Editorial Comments/ Redaksionele Kommentaar

This edition of Health SA Gesondheid provides thought provoking commentary on a variety of challenges experienced in the field of health care. Opsomming Hierdie uitgawe van Health SA Gesondheid verskaf kommentaar oor talle uitdagings wat in die veld van gesondheidsorg ondervind word. *Please note: This is a reduced version of the abstract. Please refer to PDF for full text.

Update on the pathophysiology and classification of von Willebrand disease: a report of the Subcommittee on von Willebrand Factor

von Willebrand disease (VWD) is a bleeding disorder caused by inherited defects in the concentration, structure, or function of von Willebrand factor (VWF). VWD is classified into three primary categories. Type 1 includes partial quantitative deficiency, type 2 includes qualitative defects, and type 3 includes virtually complete deficiency of VWF. VWD type 2 is divided into four secondary categories. Type 2A includes variants with decreased platelet adhesion caused by selective deficiency of high-molecular-weight VWF multimers. Type 2B includes variants with increased affinity for platelet glycoprotein Ib. Type 2M includes variants with markedly defective platelet adhesion despite a relatively normal size distribution of VWF multimers. Type 2N includes variants with markedly decreased affinity for factor VIII. These six categories of VWD correlate with important clinical features and therapeutic requirements. Some VWF gene mutations, alone or in combination, have complex effects and give rise to mixed VWD phenotypes. Certain VWD types, especially type 1 and type 2A, encompass several pathophysiologic mechanisms that sometimes can be distinguished by appropriate laboratory studies. The clinical significance of this heterogeneity is under investigation, which may support further subdivision of VWD type 1 or type 2A in the future.

The Healthy Tree: A Metaphorical Perspective of Counselor Well-being

Counseling is a risky and rewarding business. While counseling invites mental health counselors to participate with their clients in the awesome process of human growth and healing, it also may threaten their well being through exposure to their clients' trauma and its painful consequences.The authors present a metaphor of a healthy tree to organize an overview of recent research regarding the risk and protective factors of vicarious traumatization of counselors. Implications for the practice, supervision, and management of counseling are presented.

PD-1/PDL-1 expression in colorectal cancer and its implications for tumor immune evasion

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Background: Malignant tumors may evade immunological surveillance by an active downregulation of T cell activation by PD-1 (programmed death 1)/ PDL-1 signaling. This would result in a decreased immune response, thus, promoting tumor growth. Methods: We analyzed the expression of PD-1/PDL-1 genes, cytokines, and T cell subpopulations in tumor tissues of 81 consecutive patients who underwent surgery for primary colorectal cancer according to their UICC stage. Expression of PD-1/PDL-1, T cell subpopulations, and cytokines in tumor tissues were assessed using immunostaining, immunofluorescence, and Real Time PCR. Results: PDL-1 expression on tumor cells was significantly increased, whereas PD-1 expression on tumor cells was decreased at UICC stage III/IV. However, PD-1 expression on infiltrating CD4+ T cells was detectable in patients with advanced tumors whereas PDL-1 expression on CD4+ cells was particularly found at early stages. More regulatory T cells (CD4+CD25+CTLA-4+Foxp3+) were observed in tumors of stage III/IV patients compared to early stages. In addition, a remarkably increased amount of IL-10 was observed in the tumors of UICC III/IV patients. High expression of TGF-ß receptor II in tumors correlated with a progressive course of the disease and tumor relapses, i.e. TGF-ß RII in early tumor stages was indicative for early tumor progress. Conclusions: Our findings indicate that PDL-1 plays a key role during tumor progression and that regulatory T cells are involved in the process of evasion from immune surveillance. The elevated PDL-1 expression on T cells at early tumor stages suggests that PD1/PDL-1 interaction mediates inhibitory signals between T cells enabling the tumor to progress. PDL-1 blockade may prove to be a valuable approach for cancer immunotherapy.

No significant financial relationships to disclose.

Applying biofluid 1H NMR-based metabonomic techniques to distinguish between HIV-1 positive/AIDS patients on antiretroviral treatment and HIV-1 negative individuals

Metabonomics, the study of metabolites and their role in various physiological states, is a novel methodology arising from the post-genomics era and has extensive biomedical application. This technology has exhibited vast success in the identification and study of human diseases and may find further application in the study of HIV/AIDS. Specifically, the wide range of clinical and metabolic abnormalities associated with the use of antiretroviral (ARV) treatment may be investigated. To this end, this preliminary study evaluated whether metabonomic techniques could distinguish between HIV-1 positive/AIDS patients utilizing antiretroviral therapy and HIV-1 negative individuals. Serum metabolic profiles determined by 1H nuclear magnetic resonance (NMR) spectroscopy combined with pattern recognition analysis of the data showed that this distinction was attainable; suggesting that ARV-associated side-effects could be monitored utilizing NMR metabonomic techniques.

