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Biomedical subjects

J S Cameron

Publications and source records attributed to J S Cameron.

At least 55 records · Page 3Linked to original sources
PubMed1996

Nephrotic syndrome in the elderly.

A review is presented of 164 nephrotic patients who were older than 60 years at the onset of their nephrotic syndrome, together with a review of more than 1,000 patients from the literature. The nephrotic syndrome in elderly patients is as common as in younger adults, but is often misdiagnosed as "heart failure" by primary physicians because of its rarity, especially if the jugular venous blood pressure (BP) is increased. Clinical features differ little from those of younger patients, although both an increased jugular venous BP and a presentation in potentially reversible acute renal insufficiency is more common than in the young. Inevitably, both survival and the toll of treatment side effects are higher than in their younger counterparts. Nevertheless, the effects of the nephrotic syndrome itself can be disastrous in debilitated elderly individuals and treatment, where available, should not be withheld on grounds of age alone. Membranous nephropathy is particularly common as a cause of the nephrotic syndrome in the elderly (35%), as well as minimal change disease (16%) and primary amyloidosis (12%), so that renal biopsy is even more necessary in elderly nephrotics, and again should never be withheld on grounds of age alone. It remains controversial whether neoplasias are more common in elderly nephrotics than the control population, and screening need only consist of a chest radiographic and fecal occult blood testing.

Adult↗
PubMed1995

Host defences in continuous ambulatory peritoneal dialysis and the genesis of peritonitis.

Continuous ambulatory peritoneal dialysis (CAPD) has come to be extensively used for the treatment of end-stage renal failure in children, and especially infants, such that now more than half of children on dialysis worldwide receive treatment by this means. Peritonitis, however, is commoner in children than in adults receiving treatment, and is a major source of morbidity and treatment failure in children started on CAPD. Only recently has the immunology of the normal peritoneum been studied extensively, with the need to assess the impact of the installation of large volumes of fluid into the peritoneal sac during dialysis. The main phagocytic defences of the peritoneum depend upon a unique set of macrophages which are present free in the peritoneal fluid but also in the submesothelium and in perivascular collections together with B lymphocytes in the submesothelial area. Both the number of macrophages per unit volume and the concentration of opsonic proteins, such as IgG, complement and fibronectin, are reduced to between only 1% and 5% when dialysis fluid is continuously present in the peritoneal sac. In addition, the fluids used for CAPD are toxic to both macrophages and to mesothelial cells. Thus minor degrees of contamination frequently lead to peritonitis and in addition the majority of patients have catheters inserted in their peritoneum which become colonised with organisms capable of producing exopolysaccharide (slime), which promotes adhesion of the organism to the plastic and protects them against phagocytic attack and the penetration of antibiotics. Thus the peritoneum is in a state of continual inflammation, as well as being a markedly more vulnerable site than the normal peritoneum to the entry of organisms. Whether clinical peritonitis appears in this state of chronic contamination probably depends on perturbation in the balance between host defences and the organism. Whilst Staphylococcus epidermidis is the commonest cause of peritonitis, Staphylococcus aureus and Gram-negative organisms are much more serious and more frequently lead either to temporary catheter removal or discontinuation of dialysis altogether. This review describes the peritoneal defences in relation to the genesis of peritonitis.

Child↗
PubMed1995

Early prediction of treatment outcome in idiopathic membranous nephropathy.

Most patients with idiopathic membranous nephropathy have a benign course, but a minority develop severe persistent nephrotic syndrome or endstage renal failure. The disease appears to have an immunological basis and immunosuppression has been used with some benefit. Unfortunately, treatment can be toxic and not all patients respond. For this reason it would be useful to identify at an early stage those patients who might benefit from treatment. This information could be used to minimize the exposure of patients to unnecessary treatment toxicity. We studied a cohort of 128 patients over a 2-year period. A clear relationship exists between the early response to treatment at one month and the long-term outcome from treatment across a number of treatment types. Those patients who might benefit from treatment and those who are unlikely to benefit, can be clearly distinguished at an early stage.

Adult↗
PubMed1994

Lupus nephritis in childhood and adolescence.

