Mucopolysaccharidosis VI in a Siamese/short-haired European cat.

A 3-year-old Siamese/short-haired European cat was referred for clinical disease characterized by dwarfism, facial dysmorphia, paralysis, small and curled ears, corneal clouding and large areas of alopecia. X-ray examination showed multiple bone dysplasia. On the basis of clinical features a form of mucopolysaccharidosis was suspected. The cat, killed at the owner's request, presented several severe skeletal deformities such as long caudal limbs, enlarged thorax with sunken breastbone, vertebral ankylosis in many spinal segments and visceral involvement. Histologically, the cat showed diffuse vacuolization and enlargement of cells in cartilage, bone and visceral organs. Ultrastructurally, membrane-bound vacuoles were filled with fibrillar and fluffy-material or concentrically whorled lamellae. Arylsulphatase B activity was 3.24 nm/mg/h in the affected cat and 30.6 in a normal age-matched control (NC). The L-iduronidase activity was slightly increased. Quantitation of total glycosaminoglycans (GAGs) revealed a 4.5-fold increase in the affected cat as compared with NC, while electrophoretic run of specific GAGs [chondroitin sulphate (CA); hyaluronan (HA); heparan sulphate (HS); dermatan sulphate (DS); keratan sulphate (KS)] performed on a cellulose acetate sheet, showed a striking increase in the DS band. On densitometric analysis of the electrophoretic run stained with Alcian Blue 8GX, the absorption of DS was eight-fold increased as compared with NC. The clinical and morphological features, and the biochemical findings, were consistent with the diagnosis of feline mucopolysaccharidosis VI.

Uremic autonomic neuropathy studied by spectral analysis of heart rate.

BACKGROUND: There is good evidence that power spectral analysis (PSA) of heart rate variability may provide an insight into the understanding of autonomic disorders. METHODS: We investigated 30 chronic uremic patients who were on periodic bicarbonate hemodialysis by a battery of six cardiovascular autonomic tests (beat-to-beat variations during quiet breathing and deep breathing, heart rate responses to the Valsalva maneuver and standing, blood pressure responses to standing and sustained handgrip) and PSA of heart rate variations. RESULTS: Eleven patients (37%) had an abnormal response to only one parasympathetic test. Twelve patients (40%) had a definite parasympathetic damage, as indicated by at least two abnormal heart rate tests, whereas four (13%) had combined parasympathetic and sympathetic damage. Multivariate analysis of the cardiovascular tests revealed that 19 patients (63%) had moderate-to-severe autonomic neuropathy (AN), and 11 patients exhibited normal autonomic function. Among the symptoms suggestive of autonomic dysfunction, only impotence in males was significantly associated with test-proven AN. The PSA of the heart rate variability demonstrated a good discrimination of low-frequency (LF) and high-frequency (HF) bands (LF, 0.03 to 0.15 Hz; HF, 0.15 to 0.33 Hz) among controls, uremic patients without test-proven AN, and uremic patients with test-proven AN. A significant reduction of the LF value on supine uremic patients without AN suggests that an early sympathetic involvement exists that traditional autonomic tests were unable to detect. CONCLUSIONS: Our study indicates that the current opinion of a major parasympathetic damage in chronic uremic patients on hemodialysis has to be modified in favor of a more widespread autonomic dysfunction involving both the sympathetic and parasympathetic pathways.

Uremic autonomic neuropathy: recovery following bicarbonate hemodialysis.

Autonomic function was followed in 8 chronic uremic patients on periodic hemodialysis over a period of almost eight years. The cardiovascular autonomic testing included R-R interval variation test, deep breathing, Valsalva manoeuvre, heart rate and blood pressure responses to standing, sustained handgrip. The patients were investigated on entry into the study and after 18, 56, and 92 months. Six months after the study at time 56 months, they switched from acetate to bicarbonate dialysis. The response to deep breathing test was significantly reduced at time 18 months versus baseline (P = 0.014), but significantly increased at time 92 months versus 56 months (P = 0.042). A significant decrease was found in the systolic blood pressure response to standing between baseline and 18 months (P = 0.014) and in the response to handgrip test between 18 and 56 months (P = 0.014). Multivariate analysis of the autonomic tests by a pattern recognition method (Bayesian analysis) showed that, at the time of entry into the study, two out of eight patients had autonomic damage. At 18 and 56 months, 6/8 patients had autonomic dysfunction. At the last time of investigation, 30 months after the onset of bicarbonate dialysis, all the patients showed a reversal of autonomic damage. Age and duration of dialysis on entry did not affect autonomic function. The present study is the first demonstration that autonomic neuropathy can recover after long-term dialysis. Since chronic hypoxemia is a cause of polyneuropathy, we postulate that: 1) hypoxemia in dialysis patients may have a role in the pathogenesis of uremic polyneuropathy, and particularly of autonomic dysfunction; 2) in patients on bicarbonate dialysis, a greater hemodynamic stability with less hypoxemia may lead to a recovery of autonomic function.