A quantitative analysis of bleeding symptoms in type 1 von Willebrand disease: results from a multicenter European study (MCMDM-1 VWD)

BACKGROUND

A quantitative description of bleeding symptoms in type 1 von Willebrand disease (VWD) has never been reported.

OBJECTIVES

The aim was to quantitatively evaluate the severity of bleeding symptoms in type 1 VWD and its correlation with clinical and laboratory features.

PATIENTS AND METHODS

Bleeding symptoms were retrospectively recorded in a European cohort of VWD type 1 families, and for each subject a quantitative bleeding score (BS) was obtained together with phenotypic tests.

RESULTS

A total of 712 subjects belonging to 144 families and 195 controls were available for analysis. The BS was higher in index cases than in affected family members (BS 9 vs. 5, P < 0.0001) and in unaffected family members than in controls (BS 0 vs. -1, P < 0.0001). There was no effect of ABO blood group. BS showed a strong significant inverse relation with either von Willebrand ristocetin cofactor (VWF:RCo), von Willebrand antigen (VWF:Ag) or factor VIII procoagulant activity (FVIII:C) measured at time of enrollment, even after adjustment for age, sex and blood group (P < 0.001 for all the four upper quintiles of BS vs. the first quintile, for either VWF:RCo, VWF:Ag or FVIII:C). Higher BS was related with increasing likelihood of VWD, and a mucocutaneous BS (computed from spontaneous, mucocutaneous symptoms) was strongly associated with bleeding after surgery or tooth extraction.

CONCLUSIONS

Quantitative analysis of bleeding symptoms is potentially useful for a more accurate diagnosis of type 1 VWD and to develop guidelines for its optimal treatment.

Linkage analysis in families diagnosed with type 1 von Willebrand disease in the European study, molecular and clinical markers for the diagnosis and management of type 1 VWD

BACKGROUND

von Willebrand disease (VWD) type 1 is a congenital bleeding disorder caused by genetic defects in the von Willebrand factor (VWF) gene and characterized by a reduction of structurally normal VWF. The diagnosis of type 1 VWD is difficult because of clinical and laboratory variability. Furthermore, inconsistency of linkage between type 1 VWD and the VWF locus has been reported.

OBJECTIVES

To estimate the proportion of type 1 VWD that is linked to the VWF gene.

PATIENTS AND METHODS

Type 1 VWD families and healthy control individuals were recruited. An extensive questionnaire on bleeding symptoms was completed and phenotypic tests were performed. Linkage between VWF gene haplotypes and the diagnosis of type 1 VWD, the plasma levels of VWF and the severity of bleeding symptoms was analyzed.

RESULTS

Segregation analysis in 143 families diagnosed with type 1 VWD fitted a model of autosomal dominant inheritance. Linkage analysis under heterogeneity resulted in a summed lod score of 23.2 with an estimated proportion of linkage of 0.70. After exclusion of families with abnormal multimer patterns the linkage proportion was 0.46. LOD scores and linkage proportions were higher in families with more severe phenotypes and with phenotypes suggestive of qualitative VWF defects. About 40% of the total variation of VWF antigen could be attributed to the VWF gene.

CONCLUSIONS

We conclude that the diagnosis of type 1 VWD is linked to the VWF gene in about 70% of families, however after exclusion of qualitative defects this is about 50%.

Behavioral phenotyping of mice lacking the K ATP channel subunit Kir6.2

ATP-sensitive potassium (K(ATP)) channels are expressed in various tissues and cell-types where they act as so-called metabolic sensors that couple metabolic state to cellular excitability. The pore of most K(ATP) channel types is built by Kir6.2 subunits. Analysis of a general Kir6.2 knockout (KO) mouse has identified a variety of different functional roles for central and peripheral K(ATP) channels in situations of metabolic demand. However, the widespread distribution of these channels suggests that they might influence cellular physiology and animal behavior under metabolic control conditions. As a comprehensive behavioral description of Kir6.2 KO mice under physiological control conditions has not yet been carried out, we subjected Kir6.2 KO and corresponding wild-type (WT) mice to a test battery to assess emotional behavior, motor activity and coordination, species-typical behaviors and cognition. The results indicated that in these test situations Kir6.2 KO mice were less active, had impaired motor coordination, and appeared to differ from controls in their emotional reactivity. Differences between KO and WT mice were generally attenuated in test situations that resembled the home cage environment. Moreover, in their home cages KO mice were more active than WT mice. Thus, our results suggest that loss of Kir6.2-containing K(ATP) channels does affect animal behavior under metabolic control conditions, especially in novel situations. These findings assign novel functional roles to K(ATP) channels beyond those previously described. However, according to the widespread expression of K(ATP) channels, these effects are complex, being dependent on details of test apparatus, procedure and prior experience.