Lupus nephritis in childhood usually presents after the age of 10 years, and presentation under 5 years is very rare. More males (F:M ratio 4.5:1) are affected than in adult-onset cases, but the ratio is the same in prepubertal and pubertal children. The incidence of clinically evident renal disease is greater at onset than in adults (82%), the usual presentation being with proteinuria, 50% having a nephrotic syndrome. Half the children show World Health Organisation class IV nephritis in renal biopsies. Neuropsychiatric lupus is present at onset in 30%, may complicate 50% at some point and remains a major problem. Prognosis has improved greatly over the past 30 years, at least in part the result of immunosuppressive treatment. Treatment of the initial phase may be guided by the severity of the renal biopsy appearances, more aggressive treatment including cytotoxic agents, i.v. methylprednisolone and perhaps plasma exchange, although the value of exchange is not established. Controversy persists as to the most effective cytotoxic treatment in the acute phase, both oral and i.v. cyclophosphamide and azathioprine being used in different units. In the chronic maintenance phase it seems established both clinically and histologically that addition of a cytotoxic agent improves outcome, but again the drug and route of administration are contentious. Azathioprine has the advantage of being safe for pregnancy and not gonadotoxic, whilst i.v. cyclophosphamide has been demonstrated to improve results over prednisolone alone in controlled trials and has advantages in non-compliant patients. No trial comparing the two regimes has been carried out, and one is needed. Today children much less commonly go into renal failure, and the main causes of actual death (15% of patients over 10 years) are now infections and extra-renal manifestations of lupus, principally neurological. Morbidity of the disease and the treatment remain a major problem, especially when treatment exacerbates complications of the disease itself, such as infections, osteonecrosis, thrombosis, vascular disease and possibly neoplasia.

Adolescent↗
PubMed1994

Immunohistochemical studies of the peritoneal membrane and infiltrating cells in normal subjects and in patients on CAPD.

We performed immunohistochemical studies on biopsies of the parietal peritoneal membrane of 33 subjects to investigate whether other cell populations, in addition to mononuclear cells free in the dialysate, might participate in the defense of the peritoneum against microbial invasion during CAPD. Leukocytes were found to concentrate in two areas: a submesothelial layer composed of elongated macrophages displaying activation and maturation markers, and perivascular, less mature macrophages closely associated with T cells and HLA-DR, ICAM-1 and VCAM-1 expressing endothelial cells. Normal mesothelial cells were found to express constitutively the transferrin receptor and the adhesion molecules ICAM-1 and VCAM-1 but not ELAM-1. There were no major differences between normal and uremic subjects, while peritoneal dialysis patients exhibited minor derangements of the submesothelial layer and slight up-regulation of the expression of HLA-DR on endothelial cells. Peritonitis was associated with increased submesothelial cellularity and, particularly, perivascular leukocyte infiltration accompanied by increased expression of HLA-DR and adhesion molecules. Besides mononuclear cells free in the dialysate, this study demonstrates the existence of two additional peritoneal membrane leukocyte populations: submesothelial macrophages, and perivascular macrophages and T cells. It also suggests the existence of a fourth population of intracavitary leukocytes adherent to mesothelial cells. Studies are now necessary to evaluate their exact role in the host defence against peritonitis during CAPD.

Adult↗
PubMed1994

Role of ATP sensitive potassium channels in long term adaptation to metabolic stress.

Cardiac KATP channel activation during metabolic inhibition has been implicated in effects ranging from malignant arrhythmogenesis and sudden cardiac death to reduction in infarct size, preconditioning, and a more rapid recovery of contractile ability. Given these disparate consequences, and the repeated observation that KATP currents are altered under a wide variety of metabolically stressful conditions, it becomes increasingly more critical to determine whether the changes described are part of the underlying pathology, or whether they reflect an endogenous adaptation to protect cardiac function. We support the view that enhanced KATP channels are intrinsically altered during long term metabolic inhibition, at least in part through a reduction in channel sensitivity to ATP, and that the change manifests itself in most cases as an adaptive mechanism. Increased channel activity in a chronically ischaemic environment could serve to maintain resting potential, limit calcium influx, conserve [ATP]i, and prevent excessive prolongation of action potential duration.

Adaptation, Physiological↗
PubMed1994

Recurrent renal disease after renal transplantation.

Recurrent disease does not lead to the loss of large numbers of allografted kidneys, but it is a source of serious concern in recipients with type I hyperoxaluria and focal segmental glomerulosclerosis. In patients with a number of other causes of renal failure, it may affect the use of living related donors. Recent topics for debate include the failure of cyclosporine to modify the incidence of recurrent disease, the realization that IgA nephropathy may in the long term lead to graft destruction, the fact that membranous nephropathy may recur in a quarter of the cases, and the knowledge that a nephrotic syndrome may reappear after transplantation for the Finnish congenital nephrotic syndrome.

