Evolution of Autoimmune Retinopathy in Stiff Person Syndrome: A Case Report

PURPOSE

To report a case of autoimmune retinopathy (AIR) as the presenting feature of Stiff Person Syndrome (SPS) and assess its evolution.

OBSERVATIONS

A 35-year-old man presented with progressive, chronic, vision loss. On initial examination, visual acuity measured 20/20 OD and 20/50 OS. Humphrey Visual Field testing (HVF) demonstrated decreased foveal threshold OU. Mild subfoveal ellipsoid zone loss was noted on Optical Coherence Tomography (OCT). Five years later the patient presented with painful lower extremity muscle spasms and stiffness and complained of increasing vision loss with difficulty distinguishing colors. OCT showed marked progression of ellipsoid zone loss. Scotoma were demonstrated on HVF and electroretinography demonstrated reduced responses consistent with bilateral severe maculopathy. Serum testing showed autoantibodies to the glutamic acid decarboxylase 65-kilodalton isoform (GAD65) at a high titer and a diagnosis of AIR in the setting of SPS was made. A systemic workup for malignancy was negative. The patient was treated with IVIG and transitioned to rituximab with improvement in systemic symptoms.

CONCLUSIONS

and Importance: Unlike previous cases of AIR in the setting of SPS, vision symptoms and OCT changes presented years before the onset of muscle spasms. Etiologies such as SPS should be on the differential of unexplained retinopathy, even in the absence of systemic symptoms, especially when paraneoplastic etiologies are ruled out.

IMPLICATIONS OF COMPLETE POSTERIOR VITREOUS DETACHMENT IN EYES WITH CENTRAL RETINAL VEIN OCCLUSION

BACKGROUND/PURPOSE

To evaluate the status of the posterior vitreous hyaloid on presenting optical coherence tomography images of the macula and its relationship to clinical characteristics, treatment patterns, and outcomes in eyes with central retinal vein occlusion.

METHODS

This is a retrospective longitudinal cohort study of consecutive patients with acute, treatment-naive central retinal vein occlusion diagnosed between 2009 and 2021 who had at least 12 months of follow-up. Clinical characteristics, treatment patterns, and outcomes were analyzed between eyes stratified based on the presence or absence of a complete posterior vitreous detachment (PVD) on optical coherence tomography at presentation.

RESULTS

Of 102 acute, treatment-naive central retinal vein occlusions identified, 52 (51%) had complete PVD at presentation and 50 (49%) did not. Central subfield thickness was significantly lower in those with complete PVD (12 months: 284.9 ± 122.9 µ m vs. 426.8 ± 286.4 µ m, P < 0.001; last follow-up: 278 ± 127.9 vs. 372.8 ± 191.0 µ m, P = 0.022). One-year intravitreal injection burden was significantly less for those with a complete PVD than those without (5.1 ± 3.6 injections vs. 6.7 ± 3.3 injections, P = 0.013).

CONCLUSION

Central retinal vein occlusion with complete PVD on presentation had significantly lower central subfield thickness and 1-year injection burden. Assessment of the vitreomacular interface in central retinal vein occlusion may serve as a prognostic imaging biomarker.

The Lucy Thermal Emission Spectrometer (L'TES) Instrument

The Lucy Thermal Emission Spectrometer (L'TES) will provide remote measurements of the thermophysical properties of the Trojan asteroids studied by the Lucy mission. L'TES is build-to-print hardware copy of the OTES instrument flown on OSIRIS-REx. It is a Fourier Transform spectrometer covering the spectral range 5.71-100 μm (1750-100 cm-1) with spectral sampling intervals of 8.64, 17.3, and 34.6 cm-1 and a 7.3-mrad field of view. The L'TES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly to a single uncooled deuterated l-alanine doped triglycine sulfate (DLATGS) pyroelectric detector. A significant firmware change from OTES is the ability to acquire interferograms of different length and spectral resolution with acquisition times of 0.5, 1, and 2 seconds. A single ∼0.851 μm laser diode is used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target, together with observations of space, provides radiometric calibration. The radiometric precision in a single spectrum is ≤2.2 × 10-8 W cm-2 sr-1 /cm-1 between 300 and 1350 cm-1. The absolute temperature error is <2 K for scene temperatures >75 K. The overall L'TES envelope size is 37.6 × 29.0 × 30.4 cm, and the mass is 6.47 kg. The power consumption is 12.6 W average. L'TES was developed by Arizona State University with AZ Space Technologies developing the electronics. L'TES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ. Initial data from space have verified the instrument's radiometric and spatial performance.

