959 A Double Case Review: Arteria Comitans Nervi Ischiadici, Two Rare Presentations of Persistent Sciatic Artery Aneurysm

Background

In the embryo, the blood flow of the lower limb bud originates from the umbilical artery and becomes the sciatic artery following the course of the sciatic nerve. By the 12th week, the sciatic will involute, in rare instances that this fails it is referred to as ‘arteria comitans nervi ischiadici’. This variant is rare with an incidence of 0.01%-0.05% is of the utmost surgical significance as failure to accurately diagnose and treat can ultimately threaten limb loss.

Cases

1. A middle aged gentleman who presented with a 9-month history of posterior thigh pain with sensations of pressure related to posture and back pain following heavy lifting. Initially this patient was managed conservatively for claudication symptoms until they represented to clinic 4 years later with a 5month history of left buttock discomfort when sitting in the absence of claudication. An endovascular intervention with coil embolisation was undertaken reasons with a satisfactory outcome.

2. A young female with AVM to the left thigh and bilateral PSA's, presented with a painful swelling of the upper inner aspect of the mid-thigh, with a normal venous examination. On representing, despite repeated sclerotherapy, the patient had developed increasingly severe discomfort at the site of the thigh malformation, posterior aspect of the left leg. The patient was referred to a tertiary centre for reassessment.

Conclusion

Due to the variety and evolving nature of clinical presentations, a high degree of clinical suspicion is an important factor in providing a diagnosis. We also highlight the advantages of endovascular intervention.

Bio-scaffolds in organ-regeneration: Clinical potential and current challenges

Cadaveric organ transplantation represents the definitive treatment option for end-stage disease but is restricted by the shortage of clinically-viable donor organs. This limitation has, in part, driven current research efforts for in vitro generation of transplantable tissue surrogates. Recent advances in organ reconstruction have been facilitated by the re-purposing of decellularized whole organs to serve as three-dimensional bio-scaffolds. Notably, studies in rodents indicate that such scaffolds retain native extracellular matrix components that provide appropriate biochemical, mechanical and physical stimuli for successful tissue/organ reconstruction. As such, they support the migration, adhesion and differentiation of reseeded primary and/or pluripotent cell populations, which mature and achieve functionality through short-term conditioning within specialized tissue bioreactors. Whilst these findings are encouraging, significant challenges remain to up-scale the present technology to accommodate human-sized organs and thereby further the translation of this approach towards clinical use. Of note, the diverse structural and cellular composition of large mammalian organ systems mean that a "one-size fits all" approach cannot be adopted either to the methods used for their decellularization or the cells required for subsequent re-population, to create fully functional entities. The present review seeks to highlight the clinical potential of decellularized organ bio-scaffolds as a route to further advance the field of tissue- and organ-regeneration, and to discuss the challenges which are yet to be addressed if such a technology is ever to become a credible rival to conventional organ allo-transplantation.

Superior mesenteric artery syndrome: a single centre experience of laparoscopic duodenojejunostomy as the operation of choice

INTRODUCTION The superior mesenteric artery (SMA) syndrome, or Wilkie's syndrome, is a rare cause of postprandial epigastric pain, vomiting and weight loss caused by compression of the third part of the duodenum as it passes beneath the proximal superior mesenteric artery. The syndrome may be precipitated by sudden weight loss secondary to other pathologies, such as trauma, malignancy or eating disorders. Diagnosis is confirmed by angiography, which reveals a reduced aorto-SMA angle and distance, and contrast studies showing duodenal obstruction. Conservative management aims to increase intra-abdominal fat by dietary manipulation and thereby increase the angle between the SMA and aorta. Where surgery is indicated, division of the ligament of Treitz, anterior transposition of the third part of the duodenum and duodenojejunostomy have been described. METHODS We present four cases of SMA syndrome where the intention of treatment was laparoscopic duodenojejunostomy. The procedure was completed successfully in three patients, who recovered quickly with no short-term complications. A fourth patient underwent open gastrojejunostomy (complicated by an anastomotic bleed) when dense adhesions prevented duodenojejunostomy. CONCLUSIONS The superior mesenteric artery syndrome should be considered in patients with epigastric pain, prolonged vomiting and weight loss. Laparoscopic duodenojejunostomy is a safe and effective operation for management of the syndrome. A multi-speciality team approach including gastrointestinal, vascular and radiological specialists should be invoked in the management of these patients.

Open Abdominal Aortic Aneurysm Replacement in the Awake Patient

Nonintubated aortic surgery using various techniques has been reported, but despite publication of favorable outcomes in select patient groups, awake aortic surgery remains unpopular. Our patient had an abdominal aortic aneurysm that was unsuitable for endovascular repair. Because of the significant respiratory disease, general anesthesia represented an unacceptably high risk. As a result, he underwent open AAA repair via a retroperitoneal approach with the aid of epidural anesthesia. Here, we highlight the benefits of the procedure which offer a select cohort of patients the chance of life-saving surgery.

