Reduced speed of sound in tibial bone of haemodialysed patients: association with serum PTH level

BACKGROUND: In end-stage renal disease, average bone mineral density has been reported to be normal or only modestly reduced, more so in the cortical bone. The purpose of the present study was to explore the potential use of quantitative ultrasound, a method reflecting both quantitative and qualitative properties of bone, in assessing bone status in patients on maintenance haemodialysis. METHODS: We studied 71 patients (age 17-81 years, time on dialysis 0-18 years). The speed of sound waves (tSOS; m/s) propagating along the cortical bone has been determined at the tibial shaft. tSOS results were expressed as Z scores, i.e. units of standard deviations from age- and sex-matched normal mean values, and correlated with relevant clinical and biochemical variables. RESULTS: SOS Z score averaged -2. 0 (range -6.8 to 0.6; P<0.001) and was negative in 93% of the patients. Significant inverse correlations were found between SOS Z score and both time on dialysis (r=-0.52; P<0.0001) and serum PTH (r=-0.39; P=0.0002). Markedly reduced SOS Z score, below -2, was found in 80% of the patients whose PTH levels exceeded 34 pmol/l (five times the upper normal limit), compared with 43% of the patients whose PTH levels were below 34 pmol/l(P=0.04). Compared to patients without bone pain (n=51), subjects with bone pain (n=20) had somewhat lower SOS Z scores -2.5+/-2.0 versus -1.8+/-1.4; P=0. 08), but this could be accounted for by longer time on dialysis. CONCLUSIONS: tSOS is substantially reduced in the majority of haemodialysed patients and is related to time on dialysis and serum PTH level. The clinical value of this novel method needs further exploration.     

Phenotypic analysis of antigen-specific T lymphocytes

Identification and characterization of antigen-specific T lymphocytes during the course of an immune response is tedious and indirect. To address this problem, the peptide-major histocompatability complex (MHC) ligand for a given population of T cells was multimerized to make soluble peptide-MHC tetramers. Tetramers of human lymphocyte antigen A2 that were complexed with two different human immunodeficiency virus (HIV)-derived peptides or with a peptide derived from influenza A matrix protein bound to peptide-specific cytotoxic T cells in vitro and to T cells from the blood of HIV-infected individuals. In general, tetramer binding correlated well with cytotoxicity assays. This approach should be useful in the analysis of T cells specific for infectious agents, tumors, and autoantigens.     

Phytohemagglutinin-induced gut hyperplasia and the growth of a mouse lymphosarcoma tumor

OBJECTIVE: To identify possible causes for the increased cardiovascular morbidity and mortality seen in patients with primary hyperparathyroidism. DESIGN: Prospective, blind study. SETTING: University hospital, Sweden. SUBJECTS: 44 Patients with primary hyperparathyroidism and 23 (sex and age matched) control patients with atoxic nodular goitres. INTERVENTIONS: Exploration of the neck with removal of pathological parathyroid glands or thyroid resection. Echocardiography before, and one year after, the operation. MAIN OUTCOME MEASURES: Blood pressure and echocardiographic findings. RESULTS: Hyperparathyroid patients had higher blood pressure and greater left atrial diameter than control patients preoperatively. They also had a significantly lower E:A ratio (mitral flow velocity pattern) than the controls (p = 0.02) indicating a disturbance in early diastolic filling of the left ventricle. The E:A ratio correlated negatively with the systolic blood pressure. 19 of the hyperparathyroid patients (43%) had cardiac calcifications as did 14 (61%) of the controls. Most of calcifications were located in the aortic and mitral valves; only a few patients had calcifications in the myocardium. No significant changes had occurred one year after parathyroidectomy, except for a reduction in systolic blood pressure, in the hyperparathyroid patients. CONCLUSION: Echocardiographic investigation of patients with primary hyperparathyroidism shows early signs of left ventricular dysfunction that may be of clinical importance.     

Corrosion of implantable materials and aging of bone

This article is a review of how metallic implant corrosion byproducts affect the long-term survival of the dental implant bone bed. Cell structure, bone loss, metal release and corrosion mechanisms are explained in relation to how they influence the metabolic factors that control bone remodeling.     

