A new mtDNA mutation showing accumulation with time and restriction to skeletal muscle

We have identified a new mutation in mtDNA, involving tRNALeu(CUN) in a patient manifesting an isolated skeletal myopathy. This heteroplasmic A-->G transition at position 12320 affects the T psi C loop at a conserved site and was not found in 120 controls. Analysis of cultured fibroblasts, white blood cells/platelets, and skeletal muscle showed that only skeletal muscle contained the mutation and that only this tissue demonstrated a biochemical defect of respiratory-chain activity. In a series of four muscle-biopsy specimens taken over a 12-year period, there was a gradual increase, from 70% to 90%, in the overall level of mutation, as well as a marked clinical deterioration. Single-fiber PCR confirmed that the proportion of mutant mtDNA was highest in cytochrome c oxidase-negative fibers. This study, which reports a mutation involving tRNALeu(CUN), demonstrates clearly that mtDNA point mutations can accumulate over time and may be restricted in their tissue distribution. Furthermore, clinical deterioration seemed to follow the increase in the level of mutation, although, interestingly, the appearance of fibers deficient in respiratory-chain activity showed a lag period.

Mitochondrial function in muscle from elderly athletes

The extent to which mitochondria are involved in the aging process is controversial; much of the reported decline in mitochondrial oxidations in human skeletal muscle may be due to disease and inactivity rather than age. To study true aging, mitochondrial respiratory chain function was studied in 9 young and 12 elderly athletes. No significant deterioration with age was observed. If mitochondria are involved in aging, it must be through a more subtle mechanism than a global decline in respiratory chain activity.

Progression of HIV disease is associated with increased expression of Fc gammaRI and CR1 on alveolar macrophages

The expression of receptors for complement and the Fc region of immunoglobulin by alveolar macrophages (AM) constitutes a valuable aid to effector function of these cells. However, during HIV infection such expression may also act to increase binding of immune complexes, thus facilitating viral infection of these cells. This study was designed to determine whether changes in the expression of these receptors occurs in situ during HIV infection. Lung macrophages were isolated by bronchoalveolar lavage in groups of HIV+ subjects segregated on the basis of peripheral CD4 count. A group of normal subjects was also investigated. Expression of CR1 and Fc gammaRI was quantified by measuring the optical density of reaction product following controlled immunoperoxidase staining with MoAbs CD35 and CD64. Both CR1 and Fc gammaRI were increased over normal in all HIV+ subjects. This increase was progressive with advancing disease as determined by correlation with declining peripheral CD4 count. Comparison of asymptomatic and symptomatic subjects with HIV infection showed no difference in CR1 expression but a rise in Fc gammaRI expression in the latter group. An overall inverse correlation was also found between peripheral CD4 count and Fc gammaRI expression, but not CR1 expression. These data demonstrate a significant increase in the expression of these receptors on AM from HIV+ subjects, and show that this increase may occur before any symptoms in these patients.

Health and dietary characteristics of supplement users in an elderly population

The purpose of this study was to investigate the association of health and dietary characteristics with the use of vitamin and mineral supplements in community-dwelling, cognitively intact elders aged in their 60s (n = 89), 80s (n = 92), and 100s (n = 76) who resided in Georgia in the southeastern United States. Elders who were physically active (p = 0.008), had stomach problems (p = 0.042), or used arthritis medication (p = 0.015) were more likely to take a nutritional supplement than elders without these characteristics. Physically active elders were more likely to take calcium (p = 0.004), vitamin E (p = 0.022), and vitamin C (p = 0.046) than non-physically active elders. Compared to non-users, supplement users were also more likely to comply with nutritional health seeking behaviors such as avoiding too much salt, fat, cholesterol, sugar, caffeine, and eating enough fiber, vitamins and minerals from food or supplements, and calcium in foods or supplements. The observation that the use of certain vitamin or mineral supplements is associated with dietary fat intakes, dietary protein intakes, and patterns of alcohol, decaffeinated coffee, and tea consumption suggests that supplement use is one of a cluster of health behaviors. Thus, it may be important that future investigations concerning the impact of supplement use on diseases, such as heart disease or cancer, control for the effects of dietary patterns and physical activity.