Increased metastatic potential of tumor cells in von Willebrand factor-deficient mice

BACKGROUND

The key role played by von Willebrand factor (VWF) in platelet adhesion suggests a potential implication in various pathologies, where this process is involved. In cancer metastasis development, tumor cells interact with platelets and the vessel wall to extravasate from the circulation. As a potential mediator of platelet-tumor cell interactions, VWF could influence this early step of tumor spread and therefore play a role in cancer metastasis.

OBJECTIVES

To investigate whether VWF is involved in metastasis development.

METHODS

In a first step, we characterized the interaction between murine melanoma cells B16-BL6 and VWF in vitro. In a second step, an experimental metastasis model was used to compare the formation of pulmonary metastatic foci in C57BL/6 wild-type and VWF-null mice following the injection of B16-BL6 cells or Lewis lung carcinoma cells.

RESULTS

In vitro adhesion assays revealed that VWF is able to promote a dose-dependent adhesion of B16-BL6 cells via its Arg-Gly-Asp (RGD) sequence. In the experimental metastasis model, we found a significant increase in the number of pulmonary metastatic foci in VWF-null mice compared with the wild-type mice, a phenotype that could be corrected by restoring VWF plasma levels. We also showed that increased survival of the tumor cells in the lungs during the first 24 h in the absence of VWF was the cause of this increased metastasis.

CONCLUSION

These findings suggest that VWF plays a protective role against tumor cell dissemination in vivo. Underlying mechanisms remain to be investigated.

Mutations C1157F and C1234W of von Willebrand factor cause intracellular retention with defective multimerization and secretion

The D3 domain of von Willebrand factor (VWF) is involved in the multimerization process of the protein through the formation of disulfide bridges. We identified heterozygous substitutions, C1157F and C1234W, in the VWF D3 domain in two unrelated families with unclassified and type 2A von Willebrand disease, respectively. VWF was characterized by a low plasmatic level, an abnormal binding to platelet GPIb and a high capacity of secretion from endothelial cells following DDAVP infusion. Using site-directed mutagenesis and expression in mammalian cells, we have investigated the impact of these mutations upon the multimerization, secretion and storage of VWF. Using COS-7 cells both mutated recombinant VWF (rVWF) displayed only lower molecular weight multimers. Pulse-chase analysis and endoglycosidase H digestion experiments showed the intracellular retention of mutated rVWF in pre-Golgi compartments. Study of hybrid rVWF obtained with a constant amount of wild-type (WT) DNA and increasing proportions of mutated plasmids established that both substitutions reduced the release of WT VWF in a dose-dependent manner and failed to form high molecular weight multimers. Using transfected AtT-20 stable cell lines, we observed similar granular storage of the two mutants and WT rVWF. Our data suggest that cysteines 1157 and 1234 play a crucial role in the early step of the folding of the molecule required for a normal transport pathway, maturation and constitutive secretion. In contrast, their substitution does not prevent the storage and inducible secretion of VWF.

Eye signs that alert the clinician to a diagnosis of AIDS

One of the hallmarks of progressive immune deficiency is a steady decline in the absolute number of CD4+ T-lymphocytes. As the immune response thus becomes suppressed, opportunistic systemic infections such as protozoal (Pneumocystis carinii pneumonia, disseminated toxoplasmosis), viral (Cytomegalovirus pneumonitis and colitis and persistent invasive herpes simplex lesions), fungal (cryptococcossis and esophageal candidiasis) and bacterial infections (atypical mycobacterial and extrapulmonary tuberculosis) set in to claim their toll. Ocular complications occur in about 75% of AIDS patients and may be divided into four categories: Retinal microangiopathy, Opportunistic infections, Tumours, Neuro-ophthalmological lesions. Only the most frequently occurring manifestations will be highlighted.

Prediction of Manure and Nutrient Excretion from Dairy Cattle

Accurate estimates of manure excretion are needed for planning manure storage facilities and for nutrient management. Data sets from metabolism studies conducted at several universities were compiled and evaluated for excretion of total manure, N, P, and K. Animal groups included calves weighing up to 204 kg, heifers weighing between 274 and 613 kg, nonlactating cows, and lactating cows. Regression equations were developed to predict excretion of total manure, total dry matter, N, P, and K. Predictors used in the regression equations for lactating cows included milk yield, percentages of protein and fat in milk, dietary concentrations of crude protein and neutral detergent fiber, and intakes of nutrients. The regression equations provide improved predictions of excretion and enable more accurate planning of manure storage and nutrients to be managed at the farm level.