Bilateral Panuveitis in an Adolescent with Autoimmune Lymphoproliferative Syndrome Due to CTLA4 Haploinsufficiency

PURPOSE

To describe a case of bilateral panuveitis in an 11-year-old girl with autoimmune lymphoproliferative syndrome (ALPS) due to CTLA4 haploinsufficiency.

CASE DESCRIPTION

A 5-year-old girl developed cervical adenopathy, and autoimmune hemolytic anemia and thrombocytopenia consistent with Evan's Syndrome. She was subsequently diagnosed with autosomal dominant CTLA4 haploinsuffciency and treated with immunosuppressants. Ocular symptoms developed 6 years later when she complained of blurry vision and photophobia. There were 3+ anterior chamber cells and 1+ flare, stellate keratic precipitates, and 3+ vitreous cells in both eyes. On fluorescein angiography, there was staining along the arcades and peripheral perivascular leakage in both eyes. On indocyanine green angiography, there were hypofluorescent spots throughout the posterior pole. The inflammation was partially responsive to topical and oral corticosteroids.

CONCLUSION

Panuveitis may be associated with ALPS due to CTLA4 haploinsufficiency. Retinal and choroidal involvement should be assessed when anterior chamber inflammation is the presenting sign.

Asymmetric Purtscher-Like Retinopathy Caused by a Hypertensive Emergency and Undiagnosed Type 2 Diabetes

Purpose: To report a case of Purtscher-like retinopathy (PLR) in the setting of a hypertensive emergency and undiagnosed type 2 diabetes mellitus (DM). Methods: A case was analyzed. Results: A 29-year-old, obese, hypertensive man presented with a 10-day history of progressive vision loss in the left eye with no history of trauma. The visual acuity was 20/25 OD and hand motions OS. A fundus examination showed dilated, tortuous veins; dot-blot and flame hemorrhaging; numerous cotton-wool spots; and polygonal areas of retinal whitening consistent with Purtscher flecken in the right eye and a vitreous hemorrhage in the left eye. The blood pressure was 226/125 mm Hg, and the hemoglobin A1c was 11.6%. The patient's presentation was concerning for a hypertensive emergency and type 2 DM as the etiology for the ocular findings. Conclusions: The presence of one condition in association with PLR does not exclude the presence of another concurrent etiology.

Autoimmune Inflammatory Eye Disease: Demystifying Clinical Presentations for the Internist

PURPOSE OF REVIEW

Provide a framework for recognizing key symptoms and clinical findings in patients with autoimmune inflammatory eye disease.

RECENT FINDINGS

The most common manifestations of autoimmune inflammatory eye disease are episcleritis, scleritis, uveitis (anterior, intermediate, posterior, and panuveitis), and keratoconjunctivitis sicca. Etiologies can be idiopathic or in association with a systemic autoimmune condition. Referral of patients who may have scleritis is critical for patients presenting with red eyes. Referral of patients who may have uveitis is critical for patients presenting often with floaters and vision complaints. Attention should also be directed to aspects of the history that might suggest a diagnosis of a systemic autoimmune condition, immunosuppression, drug-induced uveitis, or the possibility of a masquerade condition. Infectious etiologies should be ruled out in all cases. Patients with autoimmune inflammatory eye disease may present with ocular or systemic symptoms alone, or in combination. Collaboration with ophthalmologists and other relevant specialists is vital to optimal long-term medical care.