Comparison of CO2 laser, electrocautery, and scalpel incisions on acute-phase reactants in rat skin

Lasers and electrocautery devices have been applied as an alternative to the scalpel because of better hemostasis and lymphatic sealing. However, previous studies have demonstrated conflicting data regarding the effects of these modalities on the inflammatory response, the first reaction by tissue during wound healing. The purpose of this study is to quantitate inflammatory responses in rat skin following laser, electrocautery, and scalpel injury by measuring T-kininogen (T-KGN), a major acute-phase protein in the rat and its endogenous substrate, cathepsin B, an important inflammatory mediator. Full-thickness wounds (6 cm) were created on the dorsum of Sprague Dawley rats by using a laser, electrocautery, or scalpel. Tissue samples were harvested at 1 hour to 21 days after injury. T-KGN levels were radioimmunoassayed; cathepsin B activity was assayed by using a synthetic substrate Z-Arg-Arg-MCA. Data were analyzed by analysis of variance. T-KGN levels peaked at 3 days for all modalities, although the laser group was statistically (P < or = 0.01) higher at 1, 3, and 7 days after injury. In contrast, cathepsin B activity was significantly (P < or = 0.01) lower at 3 days in the laser group. CO2 laser ablation incites a greater inflammatory response than electrocautery or scalpel injuries. High levels of T-KGN may provide protection from proteolytic damage associated with cathepsins.

Cleaning of endodontic files, Part I: The effect of bioburden on the sterilization of endodontic files

Ninety-two new endodontic files were randomly assigned to five groups with varying parameters of contamination, cleaning method, and sterilization (steam or chemical). Files were instrumented in bovine teeth to accumulate debris and a known contaminant, Bacillus stearothermophilus. Positive controls produced growth on both T-soy agar plates and in T-soy broth. Negative controls and experimental files (some with heavy debris) failed to produce growth. The results showed that there was no significant difference between contaminated files that were not cleaned before sterilization and contaminated files that were cleaned before sterilization. Bioburden present on endodontic files does not appear to affect the sterilization process.

Lessons from the natural history of cytomegalovirus

BACKGROUND

More than 90% of patients with HIV have been infected at some time with cytomegalovirus (CMV) and up to 40% of those with advanced HIV will develop CMV disease. The incidence of CMV disease is increasing but the prognosis for the patient remains poor.

MONITORING FOR CMV

It is therefore important to monitor patients with low CD4+ counts in order to identify those most at risk of developing CMV disease and to treat them before the disease becomes established. Polymerase chain reaction (PCR) is probably the most effective and sensitive method of detecting CMV and a positive result is predictive for development of CMV disease; more than 80% of patients with CMV retinitis are CMV PCR-positive at the time of diagnosis. PCR can also detect the presence of CMV up to 14 months before the development of retinitis.

TREATMENT OF CMV RETINITIS

In patients with detectable CMV, but no evidence of active infection, pre-emptive treatment with ganciclovir or valaciclovir has been shown to reduce the risk of developing retinitis in these high-risk patients. Such oral therapy, which is generally better tolerated than intravenous therapy and results in a better quality of life for the patient, is likely to be more effective at this stage whilst viral loads are low.

CONCLUSIONS

CMV PCR can be used to prospectively monitor patients in order to identify those most at risk of developing CMV retinitis. If CMV infection is diagnosed early, while viral loads are still low, pre-emptive oral therapy can be instituted which will reduce the chances of developing retinitis in those patients most at risk.

Screening for sexually transmitted diseases in an HIV testing clinic; uptake and prevalence

OBJECTIVE

To estimate the prevalence of sexually transmitted diseases (STDs) and the acceptability of STD screening among people seeking an HIV antibody test in an established free standing HIV testing clinic.

DESIGN

A 9 month period prevalence study conducted between August 1993 and April 1994.

SETTING

The Same Day Testing Clinic (SDTC) for HIV antibodies at the Royal Free Hampstead NHS Trust Hospital, London.

SUBJECTS

242 males and 160 females attending the Same Day Testing Clinic.

OUTCOME MEASURES

The prevalence of STDs including gonorrhoea, chlamydia, syphilis and hepatitis B and the percentage of clinic attenders accepting an STD screen.

RESULTS

Of those invited to take part in the study 69% of the males (242/350) and 59% (160/269) of the females agreed to be screened although for a variety of reasons not everyone agreed to a full screen. Two cases of untreated syphilis, no cases of gonorrhoea and six cases of chlamydia were detected. Four people had active, previously undiagnosed herpes while three had genital warts. Evidence of previously unknown hepatitis B infection was found in 26 people. Despite a high level of previous contact with genitourinary medicine services, uptake of hepatitis B vaccination among those homosexual men eligible for immunisation was low (28%; 23/83). Nine (4%) of the males, but none of the females screened for STD were found to be HIV antibody positive.

