Calcium mass transfer in peritoneal dialysis patients using 2.5 mEq/l calcium dialysate.

Standard peritoneal dialysate has a relatively high calcium concentration of 3.5 mEq/l. Peritoneal dialysis patients thus gain calcium from the dialysate which contributes to the risk of hypercalcemia. Dialysate with 2.5 mEq/l calcium is now available. Theoretically, using dialysate with this calcium content, calcium transfer should be negative (from the patient into the dialysate) when the patient is hypercalcemic, and positive when the patient is normocalcemic or hypercalcemic. Thus, 2.5 mEq/l calcium dialysate may allow larger doses of calcium carbonate to be prescribed. We compared calcium mass transfer (CMT) in 17 stable peritoneal dialysis patients using 3.5 and 2.5 mEq/l calcium dialysate. A solution of 2.05 l, 1.5 g/dl dextrose was dwelled for 4 hours. Calcium was measured in the drained dialysate and serum (total and ionized). Mean CMT was 0.7 +/- 0.5 mEq/exchange using 3.5 mEq/l calcium dialysate and -0.9 +/- 0.9 mEq/exchange using 2.5 mEq/l calcium dialysate (p less than 0.0001). At the time of the CMT studies, the mean serum ionized calcium levels were identical for the two groups (2.6 mEq/l). CMT correlated inversely with serum total calcium, serum ionized calcium, and drained dialysate volume. During hypercalcemia calcium transfer was from the dialysate to the patient when 3.5 mEq/l calcium dialysate was used, but from the patient to the dialysate when 2.5 mEq/l calcium dialysate was used. We conclude that 2.5 mEq/l calcium dialysate is effective in removing calcium and will be helpful in preventing hypercalcemia when large doses of oral calcium compounds are prescribed as a phosphate binder.     

Preparation and characterization of an antibody specific to the rat dopamine D2 receptor.

Antibodies specific to the dopamine D2 receptor have been raised in rabbits using synthetic peptides. The resulting antiserum was sensitive to picogram quantities of peptide as measured by enzyme-linked immunoassay and was shown to have a 33% cross-reactivity with partially purified D2 receptor protein. No detectable cross-reactivity with similarly prepared fungal membranes was observed. D2 receptor preparations from normal rat pituitary cells were used in Western blot analysis. Bands of M(r) = 95,000 and 34,000 were detected in these preparations with a third faint band at 120,000. These correspond to the pituitary D2 receptor.     

Duplex Doppler ultrasound for the detection of vascular occlusion following liver transplantation in children.

Sixty-three children and adolescent patients who received 78 consecutive orthotopic liver transplants and had serial duplex ultrasound monitoring were retrospectively reviewed for episodes of occlusion of the hepatic artery or portal vein. There were 13 documented episodes of complete occlusion of the main hepatic artery or a major branch, of which nine were diagnosed by the absence of flow during duplex ultrasound examination. Four occlusions were not detected, two affected hepatic artery branches, one an accessory hepatic artery, and one the main hepatic artery. The overall sensitivity of the method was 69% and specificity 100%. Six portal vein occlusions were documented in five patients and all six were successfully diagnosed on ultrasound examination, giving a sensitivity and specificity of 100%. Three of the patients had simultaneous occlusions of both vessels. In the early post-operative period duplex Doppler ultrasound examination has proved an effective non-invasive method for the detection of vascular occlusion, but is not yet sensitive enough to replace angiography fully for the detection of hepatic artery occlusion, particularly when this occurs distal to the main hepatic artery.     

Recent Advances in Elucidating Niemann-Pick C Disease

Lysosomal sequestration of endocytosed LDL-derived cholesterol, premature and abnormal enrichment of cholesterol in trans Golgi cisternae and accompanying anomalies in intracellular sterol trafficking are the hallmark phenotypic features of the Niemann-Pick C (NPC) lesion. A variable severity of these alterations has been observed, with only partial correlation between clinical and biochemical phenotypes. NPC also affects the metabolism of sphingolipids, and other biochemical abnormalities have been reported. Occurrence of neurofibrillary tangles in the brain of patients with a slowly progressive course is a recent intriguing observation. Genetic heterogeneity was established by cell hybridization and linkage studies. The two complementation groups could not be distinguished from each other by clinical, cellular or biochemical criteria, suggesting that the two gene products may interact or function sequentially. The major (> 90% of patients) NPC1 gene was mapped to 18q11 and recently isolated by positional cloning. The cDNA sequence predicts a 1278-amino acid protein, with 13 to 16 possible transmembrane regions and a putative cholesterol-sensing domain. Two murine models of the disease involving the same gene are known. The murine cDNA and the npc^nih mutation have been characterized. Described homologies of the NPC1 protein are in line with its putative involvement in cellular cholesterol traffic.     