Some Personality Correlates of Suggestibility in Normals and Neurotics

Groups of 25 normals and 21 neurotics were given a Sway test, Rorschach Compliance Test, and questionnaire measures of anxiety, dependency, hostility and neuroticism. The two groups differed significantly in neuroticism, dependency, anxiety, and hostility. The groups did not differ significantly in Sway test suggestibility, nor was there a correlation in either group between suggestibility and neuroticism score. Dependency correlated significantly with sway in both groups. Anxiety significantly predicted sway in the normal but not in the neurotic group. Several factors possibly accounting for this difference in relationship were discussed.

Chronic herpes simplex virus type-2 infection and HIV viral load

By December 2003, the estimated adult HIV/AIDS prevalence rate in sub-Saharan Africa was 7.5–8.5%, and rates of herpes simplex virus type-2 (HSV-2) infection among adults aged >30 years ranged from 60% to 82%. However, little is known about the natural history of HIV/HSV-2 co-infection in this population. We evaluated HIV viral load and CD4+ cell counts among persons with and without chronic HSV-2 co-infection in a cross-sectional study of HIV-infected persons not receiving antiretroviral therapy. HSV-2 and HIV co-infection was associated with a 0.3 log copies/mL higher HIV viral load compared with persons without HSV-2 infection ( P=0.014). Chronic HSV-2 infection may have a negative effect on the clinical course of persons with HIV.

Aetiology of diarrhoea among persons with HIV and their family members in rural Uganda: a community-based study

OBJECTIVES

To identify pathogens associated with diarrhoea in HIV-infected persons and their HIV-uninfected family members.

DESIGN

Prospective cohort study.

SETTING

Rural community in eastern Uganda.

SUBJECTS

Eight hundred and seventy nine HIV-infected adults (74% females and median age 35 years (IQR, 29-41) and 2771 HIV-uninfected family members (51% females and median age 11 years (IQR 6-16) were included.

MAIN OUTCOME MEASURES

Using microscopy and culture, stools were tested for parasites, bacteria and bacterial-antimicrobial-susceptibility. Logistic regression models, adjusting for age, CD4 cells, season, household clustering and use of safe-water system were used for relationships between pathogens, diarrhoea and HIV.

RESULTS

Persons with HIV had similar pathogens in diarrhoeal (69%) and nondiarrhoeal stools (57%). Most diarrhoea was not associated with identifiable aetiology; the population attributable risk of diarrhoea for known diarrhoea pathogens was 32%. Enteric bacteria (19%), enteropathogenic or enterotoxigenic E. coli (8%), Aeromonas species (7%), Strongyloides stercoralis (8%) and Cryptosporidium parvum (5%). HIV-infected, stools had more Cryptosporidium parvum than HIV-uninfected (OR 2.64, 95% CI 1.43-4.87). Most bacteria were resistant to commonly used antimicrobials irrespective of HIV status.

CONCLUSIONS

Irrespective of HIV-status, aetiologies of majority of their diarrhoea in Uganda cannot be identified by microscopy and culture. Bacterial pathogens isolated have high resistance to common antimicrobials. Empiric treatment should be tailored to local bacterial-resistance patterns.

Rotational co-culture of clonal β-cells with endothelial cells: effect of PPAR-γ agonism in vitro on insulin and VEGF secretion

AIM

Delayed graft revascularization impedes the success of human islet transplantation. This study utilized rotational co-culture of insulin secreting β-cells with human umbilical vein endothelial cells (HUVECs) and a peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist to promote insulin and vascular endothelial growth factor (VEGF) secretory function.

METHODS

Clonal BRIN-BD11 (D11) cells were maintained in static culture (SC) and rotational culture (RC) ± HUVEC and ± the TZD (thiazolidinedione) rosiglitazone (10 mmol/l) as a specific PPAR-γ agonist. HUVECs were cultured in SC and RC ± D11 and ± TZD. D11 insulin secretion was induced by static incubation with low glucose (1.67 mmol/l), high glucose (16.7 mmol/l) and high glucose with 10 mmol/l theophylline (G+T) and assessed by enzyme-linked immunosorbent assay (ELISA). HUVEC proliferation was determined by ATP luminescence, whereas VEGF secretion was quantified by ELISA. Co-cultured cells were characterized by immunostaining for insulin and CD31.

RESULTS

D11 SC and RC showed enhanced insulin secretion in response to 16.7 mmol/l and G+T (p < 0.01); without significant alteration by the TZD. Co-culture with HUVEC in SC and RC also increased D11 insulin secretion when challenged with 16.7 mmol/l and G+T (p < 0.01), and this was slightly enhanced by the TZD. The presence of HUVEC increased D11 SC and RC insulin secretion in response to high glucose and G+T, respectively (p < 0.01). Addition of the TZD increased SC and RC HUVEC ATP content (p < 0.01) and VEGF production (p < 0.01) in the presence and absence of D11 cells.

