supply, increased workload and stress for providers, and the closure of psychosocial and therapeutic services. Innovations used by providers to mitigate these impacts included telehealth, online training, peer support groups, and community outreach. The study concludes that Covid-19 and the lockdowns exposed and exacerbated the existing gaps and challenges in mental health service provision in South Africa. Key recommendations for policy formation and response to future pandemics in the public mental health sector include: classifying psychological treatments as essential services, establishing an intersectoral mental health emergency response plan, involving mental health care users in the development of pandemic responses, creating policies for managing health emergencies in psychiatric facilities, and increasing resources for the mental health sector in South Africa. These recommendations are relevant for South Africa and other LMICs in ensuring adequate mental health care during public health emergencies.

Incisional hernia following colorectal cancer surgery according to suture technique: Hughes Abdominal Repair Randomized Trial (HART)

BACKGROUND

Incisional hernias cause morbidity and may require further surgery. HART (Hughes Abdominal Repair Trial) assessed the effect of an alternative suture method on the incidence of incisional hernia following colorectal cancer surgery.

METHODS

A pragmatic multicentre single-blind RCT allocated patients undergoing midline incision for colorectal cancer to either Hughes closure (double far-near-near-far sutures of 1 nylon suture at 2-cm intervals along the fascia combined with conventional mass closure) or the surgeon's standard closure. The primary outcome was the incidence of incisional hernia at 1 year assessed by clinical examination. An intention-to-treat analysis was performed.

RESULTS

Between August 2014 and February 2018, 802 patients were randomized to either Hughes closure (401) or the standard mass closure group (401). At 1 year after surgery, 672 patients (83.7 per cent) were included in the primary outcome analysis; 50 of 339 patients (14.8 per cent) in the Hughes group and 57 of 333 (17.1 per cent) in the standard closure group had incisional hernia (OR 0.84, 95 per cent c.i. 0.55 to 1.27; P = 0.402). At 2 years, 78 patients (28.7 per cent) in the Hughes repair group and 84 (31.8 per cent) in the standard closure group had incisional hernia (OR 0.86, 0.59 to 1.25; P = 0.429). Adverse events were similar in the two groups, apart from the rate of surgical-site infection, which was higher in the Hughes group (13.2 versus 7.7 per cent; OR 1.82, 1.14 to 2.91; P = 0.011).

CONCLUSION

The incidence of incisional hernia after colorectal cancer surgery is high. There was no statistical difference in incidence between Hughes closure and mass closure at 1 or 2 years.

REGISTRATION NUMBER

ISRCTN25616490 (http://www.controlled-trials.com).

Debate: Is there a true global children and young people mental health crisis? Fact or Fiction: A South African Perspective

The article seeks to discuss the complexities that prevail in South Africa in attempting to understand the debate about whether there is a true global children and young people mental health crisis in the country. In the absence of reliable and current epidemiological data and prevalence studies, assumptions can only be made about the extent of the crisis when considering the prevailing social determinants of mental disorders. The lack of investment, limited child and adolescent mental health resources, and inadequate access to treatment complicate this crisis as many children and young people go untreated. The author argues that the debate should be focused on the need to address the risk factors that perpetuate the ever-increasing mental health concerns of children and youth in South Africa.

Abstract A015: Protein arginine deiminase enzymes which citrullinate epitopes for MHC II presentation are independent predictors of survival in colorectal cancer

Citrullination of proteins is associated with a number of autoimmune diseases. Protein Arginine Deiminases (PADs) are a family of Ca2+ dependent enzymes that under cellular stress post-translationally convert arginine to citrulline within protein substrates to generate self-modified neo-antigens. It has been shown that presentation of citrullinated peptides on MHC class II stimulates CD4 T cells to mediate potent anti-tumor immunity (1). In this study we focus on the role of the PADI2 and PADI4 family members in colorectal cancer. Using a tissue microarray of colorectal cancers and compiling a comprehensive database of clinicopathological variables, the expression of PADI2 and PADI4 was assessed by immunohistochemistry in a study cohort. This data was used to correlate PADI2 and PADI4 expression with patient survival.