Humans↗
PubMed1994

John Bostock MD FRS (1773-1846): physician and chemist in the shadow of a genius.

John Bostock has a reasonable claim to being one of the first chemical pathologists. Most of his work was done before that of William Prout, with whom both he and Bright were in contact. Bostock's work was done about the same time as that of his friends and colleagues Marcet and Wollaston. Although other, notably Cruickshank, Wells and Blackall had previously studied the chemistry of normal and pathological urine, the breadth and detail of Bostock's observations were unprecedented, and he and Wells were the first to relate findings in the urine in disease to findings in the serum. Bostock, however, was the first to realize the relationship between the diminution of urea in urine as it rose (or in his terms, appeared) in the blood, while the albumin in the blood fell as that in the urine increased.

Animals↗
PubMed1994

The history of urinary microscopy to the end of the 19th century.

In the 17th and 18th centuries, several authors performed urinary microscopy occasionally and were often unable to give their observations a practical diagnostic application. Such men included De Peiresc, Boerhaave, Ledermüller and Galeazzi. In the 1st half of the 19th century, however, urinary microscopy began to be used systematically. Rayer and Vigla identified for the first time elements other than crystals in urine and contributed to the methodology of handling samples for microscopy. Becquerel described dysmorphic erythrocytes, and Simon and Henle observed casts in urine and in histological preparations. In contrast, Bird mentioned casts only in passing, though he described many other elements and published the first complete book on urinary microscopy. The 2nd half of the 19th century was characterized by further advances, and in the book of Beale tubular cells were distinguished from other epithelial cells. Different types of casts were also linked with different renal diseases. By 1875 the classification of casts was complete. The work of the 19th century microscopists culminated in Rieder's book on clinical microscopy, which described each element of urinary sediment through 36 beautiful chromolithographic plates.

England↗
PubMed1994

Long-term follow-up after total parathyroidectomy without parathyroid reimplantation in chronic renal failure.

Forty-three patients with secondary or autonomous hyperparathyroidism complicating chronic renal failure (CRF) underwent total parathyroidectomy (PTX) (follow-up 2-18 years, mean 8.7 years). Five were on conservative treatment for CRF, 35 on regular dialysis, and only three had a functioning allograft. At PTX, the most frequent findings were uncontrollable hypercalcaemia, musculo-skeletal pain, radiographic changes in the phalanges, and raised plasma parathyroid hormone (PTH) concentration. Pre-operatively, all patients were loaded with dihydrotachysterol or 1-alpha-OH cholecalciferol. Postoperatively, they were maintained on tapering doses of the same drugs and, briefly, oral calcium supplements. Five glands were identified and removed in two patients, four in 35 patients, three in three patients and only two in one patient. All had changes of hyperplasia and adenoma formation, except for one with a parathyroid carcinoma. Prompt symptomatic and radiographic improvement occurred, with normalization of plasma calcium and alkaline phosphatase. Postoperative PTH levels were available in 33 patients (23 by intact PTH assay): they were persistently high in 10/33 (2/23 intact); normal in seven (6 intact); low in 11 (3 intact), and undetectable in four (3 intact). Thus, PTX was incomplete in the majority of patients. Following transplantation, 3/20 (3/18 intact) patients still had detectable PTH. Only one patient developed symptomatic recurrent parathyroid disease requiring re-operation, and complications were few. Small dosages of vitamin D continue to be required, but not calcium supplementation, and no clinical effects of possible adynamic bone have been noted. At later renal transplantation in 27 patients, an easily treatable, uncomplicated hypocalcaemia was noted in 33%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1993

Low-dose allopurinol plus azathioprine/cyclosporin/prednisolone, a novel immunosuppressive regimen.

Early rejection can still complicate renal transplantation even with cyclosporin. We added low-dose allopurinol (25 mg on alternative days) to "triple" immunosuppression with cyclosporin, prednisolone, and azathioprine for twelve recipients of cadaver renal grafts. The controls were fifteen patients on triple therapy alone. Only one rejection episode occurred among the allopurinol-treated patients, whereas eleven controls had rejections (seven with more than one episode). Allopurinol may be toxic when combined with azathioprine, yet the bone marrow tolerated the new regimen well. As expected, reduction of the azathioprine dose was necessary in the treated group.

Allopurinol↗