CONCLUSIONS

Rotational co-culture of insulin secreting cells with endothelial cells, and exposure to a PPAR-γ agonist may improve the prospects for graft revascularization and function after implantation.

Sustained insulin secretory response in human islets co-cultured with pancreatic duct-derived epithelial cells within a rotational cell culture system

AIMS/HYPOTHESIS

Loss of the trophic support provided by surrounding non-endocrine pancreatic cell populations underlies the decline in beta cell mass and insulin secretory function observed in human islets following isolation and culture. This study sought to determine whether restoration of regulatory influences mediated by ductal epithelial cells promotes sustained beta cell function in vitro.

METHODS

Human islets were isolated according to existing protocols. Ductal epithelial cells were harvested from the exocrine tissue remaining after islet isolation, expanded in monolayer culture and characterised using fluorescence immunocytochemistry. The two cell types were co-cultured under conventional static culture conditions or within a rotational cell culture system. The effect of co-culture on islet structural integrity, beta cell mass and insulin secretory capacity was observed for 10 days following isolation.

RESULTS

Human islets maintained under conventional culture conditions exhibited a characteristic loss in structural integrity and functional viability as indicated by a diminution of glucose responsiveness. By contrast, co-culture of islets with ductal epithelial cells led to preserved islet morphology and sustained beta cell function, most evident in co-cultures held within the rotational cell culture system, which showed a significantly (p < 0.05) greater insulin secretory response to elevated glucose compared with control islets. Similarly, insulin/protein ratio data suggested that the presence of ductal epithelial cells is beneficial for the maintenance of beta cell mass.

CONCLUSIONS/INTERPRETATION

The data indicate a supportive role for ductal epithelial cells in islet viability. Further characterisation of the regulatory influences may lead to novel strategies to improve long-term beta cell function both in vitro and following islet transplantation.

Role of the laboratory in ensuring global access to ARV treatment for HIV-infected children: consensus statement on the performance of laboratory assays for early infant diagnosis

A two day meeting hosted by the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC) was held in May 2006 in Entebbe, Uganda to review the laboratory performance of virologic molecular methods, particularly the Roche Amplicor DNA PCR version 1.5 assay, in the diagnosis of HIV-1 infection in infants. The meeting was attended by approximately 60 participants from 17 countries. Data on the performance and limitations of the HIV-1 DNA PCR assay from 9 African countries with high-burdens of HIV/AIDS were shared with respect to different settings and HIV- subtypes. A consensus statement on the use of the assay for early infant diagnosis was developed and areas of needed operational research were identified. In addition, consensus was reached on the usefulness of dried blood spot (DBS) specimens in childhood as a means for ensuring greater accessibility to serologic and virologic HIV testing for the paediatric population.

Prognostic Significance of Raised Cardiac Troponin T in Patients Presenting with Acute Limb Ischaemia

OBJECTIVE

To study the relation between serum cardiac troponin T (cTnT) and mortality in patients presenting with acute limb ischaemia secondary to an embolism.

MATERIAL AND METHODS

A two years prospective study of all patients admitted to the vascular unit with a diagnosis of acute limb ischaemia secondary to an embolism. On admission all patients had an ECG. A blood sample was taken for measurement of cTnT, CRP, serum biochemistry, full blood count and clotting. All embolectomies were performed under local anaesthesia. Patients were followed until discharge from hospital and up to twelve months after surgery.

RESULTS

There were 37 patients with lower limb and 2 patients with upper limb ischaemia. Twenty four patients were female and fifteen were male, with the mean age of 76 years (50-95) for women and 84 years (77-90) for men. Seventeen patients (44%) had a raised cTnT. The patients with raised cTnT were older than those with normal cTnT [86y (77-92) vs 77y (51-95), p = 0.01, t test]. The mean cTnT was 0.20 microg/L (range: 0.11-0.27). Only two patients with raised cTnT gave a history of chest pains. All of the patients with an elevated cTnT had also raised CRP. There was no significant difference in the serum creatinine in the group of patients with elevated cTnT compared to those with normal cTnT [112 micromol/L (range 98-159) vs 119 micromol/L (range: 47-177), p = ns]. The cumulative survival for cTnT+ patients at 7 days was 53% and that of cTnT- patients was 100%. The cumulative survival for cTnT+ and cTnT- patients was statistically different (p = 0.0000, chi2 = 13.1, Log Rank test). Using regression analysis, an elevated cTnT was found to be an independent predictor of outcome.

CONCLUSION

A significant proportion of patients presenting with an acutely ischaemic limb have an elevated cTnT. An elevated cTnT may be an early marker of overall disease severity and a predictor of outcome.