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Role of inpatient coronary CT angiography on clinical decision making during COVID- 19 pandemic

Funding Acknowledgements

Type of funding sources: None.

Background

The COVID-19 pandemic has had a profound effect on healthcare delivery. Here we describe the effect of repurposing of a research Computed Tomography scanner on clinical care of cardiology patients in an urban academic medical centre which did not have routine access to CCTA prior to the pandemic. 

Patients requiring invasive coronary angiography require transfer to a regional cardiac centre (no ICA available on site).

Purpose

We investigated the effect of CCTA on i) diagnostic certainty ii) avoidance of clinician defined unnecessary invasive angiography in hospitalised patients.

Methods

This was a prospective, longitudinal cohort study involving hospitalized patients admitted to an urban academic medical centre (catchment population 650 000) between March 29 and September 21, 2020. Routinely collected (usual care) data were gathered by clinicians who were members of the usual care medical team and ethics approval or explicit patient consent was not required. High-sensitivity Troponin-I was measured on admission and 3- and 6– hours after if mandated (Abbott Architect TnI assay).

A 320-detector scanner (Aquilon ONE, Canon) was used. Intravenous metoprolol was used where required to control the heart rate (target 60 b.p.m.) and sublingual glyceryl trinitrate will be given to all patients immediately before the scan acquisition.

Results

Forty-three patients underwent inpatient CCTA, mean age: 61 ± 13 years (range 30-88y), 54% female. The presenting complaint was typical chest pain in 28 (65%), atypical chest pain in 10 (23%), and a variety of symptoms in 5 (12%) including palpitations, syncope, breathlessness.

Thirty-six (84%) of patients had a detectable TnI above the 99% centile. Median(IQR) peak TnI was 127 (33-635)ng/L.

CCTA was carried out on average 1 day post request. 

CCTA resulted in an improvement in clinician diagnostic certainty (Initial review: 21% yes, 79% probable, post-CCTA review: 84% yes, 16% probable) in providing a diagnosis.

21 (49%) of invasive coronary angiograms were avoided due to CCTA, whilst an inpatient invasive coronary angiogram (ICA) was performed in 4(9%) due to CCTA demonstrating significant disease, and in 2(%) the ICA was changed from out-patient to in-patient. Three ICA tests were requested as OP due to CCTA findings. CCTA did not overestimate disease severity in this cohort. 

We saved 21 inter hospital transfers for ICA during this time period. 

Using NHS England cost tariffs, a cost saving of &gt;£36,000 was made for using CCTA instead of ICA in these 21 patients who would have required ICA.

Conclusion

Inpatient CCTA resulted in greater clinician diagnostic confidence, avoidance of unnecessary invasive angiograms and a significant cost saving. This also reduced the duration of patient stay, reducing the potential exposure of patients to COVID-19.

Cell-Free DNA Tissue Damage Mapping in Transplant Patients Infected with COVID-19

Purpose

Patients with COVID-19 show variable clinical course; transplant patients often show worse outcomes. The effect of COVID-19 on the allograft and the sources of tissue injury that contribute to such poor outcomes are poorly defined. This study leverages cell-free DNA (cfDNA) to measure allograft injury as donor-derived cfDNA (ddcfDNA) and injury from different tissue types using tissue-specific DNA methylomic signatures.

Methods

14 consecutive COVID-19 transplant patients (8 Kidney, 3 Lung, 1 Heart, 1 Liver, and one multi-organ transplant patients) and 30 healthy controls were included. Plasma nuclear cfDNA (ncfDNA) and mitochondrial cfDNA (mtcfDNA) level were measured via digital droplet PCR, and ddcfDNA using AlloSure (CareDx). cfDNA whole-genome bisulfite sequencing was performed to identify cfDNA tissues of origin leveraging tissue specific DNA methylomes and deconvolution algorithm.