Selection and interpretation of clinical pathology indicators of hepatic injury in preclinical studies

This position paper delineates the expert recommendations of the Regulatory Affairs Committee of the American Society for Veterinary Clinical Pathology for the use of preclinical, clinical pathology endpoints in assessment of the potential for drug-induced hepatic injury in animals and humans. Development of these guidelines has been based on current recommendations in the relevant preclinical and human clinical trial literature; they are intended to provide a method for consistent and rigorous interpretation of liver-specific data for the identification of hepatic injury in preclinical studies and potential liability for hepatic injury in human patients.

GC-IR based two-dimensional structural group analysis of petroleum products

To characterize petroleum products, a method based on the combination of IR-spectrometric structural group analysis, GC-simulated boiling analysis and multivariate regression techniques (PLS, PCR) has been developed. The best performance was achieved by a PLS regression model with six aliphatic and aromatic structural groups. Thereby, structural group distribution related to the boiling temperature could be obtained in order to quantify product-specific distribution parameters and to control material-conversion processes caused by biodegradation.

[Nononcologic abdominal surgery in the elderly]

Due to rising life expectancy of the population, the proportion of elderly patients requiring surgery is rising as well. Present aspects of selected, typical, nononcologic diseases of elderly people are discussed. The key to success in their treatment is not to consider primarily the patient's calendrical age but to assess the individual profile of risk factors on the basis of comorbidities. The kind, extent, and timing of an operation has to be based on this assessment. For the treatment of acute diseases (e.g., complicated ulcera, cholecystitis, appendicitis, mesenteric ischemia, and diverticulitis), a rapid and efficacious diagnostic algorithm is essential that takes into account the reduced functional reserve of old people. Constructive interdisciplinary cooperation and minimally invasive techniques play dominant roles in both diagnosis and therapy. Given these prerequisites, there is no reason to withhold surgical intervention from elderly patients.

Evaluation of a synthetic vaccine construct as antigen for the detection of HIV-induced humoral responses

Synthetic V3 loop peptides hold numerous benefits for the development of HIV vaccines and in immunodiagnosis; however, their use is limited due to the extensive antigenic variability of this region. The effectiveness of a potential HIV vaccine component, which accounts for V3 loop variability, is evaluated here. A branched peptide construct representing multiple sequences and allowing 1.8 x 10(16) possible permutations was developed to mimic circulating HIV-1 subtype C, V3 loops. The construct was found to be immunogenic, able to induce neutralizing antibodies and sensitive to HIV-1 subtype B/C and HIV-2. This alternative antigen format also incorporates conformational epitopes.

Simulation of a subsurface vertical flow constructed wetland for CSO treatment

Constructed wetlands (CWs) have proved to be a highly effective measure to reduce the ecological impact of combined sewer overflows (CSOs) on receiving waters. Due to the stochastic nature of the loading regime and the multitude of environmental influences, assessment of the performance of such plants requires detailed mathematical modelling. A multi-component reactive transport module (CW2D) was applied to simulate the flow, transport and degradation processes occurring in a CW for CSO treatment. CW2D was originally developed to simulate the treatment of municipal wastewater in subsurface flow CWs. Loading and operational conditions in CSO treatment differ fundamentally from the conditions occurring for wastewater treatment. Despite these differences, first results from the simulation of lab-scale experiments show, that the model is generally applicable to this type of plant. Modelling of adsorption, degradation processes, and influent fractionation, however, require further research.

A pilot study of deep sclerectomy with implantation of chromic suture material as a collagen implant: medium-term results

AIMS

A pilot study of the safety and efficacy of deep sclerectomy with a chromic suture implant (DSCI) for open angle glaucoma.

METHODS

This prospective trial involved 23 eyes of 16 consecutive patients with uncontrolled open angle glaucoma. The DSCI procedure involved radial suturing of a 2 mm piece of 1/0 chromic suture as an implant. Intraocular pressure (IOP) measurements and eye examinations were performed preoperatively and regularly postoperatively for up to 66 months.