Prevalence and screening costs of hepatitis C virus among Ugandan blood donors

BACKGROUND

Screening donated blood for hepatitis C virus (HCV) is important for HCV prevention and is routinely practiced in North America and Europe. However, in many African countries little is known about HCV prevalence or cost-effectiveness of HCV antibody (anti-HCV) screening.

METHODS

We investigated 2592 plasma specimens collected consecutively from blood donors in central Uganda in 1999. Routine screening by the blood bank included human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), and syphilis. To assess HCV prevalence and cost-effectiveness of testing, specimens were additionally tested for anti-HCV IgG by enzyme immunosorbent assay (EIA). Specimens repeatedly reactive (RR) on EIA were tested with a recombinant immunoblot assay (RIBA).

RESULTS

Overall, 107 (4.1%) specimens were HCV EIA RR. Fifteen EIA RR specimens (0.6%, 95% confidence interval = 0.3-0.9%) were RIBA positive and 47 (1.8%) were RIBA indeterminate. Most (80%) RIBA-positive specimens were non-reactive for HIV, HBsAg, and syphilis. RIBA positivity was not associated with donor age, sex, number of donations, HIV, or HBsAg positivity. Costs of screening donors for anti-HCV by using EIA were estimated at US Dollars 782 per potential transfusion-associated HCV infection (exposure to RIBA-positive blood) averted.

CONCLUSIONS

Current screening tests for other infections are ineffective in removing HCV-positive donations. Testing costs are considerable; cost-effectiveness of identifying HCV-infected donors will be critical in decision making about HCV screening in Uganda.

Evaluating the role of human papillomaviruses in conjunctival neoplasia

Mucosal, cutaneous and Epidermodysplasia verruciformis (EV)-related human papillomaviruses (HPVs) were searched by broad-spectrum PCR in 86 conjunctival neoplasia biopsies and 63 conjunctival non-neoplastic control tissue from Ugandan subjects. Seven different EV-related HPV types, including a putative new HPV, and two mucosal HPVs were detected in 25% (14 out of 56) of HIV-positive, in 10% (three out of 30) of HIV-negative conjunctival neoplasia samples, and rarely (0-1.6%) in control subjects. The absence of high-risk HPVs and the low detection frequency of EV-related HPV types in more advanced tumour stages (10%) raise doubts about their role in conjunctival carcinomas.

Are organ preservation solutions useful for the storage of isolated human islets?

Clinical islet transplantation invariably requires more than one donor per recipient. Delay between transplants could be reduced if islets were stored and transported between centers. This study assessed viability and response to glucose of isolated human islets after storage in tissue culture medium (TCM) 199 at 30 degrees C (control), TCM 199 at 22 degrees C (RT), University of Wisconsin solution @ 4 degrees C (UW), or Eurocollins Solution at 4 degrees C (EC) and compared 18 hours storage (group 1) or overnight culture followed by 4 hours storage (group 2). Insulin stimulation index (SI) (mean +/- SD, n = 5), after 1 hour glucose static challenge was not significantly different (P >.05) from islets in group 1 stored in RT 1.76 +/- 1.08 or EC 1.14 +/- 0.29 versus control 2.41 +/- 1.13 or group 2, RT 1.73 +/- 0.51, EC 2.07 +/- 0.63 versus control 2.12 +/- 0.58. However, SI UW was significantly lower (P <.05) than the control in group 1 (1.19 +/- 0.30) and group 2 (1.36 +/- 0.34). Islet viability represented by the ATP/ADP ratio (mean +/- SD, n = 5) was not significantly different after storage in RT 0.201 +/- 0.159; EC 0.205 +/- 0.123; or UW 0.611 +/- 0.992 versus the control 0.223 +/- 0.158 in group 1, and RT 0.178 +/- 0.055; EC 0.137 +/- 0.018; or UW 0.173 +/- 0.085, compared with the control 0.199 +/- 0.069 in group 2. We conclude, organ preservation solutions EC and UW do not have an advantage over TCM 199 for the storage of isolated human islets.

Immunoglobulin levels amongst persons with and without human immunodeficiency virus type 1 infection in Uganda and Norway

CD4+-cell count and viral load monitoring are expensive and unavailable to most human immunodeficiency virus (HIV)-infected people in Africa. In an attempt to evaluate alternative methods for monitoring antiretroviral (ARV) therapy, we measured concentrations of immunoglobulin (Ig)A, IgM, IgG and IgG1 amongst adults with and without HIV in Uganda and Norway. We adjusted for disease severity by stratifying HIV-positive subjects on CD4+-cell counts above and below 200 cells/ micro l. Median serum levels of IgG, IgG1 and IgA were significantly higher in HIV-positive persons compared with HIV-negative persons in both countries (P < 0.001 and P = 0.018 for IgA in Ugandan patients). Levels of IgA in Ugandan HIV-negative subjects were significantly lower than those in HIV-positive subjects with low CD4+ compared with those with high CD4+-cell counts (P < 0.001 and P = 0.069, respectively). IgM levels were different between the HIV-negative and the two HIV-positive groups in Norway (P < 0.001). The mean levels of IgM, IgG and IgG1 in HIV-negative and -positive African subjects were generally higher than those in comparable groups of Western subjects. Our results verify that levels of IgA, IgG and IgG1 vary between HIV-negative and -positive individuals in both study populations. Their determination may be useful in monitoring both disease progression and response to ARV therapy.