Endothelium-dependent vasodilatation is impaired in peritoneal dialysis patients

BACKGROUND: Peritoneal dialysis (PD) patients have a high risk of cardiovascular mortality, which is not completely explained by conventional risk factors. Other factors related to chronic renal failure and/or dialysis treatment might lead to endothelial dysfunction, which is associated with an adverse cardiovascular outcome. One such factor is hyperhomocysteinaemia, which has a high prevalence in PD patients. METHODS: A vessel wall movement detector system was used to investigate endothelium-dependent, flow-mediated, and endothelium-independent, glyceryl trinitrate-induced, vasodilatation of the brachial artery in 29 PD patients and 29 control subjects. RESULTS: Endothelium-dependent vasodilatation was markedly reduced in the PD group: 5.7 +/- 1.0% vs 10.4 +/- 1.3% in the control group (P = 0.004). Endothelium-independent vasodilatation was not impaired. Plasma total homocysteine was elevated in the PD patients (45.2 +/- 6.2 micromol/l), but was not related to endothelium-dependent vasodilatation. CONCLUSION: Chronic peritoneal dialysis patients have impaired endothelium-dependent vasodilatation, which may reflect an increased susceptibility for the development of atherosclerosis and thrombosis.     

Low total serum cholesterol and intracerebral hemorrhagic stroke: is the association confined to elderly men? The Kaiser Permanente Medical Care Program

BACKGROUND AND PURPOSE: Epidemiological studies indicate a higher incidence of intracerebral (but not subarachnoid) hemorrhagic stroke among persons with low total serum cholesterol levels. This report further examines the prospective relationship of total serum cholesterol with subsequent intracerebral hemorrhage in a large, well-defined population. METHODS: The cohort included 61756 enrollees in a health plan from the San Francisco-Oakland metropolitan area (46% men, 63% white), aged 40 to 89 years and free of cardiovascular disease at baseline. Sixteen-year incidence of combined nonfatal and fatal intracerebral hemorrhagic stroke (International Classification of Diseases [ICD], 8th revision, code 431, or ICD, 9th revision, codes 431 and 432) was investigated in relation to serum cholesterol measured in multiphasic health checkups made in 1977 through 1985. Intracerebral hemorrhagic events were ascertained using hospital discharge records and as underlying cause of death by the California Mortality Linkage Information System. RESULTS: From 1978 through 1993 (average of 10.7 years), there were 386 events (201 in men, 29% fatal; 185 in women, 42% fatal). By multivariate proportional hazards life-table regression analysis, serum cholesterol level below the sex-specific 10th percentile (< 4.62 mmol/L [178 mg/dL] in men), compared with higher cholesterol level, was associated with a significantly increased risk of intracerebral hemorrhage in men aged 65 years or older (relative risk, 2.7; 95% confidence interval, 1.4 to 5.0). An excess risk was also observed among elderly women at the lowest cholesterol range, but a chance finding could not be ruled out. No relationship was seen among men or women aged 40 to 64, and no statistical interaction of low serum cholesterol with hypertension was found in either sex. CONCLUSIONS: In these data, the association between low serum cholesterol level and intracerebral hemorrhage was confined to elderly men.     

Single-laser approach for fluorescence guidance of excimer laser angioplasty at 308 nm: evaluation in vitro and during coronary angioplasty

BACKGROUND AND OBJECTIVE: Spectroscopic guidance of laser angioplasty has been attempted using a diagnostic He-Cd laser in addition to the therapeutic laser system. This study evaluated a single-laser approach for simultaneous ablation and fluorescence excitation. STUDY DESIGN/MATERIALS AND METHODS: A spectroscopy system was coupled to a clinical XeCl excimer laser. Ablation of 162 human aortic samples in saline and blood with 45 mJ/mm2 per pulse yielded 676 fluorescence spectra validated histologically. The same equipment was used in 16 patients for angioplasty of 18 coronary stenoses applying 500 to 1,725 pulses with 45 to 60 mJ/mm2 under saline flushing. A total of 783 spectra were recorded and validated by intracoronary ultrasound (categories: atheroma, fibrous plaque, calcified lesion). RESULTS: In vitro, 5 types of spectra could be differentiated: (1) atheroma, (2) fibrous plaque, (3) calcified lesion in saline, (4) media, and (5) calcified lesion in blood. Discriminant analysis prospectively classified 576 validation spectra with the following sensitivity and specificity for each type: (1) 83.5 and 97.1%, (2) 85.7 and 96.8% (3) 100 and 98.5%, (4) 98.1 and 99.3%, (5) 98.9 and 100%, respectively. In vivo type 1, 2, 3, and 5 spectra were also observed, but not the media spectrum. The predominant sonographic category also prevailed in spectroscopy. Calcified lesions yielded type 3 and 5 as well as mixed spectra. CONCLUSIONS: Using an excimer laser for angioplasty allows combining ablation and fluorescence excitation without a diagnostic laser. Principal types of atherosclerotic lesions and the media can be differentiated spectroscopically with this approach.