High frequency of vitamin D deficiency in ambulatory HIV-Positive patients.

Several reports have suggested an increased prevalence of osteopenia and osteoporosis in HIV-infected individuals. Vitamin D deficiency may be a risk factor for osteoporosis and bone fractures. We aimed to determine the prevalence of vitamin D insufficiency in an outpatient HIV clinic in Boston. We collected serum levels of 25-OH vitamin D and evaluated calcium and vitamin D intake in adult HIV-positive outpatients during the winter and spring of 2005. Fifty-seven subjects were enrolled. The prevalence of moderate (< or = 20 and>10 ng/ml) and severe (< or =10 ng/ml) 25-OH vitamin D deficiency was 36.8% and 10.5%, respectively. Lower vitamin D intake was significantly associated with severe 25-OH vitamin D deficiency (p=0.01). Lactose intolerance tended to be associated with severe vitamin D deficiency (p=0.08). Antiretroviral use and low daily calcium intake were significantly associated with elevated parathyroid hormone levels (p=0.01 and 0.03, respectively). Vitamin D deficiency was frequent in ambulatory HIV-positive patients. HIV-infected individuals living in areas with low exposure to ultraviolet light during winter may benefit from vitamin D supplementation.

The mitochondrial pharmacogenomics of haplogroup T: MTND2*LHON4917G and antiretroviral therapy-associated peripheral neuropathy.

Peripheral neuropathy (PN) due to mitochondrial injury complicates HIV therapy with some nucleoside reverse transcriptase inhibitors (NRTIs). Variation in the mitochondrial genome may influence susceptibility to NRTI toxicities. Two non-synonymous mitochondrial DNA polymorphisms, MTND1*LHON4216C (4216C) and MTND2*LHON4917G (4917G) were characterized in HIV-infected participants exposed to NRTIs in a randomized clinical trial. Among 250 self-identified white, non-Hispanic participants, symptomatic PN (> or = grade 1) developed in 70 (28%). Both 4216C (odds ratio (OR)=1.98 (95% confidence interval (CI) 1.05-3.75); P=0.04) and 4917G (OR=2.93 (95% CI 1.25-6.89); P=0.01) were more frequent in PN cases. These two polymorphisms remained independently associated with PN after adjusting for age, baseline CD4 count, plasma HIV RNA level, and NRTI randomization arm; 4216C (OR=2.0 (95% CI 1.1-4.0) P=0.04) and 4917G (OR=5.5 (95% CI 1.6-18.7) P<0.01). When 4917G individuals were excluded from the analysis, the association with 4216C was no longer seen. The mitochondrial 4917G polymorphism may increase susceptibility to NRTI-associated PN.

Triplate fixation: a new technique in limb-salvage surgery.

Massive endoprostheses using a cemented intramedullary stem are widely used to allow early resumption of activity after surgery for tumours. The survival of the prosthesis varies with the anatomical site, the type of prosthesis and the mode of fixation. Revision surgery is required in many cases because of aseptic loosening. Insertion of a second cemented endoprosthesis may be difficult because of the poor quality of the remaining bone, and loosening recurs quickly. We describe a series of 14 patients with triplate fixation in difficult revision or joint-sparing tumour surgery with a minimum follow-up of four years. The triplate design incorporated well within a remodelled cortex to achieve osseomechanical integration with all patients regaining their original level of function within five months. Our preliminary results suggest that this technique may provide an easy, biomechanically friendly alternative to insertion of a further device with an intramedullary stem, which has a shorter lifespan in revision or joint-sparing tumour surgery. A short segment of bone remaining after resection of a tumour will not accept an intramedullary stem, but may be soundly fixed using this method.

Treatment of hip instability.

Instability after total hip arthroplasty is a major source of patient morbidity, second only to aseptic loosening. Certain patient groups have been identified as having a greater risk of instability, including patients undergoing revision arthroplasty as early or late treatment for proximal femoral fractures.

