[Clinical examination of renal function in Cockayne syndrome].

Cockayne syndrome (CS) is a rare hereditary disease, characterized by profound postnatal brain and somatic growth failure and by the degeneration of multiple tissues resulting in cachexia, dementia, and premature aging. This syndrome is often associated with renal dysfunction, which usually correlates with the patient's prognosis. In the present study, we evaluated the longitudinal changes in serum creatinine and serum cystatin C levels in three patients with CS to examine whether these markers can help detect renal disorders at the earlier stages. The serum creatinine level in these CS patients gradually exceeded the reference level from 5 to 7 years of age, after correcting for body length. The cystatin C level of the CS patients increased to above the reference level while their estimated glomerular filtration rate remained within stage 2 or 3. Thus, we conclude that the serum creatinine level, following correction by body length, is very useful for the evaluation of renal function in CS. Moreover, the appropriate estimation of renal function facilities the administration of suitable medication, thus avoiding some harmful effects on the kidney.

Serum N-glycan profile shift during human ageing.

Biomarkers indicating biological age are of significant interest for prevention, diagnosis and monitoring (and the treatment) of age-related diseases. We previously reported an alteration of serum N-glycan profile in old humans using "DNA Sequencer Adapted-Fluorophore Assisted Carbohydrate Electrophoresis" (DSA-FACE). To validate the shift in serum N-glycan profile during ageing, we studied serum N-glycan profiles in different age groups of healthy volunteers, patients with dementia, and patients with Cockayne syndrome, a genetic DNA repair disorder involving neurodegeneration and premature ageing. We found that the log of the ratio of two glycans (NGA2F and NA2F), named GlycoAgeTest, remained steady up to the age of 40years and thereafter gradually increased to reach its highest level in nonagenarians. Patients with dementia or Cockayne syndrome had a higher GlycoAgeTest level than age-matched healthy individuals. We thus demonstrate that the value of GlycoAgeTest is better than chronological age for estimating the physiological age of a human individual, and that it could be used as an ageing biomarker for healthy humans. Our data indicate that the GlycoAgeTest could be used as a non-invasive surrogate marker for general health, for forecasting disease progression during ageing, and for monitoring the efficacy of anti-ageing food compounds.

Effects of topoisomerase II inhibition in lymphoblasts from patients with progeroid and "chromosome instability" syndromes.

DNA topoisomerase II is involved in DNA topologic changes through the formation of a cleavable complex. This is stabilized by the antitumor drug VP16, which results in DNA breakage, aberrant recombination, and cell death. In this work, we compare the chromosomal damage induced by VP16 with that induced by bleomycin (BLM) in lymphoblasts from patients affected by the chromosome breakage syndromes ataxia telangiectasia (AT), xeroderma pigmentosum (XP), and Bloom syndrome (BS), and by the progeroid syndromes Werner (WS) and Cockayne (CS). Patients affected by AT, XP, BS, and WS have a greatly enhanced risk of developing cancer. The results show that AF and WS cells are hypersensitive to VP16, as revealed in the higher proportion of metaphases showing exchange figures and more than two breaks. All lines except AT and one CS line showed normal sensitivity to BLM. Our data on the sensitivity to VP16 of all these mutant cells underline the fact that VP16 damage is amplified only in cells that have abnormal illegitimate recombination (i.e., AT and WS).

Serum lipid and lipoprotein levels in premature ageing syndromes: total lipodystrophy and Cockayne syndrome.

Serum lipids and lipoproteins were investigated in two girls who suffered from total lipodystrophy, in their family members, and in two brothers suffering from Cockayne syndrome. Hyperlipoproteinemia type IIb (Fredrickson) was detected in one case with total lipodystrophy. Very low levels of serum high density lipoprotein cholesterol (HDL-Ch) were observed in both of total lipodystrophic cases, in most of their first degree relatives, and in one of patients with Cockayne syndrome. Because total lipodystrophy and the Cockayne syndrome belong to ageing syndromes they can serve as a useful model of premature arteriosclerosis and the defect lipid metabolism.

Use of lymphoblastoid cell lines to evaluate the hypersensitivity to ultraviolet radiation in Cockayne syndrome.

Cockayne syndrome (CS) is a rare autosomal recessive disease characterized by acute sun sensitivity, cachectic dwarfism, and neurologic and skeletal abnormalities. Cultured skin fibroblasts from patients with this disease are known to be hypersensitive to the lethal effects of 254-nm UV radiation. We have studied the sensitivity of 254-nm UV radiation of lymphoblastoid lines derived from 3 typical CS patients, 1 atypical CS patient who had a very late age of onset of clinical manifestations, 2 patients who had both xeroderma pigmentosum (XP) and typical CS, and 3 heterozygous parents of these patients. Post-UV survival was determined by the trypan-blue dye-exclusion method. The lymphoblastoid lines from the 3 typical CS patients, the atypical CS patient, and the 2 patients with both CS and XP had decreased post-UV viability in comparison with lines from normal donors. Lines from the heterozygous parents had normal post-UV viability. The post-UV viability of the typical CS lines was similar to that of a XP complementation group C line. The relative post-UV viability of lymphoblastoid lines from the typical CS patients was similar to the relative post-UV survival of their fibroblast lines. The lymphoblastoid line from the atypical CS patient had a post-UV viability similar to that of the typical CS patients. Thus, the relative hypersensitivity of CS patients' cells in vitro does not reflect the severity or age of onset of the patients' clinical manifestations. The lymphoblastoid lines from the 2 patients who had both CS and XP were significantly more sensitive to the UV radiation than those from patients with only CS. Our studies demonstrate that lymphoblastoid lines from patients with CS are appropriate and useful cell lines for the study of the inherited hypersensitivity to UV radiation.

Decrease of thymic hormone serum level in Cockayne syndrome.

Previous reports concerning children with Cockayne syndrome had described decreased T cell proliferative responses and renal anomalies which could be associated with immunologic disturbances. Herein, the thymic function was evaluated by measuring the serum level of thymic hormone. This serum level was found to be undetectable or decreased in seven cases of Cockayne syndrome. Active serum concentrations varied between 0 and 1/8, whereas normal children of the same age show activity in the range between 1/16 and 1/64. In contrast, T cell function, explored by phytohemagglutinin and Concavalin A responses, and mixed lymphocyte cultures was normal. Whether or not this premature sign of immunological aging is primary or secondary to other manifestations of the syndrome is still difficult to assess.