CONCLUSION

Among people seeking an HIV antibody test in an established free standing HIV testing clinic, the prevalence of acute STDs was low. However, evidence of previously undiagnosed hepatitis B infection was found in a number of subjects and uptake of vaccination among those most at risk had been low. While opportunistic screening for STD was acceptable to almost two thirds of HIV testing clinic attenders, a substantial minority nonetheless declined this offer. Selective STD screening could be offered to those people seeking an HIV test who report never having been screened before, as both cases of positive syphilis serology and all those of chlamydia were in people who had not previously been screened. All those at risk for hepatitis B infection should be encouraged to establish their infection status and be immunised where appropriate.

Will we ever know when to treat HIV infection?

Confidence in the efficacy of using antiretroviral drugs to treat HIV infection has grown in the past year as a result of the prolonged survival of those randomly allocated to receive an additional drug in comparative controlled trials. HIV remains, however, the only serious infectious disease for which antimicrobial treatment is deliberately delayed. This is because infected subjects can often be symptomless for more than a decade in the absence of any treatment, and results from trials with the nucleoside analogue reverse transcriptase inhibitor zidovudine have failed to show any evidence for extended survival in those beginning treatment early compared with those who deferred treatment. The new confidence in currently available treatments, and in the prospects for new ones, inevitably leads to renewed questioning of the current strategy of waiting for signs of immune deficiency before electing to intervene. A new randomised controlled trial comparing strategies of early and deferred treatment is required to assess whether the time has come for intervention immediately after HIV has been diagnosed.

Quantification of human herpesvirus 6 in immunocompetent persons and post-mortem tissues from AIDS patients by PCR

A quantitative competitive PCR assay for human herpesvirus 6 (HHV-6) was developed. Firstly, viral burden was determined in the blood of 25 healthy persons. Using 1 microgram of DNA, the prevalence of HHV-6 was 36% (9/25). Eight persons had viral loads of < or = 32 HHV-6 genomes/microgram DNA. The viral burden in the ninth individual was 1.2 x 10(6) HHV-6 genome copies/microgram DNA, which remained constant over a period of 10 months. This demonstrates the persistence of a high HHV-6 load in the absence of apparent disease. Secondly, HHV-6 burden was determined in 100 post-mortem tissues from seven AIDS patients and three controls. For all tissues combined, there was a statistically significant higher median viral load in AIDS patients (56 copies/microgram DNA, range 0-43321) compared to controls (10 copies/microgram DNA, range 0-423) (P = 0.04). The precision and reproducibility of this assay will allow hypotheses concerning the pathogenic potential of HHV-6 to be tested quantitatively.

Developing an instrument to measure the influence of knowledge, behaviors, and attitudes on milk consumption patterns in older participants of a community wellness group: a pilot study

An instrument was developed to assess the relationship between knowledge of dairy products and milk consumption in participants of a community wellness program (age = 50 to 89; n = 103). Multiple regression analyses indicated that consumption of lower fat milk was predicted by nutrition knowledge and trying to reduce fat intake (R2 = .19, p < or = .0001), whereas, frequency of milk intake was predicted by milk consumption during youth, following a weight loss diet, and attitudes related to spoilage, packaging and expense (R2 = .24, p < or = .0001). Thus, nutrition knowledge about dairy products is a better predictor of the type of milk consumed rather than the frequency of milk consumption.

Safety and efficacy of lamivudine-zidovudine combination therapy in zidovudine-experienced patients. A randomized controlled comparison with zidovudine monotherapy. Lamivudine European HIV Working Group

OBJECTIVE

To compare the safety and efficacy of 2 doses of lamivudine given in combination with zidovudine with continued zidovudine monotherapy.

DESIGN

Double-blind, randomized, multicenter, comparative trial of 223 patients treated for 24 weeks.

SETTING

Patients from 32 hospitals in Europe were enrolled throughout a 1-year period.

PATIENTS

Adult human immunodeficiency virus type 1 (HIV-1)-positive, zidovudine-experienced ( > or = 24 weeks prior zidovudine) patients with CD4+ cell counts between 0.10 and 0.40 x 10(9)/L (100-400 cells/microL).