Resistance to antiretroviral therapy among patients in Uganda

OBJECTIVE

To characterize HIV-1 phenotypic resistance patterns and genotypic mutations among patients taking antiretroviral medications in Uganda.

METHODS

We reviewed charts and retrieved archived plasma specimens from patients at an AIDS specialty center in Uganda where antiretroviral therapy has been used since 1996. Phenotypic and genotypic resistance testing was done on specimens associated with a viral load of 1000 copies/ml.

RESULTS

Resistance testing of specimens was completed for 16 patients. Among 11 specimens collected before initiation of antiretroviral therapy, no phenotypic resistance or primary genotypic mutations were found. Among 8 patients taking lamivudine, phenotypic resistance was found for 9 (90%) of 10 specimens and was associated with an M184V mutation in all nine cases. Among 12 patients taking zidovudine, no phenotypic resistance and few primary mutations were found. For 6 patients who were receiving protease inhibitors, we observed no phenotypic resistance and only one primary genotypic mutation associated with resistance.

CONCLUSIONS

The absence of apparent resistance among samples collected before antiretroviral therapy supports the notion that a similar approach to selection of antiretroviral therapy can generally be used against non-B subtypes. A genotypic marker of antiretroviral resistance to lamivudine in HIV-1 subtypes A, C, and D was similar to those in subtype B infections. These results suggest that the methods used for monitoring for the emergence of drug resistance in antiretroviral programs in Africa may be similar to those used in developed settings.

Evaluation of United States-licensed human immunodeficiency virus immunoassays for detection of group M viral variants

Six Food and Drug Administration (FDA)-licensed human immunodeficiency virus type 1 (HIV-1) and HIV-1/2 immunoassays, including five enzyme immunoassays and one rapid test, were challenged with up to 250 serum samples collected from various global sites. The serum samples were from individuals known to be infected with variants of HIV-1 including group M subtypes A, B, B', C, D, E, F, and G and group O. All immunoassays detected the vast majority of samples tested. Three samples produced low signal over cutoff values in one or more tests: a clade B sample, an untypeable sample with a low antibody titer, and a group O sample. It is concluded that HIV-1 immunoassays used in the United States are capable of detecting most HIV-1 group M variants.

Protease sequences from HIV-1 group M subtypes A-H reveal distinct amino acid mutation patterns associated with protease resistance in protease inhibitor-naive individuals worldwide. HIV Variant Working Group

BACKGROUND

Although numerous mutations that confer resistance to protease inhibitors (PRI) have been mapped for HIV-1 subtype B, little is known about such substitutions for the non-B viruses, which globally cause the most infections.

OBJECTIVES

To determine the prevalence of PRI-associated mutations in PRI-naive individuals worldwide.

DESIGN

Using the polymerase chain reaction, protease sequences were amplified from 301 individuals infected with HIV-1 subtypes A (79), B (95), B' (19), C (12), D (26), A/E (23), F (26), A/G (11), and H (3) and unclassifiable HIV-1 (7). Amplified DNA was directly sequenced and translated to amino acids to analyze PRI-associated major and accessory mutations.

RESULTS

Of the 301 sequences, 85% contained at least one codon change giving substitution at 10, 20, 30, 36, 46, 63, 71, 77, or 82 associated with PRI resistance; the frequency of these substitutions was higher among non-B (91%) than B (75%) viruses (P < 0.0005). Of these, 25% carried dual and triple substitutions. Two major drug resistance-conferring mutations, either 20M or 30N, were identified in only three specimens, whereas drug resistance accessory mutations were found in 252 isolates. These mutations gave distinct prevalence patterns for subtype B, 63P (62%) > 77I (19%) > 10I/V/R (6%) = 361 (6%) = 71T/V (6%) > 20R (2%), and non-B strains, 36I (83%) > 63P (17%) > 10I/V/R (13%) > 20R (10%) > 77I (2%), which differed statistically at positions 20, 36, 63, 71, and 77.

CONCLUSIONS

The high prevalence of PRI-associated substitutions represent natural polymorphisms occurring in PRI-naive patients infected with HIV-1 strains of subtypes A-H. The significance of distinct mutation patterns identified for subtype B and non-B strains warrants further clinical evaluation. A global HIV-1 protease database is fundamental for the investigation of novel PRI.