RESULTS

The mean follow-up period was 36.3 (SD 19.9) months. The mean preoperative IOP was 26.3 (SD 8.5) mmHg. The mean postoperative IOP was 14.1 (SD 2.8) mmHg at month 12, and 16.5 (SD 2.3) mmHg at 36 months. Complete success rate, defined as an IOP lower than 21 mmHg without medication was 77% of eyes at 36 months. Qualified success rate, defined as an IOP lower than 21 mmHg with medication, was 100% at 36 months. Paired t-test and Wilcoxon test analysis of preoperative vs postoperative IOP at 36 months indicated a significant reduction in IOP. Intraoperative complications included rupture of the trabecular meshwork in seven eyes. Exclusion of these patients from the results analysis revealed a mean follow-up of 37.1 months (SD 9), preoperative mean IOP was 25.9 mmHg (SD 4.1), 12-month mean IOP was 13.4 mmHg (SD 2.8), and 36-month mean IOP 16.6 mmHg (SD 2.1). Early postoperative complications included hyphaema in two eyes and dislocation of implant in one eye. One eye developed a central retinal vein occlusion and cataract progression occurred in one eye. The mean postoperative duration of use of topical dexamethasone was 5.4 months (SD 2).

CONCLUSIONS

DSCI using a chromic suture implant provides good control of IOP at medium-term follow-up with few postoperative complications. Prolonged use of postoperative anti-inflammatory medication was necessary.

Livestock nutrient management concerns: regulatory and legislative overview

A greater focus on manure nutrient disposition from concentrated animal-feeding operations has developed from environmentalists, concerned citizens, and regulatory agencies. The establishment and enforcement of manure nutrient regulations will alter the future of livestock production. Proposed legislation and strategies may provide a false sense of security regarding environmental preservation or restoration and may impose monitoring and record keeping on the livestock operators. Existing regulations and proposed regulations and strategies are presented. Implications of legislation and proposed strategies, policies, and regulations are discussed. Livestock operations will need to comply with regulations to remain in business and to minimize environmental liability.

Peptide immunogens designed to enhance immune responses against human immunodeficiency virus (HIV) mutant strains: a plausible means of preventing viral persistence

A major problem impeding the development of an effective HIV-1 vaccine is the rapid antigenic variability that occurs throughout the viral genome but is most pronounced in the envelope (env) gene and env gene products. The high number of errors made by the reverse transcriptase (RT) enzyme and the absence of an RT proofreading mechanism during HIV-1 replication leads to new antigenic variants that escape current immunological attack. In turn, accumulation of escape mutants leads to a persistent infection. It has been hypothesized through many means including mathematical modeling that preventing HIV persistence necessitates a vaccine that enhances immunity against a sufficiently large fraction of mutant stains. To this extent we have developed a 4 branched--and an 8 branched--multiple epitope immunogen (MEI) that in theory represent 6.7x10(7) and 1.8x10(16) envelope V3 loop sequences respectively. Both MEI constructs were recognized by antibodies in sera from AIDS and/or HIV-1 positive patients from South Africa and Puerto Rico. The immunogens also induced immune responses in MF1 mice and New Zealand White rabbits with the octameric MEI proving to be a more effective antigen. This data supports our hypothesis that synthetic peptides designed to represent the variable regions of HIV-1 envelope should induce immunity against a large quantity of mutant strains.

[Gastrointestinal stromal tumor of the abdominal wall. An unusual localization of a rare tumor]

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. We describe here for the first time a patient with a huge GIST of the abdominal wall without any relation to the gastrointestinal tract, omentum, or mesentery. With regard to the size of 24 cm and a low mitotic index, this GIST is considered an intermediate risk for metastasis. Radical surgical resection was performed with negative pathologic resection margins. The classic immunohistochemical phenotype of the tumor described facilitates the differential diagnosis to exclude abdominal desmoid tumor and solitary fibrous tumor (SFT). In the case of metastasis, therapeutic nihilism no longer seems justified with the availability of imatinib, a tyrosine kinase inhibitor, which shows encouraging results in the therapy of metastatic GIST.

Expression of two type 2N von Willebrand disease mutations identified in exon 18 of von Willebrand factor gene

Type 2N von Willebrand disease (VWD) is characterized by a markedly decreased affinity of von Willebrand factor (VWF) for factor VIII (FVIII). The FVIII binding site has been localized within the first 272 amino acid residues of mature VWF, encoded by exons 18-23. Two substitutions in exon 18 of VWF gene, inducing candidate mutations Y795C and C804F were identified in the heterozygous state in two French patients who also displayed the frequent R854Q mutation in exon 20. Expression studies in Cos-7 cells showed that these abnormalities, which implicate cysteine residues, induced secretion, multimerization and FVIII binding defects of corresponding recombinant VWF. Results from transfection experiments with R854Q, performed to reproduce the hybrid VWF present in patient plasma, were in agreement with those obtained for patient's plasma VWF. These findings confirm the importance of the VWF D' domain in FVIII binding. In addition, this work shows that exon 18 should preferentially be sequenced in type 2N VWD patients when the frequent R854Q mutation in exon 20 has been excluded or detected in the heterozygous state.