Preoperative planning to prevent instability in total knee arthroplasty.

Several factors can lead to persistent instability after total knee arthroplasty, including bone and soft tissue loss, preexisting ligamentous laxity, and poor operative technique. Achieving stability should not be equated with making the knee extremely tight, without any natural laxity.

A water extraction, static headspace sampling, gas chromatographic method to determine MTBE in heating oil and diesel fuel.

A method was developed to determine the fuel/water partition coefficient (KMTBE) of methyl tert-butyl ether (MTBE) and then used to determine low parts per million concentrations of MTBE in samples of heating oil and diesel fuel. A special capillary column designed for the separation of MTBE and to prevent coelution and a gas chromatograph equipped with a photoionization detector (PID) were used. MTBE was partitioned from fuel samples into water during an equilibration step. The water samples were then analyzed for MTBE using static headspace sampling followed by GC/PID. A mathematical relationship was derived that allowed a KMTBE value to be calculated by utilizing the fuel/water volume ratios and the corresponding PID signal. KMTBE values were found to range linearly from 3.8 to 10.9 over a temperature range of 5-40 degrees C. This analysis method gave a MDL of 0.7 ppm MTBE in the fuel and a relative average accuracy of +/-15% by comparison with an independent laboratory using purge and trap GC/ MS analysis. MTBE was found in home heating oil in residential tanks and in diesel fuel at service stations throughout the state of Connecticut. The levels of MTBE were found to vary significantly with time. Heating oil and diesel fuel from terminals were also found to contain MTBE. This research suggests thatthe reported widespread contamination of groundwater with MTBE may also be due to heating oil and diesel fuel releases to the environment. used extensively for the past 20 years as a gasoline additive (up to 15 wt %) to reduce automobile carbon monoxide and hydrocarbon emissions. The fact that MTBE is highly soluble in water (approximately 5 wt %) (3) and chemically inert when compared to other fuel constituents causes it to be often detected at high concentrations in groundwater in the vicinity of gasoline spills. The EPA has reported that low levels of MTBE in drinking water (above 40 microg/L) may cause unpleasant taste and odors and has designated MTBE as a possible human carcinogen (4). Past studies have concentrated on the reporting of MTBE levels in groundwater near gasoline spills. Happel et al. reported an MTBE occurrence rate of approximately 78% at locations where hydrocarbons have impacted groundwater (5). Johnson et al. estimate that 9,000 leaking underground fuel tanks have caused MTBE contamination at community water supplies in the 31 states surveyed (excluding California and Texas) (6). Robbins et al. reported finding a significant number of MTBE detections in groundwater samples taken at sites in Connecticut known to be contaminated by heating oil spills (7). Later, this same research group reported finding MTBE contamination to range from 9.7 to 906 mg/L in heating oil and from 74 to 120 mg/L in diesel fuel in samples collected from storage tanks in Connecticut (8). The method used to analyze these samples was based on fuel-water partitioning and GC analysis. This present study provides the detailed basis for that analytical method. MTBE fuel-water partition coefficients as a function of temperature, which are critical to the method, are also presented. This study also reports on variations in MTBE levels as a function of time observed at several residences and a service station. Analytical results are reported for samples taken from terminals as part of an effort to assess the sources of MTBE in heating oil and diesel fuel.

Conversion of hip arthrodesis to total hip arthroplasty.

