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Biomedical subjects

J F Maher

Publications and source records attributed to J F Maher.

At least 19 recordsLinked to original sources
PubMed1992

Diabetic nephropathy: early detection, prevention and management.

Diabetic nephropathy typically presents more than a decade after diagnosis of diabetes and correlates with the duration of poorly controlled disease. Diabetic nephropathy begins as glomerular hypertension and hyperfiltration, followed by microalbuminuria and the development of hypertension, overt proteinuria, nephrotic syndrome, and a progressive decline in the glomerular filtration rate. Increasing expansion of the glomerular mesangium correlates with loss of function, resulting in uremia. This process eventually leads to the need for dialysis or renal transplantation in 30 percent of patients with insulin-dependent diabetes. By lowering intraglomerular pressure through enhanced glycemic control, inhibition of angiotensin and limitation of protein intake, severe nephropathy may be prevented, delayed or even partially reversed. Treatment must stress control of hypertension.

Albuminuria↗
PubMed1991

The comprehension of nephrology in America a century ago.

In America 100 years ago, the leading clinician pathologists had an understanding of nephrology comparable to that in Europe. Emphasis was on clinical observations devoid of modern clinical laboratory assistance, but verified or disproved at autopsy. The clinician often functioned as the pathologist for his own patients, and although microscopy had been introduced a few decades earlier and many had the benefit of some training in Germany or elsewhere in Europe, diagnostic capabilities remained limited. Renal physiology and pathophysiology were at best embryonic in the United States and elsewhere. The frequency and severity of medical renal diseases maintained the interest of some of the most astute physicians of the late 19th century; however, they had to remain frustrated by their inadequate diagnostic and, especially, therapeutic ability.

History, 19th Century↗
PubMed1991

The origins of American nephrology (1800-1850).

Within a few years of its occurrence, American clinicians became aware of the discovery by Bright in 1827 that albuminuria in edematous patients was associated with granular degeneration of the kidney. Yet, there was a paucity of important original observations in nephrology from American in the first half of the 19th century. By the mid-19th century, however, the primitive concepts of clinical nephrology, renal physiology, and renal pathology were becoming established in the United States, after enlightenment from Europe. Because of the dreadful course of anasarca and uremia and stimulated by the advantages of innovations in microscopy, renal disease began at that time to attract the attention of eminent American clinician-pathologists. Their early observations would add to the knowledge base on which later developments such as bacteriology, radiology, clinical chemistry, and other scientific advances would build.

Albuminuria↗
PubMed1990

Physiology of the peritoneum. Implications for peritoneal dialysis.

Solute and water transport from blood to peritoneal cavity occur by diffusion and osmotic ultrafiltration, whereas absorption to blood via lymphatics negatively affects these two processes. This article delineates the physiology of peritoneal membrane and numerous factors that influence mass transport during peritoneal dialysis, thereby affecting its therapeutic efficacy. Benefits and limitations of continuous ambulatory peritoneal dialysis (CAPD) are discussed and compared to those of hemodialysis. Survival on CAPD, its complications and imperfections are reviewed in light of the widespread acceptance of the procedure.

Absorption↗
PubMed1990

Modifications of endocrine-metabolic abnormalities of uremia by continuous ambulatory peritoneal dialysis.

The endocrine-metabolic disturbances of renal failure have numerous underlying mechanisms. These include abnormal secretion, transport and target cell binding and impaired synthesis or elimination by the diseased kidney. Neither hemodialysis nor CAPD removes large quantities of retained hormones. By correcting certain metabolic, fluid and electrolyte abnormalities, however, dialysis may improve some endocrine disturbances. Other factors such as malnutrition, glucose loading, protein loss, trace metal accumulation and drug ingestion may influence the endocrine-metabolic aspects of renal failure treated by dialysis. Hormonal stimulation and action can be adversely affected by hyperendorphinism due to retained opioids which may be removed by dialysis [88]. Possibly due to the more permeable membrane or because of continuous therapy, peritoneal dialysis seems to have a more salutary effect on hormonal regulation of salt and water balance, of erythrocyte mass and of female reproductive function than hemodialysis does.

Endocrine System Diseases↗
PubMed1990

Endocrine abnormalities in patients treated by continuous ambulatory peritoneal dialysis.

Endocrine-metabolic disturbances of renal failure have many underlying mechanisms, including abnormal secretion, transport, and target cell binding, impaired synthesis and elimination by the diseased kidney, and responses to stimuli resulting from altered homeostasis. Neither hemodialysis nor continuous ambulatory peritoneal dialysis (CAPD) removes large amounts of hormones. By correcting metabolic, fluid and electrolyte disturbances, dialysis may improve some endocrine abnormalities. Possibly because of more permeable membranes, or continuous treatment including ultrafiltration, CAPD has a somewhat more salutary effect on uremic endocrinopathy than hemodialysis. In particular, hormonal regulation of salt and water balance, erythropoietic function, female reproductive function, and some aspects of renal osteodystrophy respond more favorably to CAPD. The endocrine response suggests that there is no inferiority of CAPD as a treatment for renal failure.