Sirolimus therapy in orthotopic liver transplant recipients with calcineurin inhibitor related chronic renal insufficiency

Calcineurin inhibitor-related renal toxicity affects patient and graft survival in transplant recipients. Our clinical experience has revealed sirolimus to be an effective agent in treating renal insufficiency related to calcineurin inhibitor toxicity.

METHODS

We performed a retrospective review of the medical records of OLT recipients suffering from chronic renal insufficiency and treated with sirolimus at the University of Miami.

RESULTS

Fourteen patients (nine men and five women) of mean age 57 years who had been treated with tacrolimus for at least 30 days were converted to sirolimus after developing nephrotoxicity. Mean creatinine clearances collected on day 0, 30, 60, and 90 after conversion were 40.1 mL/min, 49.6 mL/min, 53.9 mL/min, and 51.4 mL/min, respectively. Episodes of acute cellular rejection were not increased during the sirolimus conversion.

CONCLUSION

This retrospective review suggests that OLT patients suffering from tacrolimus-related renal insufficiency successfully converted to sirolimus may benefit from this therapy.

Serum lipid parameters and the prevalence of corneal arcus in a dyslipidaemic patient population

AIM

To determine whether an association exists between plasma lipoprotein constituents and the prevalence of corneal arcus in dyslipidaemic patients.

METHODS

Adult patients (n = 115) were included if their fasting total serum cholesterol concentrations exceeded the 95th percentile or their serum low-density lipoprotein (LDL) : high density lipoprotein (HDL) ratios exceeded 5. Slit-lamp assessment of the corneas was performed.

RESULTS

The study group divided into a subgroup with arcus 37% (43) and a subgroup without arcus 63% (72). Total serum cholesterol and triglyceride levels were not associated with corneal arcus. A significant difference was found (p < 0.05) between the mean levels of LDL cholesterol (LDL-C) in the group without arcus (5.61 +/- 1.74 mmol/l) and the group with arcus (5.96 +/- 1.71 mmol/l). The mean serum HDL-cholesterol (HDL-C) in the group with corneal arcus was 1.04 +/- 0.30 mmol/l as opposed to 1.31 +/- 0.38 mmol/l in the group without arcus (p < 0.005 for difference). The mean LDL-C : HDL-C ratio in the group without arcus was 4.28 (SD: 1.99), and 5.73 (SD: 2.09) in the group with a corneal arcus (p < 0.05).

CONCLUSIONS

Low HDL-C levels, high LDL-C levels and LDL-C : HDL-C ratios > 5 have been implicated as risk factors of numerous circulatory diseases. The observations in this study suggest that the presence of corneal arcus in the dyslipidaemic patient correlates strongly with these same risk indicators.

Liver transplant for the septuagenarians: importance of patient selection

With the increasing success of liver transplantation (OLT), more patients above 70 years of age are being considered for OLT. There is not enough data about the predictors for survival in this patient population. We retrospectively analyzed the medical records of 33 patients at least 70 years of age who received 34 OLT from July 1995 to July 2002. There were 16 women and 17 men of mean age 73.7 years. Etiologies of end-stage liver disease (ESLD) were: HCV (17/33, 52%), cryptogenic cirrhosis (8/33, 24%), PBC (3/33, 9%), Laennec's cirrhosis (2/33, 6%), and others (3/33, 9%). According to the UNOS classification, 15/34 (44%) were status 3, 16/34 (47%) status 2, and 3/34 (9%) status 1. Among 13/33 patients who died (39%), 1-year and 3-year survival rates were 78.79% and 71.43%, respectively. Based on UNOS criteria, 4/15 (26%) were status 3; 6/16 (37%), status 2; and 3/3 (100%), status 1 (P value = .04 for status 1 patients). There was no statistical differences between the scores using the Model for End-Stage Liver Disease (MELD) among those who died (MELD (19) versus MELD (17.35) respectively (P = .50). There was a statistically significant difference in cold ischemia time (CIT) and warm ischemia time (WIT) between those who died (P = .024 and.010, respectively). These results suggest that in this group of patients UNOS status classification, CIT and WIT correlate with survival. The sample size was too small to derive a conclusion about the association with the MELD score.