INTERVENTION

Patients received either 200 mg of zidovudine every 8 hours, 150 mg of lamivudine every 12 hours plus zidovudine, or 300 mg of lamivudine every 12 hours plus zidovudine for 24 weeks. All patients were then allowed to receive zidovudine and open-label lamivudine combination therapy. Twelve patients withdrew because of adverse events during the 24-week treatment period.

MAIN OUTCOME MEASURES

Efficacy was measured by evaluating immunological and viral load changes, and safety was assessed by evaluating clinical manifestations and laboratory indexes of toxic effects.

RESULTS

Patients receiving low- or high-dose combination therapy had greater treatment effects compared with patients receiving continued zidovudine monotherapy during the first 24 weeks as documented by changes in CD4+ cell counts (+0.04 vs +0.03 vs -0.02 x 10(9)/L, respectively; P < .001); log10 HIV-1 RNA as measured by the Roche assay (-0.96 vs -0.77 vs +0.07 copies/mL, respectively; P < .001) or log10 HIV-1 RNA measured by the quantitative nucleic acid sequence-based amplification assay (-0.59 vs -1.06 vs -0.02 copies/mL, respectively; P < .011); and immune-complex dissociated (ICD) p24 antigen (-74% vs -68% vs +27%, respectively; P < .001). There were no statistically significant differences in viral measurements, in CD4+ cell counts, or in safety profile between the groups receiving 2 doses of lamivudine in combination with zidovudine. The effects on CD4+ cell counts and ICD p24 antigen were sustained throughout 48 weeks for patients continuing combination therapy. Patients switching to combination therapy at week 24 showed improvement.

CONCLUSION

In zidovudine-experienced HIV-1-infected patients, combination treatment with lamivudine and zidovudine is well tolerated and provides greater and more sustained increases in CD4+ cell counts and decreases in viral load than continued zidovudine monotherapy.

Genomic location and nucleotide sequence of a porcine adenovirus penton base gene

The putative penton base gene of a porcine adenovirus serotype 3 (PAV3) has been identified, cloned and sequenced. The genomic location of the PAV3 penton base was deduced by probing a Southern blot with a polymerase chain reaction generated product containing the human adenovirus type 2 (HAV2) penton base gene. Sequencing revealed an open reading frame (ORF) of 1527 nucleotides coding for a polypeptide of 509 amino acids. However, cDNA analysis indicated an acceptor splice site one nucleotide upstream of the second ATG in the ORF. This produced an ORF of 1452 nucleotides coding for a polypeptide of 484 amino acids with a calculated molecular weight of 54.5 kDa. Comparison with the HAV2 penton base amino acid sequence revealed the putative PAV3 penton base homologue to be 87 amino acids shorter with an overall amino acid homology of approximately 65%. Comparison with the penton base proteins of other HAV types revealed a region between amino acid positions 283 and 379 with no similarity.

Increased numbers of primed activated CD8+CD38+CD45RO+ T cells predict the decline of CD4+ T cells in HIV-1-infected patients

OBJECTIVE

To look for surrogate markers in HIV-1 infection that can predict the decline of CD4+ T cells.

METHODS

Multiparameter flow cytometric analyses of CD8+ lymphocytes were performed. These cells were investigated for their expression of the activation marker CD38+ within the naive (CD45RA+) and primed (CD45RO+) subsets. Serial CD4 counts were plotted for each patient and the straight line that best fitted was obtained using least squares regression. Differences in rate of decline were tested using analysis of variance, after each patient was weighted by the reciprocal of the variance.

RESULTS

Baseline levels of percentages of CD8+CD38+ T lymphocytes predict the CD4 decline in HIV-1-infected patients. Within the CD8+ subset, the primed CD8+CD38+CD45RO+ population was responsible for this prediction. Conversely, the naive CD8+CD38+CD45RA+ population was not predictive. Patients who initially showed a percentage of CD8+CD38+ T lymphocytes above the median (> 25%) had a more marked decline in CD4+ T cells when compared to individuals with percentages of CD8+CD38+ T lymphocytes below the median value (79.3 and 21.2 x 10(6)/l mean CD4 cell decline per year, respectively). Similarly, percentages of CD8+CD38+CD45RO+ T cells above the median value (> 7%) were also associated with a more rapid decline (69.4 and 14.2 x 10(6)/l mean CD4+ cell decline per year). These results were statistically significant after adjustment for the baseline CD4 count and beta 2-microglobulin levels.