Results

75% of the COVID-19 transplant patients showed high ddcfDNA level compared to published quiescent values, including all lung, 50% of the kidney, liver and multi-organ transplant patients (8.5, 4.4, 30 and 16-X fold change, respectively). Total ncfDNA and mtcfDNA were 15X and 310X higher in COVID-19 transplant patients compared to controls, respectively; < 0.0001.The predominant tissues contributing to cfDNA were hematopoietic cells (80%) (Figure). More importantly, COVID-19 transplant patients showed 10 to 100 fold higher tissue specific cfDNA derived from monocyte, neutrophil, erythroblast, vascular endothelium, adipocyte, hepatocyte, kidney, heart and lung compared to controls. Analysis comparing cfDNA in transplant and non-transplant COVID-19 patients is on-going.

Conclusion

The allograft undergoes significant injury following COVID-19. Further, cfDNA from multiple tissue types is significantly higher in COVID-19 transplant patients. Future studies in a larger cohorts of transplant and non-transplant patients are needed to elucidate why transplant patients show worse COVID-19 outcomes.

Retinopathy in adults with hypertension and diabetes mellitus in Western Tanzania: a cross-sectional study

OBJECTIVE

Little is known about the retinal manifestations of arterial hypertension (HTN) and diabetes mellitus (DM) in Western Tanzania and how to maximise the utilisation of scarce eye health resources. To address this, we determined the prevalence of hypertensive and diabetic retinopathy (DR), associated risk factors and relevant patient knowledge.

METHODS

Adults with HTN or DM attending outpatient clinics at Bugando Medical Center (BMC) from June to August 2017 were enrolled. Fundus photographs were obtained, and data were collected on blood pressure (BP), body mass index (BMI), blood sugar, visual acuity (VA) and responses to questions about the effects of HTN and DM on the eye.

RESULTS

A total of 180 persons were screened. When only individuals with DR were considered, bivariate regression found systolic BP was significantly associated with severity of DR (P = 0.034). Receiver operating characteristic (ROC) curve analysis using the maximum Youden index revealed the optimum cut-off using duration of DM to predict any DR was 8 years (AUC = 0.75, 95% CI 0.65-0.85). Fewer persons with HTN were aware of the effect of high BP on the eye (61.6%) than persons with DM who were aware of the effect of high blood sugar on the eye (74.4%) (P = 0.048).

CONCLUSION

Efforts should be made to vigorously treat HTN among adults with DM and refer adults with duration of DM of 8 years or more for a dilated retinal examination. Additional efforts should be made to promote awareness of the sight threatening potential of HTN in resource-limited settings.

Tele-ophthalmology: Opportunities for improving diabetes eye care in resource- and specialist-limited Sub-Saharan African countries

Tele-ophthalmology using portable retinal imaging technology, mobile phone and Internet connectivity offers a solution to improve access to diabetic retinopathy (DR) screening services in sub-Saharan African (SSA) countries where the burden of diabetes is increasing and there is limited access to eye care services and specialists. The Zimbabwe Retinopathy Telemedicine Project (ZRTP) established routine DR screening at a hospital-based diabetic clinic in the urban capital city, Harare. A handheld 'point and shoot' digital camera operated by a trained nurse was used to acquire retina images of 203 diabetic patients. A secured 'store-and forward' approach was set up and used for sharing and transfer of images to a retinal specialist at a remote site for reading. This method enabled detection of non-macular DR (11%), diabetic macular oedema (5%), cataract (5%) and glaucoma (6%) among the patients screened. ZRTP demonstrated the utility of tele-ophthalmology for routine retinal screening for diabetic patients in Zimbabwe who have limited access to eye care services. In addition, ZRTP showed how tele-ophthalmology services can provide an empirical framework for providing patient education, and a platform for research in the detection of DR. This approach could be used as a model to address the DR challenges in other countries in SSA.