Differentiation between African populations is evidenced by the diversity of alleles and haplotypes of HLA class I loci

The allelic and haplotypic diversity of the HLA-A, HLA-B, and HLA-C loci was investigated in 852 subjects from five sub-Saharan populations from Kenya (Nandi and Luo), Mali (Dogon), Uganda, and Zambia. Distributions of genotypes at all loci and in all populations fit Hardy-Weinberg equilibrium expectations. There was not a single allele predominant at any of the loci in these populations, with the exception of A*3002 [allele frequency (AF) = 0.233] in Zambians and Cw*1601 (AF = 0.283) in Malians. This distribution was consistent with balancing selection for all class I loci in all populations, which was evidenced by the homozygosity F statistic that was less than that expected under neutrality. Only in the A locus in Zambians and the C locus in Malians, the AF distribution was very close to neutrality expectations. There were six instances in which there were significant deviations of allele distributions from neutrality in the direction of balancing selection. All allelic lineages from each of the class I loci were found in all the African populations. Several alleles of these loci have intermediate frequencies (AF = 0.020-0.150) and seem to appear only in the African populations. Most of these alleles are widely distributed in the African continent and their origin may predate the separation of linguistic groups. In contrast to native American and other populations, the African populations do not seem to show extensive allelic diversification within lineages, with the exception of the groups of alleles A*02, A*30, B*57, and B*58. The alleles of human leukocyte antigen (HLA)-B are in strong linkage disequilibrium (LD) with alleles of the C locus, and the sets of B/C haplotypes are found in several populations. The associations between A alleles with C-blocks are weaker, and only a few A/B/C haplotypes (A*0201-B*4501-Cw*1601; A*2301-B*1503-Cw*0202; A*7401-B* 1503-Cw*0202; A*2902-B*4201-Cw*1701; A*3001-B*4201-Cw*1701; and A*3601-B*5301-Cw*0401) are found in multiple populations with intermediate frequencies [haplotype frequency (HF) = 0.010-0.100]. The strength of the LD associations between alleles of HLA-A and HLA-B loci and those of HLA-B and HLA-C loci was on average of the same or higher magnitude as those observed in other non-African populations for the same pairs of loci. Comparison of the genetic distances measured by the distribution of alleles at the HLA class I loci in the sub-Saharan populations included in this and other studies indicate that the Luo population from western Kenya has the closest distance with virtually all sub-Saharan population so far studied for HLA-A, a finding consistent with the putative origin of modern humans in East Africa. In all African populations, the genetic distances between each other are greater than those observed between European populations. The remarkable current allelic and haplotypic diversity in the HLA system as well as their variable distribution in different sub-Saharan populations is probably the result of evolutionary forces and environments that have acted on each individual population or in their ancestors. In this regard, the genetic diversity of the HLA system in African populations poses practical challenges for the design of T-cell vaccines and for the transplantation medical community to find HLA-matched unrelated donors for patients in need of an allogeneic transplant.

Ten candidate ADAMTS13 mutations in six French families with congenital thrombotic thrombocytopenic purpura (Upshaw-Schulman syndrome)

ADAMTS13, the specific von Willebrand factor (VWF)-cleaving metalloprotease, prevents the spontaneous formation of platelet thrombi in the microcirculation by degrading the highly adhesive ultralarge VWF multimers into smaller forms. ADAMTS13 severe enzymatic deficiency and mutations have been described in the congenital thrombotic thrombocytopenic purpura (TTP or Upshaw-Schulman syndrome), a rare and severe disease related to multivisceral microvascular thrombosis. We investigated six French families with congenital TTP for ADAMTS13 enzymatic activity and gene mutations. Six probands with congenital TTP and their family were tested for ADAMTS13 activity in plasma using a two-site immunoradiometric assay and for ADAMTS13 gene mutations using polymerase chain reaction and sequencing. ADAMTS13 activity was severely deficient (< 5%) in the six probands and one mildly symptomatic sibling but normal (> 50%) in all the parents and the asymptomatic siblings. Ten novel candidate ADAMTS13 mutations were identified in all families, showing either a compound heterozygous or a homozygous status in all probands plus the previous sibling and a heterozygous status in the parents. The mutations were spread all over the gene, involving the metalloprotease domain (I79M, S203P, R268P), the disintegrin domain (29 bp deletion in intron/exon 8), the cystein-rich domain (acceptor splice exon 12, R507Q), the spacer domain (A596V), the 3rd TSP1 repeat (C758R), the 5th TSP1 repeat (C908S) and the 8th TSP1 repeat (R1096stop). This study emphasizes the role of ADAMTS13 mutations in the pathogenesis of congenital TTP and suggests that several structural domains of this metalloprotease are involved in both its biogenesis and its substrate recognition process.