Effect of perioperative blood transfusion on recurrence of colorectal cancer

The aim of the present study was to examine the outcome of 517 patients undergoing curative surgery for colonic and rectal cancer, and to compare the recurrence and mortality rates in transfused and non-transfused groups of patients. The two groups were evenly matched for age, sex, Dukes' stage and histological differentiation. There were significantly more rectal tumours in the transfused group (P less than 0.01), but the distribution of colonic lesions did not differ. Life table analysis revealed that the transfused patients had a 20 per cent greater probability of recurrence at 5 years (P less than 0.005) and there were 16 per cent more cancer related deaths (P less than 0.01). Even when all rectal cancers were excluded, a similar trend was seen for the colonic lesions: a 24 per cent greater probability of recurrence at 5 years (P less than 0.025) and 15 per cent more cancer related deaths (P less than 0.02). We conclude that blood transfusion may be associated with increased mortality and recurrence in patients undergoing curative surgery for colorectal cancer.     

The localization of CD44 and moesin in osteoclasts after calcitonin administration in mouse tibiae

We investigated the immunohistochemical localization of CD44, hyaluronate receptor, and moesin, of the ezrinradixin-moesin (ERM) family, in osteoclasts after calcitonin adminstration using confocal laser scanning microscopy and transmission electron microscopy to clarify the role of CD44 and moesin in their cytoskeletal organization and cell polarity. We also elucidated the localization of osteopontin (OPN) to confirm its possible role in cell-matrix recognition via CD44. In untreated mice, intense immunoreactivities for CD44 and moesin were detected on the basolateral plasma membrane of osteoclasts. Rhodamine-phalloidin reactivity was seen in a bandlike pattern on the region of contact between osteoclasts and bone and was also detected moderately along their basolateral plasma membrane. At 30 min after calcitonin administration, osteoclasts did not show either clear zones or ruffled borders. The bandlike reactivity of rhodamine-phalloidin in the contact region was diminished, although labeling was seen along osteoclasts. CD44 and moesin were colocalized along their plasma membranes, including the region facing the bone surface. Electron microscopic observation revealed that the microvillus processes in the contacting region with bone surface, as well as the basolateral plasma membrane, showed immunoreactivities to CD44 and moesin. At 60 min, some osteoclasts attached to bone and showed a bandlike pattern of rhodamine-phalloidin. On the other hand, OPN was localized under CD44-positive cytoplasmic processes and the clear zone of osteoclasts. These findings suggest that calcitonin effects on the cell polarity of osteoclasts and the CD44-moesin-actin filament system in osteoclasts plays an imporant role in cell polarity and cell-matrix recognition.     

Mandatory HIV Testing for Healthcare Workers: Is it Ethical?

The AIDS epidemic has caused hysteria among the public and concern to many healthcare workers in the past 12 years. Currently, legislation exists for mandatory AIDS testing in some populations. The questions remain: Should healthcare workers be routinely tested? If so, is mandatory testing ethical? The author explores the incidence and prevalence of AIDS among healthcare workers, discusses why mandatory testing for healthcare workers is an issue, and examines the legal and ethical principles involved in mandatory testing.     

The Impact of Family Relations on Caregivers' Positive and Negative Appraisal of Their Caretaking Activities

This study examined the impact of family support and relationship difficulties between the caregiver and the care recipient on caregivers' satisfaction received from caregiving activities and subjective burden. Ninety‐seven individuals caring for a spouse or an adult child with schizophrenia or bipolar disorder participated in the study. Using hierarchical multiple regression analyses, findings showed that relationship difficulties between the caregiver and the care recipient were associated with both satisfaction received from caregiving activities and subjective burden, after the effects of personal, contextual, and stressor variables were controlled. Family support was not associated with caregivers' appraisal of the situation.