Genetic characterization and phylogenetic analysis of HIV-1 subtype C from Uganda

To better understand the emergence of subtype C and its potential impact on vaccine efforts in Uganda, we have characterized subtype C sequences from Uganda (n = 13), Zimbabwe (n = 11), Mozambique (n = 5), South Africa (n = 4), and India (n = 3). Phylogenetic analysis of subtype C sequences in the env gp41 gene region revealed multiple subclusters within subtype C. Further, while most Ugandan specimen subclustered together, other subclusters did not reflect a clear geographic location. The nucleotide divergence within the Ugandan subset was 8.2% (6.1-9.8%) compared with 9.5% (2.5-15%) for the other subtype C gp41 sequences. The protein sequence alignment revealed marked sequence conservation of major immunodominant epitopes within the gp41 region.

Analysis of genetic variability within the immunodominant epitopes of envelope gp41 from human immunodeficiency virus type 1 (HIV-1) group M and its impact on HIV-1 antibody detection

The serodiagnosis of human immunodeficiency virus type 1 (HIV-1) infection primarily relies on the detection of antibodies, most of which are directed against the immunodominant regions (IDR) of HIV-1 structural proteins. Among these, the N-terminal region of gp41 contains cluster I (amino acids [aa] 580 to 623), comprising the cytotoxic T-lymphocyte epitope (AVERYLKDQQLL) and the cysteine loop (CSGKLIC), and cluster II (aa 646 to 682), comprising an ectodomain region (ELDKWA). To delineate the epitope diversity within clusters I and II and to determine whether the diversity affects serologic detection by U.S. Food and Drug Administration (FDA)-licensed enzyme immunoassay (EIA) kits, gp41 Env sequences from 247 seropositive persons infected with HIV-1 group M, subtypes A (n = 42), B (n = 62), B' (n = 13), C (n = 38), D (n = 41), E (n = 18), F (n = 27), and G (n = 6), and 6 HIV-1-infected but persistently seronegative (HIPS) persons were analyzed. While all IDR were highly conserved among both seropositive and HIPS persons, minor amino acid substitutions (<20% for any one residue, mostly conservative) were observed for all subtypes, except for B', in comparison with the consensus sequence for each subtype. Most importantly, none of the observed substitutions among the group M plasma specimens affected antibody detection, since all specimens (n = 152) tested positive with all five FDA-licensed EIA kits. Furthermore, all specimens reacted with a group M consensus gp41 peptide (WGIKQLQARVLAVERYLKDQQLLGIWGCSGKLICTTAVPWNASW), and high degrees of cross-reactivity (>80%) were observed with an HIV-1 group N peptide, an HIV-1 group O peptide, and a peptide derived from the homologous region of gp41 from simian immunodeficiency virus from chimpanzee (SIVcpz). Taken together, these data indicate that the minor substitutions observed within the IDR of gp41 of HIV-1 group M subtypes do not affect antibody recognition and that all HIV-1-seropositive specimens containing the observed substitutions react with the FDA-licensed EIA kits regardless of viral genotype and geographic origin.

Detection of phylogenetically diverse human immunodeficiency virus type 1 groups M and O from plasma by using highly sensitive and specific generic primers

The high degree of genetic diversity within human immunodeficiency virus type 1 (HIV-1), which includes two major groups, M (major) and O (outlier), and various env subtypes within group M (subtypes A to J), has made designing assays that will detect all known HIV-1 strains difficult. We have developed a generic primer set based on the conserved immunodominant region of transmembrane protein gp41 that can reliably amplify as few as 10 copies/PCR of viral DNA from near-full-length clones representing group M subtypes A to H (subtypes I and J were not available). The assay is highly sensitive in detecting plasma viral RNA from HIV-1 strains of diverse geographic origins representing different subtypes of HIV-1 group M as well as HIV-1 group O. Of the 253 group M plasma specimens (subtypes A, 68 specimens; B, 71; C, 19; D, 27; E, 23; F, 33; and G, 12), 250 (98.8%) were amplified by using the gp41 M/O primer set. More importantly, all 32 (100%) group O plasma samples were also amplified with these primers. In vitro spiking experiments further revealed that the assay could reliably detect as few as 25 copies/ml of viral RNA and gave positive signals in HIV-1-seropositive specimens with plasma copy numbers below the limits of detection by all commercially available viral load assays. In addition, analysis of five seroconversion panels indicated that the assay is highly sensitive for early detection of plasma viremia during the "window period." Thus, the highly sensitive assay will be useful for early detection of HIV-1 in clinical specimens from all known HIV-1 infections, regardless of their genotypes and geographic origins.