In the study cohort 462 colorectal tumors were stained for PADI2 and PADI4. Of these 171 (37%) and 231 (50%) could not be evaluated for PADI2 and PADI4 staining respectively due to the absence of enough tissue core or no evaluable tumor cells (i.e. all stroma) in the core. Of the 291 evaluable colorectal tumors stained with a PADI2 specific antibody, only 18/291 (6.2%) tumors failed to stain. A further 153/291 (52.5%) stained weakly, 102/291 (35.1%) moderate and 18/291 (6.2%) stained strongly. Of the 231 evaluable colorectal tumors stained with a PADI4 specific antibody, no tumors failed to stain. All cases stained strongly for PADI4 expression within the nucleus. In the cytoplasm 63/231 (27.3%) stained weakly, 143/231 (61.9%) moderate and 25/231 (10.8%) stained strongly.

PADI2 expression did not correlate with any clinicopathological variables whereas nuclear but not cytoplasmic PADI4 showed a strong association with histological type (p = 0.008). Kaplan-Meier analysis showed there was a correlation of PADI2 and cytoplasmic PADI4 expression with improved survival. Expression of PADI2 gave an increase in survival time from 44.8 months (95% CI 24.3 to 65.4) to 76.2 months (95% CI 69.9 to 82.4, log rank test, p = 0.012). Expression of cytoplasmic PADI4 increased survival time from 57.9 months (95% CI 43.6 to 72.3) to 77.3 months (95% CI 69.6 to 85.1, log rank test, p = 0.012). No significant correlation was observed between PADI2 and the cytoskeletal protein Vimentin or the glycolytic enzyme α-enolase both reported to be citrullinated by PAD enzymes. PADI2 expression was significantly associated with expression of the Nuclear antigen Ki67 (p = 0.046) a cellular marker for proliferation. Nuclear PADI4 significantly correlated with the cytoplasmic glycolytic enzyme α-enolase only (p = 0.001) and cytoplasmic PADI4 was highly significantly associated with α-enolase located in both the cytoplasm (p<0.001) and shorter nuclear form (p<0.001) known as MBP-1, a transcription factor known to downregulate the activity of the c-myc proto-oncogene. Cytoplasmic PADI4 expression also significantly correlated with expression of the anti-apoptotic protein Bcl2 (p = 0.028). Multivariate analysis using Cox regression showed that PADI2 (p = 0.040)/Cytoplasmic PADI4 (p = 0.036), the stress related protein MICA (p = 0.006/0.022), vascular invasion (p<0.001, 0.040) and tumor stage (p<0.001/<0.001) are all independent markers of good prognosis in colorectal cancer. These results are consistent with the hypothesis that stressed tumor cells present citrullinated epitopes allowing their growth to be controlled by T cells.

References

1. Brentville VA, Metheringham RL, Gunn B, Symonds P, Daniels I, Gijon M, Cook K, Xue W, Durrant LG (2016). Citrullinated vimentin presented on MHC-II in tumor cells is a target for CD4+ T cell-mediated antitumor immunity. Cancer Research 2016 Feb 1;76(3):548-60

Citation Format: R. Metheringham, M. Gijon, I. Daniels, K. Cook, P. Symonds, T. Pitt, W. Xue, V. Brentville, L. Durrant. Protein arginine deiminase enzymes which citrullinate epitopes for MHC II presentation are independent predictors of survival in colorectal cancer [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A015.

Declaration on mental health in Africa: moving to implementation

Urgent action is needed to address mental health issues globally. In Africa, where mental health disorders account for a huge burden of disease and disability, and where in general less than 1% of the already small health budgets are spent on these disorders, the need for action is acute and urgent. Members of the World Health Organization, including African countries, have adopted a Comprehensive Mental Health Action Plan. Africa now has an historic opportunity to improve the mental health and wellbeing of its citizens, beginning with provision of basic mental health services and development of national mental health strategic plans (roadmaps). There is need to integrate mental health into primary health care and address stigma and violations of human rights. We advocate for inclusion of mental health into the post-2015 Sustainable Development Goals, and for the convening of a special UN General Assembly High Level Meeting on Mental Health within three years.