With the predictably good outcome now found with THA, hip arthrodesis has limited indications today. The procedure still has a role in the case of the young, heavy demand male with an isolated arthritic hip condition, and developments such as the Cobra head plate have considerably improved success rates. However, a long-term hip arthrodesis can have profound effects on a patient's daily function and activities of daily living. In addition, gait pattern is considerably affected as well as other joints such as the lower back, ipsilateral knee, and contralateral hip. Many patients with a hip arthrodesis will eventually require a takedown of the fused hip and conversion to a THA. The primary indications include fusion in malposition, pseudarthrosis, or severe pain in other joints. The surgeon undertaking such a task must be familiar with the arthrodesis techniques that have been used in the past as well as the equipment that may be required to extract the fixation hardware. Clinical assessment with particular attention to leg-length discrepancy, position of the arthrodesis, and function of the abductors is of paramount importance. The surgeon must carefully review preoperative radiographs to plan the procedure. The surgeon must also be aware of the presence of pathology in other joints. After takedown of a hip arthrodesis and conversion to a THA, patients cannot expect the result to equal the success rates of primary THA. Patients generally can expect an improvement in function and mobility. Back pain and ipsilateral knee pain are usually improved postoperatively, but the effect on contralateral hip pain is less predictable. Many patients will continue to show a positive Trendelenburg sign, but further improvement in strength of the hip abductors can be expected with time. Leg-length discrepancy is generally improved substantially after THA. However, a substantial number of patients will require a walking aid postoperatively. Overall, the risk of complications and the rates of revision after converting an arthrodesed hip to a THA are quite high. The procedure can be complex. Consideration should be given to referring these patients to a specialized center under the care of an experienced arthroplasty surgeon if preoperative planning suggests that the conversion will not be straightforward.

ACTG (AIDS Clinical Trials Group) 384: a strategy trial comparing consecutive treatments for HIV-1.

ACTG (AIDS Clinical Trials Group) 384 is designed to evaluate different strategies for antiretroviral treatment in HIV-1-infected individuals with no previous exposure to antiretroviral treatment. The study is a randomized, partially double-blinded, controlled trial with 980 subjects at 81 centers in the United States and Italy. The study has a factorial design that addresses the following scientific questions: (1) Does the best initial choice of therapy include both a protease inhibitor (PI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) in a four-drug combination with nucleoside analogue (NRTI) drugs, or should these agents be used sequentially in three-drug combinations?; (2) Which sequence is best in a three-drug regimen-PI followed by NNRTI or NNRTI followed by PI ?; (3) Which is the best sequence of dual NRTI combinations-zidovudine plus lamivudine followed by didanosine plus stavudine, or the converse? Subjects in the three-drug combination arms are offered a salvage regimen after failure of their second regimen; subjects in the four-drug combination arm are offered a salvage regimen after failure of their first regimen. The primary endpoint of the study is the time until salvage; secondary endpoints include time to virological failure and time to toxicity-related discontinuation of therapy. A Division of AIDS Data and Safety Monitoring Board will review the trial for safety and efficacy. Control Clin Trials 2001;22:142-159

The HIV-1 regulatory proteins Tat and Rev are frequently targeted by cytotoxic T lymphocytes derived from HIV-1-infected individuals.

The HIV-1 regulatory proteins Rev and Tat are expressed early in the virus life cycle and thus may be important targets for the immune control of HIV-1-infection and for effective vaccines. However, the extent to which these proteins are targeted in natural HIV-1 infection as well as precise epitopes targeted by human cytotoxic T lymphocytes (CTL) remain to be defined. In the present study, 57 HIV-1-infected individuals were screened for responses against Tat and Rev by using overlapping peptides spanning the entire Tat and Rev proteins. CD8+ T cell responses against Tat and Rev were found in up to 19 and 37% of HIV-1-infected individuals, respectively, indicating that these regulatory proteins are important targets for HIV-1-specific CTL. Despite the small size of these proteins, multiple CTL epitopes were identified in each. These data indicate that Tat and Rev are frequently targeted by CTL in natural HIV-1 infection and may be important targets for HIV vaccines.

Cellular immune responses and viral diversity in individuals treated during acute and early HIV-1 infection.