The distribution of porcine pancreatic beta-cells at ages 5, 12 and 24 weeks

Islet transplantation is a potential treatment for diabetes mellitus and porcine pancreata may provide a readily available source of islets. The size, number and distribution of islets within the pancreas may influence the choice of age of donor for xenotransplantation. Samples (n = 3 per age group) from the dorsal and ventral pancreas of 5-, 12- and 24-week-old hybrid pigs were fixed in formal saline, processed in paraffin wax and stained with an avidin/biotin immunohistochemical kit for insulin, glucagon, somatostatin and pancreatic polypeptide. The arrangement of endocrine cells within the pancreata were studied and mean diameter of beta-cell groups were measured (from insulin stained sections) in 1 mm2 grid areas (n = 10 per section) and collated into groups according to size. Percentage volume density of beta-cells in relation to the whole pancreas was calculated and also the distribution of beta-cell groups, according to their size, within the total beta-cell mass. There were differences in the frequency and arrangement of endocrine cells within islets at the different ages studied. beta-Cell groups < 50 microm in diameter occupied 70 to 80% of the total beta-cell mass at 5 weeks but, as the age of the pig increased, larger cell groups were more abundant. However, the percentage volume density of beta-cells within the total pancreas did not change as the pancreas matured. This study shows that the endocrine porcine pancreas was maturing and its structure changed between the ages of 5 and 24 weeks. The relevance of these findings may have implications on the isolation and function of islets if young pigs are to be used as donors for transplantation as a treatment for diabetes mellitus.

The influence of collagenase solvent on the isolation of islets from 5 week old pigs: a comparison of TCM-199 and UW

Islet transplantation is a potential treatment for diabetes, but the techniques for islet isolation are inefficient and the recovery rates for isolated islets are often low. As the solutions employed during the isolation process may affect islet yield, we have investigated the effect of collagenase solvent, and compared the effect of dissolving collagenase in TCM-199 (TCM) or University of Wisconsin (UW) solution on yield and viability of islets isolated from 5 week old pigs. Pancreata were transported to the laboratory in UW solution, and the islets isolated using a manual method of collagenase digestion. The optimum concentration of collagenase which would liberate the maximum number of islets was determined for each solvent, and then the yield and viability of islets isolated using collagenase in TCM and UW were compared. It was found that, when UW was used as collagenase solvent, a higher concentration of collagenase was required to liberate the maximum number of islets. Comparative experiments revealed that although the total number of isolated islets was greater using UW as the solvent, the number of islet equivalents was similar in both preparations. More than 90% of the cells in both preparations excluded trypan blue, although according to a scoring system, preparations isolated using UW showed greater viability. The stimulation indices in response to glucose and theophylline were similar for both preparations, but islets isolated using UW generally responded with a lower but more sustained insulin release. In conclusion, there was no difference between the total amount of islet tissue isolated using TCM or UW as solvent for collagenase. The preparations isolated using UW were more fragmented, but exhibited superior viability.

Expression of the GALalpha(1-3)GAL epitope on pig islets

Expression of Galalpha(1-3)Gal on endothelium has been implicated in the rejection of porcine xenografts. The aim of this study was to determine whether expression of Galalpha(1-3)Gal on pig islets varies between pigs aged 5, 12 and 24 weeks, and to investigate whether it is expressed on islets isolated by collagenase digestion or islets maintained in tissue culture. Samples of pancreas were obtained from pigs aged 5, 12 and 24 weeks. Islets were isolated by manual collagenase digestion and density gradient separation. Samples were taken immediately after isolation or after maintenance in tissue culture. Pancreas and islet samples were processed, sectioned and stained with the lectin BS1-B4 (which binds to Galalpha(1-3)Gal residues), and anti-insulin antibody using a double staining technique. There was no significant difference in the staining patterns to sections of pancreas obtained from 5, 12 and 24 week old pigs. Vascular endothelium, connective tissue and the luminal surface of duct epithelial cells stained with BS1-B4 in all sections; endocrine and exocrine cells did not stain. Preliminary experiments showed that lectin staining to isolated islets was inconsistent between preparations, but expression did not appear to differ significantly between ages: lectin staining of some beta-cells was evident in the majority of freshly isolated preparations, but was not detectable on beta-cells following tissue culture. In conclusion, expression of Galalpha(1-3)Gal did not differ significantly in pancreata from 5, 12 and 24 week old pigs. Preliminary experiments showed that Galalpha(1-3)Gal was expressed by beta-cells immediately following isolation, but not after maintenance in culture.