Immunomodulating Activity of Rifampicin

It has been shown that some antibiotics can modify cytokine production. We have examined the effect of rifampicin on secretion of interleukin-1beta (IL-1beta), IL-6, IL-10, and tumor necrosis factor alpha (TNF-alpha) by lipopolysaccharide (LPS)-stimulated or heat killed staphylococci (Pansorbin) stimulated monocytes. Secretion of IL-1beta and TNF-a were significantly inhibited (P<0.002) whereas secretion of IL-6 and IL-10 were significantly increased (P<0.003) by rifampicin treated mononuclear cells. Rifampicin had immunomodulatory effects through its capacity to alter the secretion of tested cytokines by human monocytes.

Clarifying the TNM staging of rectal cancer in the context of modern imaging and neo-adjuvant treatment: 'y''u' and 'p' need 'mr' and 'ct'

Recent developments in cross-sectional imaging, particularly computerized tomography and magnetic resonance imaging have provided increasingly accurate noninvasive preoperative staging, especially for rectal cancer. Image-based TNM staging, by definition a pathological system, has entered both the literature and everyday usage with no universal agreement as to the exact terminology. Clarification of the current terminology and suggestions to reflect recent developments are outlined to facilitate multidisciplinary team decision processes and objective stratification for entry to, and monitoring of, future clinical trials in rectal cancer.

Caspase-independent killing of Burkitt lymphoma cell lines by rituximab

Caspase-independent cell death may have a critical role to play in the therapeutic destruction of tumours. Recently it has been suggested that one of the mechanisms by which rituximab, a therapeutic anti-CD20 antibody, kills B cells is caspase-independent. In this study we show that rituximab can induce death in a variety of Burkitt lymphoma derived cell lines. Rituximab-treated cells show leakage of adenylate kinase, surface expression of phosphatidylserine, upregulation of the cellular stress protein HSP70, phosphorylation of the survival protein Akt, and depolarisation of the mitochondrial membrane but no loss of cytochrome c or apoptosis inducing factor. Caspase inhibitors do not block these events. In support of these data there is no cleavage of caspases 3, 8 and 9, poly(ADP-ribose) polymerase, BH3 interacting domain death agonist or genomic DNA. Morphologically, cells show nuclear enlargement and cytoplasmic vacuolisation. Triggering of receptor mediated death in CD95 responsive lines results in "classical" apoptosis indicating that the internal machinery necessary for apoptosis is intact in these lines. The results suggest that rituximab can kill human B cells via a caspase-independent form of programmed cell death that shares features of apoptosis and necrosis. This pathway may be relevant to the clinical efficacy of rituximab.

Distribution of mesorectal lymph nodes in rectal cancer: in vivo MR imaging compared with histopathological examination. Initial observations

The aim of this work was to determine the distribution of mesorectal lymph nodes using T2-weighted magnetic resonance (MR) imaging compared with histopathological findings in patients with rectal carcinoma. Sixteen patients with rectal carcinoma undergoing primary surgery without pre-operative neoadjuvant treatment were evaluated using 3-mm axial T2-weighted MR imaging. The position of each visible mesorectal node on imaging was localised by measuring its minimum distance from the mesorectal fascia (d(m)), its minimum distance from the rectal wall (d(r)) and its distance from the distal tumour margin (d(v)). Independent assessment of d(m), d(r) and d(v) was made at histopathological examination. Eighty-five mesorectal nodes on in vivo MR imaging were matched to histopathological findings. On imaging, 67/85 mesorectal nodes were found at the level of the tumour and 84/85 were identified at or within 5 cm proximal to the tumour. Only one out of 85 nodes was seen below the inferior tumour margin. The mean difference of d(m) and d(r) obtained on in vivo MR imaging and histopathological examination was 0.7 mm (95% confidence interval, CI, -0.12 to 1.42 mm) and -1.1 mm (95% CI -2.29 to 0.14 mm), respectively. Almost all mesorectal nodes visible on MR imaging were found at the level of tumour or within 5 cm proximal to the tumour. This has implications for the planning of MR imaging and the level of mesorectal transection at surgery.