Endocrine System Diseases↗
PubMed1989

Phosphatidylcholine does not affect peritoneal transport of intact rabbits.

Ultrafiltration and solute transport during 60-min peritoneal dialyses of normal rabbits with intraperitoneal administration of phosphatidylcholine were compared to control values. The ultrafiltration rate of 0.27 mL/Kg/min did not increase when phosphatidylcholine was added. This agent had no effect on the ultrafiltration coefficient, sodium mass transport or solute clearances. Previously reported beneficial results with this agent could be due to repletion of a deficiency or an effect of the organic solvent. More studies of safety and efficacy of phosphatidylcholine are warranted before widespread clinical use.

Animals↗
PubMed1989

Continuous ambulatory peritoneal dialysis.

During the past decade, continuous ambulatory peritoneal dialysis has emerged as a successful alternative to hemodialysis in the treatment of chronic renal failure. Performed continuously, peritoneal dialysis achieves total transfer comparable to hemodialysis and removes peptides faster. Studies have shown that survival rates for the two techniques are similar. Peritonitis, the major complication of continuous ambulatory peritoneal dialysis, is decreasing in frequency and can usually be managed at home.

Humans↗
PubMed1988

Prolonged intraperitoneal dwell decreases ultrafiltration coefficient in rabbits.

In rabbits undergoing peritoneal dialysis, hypertonic (6% dextrose) dialysis solution increased the net ultrafiltration rate (UF) from 233 to 462 microL/kg/min, which was not proportional to the increment in the osmotic gradient, so the ultrafiltration coefficient decreased. As intraperitoneal dwell of hypertonic dialysate was prolonged, the gross and net UFs and ultrafiltration coefficients decreased, and the UF per dextrose absorption declined. The decrement in UF was multifactorial, including a component of fluid and solute stagnation, increasing the distance over which osmotic forces must exert their effects. Excessively hypertonic dialysis fluid should be used only briefly to achieve ultrafiltration efficiently and to avoid the high dextrose loading.

Absorption↗
PubMed1988

Nephrotic syndrome associated with Kimura's disease.

Kimura's disease consists of lesions that appear as single or multiple red-brown papules or as subcutaneous nodules with a predilection for the head and neck region. Although it principally affects the skin and soft tissues, there is a high prevalence of associated renal disease. We report a case of nephrotic syndrome associated with Kimura's disease. Our patient is distinctive in that his disease first manifested while residing in the Western hemisphere; the renal disease was characterized as mesangial proliferative glomerulonephritis with renal impairment, and his nephrotic syndrome remitted with standard doses of prednisone.

Adolescent↗
PubMed1988

Effects of histamine and its receptor antagonists on peritoneal permeability.

Peritoneal fluid and mass transfer rates were studied in rabbits undergoing control dialyses and dialyses with intraperitoneal histamine, or its receptor antagonists alone or in combination. These drugs had negligible effects on peritoneal ultrafiltration and small solute clearances. Histamine raised protein exudation from 1.6 to 2.9 mg/kg/min, an effect blocked by its antagonists which given alone did not lower protein loss. These data demonstrate the existence of histamine receptors in the peritoneal diffusion barrier and show that they do not control transport under baseline conditions, but can be blocked should abnormal histamine release occur. Increased peritoneal permeability with sterile peritonitis was unaffected by ranitidine, suggesting alternative mediators.

Animals↗
PubMed1988

The role of the capillary wall in restricting diffusion of macromolecules. A study of peritoneal clearance of dextrans.

In 5 nephrectomized rabbits the peritoneal clearance of neutral dextrans from plasma to dialysate decreased from 7.8 to 3.3 microliters/kg/min as molecular mass increased from 17,000 to 43,000 daltons, and was relatively constant at 2.8 microliters/kg/min from 49,000 to 97,000 daltons in accord with prior studies. The clearance from dialysate to plasma was measured by determining the distribution volume, which averaged 72 ml/kg, and the plasma concentration 5 h after intraperitoneal instillation. Inward clearances ranged from 11.4 to 19.9 microliter/kg/min, did not correlate well with solute size and were significantly higher than outward clearances. The data suggest that while the capillary wall is the major barrier to macromolecule transfer, absorption can bypass vascular capillaries and occur via the lymphatics. It is suggested that lymphatic flow rate from the peritoneum exceeds 16 microliter/kg/min.

Animals↗
PubMed1987

Uremic pleuritis.

Pleural abnormalities of uremia have been recognized for many years but have been given little attention despite their high incidence. Mechanisms underlying pleural effusion relate to filtration forces across subpleural capillaries and lymphatic absorption, either of which can be abnormal in patients with renal failure. Uremic patients have increased susceptibility to many causes of pleural exudate. In addition, a specific uremic pleuritis has been characterized as necrotizing fibrinous sterile exudate that is often hemorrhagic. Spontaneous remission, often with recurrences, or constrictive pleural thickening requiring surgical decortication may occur. Neither the pathogenesis nor the appropriate treatment of uremic pleuritis has been established definitively.

Humans↗