CONCLUSIONS

Percentages of activated CD8+ cells expressing CD38+ can predict the rate of decline (slope) of the CD4+ T cells. This resides in the CD45RO+ primed population. An early prediction of the CD4+ slope will allow the clinician to target treatment to those patients that are most likely to benefit.

Differential expression of perforin in muscle-infiltrating T cells in polymyositis and dermatomyositis

Polymyositis (PM) and dermatomyositis (DM) are the prototypical inflammatory diseases of skeletal muscle. In PM, CD8+ T cells invade and destroy muscle fibers, whereas humoral effector mechanisms prevail in DM. We studied the expression of the cytotoxic mediator perforin in inflammatory cells in PM and DM muscle by semiquantitative PCR, immunohistochemistry and confocal laser microscopy. Similar levels of perforin mRNA were expressed in PM and DM, and abundant perforin-expressing CD3+CD8+ and CD3+ CD4+ T cells were observed in both diseases. However, there was a striking difference in the intracellular localization of perforin. In DM, perforin was distributed randomly in the cytoplasm of the inflammatory T cells. In contrast, 43% of the CD8+ T cells that contacted a muscle fiber in PM showed perforin located vectorially towards the target muscle fiber. The results suggest (a) that the random distribution of perforin in the cytoplasm of muscle-infiltrating T cells observed in DM reflects nonspecific activation, and (b) that the vectorial orientation observed only in PM reflects the specific recognition via the T cell receptor of an antigen on the muscle fiber surface, pointing to a perforin- and secretion-dependent mechanism of muscle fiber injury.

The distribution of immunocompetent cells in the genital tract of HIV-positive women

OBJECTIVE

To study the distribution of immunocompetent cells in the female lower genital tract and to determine whether it is altered in HIV infection.

METHODS

Colposcopically directed cervical biopsies were taken in the premenstrual phase of 10 HIV-positive women with sexually acquired infection, and matched HIV-negative controls. Peripheral blood was collected from the HIV-infected group for immune studies. Histological, immunohistochemical and double immunofluorescence techniques were applied to the biopsies to reveal immunocompetent cell distribution. Comparisons were made between the immune cell populations in the cervix in the HIV-positive and negative groups, and between the cervix and peripheral blood in the HIV-positive group.

RESULTS

Cervical biopsies from HIV-positive women had significantly reduced Langerhans and plasma cell counts in the submucosa, but increased T lymphocyte counts compared with the HIV-negative group. There was an increase in CD8+ lymphocyte numbers in cervical biopsies of HIV-positive women, causing an inversion of the CD4/CD8 ratio. The majority of these CD8+ cells were 'memory' (CD45RO+) cells, with reduced proportions expressing perforin (cytoplasmic cytolytic granules) and TIA-1 (cytolytic granule-associated protein). Natural killer (CD57) cell markers were not detected. The levels of CD8+ cells expressing Bcl-2 (a gene product inhibiting cell apoptosis) in HIV-positive women with relatively high peripheral CD4 lymphocyte cell counts was higher than in HIV-negative women, but these levels fell with declining CD4 lymphocyte counts (< 300 x 10(6)/1). The reduction in CD4/CD8 ratio in the cervix occurred even with relatively high peripheral CD4 counts.

CONCLUSIONS

HIV disease is associated with alterations in the proportions of immunocompetent cells in the cervix. There is an increase in CD8+ T-lymphocytes and evidence of reduced cytolytic capacity; thus, CD8+ cells may lack the ability to respond to viral infection. Reduction in Langerhans' and plasma cells may reflect loss of signals from CD4+ T cells. These findings may, in part, explain why HIV-infected women are susceptible to recurrent fungal and viral infections, even when peripheral immune function is intact. Further studies of immune cell function are urgently required to further elucidate these findings.

Effects of physical activity and age on mitochondrial function

It has been proposed that ageing results from the accumulation of mitochondrial DNA mutations with age which interfere with respiratory chain ATP production. Insufficient ATP production impairs cell function, and tissue dysfunction ensues, leading to morbidity, decline and eventually death. Supporting this theory, mitochondrial DNA mutations accumulate with age and respiratory chain function declines dramatically in human skeletal muscle. However, the extent of decline in respiratory chain function is greater (50%) than anticipated from the low levels of mitochondrial DNA mutations (< 1%) observed in aged muscle. We hypothesized that an age-related reduction in physical activity could be an important factor in this decline and thus studied the influence of chronological age on muscle mitochondria in subjects matched for levels of physical activity. In this carefully selected group, there was little correlation between oxidative metabolism and age. However, several parameters of respiratory chain function did correlate with markers of physical activity (activity score and handgrip strength). Our results suggest that reduced physical activity is a major contribution to the decline in mitochondrial oxidations during ageing. Physical activity ameliorates and may even mask mitochondrial 'ageing' in muscle.