Effect of a gluten-free diet on plasma nitric oxide products in coeliac disease

BACKGROUND

Inducible nitric oxide synthase is expressed in the small intestine of patients with coeliac disease. This produces increased plasma concentration of nitric oxide end products (NOx), most marked in those ingesting gluten. The time-course of change in NOx with a gluten-free diet (GFD) and its correlation with histology and coeliac serology were studied.

METHODS

Fasting plasma NOx was determined by the Greiss reaction in 20 coeliac patients at diagnosis and 2, 4 and 6 months after commencing a GFD. Endomysial and gliadin antibodies were checked at the same time. Duodenal biopsies were taken at diagnosis and at 6 months, and then graded according to the Marsh classification.

RESULTS

Plasma NOx fell rapidly following the introduction of a GFD (mean before GFD 95.8 microM to 61.5 microM at 2 months), and further still by 6 months (mean = 37.0 microM). Reductions at 2 and 6 months were statistically significant compared with baseline (P < 0.01 and P < 0.005, respectively: Wilcoxon signed ranks test). Plasma NOx was correlated with histological grade initially (P = 0.03: Kruskal-Wallis) but not after 6 months on a GFD (P = 0.24). Coeliac serology correlated poorly with histology.

CONCLUSIONS

Plasma NOx falls rapidly following GFD in coeliac disease and is related to histological grade initially. However, values vary widely between individuals, which may limit its use as a clinical tool.

Pleiotropic role of lyn kinase in leukotriene B(4)-induced eosinophil activation

The authors have examined the role of the src-family of protein tyrosine kinases in leukotriene B(4) (LTB(4))-induced activation of guinea-pig eosinophils. Western blot analysis identified the src-like protein tyrosine kinases p53(lyn), p56(lyn), p56/59(hck), p55(fgr), and p56(lck) whereas p60(src), p62(yes), p55(blk), and p59(fyn) were not detected. LTB(4) promoted a rapid increase in p53/56(lyn) activity in eosinophils, which peaked at 5 seconds and remained elevated at 60 seconds; hck, fgr, and lck were not activated. A role for p53/56(lyn) in eosinophil activation was investigated with the use of the src-selective inhibitor PP1 (1 micromol/L to 10 micromol/L), which attenuated LTB(4)-stimulated p53/56(lyn) activity and the phosphorylation of extracellular signal-regulated kinase-2 in intact cells. At comparable concentrations, PP1 was also shown to attenuate LTB(4)-induced nicotinamide adenine dinucleotide phosphate (reduced form) (NADPH) oxidase activation, chemotaxis, and Ca(++)-dependent [(3)H]arachidonic acid (AA) release. Moreover, an inhibitor of mitogen-activated protein kinase kinase-1, PD 098059, significantly inhibited LTB(4)-induced chemotaxis but had no effect on oxidant production or [(3)H]AA release. Collectively, these results implicate lyn kinase in LTB(4)-induced eosinophil activation through the recruitment of divergent cell-signaling pathways.