Immune responses induced during the early stages of chronic viral infections are thought to influence disease outcome. Using HIV as a model, we examined virus-specific cytotoxic T lymphocytes (CTLs), T helper cells, and viral genetic diversity in relation to duration of infection and subsequent response to antiviral therapy. Individuals with acute HIV-1 infection treated before seroconversion had weaker CTL responses directed at fewer epitopes than persons who were treated after seroconversion. However, treatment-induced control of viremia was associated with the development of strong T helper cell responses in both groups. After 1 yr of antiviral treatment initiated in acute or early infection, all epitope-specific CTL responses persisted despite undetectable viral loads. The breadth and magnitude of CTL responses remained significantly less in treated acute infection than in treated chronic infection, but viral diversity was also significantly less with immediate therapy. We conclude that early treatment of acute HIV infection leads to a more narrowly directed CTL response, stronger T helper cell responses, and a less diverse virus population. Given the need for T helper cells to maintain effective CTL responses and the ability of virus diversification to accommodate immune escape, we hypothesize that early therapy of primary infection may be beneficial despite induction of less robust CTL responses. These data also provide rationale for therapeutic immunization aimed at broadening CTL responses in treated primary HIV infection.

Identification of novel HLA-A2-restricted human immunodeficiency virus type 1-specific cytotoxic T-lymphocyte epitopes predicted by the HLA-A2 supertype peptide-binding motif.

Virus-specific cytotoxic T-lymphocyte (CTL) responses are critical in the control of human immunodeficiency virus type 1 (HIV-1) infection and will play an important part in therapeutic and prophylactic HIV-1 vaccines. The identification of virus-specific epitopes that are efficiently recognized by CTL is the first step in the development of future vaccines. Here we describe the immunological characterization of a number of novel HIV-1-specific, HLA-A2-restricted CTL epitopes that share a high degree of conservation within HIV-1 and a strong binding to different alleles of the HLA-A2 superfamily. These novel epitopes include the first reported CTL epitope in the Vpr protein. Two of the novel epitopes were immunodominant among the HLA-A2-restricted CTL responses of individuals with acute and chronic HIV-1 infection. The novel CTL epitopes identified here should be included in future vaccines designed to induce HIV-1-specific CTL responses restricted by the HLA-A2 superfamily and will be important to assess in immunogenicity studies in infected persons and in uninfected recipients of candidate HIV-1 vaccines.

Immune control of HIV-1 after early treatment of acute infection.

Virus-specific T-helper cells are considered critical for the control of chronic viral infections. Successful treatment of acute HIV-1 infection leads to augmentation of these responses, but whether this enhances immune control has not been determined. We administered one or two supervised treatment interruptions to eight subjects with treated acute infection, with the plan to restart therapy if viral load exceeded 5,000 copies of HIV-1 RNA per millilitre of plasma (the level at which therapy has been typically recommended) for three consecutive weeks, or 50,000 RNA copies per ml at one time. Here we show that, despite rebound in viraemia, all subjects were able to achieve at least a transient steady state off therapy with viral load below 5,000 RNA copies per ml. At present, five out of eight subjects remain off therapy with viral loads of less than 500 RNA copies per ml plasma after a median 6.5 months (range 5-8.7 months). We observed increased virus-specific cytotoxic T lymphocytes and maintained T-helper-cell responses in all. Our data indicate that functional immune responses can be augmented in a chronic viral infection, and provide rationale for immunotherapy in HIV-1 infection.

Analysis of successful immune responses in persons infected with hepatitis C virus.

