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Biomedical subjects

J F Maher

Publications and source records attributed to J F Maher.

At least 37 records · Page 2Linked to original sources

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

[Does CAPD have a future?].

Five decades were between the first clinical use of the peritoneal dialysis and the introduction of the continuous ambulant peritoneal dialysis (CAPD)-five decades with many problems and little acceptance of this technique by patients and physicians. Greater week clearances in the CAPD led to a significant increase of the effectiveness in comparison to intermittent therapeutic forms, so that the popularity of this method of treatment rapidly increased. A simple technical handling and the patient's independence of the machine essentially contribute to the popularity of the CAPD. Significant results in the combat against peritonitis, the main problem of the CAPD, made the CAPD a recognized method of treatment for the terminal renal insufficiency. Should not unforeseeable innovations decisively improve the technique of haemodialysis, the CAPD will maintain its position beside the haemodialysis also in the following decade.

Forecasting↗

Trench nephritis: a retrospective perception.

An epidemic of nephritis occurred among soldiers in World War I, predominantly those in the trenches. Characterized by the sudden onset of albuminuria, hypertension, edema, and dyspnea, atypical features such as bronchitis, an evanescent course, low early mortality, and frequent relapses distinguished it from poststreptococcal glomerulonephritis. Pathologic features included glomerular ischemia, capillary thrombi, endocapillary proliferation, and frequently epithelial crescents, suggesting an underlying vasculitis. The cause was not established, but a postinfectious, possibly postviral, etiology seems most plausible. Trench nephritis was the major nephrologic problem of World War I, accounting for 5% of medical admissions and more than 10% of military hospital bed occupancy at that time.

Acute Disease↗