Role of p38 in the priming of human neutrophils by peritoneal dialysis effluent

Peritoneal dialysis effluent (PDE) contains a low-molecular-weight substance that is able to prime human neutrophils for the release of arachidonic acid and superoxide anion. Conventional priming agents, such as tumor necrosis factor alpha (TNF-alpha), are known to signal via mitogen-activated protein (MAP) kinases; at least one possible substrate for MAP kinases is cytosolic phospholipase A(2) (cPLA(2)). Phosphorylation of this enzyme results in arachidonic acid release, and this fatty acid is a potent primer and activator of the human neutrophil NADPH oxidase. Because of the striking similarities between the priming of neutrophils with agents such as TNF-alpha and PDE, we have investigated the signalling pathways evoked by PDE and explored the possibility that cPLA(2) is a target for activated MAP kinases. Our results show that PDE treatment of human neutrophils results in the phosphorylation of the p38 kinase rather than the p42 and p44 kinases. Phosphorylation of p38 is transient with maximal activity being observed 1 min after exposure to PDE. We were unable to demonstrate that activation of p38 resulted in phosphorylation of cPLA(2); furthermore, translocation of this enzyme to a membrane-containing fraction was not enhanced in PDE-treated neutrophils. Taken together, these data suggest that, in a manner similar to that of TNF-alpha, PDE primes human neutrophils by the activation of the p38 kinase. However, unlike the cytokine, the activation of this protein does not result in phosphorylation or activation of cPLA(2).

Significance of fatty acids in pregnancy-induced immunosuppression

Pregnancy can exert suppressive effects on chronic inflammatory conditions. We have previously demonstrated a depression in polymorphonuclear leukocyte (PMN) respiratory burst during pregnancy which could explain this amelioration. To elucidate the biochemical mechanism, we have examined PMN phospholipase A2 (PLA2) activity and its relationship to cellular and circulating fatty acids in pregnant women (30 to 34 weeks) and nonpregnant controls. PMN PLA2 activity was determined by arachidonic acid (AA) and leukotriene B4 (LTB4) release, respiratory burst activity was determined by lucigenin-enhanced chemiluminescence, and total serum and PMN fatty acid levels were determined by gas-liquid chromatography. AA release was significantly reduced for pregnancy PMNs in response to N-formyl-met-leu-phe (fMLP) under unprimed and tumor necrosis factor alpha (TNF-alpha)- or interleukin 8-primed conditions. Similarly, LTB4 liberation was significantly reduced in response to fMLP and phorbol myristate acetate in unprimed and TNF-alpha-primed pregnancy PMNs. All major fatty acid classes were altered in the pregnant state. Of these differences in PMNs, oleic acid and alpha-linolenic acid showed a significant increase (13 and 26%, respectively) and stearic acid and AA showed a significant decrease (8 and 30%, respectively). The stearic acid, oleic acid, and AA compositions of all cells analyzed correlated with their corresponding changes in serum fatty acid levels. Crossover serum incubations modified both fatty acid profiles and the PMN respiratory burst accordingly, while individual fatty acid incorporation studies highlighted the importance of polyunsaturated fatty acids for NADPH oxidase efficiency. These findings indicate that the attenuation of PMN function in pregnancy may originate from a reduction in the available pool of cellular fatty acids. Furthermore, this reduction arises as a direct result of a pregnancy-induced shift in circulating fatty acids from polyunsaturated to monounsaturated forms.

Role of arachidonic acid and its metabolites in the priming of NADPH oxidase in human polymorphonuclear leukocytes by peritoneal dialysis effluent

Peritoneal dialysis effluent (PDE) contains a low-molecular-weight solute that will activate and prime the NADPH oxidase of human neutrophils via a phospholipase A2 (PLA2)-dependent mechanism. Since the products of PLA2 are known to activate and prime the oxidase we have investigated their role in the dialysis effluent-mediated activation and priming of human neutrophils. NADPH oxidase activity of PDE-primed and -unprimed neutrophils was measured by lucigenin-enhanced chemiluminescence in the presence of known inhibitors of the arachidonic acid cascade. Incubation of neutrophils with the nonselective PLA2 inhibitor quinacrine (0 to 100 microM) reduced oxidase activity in both primed and unprimed cells. Furthermore, primed cells were more sensitive to the action of quinacrine than were unprimed cells. We were unable to determine the relative roles of secretory PLA2 (sPLA2) and cytosolic PLA2 (cPLA2) since the selective sPLA2 inhibitor scalaradial (0 to 100 microM) inhibited oxidase activity in both groups of cells by similar degrees, while the specific cPLA2 inhibitor AACO-CF3 (0 to 50 microM) failed to affect activity in either group. Inhibition of platelet-activating factor (PAF), cycloxygenase, and 5-lipoxygenase-activating protein by hexanolamino-PAF (0 to 25 microM), flurbiprofen (0 to 25 microM), and MK886 (0 to 5 microM), respectively, had no effect upon oxidase activity. However, the direct inhibition of 5-lipoxygenase by caffeic acid or lipoxin A4 resulted in a similar concentration-dependent attenuation of oxidase activity in both primed and unprimed cells. Leukotriene B4 (LTB4) release from primed neutrophils was comparable to that from unprimed cells with the exception of phorbol myristate acetate-stimulated cells, which released fivefold more LTB4 than control. Taken together, these results suggest that it is arachidonic acid per se, and not its metabolites, that is important in priming of the neutrophil NADPH oxidase by dialysis effluent.