Although hepatitis C virus (HCV) infection is very common, identification of patients during acute infection is rare. Consequently, little is known about the immune response during this critical stage of the disease. We analyzed the T lymphocyte response during and after acute resolving HCV infection in three persons, using interferon (IFN)-gamma enzyme-linked immunospot (ELISPOT) and human histocompatibility leukocyte antigen (HLA) peptide tetramer assays. Acute infection was associated with a broadly directed T helper and cytotoxic T lymphocyte (CTL) response, which persisted after resolution of clinical hepatitis and clearance of viremia. At the earliest time point studied, highly activated CTL populations were observed that temporarily failed to secrete IFN-gamma, a "stunned" phenotype, from which they recovered as viremia declined. In long-term HCV-seropositive persons, CTL responses were more common in persons who had cleared viremia compared with those with persistent viremia, although the frequencies of HCV-specific CTLs were lower than those found in persons during and after resolution of acute HCV infection. These studies demonstrate a strong and persistent CTL response in resolving acute HCV infection, and provide rationale to explore immune augmentation as a therapeutic intervention in chronic HCV infection.

Factors affecting the severity of motor vehicle traffic crashes involving elderly drivers in Ontario.

A population-based cross-sectional study was conducted to examine factors affecting the severity of motor vehicle traffic crashes (MVTCs) involving elderly drivers in Ontario. The study population included drivers aged 65 and over involved in injury-producing MVTCs between 1988 and 1993 on Ontario public roads. Information was obtained from the Canadian Traffic Accident Information Databank (TRAID) compiled from police reports. The severity of MVTC was classified as fatal, major, minor or minimal. Comparisons between fatal-, major-, minor- and minimal-injury crashes were conducted. Percentage distributions of crashes at each level of severity involving elderly drivers were examined according to specific factors and tested using the X2 test. Multivariate unconditional logistic regression was used to calculate the estimated relative risk as odds ratios (ORs) while controlling for confounding factors. A number of factors were significantly related to the increased risk of fatal-injury in crashes compared with a reference category for each variable. These included age (OR = 1.4 for 70-79 and OR = 2.3 for 80 + ), sex (OR = 1.4 for males), failing to yield right-of-way/disobeying traffic signs (OR = 1.7), non-use of seat belts (OR = 4.0), ejection from vehicle (OR = 11.3), intersection without traffic controls (OR = 1.7), roads with higher speed limits (OR = 7.9 for 70-90 km/h; OR= 5.8 for 100 km/h), snowy weather (OR= 1.6), head-on collisions (OR=55.1), two-vehicle turning collisions (OR = 3.1 for left-turn, OR = 8.7 for right-turn), overtaking (OR = 5.6), and changing lanes (OR = 2.1). Adverse medical/physical conditions increased the risk of fatality by a factor of 5 for drivers 75-79 years of age and a factor of 3.5 for those 80 years and over. However, in the age group 65-74, medical/physical condition did not appear to be related to risk of fatality. Similar but weaker associations between these factors and risk of major- and minor-injury in crashes were also observed. To reduce the severity of crashes involving elderly drivers, strategies could target specific factors such as head-on collisions, single-vehicle collisions, and traffic controls at intersections. Driver conditions such as medical/physical conditions and driver actions such as failing to yield right-of-way/disobeying traffic signs should be examined further.

Characterization of HIV-1-specific T-helper cells in acute and chronic infection.

HIV-1 infection is associated with progressive and relentless destruction of the immune system in the majority of infected persons, but some persons appear to be able to successfully contain the virus in the absence of antiviral therapy. Such cases suggest that the host immune response can successfully contain the virus, and provide the rationale for concerted efforts to understand the host immune response to the virus and to develop new strategies to combat the infection with immune based therapies. Historically, the greatest hole in the immune repertoire in HIV-1 infection has been the lack of strong virus-specific proliferative responses. However, new studies have identified a potent Th cell response in some infected persons, and have shown a statistically significant negative correlation between plasma viremia and virus-specific CD4 T-helper cells directed at the p24 protein. Moreover, early institution of potent antiviral therapy in the earliest stages of acute HIV-1 infection have led to persistent, strong HIV-1-specific T-helper cell responses, analogous to those seen in persons who are able to control viremia in the absence of antiviral therapy. We hypothesize that this is because potent antiviral therapy is able to protect virus-specific Th cells as they become activated, and thus these cells are not lost in the earliest stages of infection.