Social and psychological resources in the oldest old

The purpose of this study was to compare mental health resources, activities of daily living, and social and economic resources in three age groups: centenarians, octogenarians, and sexagenarians. Two hundred and seventy-two older adults were assessed with the Older Americans Resources and Services Survey (OARS). Frequency analyses revealed that centanarians rated lower in social and psychological resources than the other two age groups.

Mental health and number of illnesses are predictors of nutritional risk in elderly persons

Data from a sample of elders (N = 240) in their 60s, 80s, and 100s indicated that nutritional risk was positively correlated with age (p < .05), ethnicity (p < .05), number of illnesses (p < .001), and poor mental health (p < .001). Regression analysis suggested that number of illnesses (p = .0001) and mental health (p = .0005) were the most significant predictors of nutritional risk and that these two variables explained 28.8% of the variance for the total sample. Somatic factors of mental health were significantly related to nutritional risk (p = .0001). Regression analyses for these age cohorts indicated that mental health was a highly significant predictor of nutritional risk for 80- to 89-year-olds (p = .004), particularly somatic aspects of mental health (p = .03). Although somatic factors were highly significant among centenarians (p = .005), overall mental health was not a predictor of nutritional risk in centenarians (p = .08). Number of illnesses was the primary predictor of nutritional risk among sexagenarians and octogenarians.

Rod photoreceptor transduction is affected in central retinal vein occlusion associated with iris neovascularization

Patients with central retinal vein occlusion who later develop iris neovascularization show changes in the amplitude, the timing, and the sensitivity of the electroretinogram beta wave. We determined the extent to which rod photoreceptor dysfunction contributes to these changes by recording single-flash electroretinograms from both eyes of 52 patients with unilateral central retinal vein occlusion and fitting the leading edges of alpha waves with a model of rod phototransduction. Eyes with central retinal vein occlusion showed reductions in photoreceptor gain but no changes in photoreceptor amplitude when compared with the fellow eyes. The reductions were larger in eyes that developed iris neovascularization and were predictive of this complication. Photoreceptor gain reductions accounted for only part of the beta-wave timing delays and sensitive loss; the remainder is attributed to functional loss in the inner nuclear layer.

Intraindividual change and interindividual differences in factors influencing older women's health-seeking behavior

Our primary purpose in conducting this study was to examine the factor structure of older women's health-seeking behavior, which we assessed over 100 occasions. This was accomplished with a daily self-report of nutritional, exercise, and adherence behaviors. A secondary purpose was to determine differences in the stability and lability of health-seeking behavior factors. The sample consisted of 4 women in their 60s and 4 women in their 80s. By using P-technique factor analysis, in which the sample size is determined by number of occasions rather than participants, we examined individual factors of health-seeking behavior for variability over time. Both activity and dietary items made up the health-seeking behavior factors of participants who were in their 60s, whereas for participants in their 80s factors comprised only activity items. The stability of most of these health-seeking behaviors indicated that these behaviors may be more trait-like than state-like in these older women.

Normal respiratory chain function in patients with low-tension glaucoma

OBJECTIVE

To test the hypothesis that low-tension glaucoma has a pathogenesis similar to Leber's hereditary optic neuropathy and results from a defect in the mitochondrial respiratory chain.

METHODS

Mitochondrial fractions were prepared from skeletal muscle samples collected from eight subjects with low-tension glaucoma. Their oxidative metabolism was compared with that of age- and sex-matched controls. Skeletal muscle DNA prepared from the subjects with glaucoma was also screened for the 3,460, 11,778, and 14,484 mitochondrial DNA mutations that are associated with Leber's hereditary optic neuropathy.

RESULTS

No subject with low-tension glaucoma had a defect in respiratory chain activity or one of three mitochondrial DNA mutations that are commonly associated with Leber's hereditary optic neuropathy.

CONCLUSION

Although these results do not exclude the possibility that low-tension glaucoma is caused by an organ-specific defect of mitochondrial function, we have excluded a systemic defect of the mitochondrial respiratory chain.