Impaired bacterial killing and hydrogen peroxide production by polymorphonuclear neutrophils in end-stage renal failure

Polymorphonuclear leukocytes (PMN) isolated from a sub-population of patients with end-stage renal failure (ESRF) who were identified because they demonstrated impaired intracellular bacterial killing, were assayed for hydrogen peroxide activity using two different techniques capable of distinguishing between total and intracellular hydrogen peroxide generation. In an attempt to elucidate the mechanism of impaired intracellular bacterial killing further, hydrogen peroxide activity was compared to PMN isolated from patients receiving continuous ambulatory peritoneal dialysis and a control group of healthy normal volunteers. PMN from conservatively treated ESRF patients demonstrated reduced production of intracellular hydrogen peroxide (mean 37.7 +/- 4.3 fluorescence units), compared to PMN from both ESRF patients treated with continuous ambulatory peritoneal dialysis (mean 57.9 +/- 6.6 fluorescence units) and normal controls (mean 60.4 +/- 3.5 fluorescence units). This suggests that the probable mechanism of impaired bacterial intracellular killing by the PMN of conservatively treated ESRF patients involves the production of intracellular hydrogen peroxide.

Phospholipases and the activation and priming of neutrophils by peritoneal dialysis effluent

OBJECTIVE

To investigate the role of phospholipase during the activation and priming of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase by peritoneal dialysis effluent (PDE).

DESIGN

Examine the action of 4-hour dwell PDE upon phospholipase activation in the circulating neutrophils obtained from healthy individuals.

RESULTS

We have previously reported that PDE stimulated superoxide release by the NADPH oxidase of human neutrophils and primed the response to the bacterial peptide, fMLP (fMetLeuPhe). To elucidate the biochemical mechanisms underlying these observations, we have examined the roles of phospholipases (PL) C, D, and A2, whose activation causes the release of a range of intracellular secondary messengers. Following fMLP stimulation, we observed a rapid activation of both PLC and PLD as well as a small but nonsignificant increase in PLA2 activity. Peritoneal dialysis effluent alone failed to stimulate either PLC or PLD, while pre-incubation with PDE had no affect upon fMLP-induced PLC and PLD activation. However, PDE caused a small but nonsignificant increase in PLA2 activity (which was comparable to that observed with fMLP) and primed the fMLP-induced response. In common with a role for PLA2 and the subsequent release of arachidonic acid (AA), we have demonstrated dose-dependent inhibition of PDE-induced superoxide release by the PLA2 inhibitor mepacrine, as well as activation and priming of the fMLP-induced superoxide generation by AA.

CONCLUSIONS

These results imply that PDE-induced NADPH-oxidase activation and priming in human neutrophils is mediated via a PLA2-dependent but PLC- and PLD-independent mechanism.