Association of marital status with access to renal transplantation

In this report we evaluated the association of marital status with access to renal transplantation. We analyzed data from the USRDS. In patients with ESRD aged ≥ 27 (mean age of first marriage in the US), we analyzed the association of marital status with two outcomes: (1) likelihood of being placed on the waiting list for renal transplantation or first transplant, (2) likelihood of receiving kidney transplant in patients already listed. We analyzed marital status as a categorical variable: (1) not married (including never been married and widowed); (2) divorced or separated; and (3) currently married. Subgroups based on age, race, sex, donor type and diabetic status were also analyzed. After adjustments for the included independent variables and compared to individuals never married or widowed, those who were divorced/separated (HR 1.55, p < 0.001) and currently married (HR 1.54, p < 0.001) had a higher likelihood of being placed on the transplant waiting list. Once listed, married individuals had higher chances of getting transplanted as well (HR 1.28, p = 0.033). This trend was consistent in most of the subgroups studied. We demonstrated that being married is associated with better access to renal transplantation compared to those who were never married/widowed.

Expression of putative sex-determining genes during the thermosensitive period of gonad development in the snapping turtle, Chelydra serpentina

Modes of sex determination are quite variable in vertebrates. The developmental decision to form a testis or an ovary can be influenced by one gene, several genes, environmental variables, or a combination of these factors. Nevertheless, certain morphogenetic aspects of sex determination appear to be conserved in amniotes. Here we clone fragments of nine candidate sex-determining genes from the snapping turtle Chelydra serpentina, a species with temperature-dependent sex determination (TSD). We then analyze expression of these genes during the thermosensitive period of gonad development. In particular, we compare gene expression profiles in gonads from embryos incubated at a male-producing temperature to those from embryos at a female-producing temperature. Expression of Dmrt1 and Sox9 mRNA increased gradually at the male-producing temperature, but was suppressed at the female-producing temperature. This finding suggests that Dmrt1 and Sox9 play a role in testis development. In contrast, expression of aromatase, androgen receptor (Ar), and Foxl2 mRNA was constant at the male-producing temperature, but increased several-fold in embryos at the female-producing temperature. Aromatase, Ar, and Foxl2 may therefore play a role in ovary development. In addition, there was a small temperature effect on ER alpha expression with lower mRNA levels found in embryos at the female-producing temperature. Finally, Dax1, Fgf9, and SF-1 were not differentially expressed during the sex-determining period, suggesting these genes are not involved in sex determination in the snapping turtle. Comparison of gene expression profiles among amniotes indicates that Dmrt1 and Sox9 are part of a core testis-determining pathway and that Ar, aromatase, ER alpha, and Foxl2 are part of a core ovary-determining pathway.

Fertility control in female eastern grey kangaroos using the GnRH agonist deslorelin. 2. Effects on behaviour

In recent years fertility control has been proposed as an ethically acceptable alternative to lethal control techniques when managing overabundant kangaroo populations. A promising non-steroidal, non-immunological approach to contraception in female kangaroos involves the use of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist deslorelin. The practicality of using deslorelin implants as a management option is dependant on its effective inhibition of reproduction without negative physical or behavioural side-effects. This study investigated the behavioural effects of deslorelin implants in female eastern grey kangaroos. Treatment had no detectable effects on crepuscular activity. Alterations in the frequency of sexual interactions were observed in deslorelin-treated females, with a behavioural oestrus induced ~3 days after combined removal of pouch young and deslorelin administration. Copulation was observed during this early oestrous period, but conception was not achieved and pouch young were not observed in any treated females. Control females gave birth within 69.6 ± 10.4 days (mean ± s.e.m., n = 9) of placebo implant administration. The first births observed in treated animals were on Days 510, 637 and 643 after treatment. The remaining seven treated animals had not bred by the end of the study, a period of 647 days.

