Biomedical subjects
Publications and source records attributed to J Rubin.
Femoral arteriovenous fistula is a rare complication of percutaneous transfemoral catheterization. We report the duplex Doppler findings of three such cases. Continuous positive diastolic arterial flow, as well as an abnormal venous flow pattern, was observed in all cases. When present, these Doppler spectral changes support the diagnosis of arteriovenous fistula.
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We describe a 28-year-old woman with nonamyloidotic fibrillary glomerulopathy. She had modest but stable renal insufficiency over a ten-year period, nephrotic-range proteinuria, sarcoidosis, and seven of the 25 signs of Down's syndrome. The rarity of the co-occurrence of these conditions suggests that they are not etiologically linked.
We observed a 38% response rate from platinum-based chemotherapy among 34 patients with locally recurrent or disseminated neoplasms from salivary glands or contiguous structures. Adenocarcinoma was the predominant histology. Eleven patients manifested partial response or regression, and two had complete regressions of soft tissue disease. The most durable visceral responses were partial regressions (lung, 11 months; and central nervous system, 34 months). Eleven of the 13 responders showed tumor regression within 3 months of commencing therapy, and the median response duration was 7 months (range 2-34 months). The median survival among all 34 patients was 15 months, and was 18 months among the 13 responders. Hence, a response to treatment did not necessarily confer any long-term survival advantage. Although gastrointestinal toxicities were troublesome with the earlier regimens, contemporary antiemetics (dexamethasone, metoclopramide) have substantially modified these sequelae. Platinum programs may provide useful palliation for selected patients with these neoplasms, but the impact on survival is negligible.
Twenty patients with malignant hepatoma were treated with sequential intraarterial doxorubicin (72-hour continuous infusion) followed by systemic 5-fluorouracil (5-FU) and semustine (methyl CCNU). Objective tumor responses were seen in three patients (15%). The durations of response were 6, 19, and 27+ months, respectively. Median patient survival was 7 months. A variety of problems were encountered with the use of transcutaneous angiographic catheters for doxorubicin administration, including inability to adequately perfuse the liver, sepsis, and catheter dislodgement during chemotherapy infusion. Although some patients experienced palliation of reasonable duration, we do not believe that the overall results warrant further studies of this regimen.
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Wound infection was studied prospectively in 23 (6.5%) of 354 patients who participated in a series of antibiotic trials during major contaminated head and neck surgical procedures. Polymicrobial infection was identified in 22 (96%) of 23 cases. The most commonly encountered organisms were aerobic bacteria (91%), anaerobes (74%), and fungi (48%). All fungal infections resolved without systemic antifungal therapy. It was, therefore, concluded that the presence of fungus represented colonization. The primary treatment of an infected wound is surgical drainage accompanied by broad-spectrum antibiotic therapy to prevent sepsis. The value of postoperative wound cultures is unclear. The majority of patients who developed wound infection had a variety of organisms that appeared to be unrelated to the prophylactic antibiotic used, as well as to the particular surgery performed.
Malignant external otitis is an infection of the external ear canal, mastoid, and base of the skull caused by Pseudomonas aeruginosa. The condition occurs primarily in elderly patients with diabetes mellitus. Current theories on pathogenesis and anatomic correlations are reviewed. Severe, unrelenting otalgia and persistent otorrhea are the symptomatic hallmarks of the disease, whereas an elevated erythrocyte sedimentation rate is the only distinctive laboratory abnormality. Iatrogenic causes such as administration of broad-spectrum antibiotics and aural irrigation may play a predisposing role in high-risk populations. The disease can result in cranial polyneuropathies (with facial nerve [VII] paralysis being the most common) and death. The mainstay of treatment is administration of antipseudomonal antibiotics for four to eight weeks. Recurrence is common, and mortality remains at about 20 percent despite antibiotic therapy. Given the increasing longevity of diabetic patients, the frequency of this disease is increasing. Internists, family practitioners, and ambulatory care physicians must now be cognizant of the presenting symptoms, while infectious disease specialists and otolaryngologists need to be appraised of strides in diagnosis and therapy. The role of surgery should be minimized. Use of new diagnostic radiologic modalities and new antipseudomonal antibiotics discussed in this review should lead to improved outcome.