Hydrogen peroxide generation by polymorphonuclear leukocytes exposed to peritoneal dialysis effluent

In the presence of peritoneal dialysis effluent (PDE), human polymorphonuclear leukocytes (PMN) showed reduced production of hydrogen peroxide and hypochlorous acid (H2O2 and HOCl, respectively) when at rest and when stimulated with both soluble (formylmethionyl-leucyl-phenylalanine and phorbol myristate acetate) and particulate (Staphylococcus epidermidis) agonists. This effect occurred in a concentration-dependent manner between 0 and 70%. (vol/vol) dialysis effluent. The inhibition of H2O2 and HOCl observed in resting, formy-methionylleucyphenyalanine-stimulated, and S. epidermidis-stimulated PMN was confined to a low-molecular-mass (< 10,000-Da) fraction of PDE, whereas the inhibition of the PMA response was equally dispersed throughout both low (< 10,000-Da)- and high-molecular-mass (> 10,000-Da) fractions. Human serum albumin, a major component of PDE, also inhibited H2O2 and HOCl production by PMN; however, results from cell-free systems suggested that human serum albumin was not wholly responsible for the inhibition of PMN function seen with PDE. The solute(s) responsible did not affect myloperoxidase but very rapidly scavenged H2O2 and HOCl. These data suggest that the factors capable of affecting H2O2 and HOCl production by PMN accumulate in uremia and are removed from the circulation into dialysis effluent.

Impaired polymorphonuclear neutrophil function in end-stage renal failure and its correction by continuous ambulatory peritoneal dialysis

The polymorphonuclear neutrophil (PMN) function of 22 patients with end-stage renal failure (ESRF) was studied immediately before and 3 months after starting continuous ambulatory peritoneal dialysis (CAPD) and compared with a control group of healthy normal volunteers. The PMN functions studied were phagocytosis and killing of Staphylococcus epidermidis and respiratory burst activity. The results show that in the presence of normal pooled human serum PMN from patients with ESRF before CAPD treatment phagocytose bacteria normally, but have impaired killing. Before treatment, the PMN from patients with ESRF also showed an increase in both unstimulated and stimulated superoxide anion production. Abnormal PMN function was corrected by CAPD treatment, suggesting the involvement of a dialyzable toxin.

Refined localization of TSC1 by combined analysis of 9q34 and 16p13 data in 14 tuberous sclerosis families

Tuberous sclerosis (TSC) is a heterogeneous trait. Since 1990, linkage studies have yielded putative TSC loci on chromosomes 9, 11, 12 and 16. Our current analysis, performed on 14 Dutch and British families, reveals only evidence for loci on chromosome 9q34 (TSC1) and chromosome 16p13 (TSC2). We have found no indication for a third locus for TSC, linked or unlinked to either of these chromosomal regions. The majority of our families shows linkage to chromosome 9. We have refined the candidate region for TSC1 to a region of approximately 5 cM between ABL and ABO.

Primary and secondary granule release by polymorphonuclear leukocytes exposed to peritoneal dialysis effluent

Peritoneal dialysis effluent from patients with end-stage renal failure contains a low-molecular-weight solute that inhibits the killing of phagocytosed Staphylococcus epidermidis by polymorphonuclear leukocytes (PMN). This observation has been investigated by using luciginen-enhanced chemiluminescence to measure PMN NADPH oxidase activity, CD11b/CD18 expression and lactoferrin release to measure secondary granule discharge, and cellular levels of beta-glucuronidase (EC 3.2.1.31) to measure changes in primary granules. Peritoneal dialysis effluent had no effect on the loss of intracellular beta-glucuronidase from normal unstimulated PMN or from PMN stimulated with S. epidermidis. It did, however, cause a concentration-dependent (0 to 70%; vol/vol) increase in expression of CD11b/CD18 and NADPH oxidase activity. CD11b/CD18 expression increased over 20 min before starting to plateau. Release of lactoferrin by the same cells demonstrated a strong positive correlation with integrin expression (P < 0.001, Spearman's rank correlation coefficient). When dialysis effluent-treated PMN were stimulated with formyl-methionylleucylphenylalanine, integrin expression, release of lactoferrin, and NADPH oxidase activity were greater than in PMN treated with formyl-methionylleucylphenylalanine alone. Under these conditions, a concentration-dependent increase in CD11b/ CD18 and lactoferrin release were observed only at a concentration between 0 and 30% (vol/vol) dialysis effluent, while a concentration-dependent increase in oxidase activity was seen at a concentration between 0 and 70% (vol/vol). The results suggest that dialysis effluent does not affect PMN primary granule release but does cause increased release of secondary granules and an increase in NADPH oxidase activity in both unstimulated and stimulated PMN.