ALVAC-SIV-gag-pol-env-based vaccination and macaque major histocompatibility complex class I (A*01) delay simian immunodeficiency virus SIVmac-induced immunodeficiency

T-cell-mediated immune effector mechanisms play an important role in the containment of human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) replication after infection. Both vaccination- and infection-induced T-cell responses are dependent on the host major histocompatibility complex classes I and II (MHC-I and MHC-II) antigens. Here we report that both inherent, host-dependent immune responses to SIVmac251 infection and vaccination-induced immune responses to viral antigens were able to reduce virus replication and/or CD4+ T-cell loss. Both the presence of the MHC-I Mamu-A*01 genotype and vaccination of rhesus macaques with ALVAC-SIV-gag-pol-env (ALVAC-SIV-gpe) contributed to the restriction of SIVmac251 replication during primary infection, preservation of CD4+ T cells, and delayed disease progression following intrarectal challenge exposure of the animals to SIV(mac251 (561)). ALVAC-SIV-gpe immunization induced cytotoxic T-lymphocyte (CTL) responses cumulatively in 67% of the immunized animals. Following viral challenge, a significant secondary virus-specific CD8+ T-cell response was observed in the vaccinated macaques. In the same immunized macaques, a decrease in virus load during primary infection (P = 0.0078) and protection from CD4 loss during both acute and chronic phases of infection (P = 0.0099 and P = 0.03, respectively) were observed. A trend for enhanced survival of the vaccinated macaques was also observed. Neither boosting the ALVAC-SIV-gpe with gp120 immunizations nor administering the vaccine by the combination of mucosal and systemic immunization routes increased significantly the protective effect of the ALVAC-SIV-gpe vaccine. While assessing the role of MHC-I Mamu-A*01 alone in the restriction of viremia following challenge of nonvaccinated animals with other SIV isolates, we observed that the virus load was not significantly lower in Mamu-A*01-positive macaques following intravenous challenge with either SIV(mac251 (561)) or SIV(SME660). However, a significant delay in CD4+ T-cell loss was observed in Mamu-A*01-positive macaques in each group. Of interest, in the case of intravenous or intrarectal challenge with the chimeric SIV/HIV strains SHIV(89.6P) or SHIV(KU2), respectively, MHC-I Mamu-A*01-positive macaques did not significantly restrict primary viremia. The finding of the protective effect of the Mamu-A*01 molecule parallels the protective effect of the B*5701 HLA allele in HIV-1-infected humans and needs to be accounted for in the evaluation of vaccine efficacy against SIV challenge models.

Mucosal AIDS vaccine reduces disease and viral load in gut reservoir and blood after mucosal infection of macaques

Given the mucosal transmission of HIV-1, we compared whether a mucosal vaccine could induce mucosal cytotoxic T lymphocytes (CTLs) and protect rhesus macaques against mucosal infection with simian/human immunodeficiency virus (SHIV) more effectively than the same vaccine given subcutaneously. Here we show that mucosal CTLs specific for simian immunodeficiency virus can be induced by intrarectal immunization of macaques with a synthetic-peptide vaccine incorporating the LT(R192G) adjuvant. This response correlated with the level of T-helper response. After intrarectal challenge with pathogenic SHIV-Ku2, viral titers were eliminated more completely (to undetectable levels) both in blood and intestine, a major reservoir for virus replication, in intrarectally immunized animals than in subcutaneously immunized or control macaques. Moreover, CD4+ T cells were better preserved. Thus, induction of CTLs in the intestinal mucosa, a key site of virus replication, with a mucosal AIDS vaccine ameliorates infection by SHIV in non-human primates.

Production site transfer: successful approaches to overcoming technical, regulatory and compliance challenges. 22-23 August 2000, San Francisco, CA, USA

The conference brought together a number of process professionals, who discussed their insights on the challenges presented in transferring a process from one production site to another. It was emphasized that this transfer could occur either within a company (ie, pilot plant to full-scale manufacturing) or between companies (ie, to a contract manufacturer). The transfer process requires not only the transfer of production, but also the transfer of analytical methods. While the primary focus of the presenters was on biologics transfer, the subject matter was equally applicable to chemical processes.