Detection of genetically diverse human immunodeficiency virus type 1 group M and O isolates by PCR

A panel of 136 genetically diverse group M and 5 group O adult isolates from outside the United States and Europe were evaluated by PCR with the Roche AMPLICOR HIV-1 test, a modified version of the AMPLICOR HIV-1 test, and a new primer pair/probe system. Detection of some of these isolates was less efficient with the AMPLICOR HIV-1 test; however, the assay was significantly improved by reducing the sample input and lowering the annealing temperature. The new primer pair/probe set detected 140 of 141 isolates, including the 5 group O isolates that were not detected with either of the AMPLICOR HIV-1 test formats.

An iatrogenic arterial foreign body

The creation, possible complications and retrieval of an unusual, perhaps unique, arterial foreign body are described.

Herpesvirus-like DNA sequences detected in endemic, classic, iatrogenic and epidemic Kaposi's sarcoma (KS) biopsies

The identification of Kaposi's sarcoma (KS) clusters in sub-equatorial Africa (endemic KS, AKS) and the high frequency of KS in sexually transmitted AIDS (epidemic KS, EKS), have previously suggested a role for infectious agents in the etiopathogenesis of KS. The recent identification of herpesvirus (HHV)-like DNA sequences in one case of EKS and their detection in > 90% of all tested EKS, prompted us to determine the prevalence of these viral sequences in all types of KS, such as AKS, EKS, classic KS (CKS) and iatrogenic KS (IKS). The presence of herpesvirus(HHV)-like DNA sequences has been examined in 61 KS skin tumors obtained from Greece, Italy, USA, Uganda and Kenya. All KS types (100%) were positive by polymerase chain reaction (PCR) and Southern-blot analysis, while 5 out of 6 (83%) and 4 out of 7 (57%) uninvolved autologous skin biopsies from AKS and CKS patients, respectively, were positive for HHV-like sequences. All samples from non-KS patients were negative, i.e. 17 human biopsies from healthy individuals or patients affected by other pathologies, 5 human cell lines and 15 peripheral blood mononuclear cells (PBMC) from HIV-positive subjects. These results suggest that HHV-like sequences play a major role in the pathogenesis of this neoplasm.

Presence of multiple genetic subtypes of human immunodeficiency virus type 1 proviruses in Uganda

DNA sequences encoding the C2-V3 regions or the C2-V5 regions of the surface glycoprotein gp120 of the human immunodeficiency virus type 1 (HIV-1) were amplified by the polymerase chain reaction (PCR) from peripheral blood mononuclear cells obtained in 1990/1992 from 20 infected Ugandans. The PCR-amplified DNA was cloned into a phagemid vector and between 1 and 12 clones from each provirus were sequenced. The Ugandan proviruses were aligned into four subtypes (A, B, C, and D) by phylogenetic analysis of consensus nucleotide sequences for the C2-V3 regions. Analysis of the deduced amino acid sequences of the C2-V3 regions by a maximum parsimony program gave a similar phylogenetic relationship. The data indicated that phylogenetic analysis of nucleotide and/or amino acid sequences from the C2-V3 regions is a reliable method of subtype determination. The consensus amino acid sequence of the subtype A and D proviruses were almost identical to those of the Albert et al. group B and group A proviruses, respectively. The deduced amino acid sequences of the C2-V5 regions of six of these proviruses showed considerable diversity both between patients and within patients. The region varied in length between 234 and 243 amino acids and included deletions and repetitions, particularly in the V4 region.

Assessment of the reproducibility of alginate encapsulation of pancreatic islets using the MTT colorimetric assay

Radioisotope diffusion experiments demonstrate that alginate/polyaminoacid encapsulation can prevent antibody and cytotoxic cell contact in vitro. The unpredictable outcome of xenotransplantation of encapsulated islets may reflect incomplete encapsulation. We have assessed a cytotoxic/MTT (tetrazolium) assay to test antibody permeability of capsules. Samples of free porcine islet tissue, and islet tissue encapsulated in alginate/poly-L-lysine/alginate microspheres were incubated with fresh autologous pig serum or normal human serum overnight. Cell metabolism was assessed by the MTT assay. Data from eight experiments (10 replicates/experiment) were analyzed using the Mann-Whitney U-test. Values were deemed significant when p < 0.05. Free islets cultured in human serum showed a significant reduction in metabolism when compared with islets cultured in pig serum: percentage reduction 52 +/- 23% (mean +/- SD). The differences in formazan production were significant in all experiments (p < 0.05). Alginate encapsulation of islets or removal of xenoreactive antibodies in human serum by adsorption was shown to prevent the effects of complement-mediated lysis. However, in one of the eight experiments, there was a significant reduction in islet metabolism after exposure of encapsulated porcine islets to human serum. In conclusion, it has been shown that alginate encapsulation can prevent complement-mediated lysis. However, the encapsulation process employed was imperfect and did not prevent complement-mediated lysis of porcine islets in all experiments. The cytotoxicity/MTT assay allows investigation of the permeability of capsules to serum antibodies and could be performed to determine the viability of the islets and the integrity of microcapsules prior to transplantation.