Effect of peritoneal dialysis effluent on superoxide anion production by polymorphonuclear neutrophils

Peritoneal dialysis effluent (PDE) contains at least 2 factors capable of affecting superoxide generation by polymorphonuclear neutrophils (PMN) in response to both particulate and soluble stimuli. A low molecular weight fraction (< 1.2 kD) enhanced the response to the chemotactic peptide fMLP and to preopsonised Staphylococcus epidermidis and Candida guilliermondii. A higher molecular weight fraction (> 1.2 kD) inhibited superoxide production in response to phorbol myristate acetate (PMA). The effects of PDE were dose dependent over the range of 10-70% (v/v) and simply augmented and reduced the dose-response curve to fMLP and PMA, respectively. There was no alteration in the concentration of stimulus required to give maximal superoxide production in either case. These data suggest that factors capable of affecting superoxide production by PMN accumulate in uraemia and are removed from the circulation into dialysis fluid.

Abnormal cytoplasmic pH regulation during activation in uremic neutrophils

Neutrophils isolated from ESRF patients demonstrated abnormal cytoplasmic pH changes after FMLP stimulation; the initial cytoplasmic acidification was absent (P less than 0.001 compared to controls) and the degree of alkalinization enhanced (P less than 0.05 compared to controls). This effect was not due to the absence of any of the factors associated with acidification in normal PMN since superoxide production was enhanced (P less than 0.05 compared to controls) and intracellular calcium release was normal. Our observations are not explicable by alterations in the function of the Na:H antiport since the kinetics of antiport activation by cytoplasmic pH were not different in uremic and control cells. Other factors must therefore be important in generating the abnormal pH response to chemotactic factors in uremic PMN. Cells from CAPD patients had some degree of initial acidification (P less than 0.001 compared to controls and P less than 0.05 compared to ESRF) and enhanced alkalinization (P less than 0.05 compared to controls). Preincubation of normal PMN in four-hour dwell PDE reproduced the responses of uremic PMN with absent acidification, enhanced alkalinization and enhanced superoxide generation after FMLP stimulation (P less than 0.05 compared to controls). Changes in the control of cytoplasmic pH in stimulated PMN may influence PMN function, and our observations may be relevant to the susceptibility of uremic patients to infection.

Changes in murine tissue concentrations of dolichol and dolichol derivatives associated with age

The concentrations of the three major cellular forms of dolichol (free, esterified and phosphorylated) were determined in murine liver, kidney and heart. The tissue levels of these forms of dolichol were studied in detail as a function of age. Changes in the activities of dolichyl phosphate phosphatase and dolichol kinase were also determined. In liver, the concentration of unesterified dolichol, fatty acyl dolichol and dolichyl phosphate increased markedly over a period of 6 to 25 months (four-fold, 5.5-fold and nine-fold, respectively). In kidney only, free dolichol and phosphorylated dolichol increased (approximately four-fold in each case). However, this tissue consistently showed the highest concentrations of all forms of dolichol as compared to liver and heart. In heart, both free and esterified dolichol concentrations increased (approximately 3.25-fold in each case); dolichyl phosphate levels were not determined in this tissue. In all tissues studied, the activity of the dolichyl phosphate phosphatase enzyme was considerably higher than that of the dolichol kinase enzyme. In liver, there was no evidence to suggest that either enzyme was critical in determining the relative concentrations of dolichol and dolichyl phosphate. Evidence for such a role for the kinase in the kidney was stronger. Treatment of aging mice with meclofenoxate, a drug that is reported to cause dissolution of lipofuscin, failed to prevent accumulation of dolichol and dolichyl phosphate with age. These observations suggest that not all accumulated dolichol is associated with lipofuscin. Meclofenoxate treatment had no consistent effect on the activities of the enzymes studied.