Viremia control following antiretroviral treatment and therapeutic immunization during primary SIV251 infection of macaques

Prolonged antiretroviral therapy (ART) is not likely to eradicate human immunodeficiency virus type I (HIV-I) infection. Here we explore the effect of therapeutic immunization in the context of ART during primary infection using the simian immunodeficiency virus (SIV251) macaque model. Vaccination of rhesus macaques with the highly attenuated poxvirus-based NYVAC-SIV vaccine expressing structural genes elicited vigorous virus-specific CD4 + and CD8+ T cell responses in macaques that responded effectively to ART. Following discontinuation of a six-month ART regimen, viral rebound occurred in most animals, but was transient in six of eight vaccinated animals. Viral rebound was also transient in four of seven mock-vaccinated control animals. These data establish the importance of antiretroviral treatment during primary infection and demonstrate that virus-specific immune responses in the infected host can be expanded by therapeutic immunization.

Lack of association of the alpha2-macroglobulin locus on chromosome 12 in AD

OBJECTIVE

Analysis of AD has revealed that the apolipoprotein E locus (APOE) cannot account for all of the genetic risk associated with AD. Whole genome scanning in AD families suggests that a chromosome 12 locus may contribute significantly to disease development. The alpha2-macroglobulin gene (A2M) has been suggested as a candidate locus for AD based on analysis of familial AD.

METHOD

We determined, in 195 neuropathologically verified AD cases and 107 age-matched control subjects, the association of two common polymorphisms in A2M (a pentanucleotide deletion 5' to the bait domain exon, and a valine-1000-isoleucine polymorphism in the thiolester site of the protein).

RESULTS

Evidence was observed for linkage disequilibrium between the deletion and Ile1000 polymorphisms. No evidence was observed for an association between the thiolester polymorphism and AD alone or when accounting for the APOE-epsilon4 allele. No alteration in the frequency of the bait domain deletion was observed, although a small excess (4%) of deletion homozygotes was found in the AD group, which were absent in the control population.

CONCLUSIONS

The A2M deletion polymorphism at most accounts for a small fraction of the genetic contribution toward AD, and this is small compared with APOE. Furthermore, reverse transcriptase PCR of A2M RNA from the brains of patients homozygous for the deletion polymorphism showed that the bait domain exon still is present in the RNA. This suggests that the A2M deletion polymorphism may be nonfunctional and that the chromosome 12 AD locus is situated elsewhere.

Effect of multiple serine/alanine mutations in the transmembrane spanning region V of the D2 dopamine receptor on ligand binding

Three conserved serine residues (Ser193, Ser194, and Ser197) in transmembrane spanning region (TM) V of the D2 dopamine receptor have been mutated to alanine, individually and in combination, to explore their role in ligand binding and G protein coupling. The multiple Ser -->Ala mutations had no effect on the binding of most antagonists tested, including [3H]spiperone, suggesting that the multiple mutations did not affect the overall conformation of the receptor protein. Double or triple mutants containing an Ala197 mutation showed a decrease in affinity for domperidone, whereas Ala193 mutants showed an increased affinity for a substituted benzamide, remoxipride. However, dopamine showed large decreases in affinity (>20-fold) for each multiple mutant receptor containing the Ser193Ala mutation, and the high-affinity (coupled) state of the receptor (in the absence of GTP) could not be detected for any of the multiple mutants. A series of monohydroxylated phenylethylamines and aminotetralins was tested for their binding to the native and multiple mutant D2 dopamine receptors. The results obtained suggest that Ser193 interacts with the hydroxyl of S-5-hydroxy-2-dipropylaminotetralin (OH-DPAT) and Ser197 with the hydroxyl of R-5-OH-DPAT. We predict that Ser193 interacts with the hydroxyl of R-7-OH-DPAT and the 3-hydroxyl (m-hydroxyl) of dopamine. Therefore, the conserved serine residues in TMV of the D2 dopamine receptor are involved in hydrogen bonding interactions with selected antagonists and most agonists tested and also enable agonists to stabilise receptor-G protein coupling.