Malignant external otitis in the pediatric population is primarily a disease of children with chronic illness or immunosuppression. The presence of severe, unrelenting otalgia, otorrhea with isolation of Pseudomonas aeruginosa, a markedly elevated erythrocyte sedimentation rate, and evidence of bone destruction on computed tomography scan should alert the clinician to the diagnosis. Unlike adults, children have a higher incidence of seventh nerve paralysis earlier in the course of the infection. They also manifest more frequent involvement of the middle ear with tympanic membrane destruction. The short interval between the onset of symptoms and facial nerve dysfunction highlights the necessity of prompt diagnosis and institution of anti-Pseudomonas therapy. Our review suggests that this destructive bacterial infection is an emerging clinical entity in children; 73% of the cases have been reported since 1980. Pediatricians should therefore be familiar with the clinical presentation of this treatable infection. Substantial morbidity could be alleviated by prompt diagnosis and early antibiotic treatment.
The effects of peritonitis on dialysate nitrogen losses were investigated. Eight patients who developed peritonitis while undergoing peritoneal dialysis were compared to seven noninfected dialysis patients. Dialysate protein losses increased during peritonitis, but nitrogen losses into the dialysate did not increase. These findings were caused by reduced urea nitrogen losses in the peritonitis group, which proportionately, more than made up for the increased nitrogen losses from protein. We speculate that the smaller loss of urea nitrogen was due to diminished intake of food. Cephalothin uptake from the peritoneal cavity was unaltered by peritonitis and a dialysate flow rate of 2 L/hour averaged 26 +/- 2 mL/minute and 27 +/- 2 mL/minute in the noninfected and infected groups, respectively.
From August 1983 through August 1986, we used a dipstick culture device for outpatient dialysate cultures among patients undergoing continuous ambulatory peritoneal dialysis. The device was used in 42% of 531 peritonitis episodes. In 21% of the peritonitis episodes, patients elected to be hospitalized for treatment and, therefore, did not obtain a dialysate culture. The frequency of noncompliance was 18%. All samples were received within four days of mailing. Forty percent of isolates were gram-positive organisms, 30% were gram-negative, 3% were fungal organisms, and 27% of the cultures failed to yield a growth. Aside from a greater incidence of failure to define a bacterial growth responsible for peritonitis, the spectrum of organisms was similar to culture results obtained from the patients who elected, during this same period, to be hospitalized. We believe the dipstick device may be used effectively for outpatient dialysate cultures.
Dialysate comes into contact with the active membrane and remains in contact until the fluid is refreshed. This design exaggerates stagnant fluid films. Dialysis rate studies were done to evaluate transport when stagnant fluid films were disrupted. Following anesthesia, 30 mL of commercial 1.5% glucose dialysate containing 100 mg% urea and 25 mg% inulin warmed to 37.5 C were instilled. Dialysate was sampled at 5, 15, 30, 45, and 60 min after instillation. Experimental rats were vibrated at 25 Hz throughout the study. Diffusive mass-transfer coefficients (MTC mL/min 1000 cm2) were calculated, and control and vibrated group means were tested for differences using Student's t-test. The mean MTC values for control (n = 10) and vibrated groups (n = 12), respectively, were: urea 0.8 +/- 0.04, 1.4 +/- 0.2, p less than 0.01; glucose 0.4 +/- 0.03, 0.6 +/- 0.03, p less than 0.01; insulin 0.2 +/- 0.01, 0.2 +/- 0.01, p = NS. Disrupting stagnant fluid films augments peritoneal transport.
The peritoneal dialysis system is composed of unique membranes. To better understand the contribution of these membranes to peritoneal transport, the peritoneal surface areas were measured in human subjects and rats.