Peptide immunogens based on the envelope region of HIV-1 are recognized by HIV/AIDS patient polyclonal antibodies and induce strong humoral immune responses in mice and rabbits

Peptide immunogens produced by novel synthesis techniques and based on envelope proteins have repeatedly proven successful in inducing anti-HIV and anti-SIV responses in addition to producing anti-peptide immunity [Vaccine 12 (8) (1994) 736; AIDS Res. Hum. Retroviruses 14 (9) (1998) 751; Vaccine (2002) 2680]. We report here the design and evaluation of synthetic peptide constructs mimicking the variability of the third variable (V3) loop, or representing the conservation of the CD4 region of HIV-1 envelope. Three peptides based on the V3 region of HIV-1 subtype C gp120 and designated multiple epitope immunogens (MEI) differ in that one was randomly branched containing a spacer (b-MEI-s), another conjugated to a tetrameric lysine core (MEIV3b(4)) and the third conjugated to poly-L-lysine (poly-L-MEI). The method of synthesis employed produced peptides that were either linear, dimeric or tetramerically branched thereby providing differing levels of conformation. In addition the peptides also differed in their levels of variability. A fourth peptide designated B138 was based on a conserved region of HIV-1 envelope. The aim of this work was to evaluate the effect of variability and level of conformation on the immunogenicity of variable region peptides (MEI's) when compared to that of a known immunogenic and conserved region peptide (B138). Anti-peptide humoral immunity induced in BALB/c mice and New Zealand White rabbits produced antigen-recognizing antibody titres of </=5000 in enzyme linked immunosorbent assays (ELISA) and stimulation indices (SI) of 7 in cell proliferation assays. Plasma polyclonal antibodies collected from HIV/AIDS patients (from South Africa, Botswana and Puerto Rico) recognized the peptide constructs at antibody titres of </=5000. As demonstrated by mouse, rabbit and human antibody and proliferation responses, the immunogenicity and antigenicity of the peptides varied, with MEIV3b(4) responding better than the other three, at times even surpassing the conserved region peptide B138.

Comparing qualitative and quantitative spectroscopic techniques for the detection of the effect of direct iron loading of mammalian cell cultures

Iron overload augments diseases of the liver and microorganism infection as well as deregulates the immune system. In vitro analysis of the effects of iron loading and its chelation involves determining the amount of iron constituting overload, which metal sources and cell lines to use and reliable assay methods. The uptake of 500 microM FeSO4 or FeEDTA by CEMss, U937 or leukocytes was confirmed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Excess iron increased CEMss viability (assessed by MTT, XTT, Trypan- and Alamar Blue) by an average of 18% (P = 0.034). Flow cytometry indicated dye-viable cells to be undergoing apotosis/necrosis while still confirming an increase (9%, P < 0.001) in excess iron-induced viability. The iron chelator desferioxamine (DFO) when added in addition to Fe, reversed the effects of excess iron (and vice versa) and had detrimental effects when used on its own (33% inhibition of viability as measured by dyes and 10.85%; P = 0.0427 assessed by flow cytometry). The 4 dyes demonstrated different levels of sensitivity in detecting the influence of iron or DFO but gave a related, qualitative picture while flow cytometry and ICP-AES data was more quantitative.

Abnormal serum lipoprotein levels as a risk factor for the development of human lenticular opacities

AIM

To determine whether an association exists between the different plasma lipoprotein constituents and the prevalence of lenticular opacities in dyslipidaemic subjects.

METHODS

Adult patients (n = 115) of both genders were included if their fasting total serum cholesterol concentrations exceeded the 95th percentile of normal or their serum low-density lipoprotein (LDL): high-density lipoprotein (HDL) ratios exceeded 5. Patients were excluded if they suffered from any condition known to cause, or predispose them to, elevated lipoprotein levels or lenticular opacification. Lenticular changes were assessed by means of a slit-lamp through the fully dilated pupil.

RESULTS

An extremely strong association (p<0.0001) was found to exist between HDL cholesterol levels and the development of lens opacities. Below an HDL-C level of 1.5 mmol/l subjects had a seven-fold higher calculated probability of falling in the lens opacity subgroup than those with HDL-C levels above 1.5 mmol/l [odds ratio =7.33 (95% CI = 2.06-26.10; p = 0.0001)]. An equally strong association was found between high (>5) LDL:HDL ratios and the development of lens opacities (p<0.0003). The risk of falling into the cataract subgroup if the individual's LDL:HDL ratio exceeded 5 was 2.35 (95% CI = 1.09-5.04; p = 0.014).

CONCLUSION

This study strongly suggests that an association exists between low levels of HDL cholesterol and high LDL:HDL ratios on one hand and the development of adult lens opacification on the other.