We have previously reported a synergistic effect of 1,25-dihydroxyvitamin D [1,25-(OH)2D] and agents that elevate intracellular cAMP to induce the expression of the C5a complement receptor in U937 cells. In this report we examine the mechanism of this synergy, considering the hypothesis that the steroid hormone works by facilitating what is ultimately a cAMP-dependent process. We show that U937 cells cultured with 1,25-(OH)2D alone before culture with prostaglandin (PGE2) alone will express C5a receptor (an average of 55 +/- 4% of the receptors expressed with continuous exposure of cells to both agents; P less than 0.05). The reverse, PGE2 followed by 1,25-(OH)2D, causes very little receptor induction. This demonstrates the ability of 1,25-(OH)2D to induce changes in the state of the cell, such that activation of cAMP-dependent protein kinase has effects that are otherwise not seen, in other words 1,25-(OH)2D can prime the cell for the subsequent action of the cAMP messenger system. Furthermore, we are able to substitute, during the priming period, the protein synthesis inhibitor cycloheximide (CHX) for 1,25-(OH)2D. Cells cultured for 24 h with CHX will express C5a receptor when cultured for a second 2-day period with PGE2 at about 77 +/- 7% of the amount obtained with simultaneous exposure to 1,25-(OH)2D and PGE2. The CHX effect is time dependent and visible after 2 h. CHX is not synergistic with 1,25-(OH)2D. Other agents that can also substitute for 1,25-(OH)2D, but not for cAMP, in facilitating C5a receptor expression include retinoic acid and ionomycin, but with less potency. The 1,25-(OH)2D and PGE2 synergy is sensitive to the presence of isobutylmethylxanthine, implicating its dependence on the maintained elevation of intracellular cAMP levels. The synergy does not appear to be sensitive to changes in extracellular or intracellular calcium. We conclude from these results that 1,25-(OH)2D may promote the expression of C5a receptor in these cells in a fashion similar to that by which CHX potentiates other genes, i.e. that 1,25-(OH)2D increases levels of the mRNA encoding the C5a receptor. The mechanism of cAMP's subsequent and necessary action in the induction of C5a receptor expression is not yet clear.
There are countless three-dimensional interpretations of a set of points moving in a two-dimensional image. A unique visual interpretation of motion thus requires assumptions about the types of structure likely to be found in the three-dimensional world. We propose that the human visual system favors articulated structures in its interpretations. An articulated structure is a rigid body with moving parts that themselves are rigid and rotate in fixed planes with respect to the body. (A bicycle is an example.) We claim that an image consisting of just two moving points is seen as an articulated structure (when their motion is consistent with one), even though countless other interpretations are possible, including a rigid one of a rod moving in space. An experiment is presented in support of our claim, and a well-known display from an old experiment is reinterpreted as a special case of an articulated structure.
This study retrospectively evaluates the survival on renal replacement therapy among patients starting dialysis before their twentieth birthday. The cohort included all patients starting therapy from 1972 through August, 1987 at the University of Mississippi or Kidney Care, Inc. Fifty-five patients, median age 17 years, range 5-19 years, underwent 335 patient years of therapy. Nineteen initially received CAPD; 12 home hemodialysis, 2 were transplanted prior to dialysis, and the remaining 22 patients were entered into dialysis in a free standing facility. Thirty-one patients received a cadaveric transplant and four patients received a living related transplant. The median transplant survival was 1360 days. There were 10 patients on renal replacement therapy over 10 years and a survival plot projected a 70% survival at 10 years. Nine patients died. Three percent of the time on renal replacement therapy was spent hospitalized. Although the hospitalization rate is significant, the pediatric patient may be expected to have a long survival on renal replacement therapy.
There are a number of rather obvious conclusions from these experimental data that have implications in clinical radiotherapy: (1) Survival curves for cells of human origin, in general, have a smaller initial shoulder and exhibit greater sensitivity to ionizing radiation than cells of rodent origin. (2) Nevertheless, the response of human cells to gamma-rays, in a fractionated or low-dose schedule, is dominated by repair. (3) Radiosensitivity, as well as the repair of sublethal damage as evidenced by the dose rate effect, is very similar for a range of normal human cells, including skin and lung fibroblasts, as well as endothelial cells from umbilical cord veins. (4) Human tumor cells are much more variable than normal cells in radiosensitivity, and in the repair of sublethal damage, evident in the dose rate effect. Some show a smaller, and some show a larger dose rate effect than normal cells. (5) Consequently, the use of a large number of fractions, as for example in hyperfractionation regimens, is contraindicated in those tumors that show repair factors larger than for normal tissues; though of course it is a substantial advantage in other cases.